Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Jeb Jeb on July 15, 2015, 04:55:26 AM
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Hi Guys,
Just beginning the build process so thought I would start a thread rather than opening a new one every time I have a question as I've already asked a few about painting and finishing the case and transformer bell. Unfortunately for you guys I'm the kind of person that asks a lot of questions..... :)
While everything was sticking and drying, before commencing the main build I thought I should probably practice some soldering. I've never soldered anything before. I got a new soldering station - a Hakko FX-888D (which seems very nice) and also picked up a few very cheap components with terminals and some wire to practice some joints. I'm using Cardas Quad solder and the recommended small chisel tip. Temp set to 350 degrees celsius. I'm heating the terminal and the wire as evenly as possible for around 5 or 6 seconds or so before feeding in the solder.
I thought I would use single stranded wire of similar gauge to practice on but all they had was copper wire. My results trying to solder this to the terminals was very poor. Could not get the solder to stick to wire at all, in fact it seemed to repel it and just run off and go anywhere but on the wire. I was really starting to doubt my ability at this point.
Just to experiment I got some other wire I had in the house which was some stranded wire, but silver, and tried that, and it worked like a charm first time and it was easy to load on as much or as little solder as I wanted. Joint seemed nice and secure and shiny.
Was I doing anything wrong or is it just that its a different type of wire?
Pic attached below - showing the difference, with the successful silver stranded wire joint in the middle.
In other news, the new solder-sucker has been performing admirably and has already seen plenty of action.
Jeb.
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The copper wire looks to be the type used for coils or transformers. As such it has an insulating coating. This is resistant to solder, hence your problem. As a test you can scrape or abrade off some of the coating and then see if it will take solder.
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Deluk - THANKS!
I did as you suggested and was able to scrape some of it off and it was much improved. Ugh. Rookie mistake! The only way is up now.
Thanks again,
Jeb.
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That enamel coating is a pain to work with, you can either scrape it off, or burn it off. Sometimes you can just dip the end of the wire into a hot molten pool of solder and it will burn the coating off.
Also the wire and terminals you are soldering onto will absorb a lot of heat so try bumping the temperature up to 400c. Profile 4 assuming your soldering iron is setup with default values ;)
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awesome thanks for the tip - is 400 recommended for when doing the crack soldering or do you mean just for the practice terminals/wire?
Is there such a thing as over-heating terminals/solder or as long as you're not melting anything (except the solder) is it all good ?
Jeb.
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It really depends on what you are soldering. If your trying to join thick solid wire to a large metal tab you have more material to soak up the heat so it will take much longer to get the two parts hot enough for a good solder connection. Its best to get in/out quickly with an iron that is hot enough to do the job. If you find you have to wait for a few seconds for things to heat up enough to flow the solder, your iron isn't hot enough.
On the flip side, small delicate components like LED's and transistors can be damaged with too much heat. i.e. the little LED's on the speedball boards, you want to add heat, solder, then remove in about the same time it took to read that.
One exception being the center pin of the large TIP50 transistors, those are attached to the metal heatsinks and will require a larger dose of heat to get a proper connection. Personally i would go to 400c to solder those.
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I don't know if you are doing so but melting a little solder onto the tip of the iron before you put the solder iron tip on the item to be soldered helps by speeding up the transfer of heat to the terminal/wire much quicker.
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Great info thank you! In general so far yes I think the solder does take a bit longer than I would like to flow - definitely in comparison to the innerfidelity video I watched where he was in and out with the iron pretty quickly. I'll try 400 next time, except for the delicate parts, as you say. I can also work on trying to have more surface area of the tip in contact with the joint.
and Jamie, thanks - that's a great little tip to add a bit of solder to the tip to speed of heat transfer, I remember seeing Tyll do that too - i'll remember to give it a go.
It feels good to have done some soldering practice - I was a bit nervous about it before and now feel more confident about cracking on with the build.
Jeb.
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Hi!
Watch these training videos from PACE. Old school, real craftsman stuff.
Great explanations and quick to watch: https://www.youtube.com/playlist?list=PL926EC0F1F93C1837
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That was very cool & much appreciated - I just watched lesson 1 as well as the Bifurcated and hook terminal lessons. As you say, very old-school and some great information to help understand exactly what I am doing and why. The dude was pretty emphatic about ideally keeping the solder time to around 2 seconds.
The whole thing was made more epic because the intro to video 1 is somehow reminiscent of the A-Team. At least to me. I'm a child of the 80s.
Jeb.
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I generally solder with the temperature all the way up. The only places where you have to be careful is on the RCA jacks and power switch. It can help on the RCA jacks to quickly flow a little solder into the center cup, let it cool, then reheat that solder after 20 seconds and quickly insert the wire to form the connection.
On the power switch, it helps to have a good balance of the tip touching both the switch terminal and the wire. Properly soldering a switch lug with a soldering station like the FX88 (good choice) will take just a couple of seconds per lug.
-PB
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Those Pace videos are awesome. We have actually been working on a very introductory video, focused on the actual t-strips and PC boards we use. I think we will simply link the Pace videos for more detailed explanations of solder types, how flux works, etc.
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Hi guys - thanks for those words of advice.
Unfortunately the thread on one of the locknuts for one of the RCA jacks seems to be shot (it more or less just wiggles its way down over the thread on the RCA jack) so I'm unable to tighten it securely.
I don't have a spare that fits here - since i'm here in the UK I'm fine to just go and grab a new one from a local hardware store but I presume it's imperial sizes right ? so might need to order one online - what size is it and if I can only get a normal thickness nut is that okay to use?
will just crack on securing all the other components in the mean-time.
Cheers!
Jeb.
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. . . Unfortunately the thread on one of the locknuts for one of the RCA jacks seems to be shot (it more or less just wiggles its way down over the thread on the RCA jack) so I'm unable to tighten it securely. . . .
Is the thread stripped or does it not have enough room to tighten down? My first read made me think that the isolating washers were misaligned and you couldn't get enough threads to tighten it. If the threads are stripped be certain it is the nut not the jack itself.
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Thanks Grainger - very quick!
The other non-stripped nut seems to fit both of the jacks okay. So I think it's just that one stripped nut.
the threads on the RCA jacks are indeed subtly different since the stripped nut passes more or less right over the thread on one of them but still has a little bit of grip on the other jack but not enough to be secure.
But since the good nut seems to fit both okay, I think a new nut will still do the trick, but i'm not sure I can get one locally if its imperial sizes.
Or I can just grab one of these locally if its easier to replace the whole thing and this is a like for like replacement http://www.maplin.co.uk/p/maplin-gold-teflon-insulated-chassis-phono-socket-black-jz05f (http://www.maplin.co.uk/p/maplin-gold-teflon-insulated-chassis-phono-socket-black-jz05f)
One other thing I need to check before I go any further is when fitting the transformer I noticed that it had some excess varnish/glue around the sides. I didn't feel like removing them completely but just to tidy up I very gently sanded them flat. Having read a couple of threads now I'm wondering if that was a bad thing I did - I didn't go crazy with the sanding, just enough to flatten the varnish runs but there were places where the sanding also touched the stacks. I'm not worried about applying any kind of paint finish if I don't need to. Pic attached.
Thanks for patience with all the questions. New HD650s arriving later today :)
Jeb.
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We did switch earlier this year to a different RCA jack because of some weirdness to the threads in the jacks we were using. Assuming you have these jacks, you can replace them with any insulated RCA jack that fits a 3/8" hole.
The new jacks that we use require the hole to be enlarged just slightly.
-PB
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Thanks Paul,
I bought a cheap replacement jack - I don't like it as much as the kit supplied one - but the nut is much better and it fits the original jack perfectly. So I'm all good
any comments on the pic of the transformer I posted before and the light sanding I gave it ? do I need to paint it eventually?
Cheers!
Jeb.
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If You have scrubbed down the transformer bell and sanded the coating, You should definitely paint with something that withstands heat. Preferably before soldering for easier access.
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Hi there Strikkflypilot,
I have cleaned and sanded the bell & that has been protected with a couple of coats of clear-coat, it was the sides of the transformer itself I was wondering about, since I rubbed them just slightly to remove the slightly unsightly runs of varnish or glue or whatever it is holding everything together. I think I could quite easily do that with it in situ if need be at some point - but I won't unless anyone thinks its necessary, because in terms of how it looks it seems fine.
Cheers!
Jeb.
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The initial "smoke test" will tell. Seriously, looking at your picture you should be just fine. It looks like you were careful not to disturb the laminations that were not drooled on.
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Thanks Grainger - you've been really helpful!
Remind me to buy you a drink or two next time you're in Bristol, UK.
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You are most welcome. Now I have to find Bristol. An older Bottlehead, Gaspode, lives in Windsor. I found that, once.
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Just make your way up the little channel to the south of Wales. Keep sailing until you hit Bristol. You cant miss it.
If you end up in Paris you've taken a wrong turn.
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it was the sides of the transformer itself I was wondering about, since I rubbed them just slightly to remove the slightly unsightly runs of varnish or glue or whatever it is holding everything together.
We don't generally recommend messing with the lamination stack on the transformer, as that goop is indeed what holds it together. As long as there is no exposed metal, you can leave it as-is. If there is exposed metal, you would want to apply more varnish.
-PB
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Paul - thanks - damn on one side I can see a bit of exposed metal - only just, but some and can no longer see that shiny varnish surface. I guess I would rather be safe now than sorry and run into problems later.
Do you mean just any general purpose varnish? And would some black metal paint also do the same job?
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PJ might have specific recommendations, but I'd just buy the smallest container of varnish that you can find at the hardware store, then brush it on with a small brush.
-PB
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Nice one - will do. Much appreciated. Have a great weekend!
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Cosmetically, any exposed iron will eventually rust. Technically, as long as there is no short between adjacent laminations it's good.
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Cool -thanks again! since there was some metal exposed I put a thin layer of varnish around the stacks to prevent rust. When I came back later I could see lots of tiny brownish patches (pic) - I hope that it's just bits of the old brownish varnish, rather than rust spots that formed with the addition of the varnish, if that's possible?. In any case there's not too much I can do about it now. The lesson - don't mess with the transformer stacks! You guys said that. ;)
I've begun the main build - and really enjoying it - about half-way through now. So far so good .... I think!! Proof will be in the pudding as they say.
on a couple of the first solder joints I made (on the IEC module and the transformer terminals) the insulation of the wire was touching the terminal so melted a little bit - apart from that the joint looks good and shiny and secure. I've improved a lot with subsequent joints, always leaving a mm or two of bare wire but should I re-do those first ones or does it not matter if the insulation was touching?. I've tried to take a pic of the first one I did.
Cheers!
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Hey...I don't think your lightly sanding down the outsides of the transformer will hurt anything....all the best on your build! I would lightly varnish them as well as the rest of the experts stated....
Alex
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Hey thanks Alex - Appreciate that and the encouragement!
would appreciate a bit of advice on soldering - on the transformer terminals, is the idea that the entirety of the hole and the terminal be covered in solder to create one solid block? or just enough to firmly secure the wire to the terminal?
I thread the wire through the hole and crimp tightly around the top or side to create a good tight connection. When I apply the solder it sticks to the terminal and to the wire but still leaves most of the hole empty - is this still okay? It seems secure, but in the manual pics it looks like the hole should be full of solder too.
Have attached a pic of a couple of joints. Would appreciate any pointers!
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Hey Jeb....
You dont have to fill the entire hole with solder. The main thing is to make a good electrical joint with the solder being the electrical "glue".
Attach and crimp the wire to the terminal hole and heat the joint well and let the solder flow around the crimped with and terminal so they get
"Glued" together well, a nice shiney joint. When its cooled down you should be able to see a nice shiny joint with a little flux on it from the soldering process.
Dont worry about the flux or resin stuff left over on the joint....some like to take a q-tip or small bristle brush and clean with alcohol but this also can make a mess!!
One thing when I built my crack (and I have built many, many amps and circuuts in 35+ yrs!!) is to follow the instructions very carefully..being an old timer I can solder this stuff from the schematic but the items used in this kit have some small important things like upper and lower holes etc....and the crack designers have utilized these mechanical things to the utmost...to make it easier for a DIY first timer to be successful...(wire layout to help minimize noise, hum etc...).
The point I am trying to make is if you did fill in an entire teminal hole and had to later wire something to it, you have no hole!! So solder when they indicate and not before!
Enjoy you kit building experience its really neat when you turn it on for the first time and hear wonderful music!!
Post any questions here and many folks will help you!
Alex
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Hey Alex - thanks so much for those wise words! so helpful!!
One things i've find on a number of joints is that I had the wire's insulation slightly too close to the joint and it melted a little bit as the solder flowed - not so much that it is *inside* the joint or mixed in the solder but some is now touching the joint - I'm not sure if this causes any problems, besides being a bit unsightly? the insulation won't melt anymore when powered up because it's touching the terminal will it - do the terminals get any hotter than the wire itself?
This is my first DIY audio (as you probably guessed) and i'm enjoying it - but I would say it is challenging me quite a bit! Partly because I am a safety freak so am double checking, triple checking! But I am determined to get there in the end :) just finished p.26 - going to call it a day for today. Hopefully make it through to the end of wiring, tomorrow.
Cheers,
Jeb.
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Alex's tips are excellent, but I do have to pick one small bone regarding terminology. One of the tenets of mil-spec soldering classes is that "solder is not glue". It is used to cover the joint and maintain the integrity of the electrical contact surfaces against corrosion. For optimal reliability the connection should be mechanically sound before it is soldered so that the wire does not move as the solder cools and solidifies. In the days of point to point wiring the test to pass was wiring up a circuit and demonstrating its reliable operation without any solder applied to the joints.
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Some light reading on the subject http://www.electromet.com/documents/milstd2000a.pdf (http://www.electromet.com/documents/milstd2000a.pdf)
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Cool, thanks Doc. I want my build to be mil-spec!
As per yours and Alex advice - I'm trying to make sure all my joints are crimped and sound with good contact and no movement prior to soldering. That's actually what's taking me the most time and fiddling.
Any thoughts on the point above about wire insulation just touching the joint - is it a technical no-no or just slightly unsightly?
Got the LEDs on the tube socket in place earlier - prob the fiddliest bit so far. Can't wait to stick the bottlehead badge on the front when it's all tested and working. Saving that till last. Must be earned!
Best wishes from this side of the Atlantic.
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Hey Doc.... agree on the Glue part I use that as an analogy.... to many soldering is one of those mysteries in life!! LOL....I call solder my special electrical "glue" that transforms before your eyes under high heat..that's why I used the "" for "glue:......:>)
Soldering when done right promotes a good electrical and mechanical bond.... crimping a wire or lead so it doesn't move while soldering is very important to getting a good joint!!
I used to work on fuel gauges for jet aircraft and did lots of DARPA inspections for the US AirForce planes and they were sticklers for good solder joints, wire braiding etc...
Happy Soldering everyone!
Alex
Oooops almost forgot... the insulation on the wires touching a joint should not be an issue, but may get in your way when trying to solder. I would try to remove the amount of insulation DocB has stated in the instructions it should be enough to connect and solder with the insulation being just abit away etc....I found more often than not that the length of the wires to be cut were always long enough if not a bit too long for some.
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You might try stripping the wire a little more, say 3mm, than you have been. That way you have enough bare wire to get a good mechanical crimp and don't sniff burned insulation when you solder.
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Agree the smell of burning teflon or other insulation is NOT a good thing.....
Alex
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Not only that, but when the joint has been made, it is also possible to push the insulation back towards the joint over the core if that is what You want, since the wires are so short.
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Thanks guys - you're right - for my own crimping style I just need another few mm stripped back. As you say, prob another 2 or 3mm on the standard 6mm that most of them are.
I see why some people do multiple builds - you learn a lot along the way!
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Just had an hour or so to spare so just got the UF4007 rectifiers installed. I think this was the trickiest bit so far for me - quite fiddly with quite a lot going on in each hole and a challenge for me to get a good contact with the soldering tip without doing any damage.
If anyone has a minute just to take a look at the pics of my work below I'd appreciate any feedback in case there's anything about the joints that leaps out as being poor before the caps go in tomorrow and anything gets covered up. I probably put a little bit too much solder on 18U and got a little bit between the rectifier leads just as they enter the terminal hole. I'm guessing this isn't a problem since they're joined at the terminal anyway?
Cheers! thanks for your help & encouragement!
Jeb
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Hey...looking good....you might want to trim off any excess leads. like it mentions on page 27 of the manual. "trim excess leads" It might be hard to get at if your cutters are big etc...they dont look that long or excessive and I don't think they will touch anything. The only wires near will be the RCA inputs three wire braided ones see on page 36.
If u can clip them off great, and when u do clip off excess leads make sure these small pieces are removed and dont go flying somewhere in the amp!! They could short something out later etc..
Keep up the Great Work...oh the diodes to me look like they are installed in the right direction as well.
Alex
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Cheers Alex - once again !!
I have some pretty small nippers & I'll clip back the excess leads a liitle more during tomorrow's session.
Is the little blob of solder between the rectifier leads just as they enter the terminal 18L at the bottom an issue? There was a bigger blob there originally but I managed to suck up most of it - they're joined at the terminal so it doesn't make any difference right? It just means the joint is a bit longer - correct?
Jeb
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Yeah, those leads look to be trimmed pretty short already. I'd say you're good to go forward.
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Yes pretty much your ok...I would try to keep leads separate as best possible. Leads that touch well before the solder joint sometimes could cause issues in a high current application. Your work here looks ok to me.
Its just good practice to me to keep things separate and neat.
Alex
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Noted! Alex and Doc, cheers!
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Hi guys!
after every session I come in and say "well that was the trickiest bit so far" It was today. Manual must be a good learning-curve then!
getting those caps in position with everything else going on took me a fair bit of time and jiggling.
Couple of questions:
1) I wanted to check do the caps get hot? I noticed they say 85 degrees C on the side? so is it bad if they are just touching any wire insulation for example where the wire from the headphone jack enters 12L underneath one of the caps?
2) is it normal that I couldn't get the last 220UF capacitor pushed all the way so it was snug against the terminal strip (the other cap was in the way). The lugs went through to the other-side by 2 or 3mm, which seemed about the right amount so as not to get in the way of the resistor. It seemed to match the picture in the manual .
I posted a couple of pics for inspection.
I'm sure I'll get it finished tomorrow - I must be close - all i've got left on the parts table is 2 small caps, a few more resistors and some rubber feet. And the badge of course!
Thanks again,
Jeb.
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I don't think this is an issue, your joints look nice and shiney!!
I dont know if these caps get warm at all....I never checked, but they are out in the air so to speak and shoulddisappate any heat fairly well.
The insulation slightly touching is ok, if it were rubbing up against on the tabs on the cap itself I would concerned a small amount and might re-wire or position...but yours is ok to me!
Your almost home!!
Alex
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Thanks Alex! Yes I reflowed a number of joints today as there were some dull ones.
Almost home. The caps were tricky - on the ones on the tops of the terminal strips I bent the lugs to 90 degrees as per the manual, then when they were through the terminal hole I crimped them round the terminal to lock them in place so they were secure even without solder - not sure if that was the right thing, but it held them properly while I soldered.
Afterwards I realised I'd probably regret that if I ever want to remove them & upgrade as everything is extremely tight and locked in the hole now and would be pretty tricky to remove!
Cheers,
Jeb.
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The 85 degree C rating is because of the transformer and tubes. They get hot and PB doesn't want the capacitors to fail.
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To clarifiy a little, the caps themselves do not get hot. the 85c refers to how hot a place you can put them...John
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Ahh cool - understood! Thanks Grainger & John.
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Jeb...so far so good!!
I didn't bend my cap leads, just made sure they didn't move while soldering in.....great take your time and be careful measuring the
resistances and voltages....
I am listening to mine right now and its pure heaven...Eva Cassidy Live!
Alex
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Yes - I will be super-careful with the resistances and voltages. I have to just wait a couple of days for new multimeter leads I ordered to arrive that have optional clips so I can clip one on to ground.
Today I made a bit of an error when soldering and managed to slightly melt some of the insulation on one of the wires that leads to the octal socket. I'm not sure what the rules are here and whether its deemed acceptable to leave it as it is as I did not melt through to bare wire and it is still sealed, but have obviously thinned the insulation slightly at that point. Since I'm fussy I would normally just replace it but the other end is right in a tricky spot - not impossible, but thought I'd check first. I'm kicking myself because it was probably the easiest joint to get to of all the ones I did today!
Jeb.
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If you don't see bare wire the "insult" to the insulation is minimal. Don't worry with it. I have seen worse on operating kits. Shoot! I have done worse.
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awesome Grainger thanks - just what I wanted to hear! In terms of aesthetics - it looks like the smaller caps might cover it once fitted!
Jeb.
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That slightly melted cable doesn't look too bad.
You have a good build going.
Like You say yourself, trying to improve one thing might make other end worse.
that said, I rewired my Crack twice, the second time with cotton clad wire. :) sure won't hear the difference:)
Enjoy Yourself, that's the most important bit.
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Great advice & thank you. I am very much enjoying it and finding that a couple of hours per day is optimal for me for enjoyment otherwise small mistakes/frustration can creep in. Perhaps stamina comes with practice. I'm sure the guys over at Bottlehead HQ have had some epic soldering sessions.
The cotton clad wire sounds very cool - I can totally see why you and others would re-wire and do multiple builds - there's something really beautiful about perfect looking point to point wiring. I've seen pictures where people made all the wires perfectly straight with 90 degree turns - that looks very cool too.
I definitely have massive respect for people who do this for a living - it's an art!
Jeb.
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Jeb, it will be fine....I know how you feel, I would probably replace it but at this point you might cause other issues....Its still insulated, albeit not as well in that one spot as the rest of the wire, but nothing is close to it or will rub on it....we all have done this to some degree!!
I have even used some electrical tape as a bandage when I thought it was really necessary. Ha!!
I cant wait to hear your first impressions!!
Ale
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Indeed! Actually a little bit of tape isn't a bad idea - for my peace of mind - i'll see how close the last wires and caps get to it - but as you guys say, i'm sure it'll be fine :)
Yes, looking forward to firing her up after testing in the next couple of days. Everything is going to sound quite new to me at this point because I only just got the HD650s and don't know them very well yet. Still first things first, finish the job at hand!
Thanks again all for your help, it's making the whole process very enjoyable, educational and reassuring! :)
Jeb.
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One thing I could recommend before you start the resistances checks, is to practices with your meter a bit. set it to ohm's and connect the leeds together and see what the reading is, it probably won't be 0 but an ohm or two. This is the resistances of the leeds. People tend to stress out if they don't see 0 when called out in the manual. Also if you have any resistors measure them. Check a battery or two for DC and if it convenient check your AC wall voltage.
A little familiarity goes a long way to trusting the reading you get...John
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John, that seems like excellent advice. I'll do just as you suggested when my leads arrive.
Thanks for your thoughts,
Jeb.
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Good idea to practice especially if you have never used a meter before, some of the symbols and icons can be confusing, with amps, ohms, volts ac and volts dc.
If you have any resistors lying around you can try to measure them for resistance etc.
If you measure resistance make sure the range your on will allow you to measure it.... if you try to measure say a 21K ohm resistor on a range that only goes up to 20K for example, the reading will be off this scale etc...you need to bump up the range to 20K - 200K for example..
If you measure a resistor on the low end of that range it may be a decimal point readout.... its not that hard, but make sure you use volts ac for ac voltages and the ohms ranges for resistors.... and don't try to measure resistances with power on!
Alex
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Ahh cool - all good tips Alex. Yes pretty new to the multimeter thing - the most i've ever done with mine is test a few car batteries.
I did read forward and go over the voltage and resistance test pages of the manual while I wait for bits to arrive. Sorry if these are simple questions:
1) The manual recommends to clip the black lead onto terminal 12 for a ground point. It seems quite tight there and i'm not sure i'll be able to get the clip that I ordered around there securely very easily (should have ordered a smaller one). Is it acceptable to clip onto a different clearer place like terminal "Earth" on the IEC module, or directly onto the ground-buss wire, or even the empty upper terminal 16 ?
2) For the ideal voltage measurements the manual also states these were recorded with 119VAC. Since I'm in UK and using 240VAC does that mean the readings will be different?
3) Since the first part of the voltage checks is to check the tube filaments glow correctly - is the idea to safely prop the plate up (in each corner, or on the sides) high enough so that the 6080 doesn't touch the desk and so that a visual inspection can be made from underneath ?
4)I'm also interested in any tips about general safely probing technique - do you have the crack lengthways or widthways? do you rest your probing arm's elbow on the desk for stability a safe distance from the chassis then carefully go in? or do you keep the whole arm off the desk ?
I finished the last of the wiring today and got the last resistors and caps installed. I reflowed a number of my early joints and they all look shiny as far as I can tell. I knew I was getting to the end of my build this afternoon when I realised I was trying to solder in the last capacitor with a piece of the left over ground wire instead of a piece of solder... :)
Jeb!
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This looks clean. Is there any solder on B3?
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man you're good.... just doing it now. don't know how I missed it. Think I was keeping it raw until I'd manoeuvred in the cap at the opposite end.
well spotted!
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Yup B3 needs some solder.... check all your joints from different angles, the lighting from different views helps to inspect the solder joints etc.
Its ok to use a different ground point other than 12, just make sure its indeed a ground. You can look on the schematic and see many components have one side on them on the ground side .....you can use anyone to your liking. Just be careful not to slip off etc and or short the probe to something else while checking the voltages.
Checking resistances this isn't that important, seeing how there is now power on. But having a good ground will aid in accurate measurements.
The question on the 119vac vs 240 vac is a good one...I assume that you have a proper step down transformer or a transformer that is wound for 240 VAC that will drop the voltage down from 240 as needed. "Someone from Bottlehead should answer this." I think the voltages will be in the same area. Even here in the states the vac can vary a few volts etch and there reading are approximate... but close. (10-15%) as stated in the manual.
For resistances you can flip the build upside down and suspend from the wood case.... for the voltage tests volts DC not AC... unless specified I had the tubes in and proped up on a table on a towel, at a angle so I could easily probe for voltages. I attach one probe to a ground point and then use the other probe to carefully touch a joint to check the voltage. Just take your time and be slow and methodical.... don't slip off a joint and short something out.
Your build looks nice and neat! When you first turn in on with the tubes in you should see the filaments glow in a few seconds.... watch for anything getting hot or smoke from the underside/component side... if after a few minutes nothing smokes etch, no fuse blow your probably ok fine and do the dc voltages checks...( this is after u check resistances of course)
Good luck!!
Alex
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Fantastic! - Alex - will do. Nice explanation of your technique and all things to watch out for. It seems like for ground it would be easiest just to clip on to the ground-buss wire.
I hope to get to it tomorrow or Sat/Sunday. :)
Yes the transformer that bottlehead supplied is suitable for 240v, so i'll assume i'm looking for the same voltages as those listed, unless anyone pops in with different info in the meantime.
Cheers all and have great weekends!!
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The question on the 119vac vs 240 vac is a good one...I assume that you have a proper step down transformer that will drop the voltage down from 240 as needed.
Alex, please don't comment on the products if you not familiar with them. There is no need for step-down transformers! Bottlehead supplies 240V transformers for the many parts of the world that use this voltage.
Jeb,
Just follow the manual instructions they tell all you need to know regarding the checks & safety.
Voltage readings should be as per the manual (within 10-15%), the mains voltage makes no difference (you are measuring what comes out of the transformer & in the circuit, not what goes into the transformer).
Nice build btw.
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Hi Jeb, your build looks to be coming along nicely, its good to see another UK Crack builder.
Just a little heads up as you will soon be doing your voltage checks, there used to be a misprint in the manual (not sure if its been updated in your version) but in the voltage check on page 39, Terminal 20 should read 0VDC and terminal 21 should read 206VDC
This is detailed in the manual corrections sticky at the top of the Crack forum.
http://bottlehead.com/smf/index.php?topic=657.0
Look forward to reading you are up and running
Cheers
Jamie
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So... where do the UK Bottleheads gather? I would assume in a pub, with a pint and a good sandwich.
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Thanks again guys - Jamie - I will check on those manual misprints and revisions when I perform the checks this weekend. Thanks for the heads-up.
Grainger lol! - I'm yet to be fully initiated into the secret UK bottlehead meetings but yes I would assume so too! A nice big tankard of ale and a bacon-butty at the Dog & Pheasant. Good times ;)
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Sorry Chris didnt mean to ruffle any feathers....thats why I said someone from bottlehead should answer this.
Thanks your input.
Alex
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Alex, you've been nothing but helpful and conscientious the whole time. I asked for your help and on that one matter you gave your best answer while also suggesting it should be clarified by Bottlehead. It's all good. It's fair to say I ask a LOT of questions and you've done a lot of work on that front! We're all clear now - and no harm done at all.
Chris also - thanks for your points and compliments on my build! Let's hope she works!
I really appreciate everyone's help on this thread. While I'm not at home and able to work on the build i've been able to read through the tube-rolling thread too!
Cheers & let the good times roll.
Jeb.
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Jeb,
The product page lists a number of options to the right. The top one is the 120V/240V option. It says:
"The stock kit is designed for 120VAC mains. Select this option to order the kit with a 240VAC power transformer instead at no additional charge "
If you did not select this option you probably got the 120V transformer. The transformer indicates the incoming voltage at the upper left at the terminals. What does yours read?
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Hi Grainger,
yes I selected 240 when ordered and the transformer indeed says 240V PT-3 - so I think I'm all good :) Not knowing anything about this I just wondered if it made any difference to the voltage readings using 240V but now I understand that it would make no real difference to the readings between 120v into 120v transformer vs 240v into a 240v transformer. Just creating confusion with my limited knowledge 8)
Jeb
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You are in good stead. You will get proper voltages out of the transformer. You will get them all around the circuit if it is wired properly too. A lot of Cracks run right off the bat. What we see on the forum are those that don't.
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I am interested to know if the 240 VAC primary side steps down the voltage on the secondary side or not?? Any one that is an expert here have a answer to that???
Alex
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Transformers change voltage. The heater winding is transformed down to 6.3V. The high voltage windings (2) transforms the voltage up to (120V, down to 240V) 150V. So it depends on what the primary winding is as to whether it goes up or down.
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Yup the sure do.... some step up, some step down, some don't at all depending on the requirement.
The heater voltage windings is an obvious step down, while the 170 Volts DC B+ seem to indicate a step up.
Alex
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Think of it as turns around the core. If the primary and secondary windings have the same numbers of turns around the core then the input and output voltage will be the same. (i.e. an isolation transformer). If the secondary has half the number of the turns than the primary it will have half the voltage. Double the turns, double the voltage and so on.
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It looks like the crack transformer has two sets of windings for the plates and one for the filaments? on the secondary side that is...
Alex
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Hi guys,
just performed the resistance checks.
1) The only terminal that gave me some varying readings was Terminal 13. I understand it has a "*" so we can expect some variation here. Sometimes It would read 230K Ohms and climb up slowly (as stated in the manual) while checking again would reveal a different reading starting at 3 or 400K Ohms and climbing downwards. Another time it started at 80K and crept up
So some variation is okay but is it okay if I'm getting some different readings on this terminal each time I check?
2) The first time I measured the terminals that should measure 0 ohms I used the 2K setting and got 0 on each terminal. I wondered if I should have been checking these on the very finest setting so on the multimeter I bumped down to the smallest setting (200 ohms) . On this setting these terminals read between 00.4 and 00.6 ohms
As suggested earlier I tested to see what the reading was when I clipped the black lead onto the tip of the red probe itself
and it reads around 00.3 to 00.5 ohms on that same finest setting.
At first I thought all this seemed as expected but then doubt got the better of me so thought I would just run this by you guys first before moving on. During tests Black lead has been clipped directly onto the ground buss wire.
readings/pics are attached!
and..thank you!
Jeb.
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Your readings look good. Anything under an Ohm should be considered zero. You are reading the meter lead and wire resistance when it reads under an Ohm.
Terminal 13 is an odd ball. It has 3 big capacitors in parallel with a high resistance (470k) to ground. If there is a slight charge on the capacitors you will not get the exact reading. It often gives an odd reading.
Go on and move on to the voltage tests.
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Ok now for the voltage checks!!
Good Luck!
Alex
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Grainger, Alex - thanks I've gone ahead and done the voltage checks. Probably the stage that was most daunting to me!! To me readings seem okay and within the tolerances given but for peace of mind would appreciate a second look.
As with the resistance checks, on the 0 reading terminals, I saw 0 when using the higher 200v setting but when bumping the meter down to the lower setting (2V) I did occasionally see a slightly varying .002-3 fluctuations but I guess this is nothing to worry about?
Jeb.
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All Your readings are within the 10-15% limits
Your fluctuations are fluctuations of 0 and nothing to worry about
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Wow! Jeb how does it sound!???
I just tore mine down to install the speedball mod...
Alex
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adydula - in a word - Magical!
Guys - it's working like a dream. Using my new 650s it Sounds absolutely wonderful! I've had the 650s since the beginning of the build but because I had to clear the decks of all other equipment, up to this point I've only been able to test them out a portable dac/amp and I wasn't sure I liked them. Clearly the little amp was not driving them to anywhere near their potential - The transformation using them out of the Crack is really outstanding!
I'm planning a full review and some comparisons in due course but for now I'd really like to extend my sincere gratitude to the Bottlehead team and everyone here on the forum who has helped me along the way. Prior to this my experience with electrical was precisely zero and you've all helped me achieve something I wasn't totally sure I would be able to do. I'm sure that was evident and you've all been extremely patient! It's been an amazing, confidence building exercise.
I've posted a few photos I've taken:
I wanted to keep the look clean and simple so took Doc's advice and just applied a few coats of a satin-water-based clear varnish to the well-sanded base. The top plate is left unfinished. I added some little oak squares to the inside of the case and added M6 threaded inserts so I could screw in some feet. Along the way I also built a platform for the Crack to sit on, on my desk - this is made out of a slab of thick birch ply, some aluminium feet with a clear acrylic top. The aluminium spike shoes are inset flush in holes I cut into the acrylic, so once it's seated the Crack doesn't move at all. I added a clear, vented base to the bottom of the crack.
Finally, the bit i'd been most looking forward to - I stuck on the badge :)
Again, thank you everyone!!!
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That's great to hear.
You have built a real good looking set, there.
How did You get the acrylic done?
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Thanks! - the sound is amazing. One of the best compliments I can give it right now is I was so lost in the music after an hour I didn't realise how much of a headache I was getting from the clamping force of the new HD650s! I'm sure that gets better with use!?
The acrylic for the desktop platform I just bought a piece online cut to the same size as the piece of birch ply I got. I was able to drill the holes for the screws for the feet and the 10mm holes for the spike feet with a very sharp forstner bit. My first idea was to use glass but it wasn't really feasible to drill at home. But the plastic cutters were able to polish the edges so it seems quite glass-like in the flesh.
The clear base for the amp I downloaded a trial of adobe illustrator and drew up a quick design for the exact size with some vents and sent off for it to be cut by an online laser-cut place where you can just upload your design and then they send it to you in a few days. I thought I may as well get the "bottlehead" name too :) It was pretty inexpensive for a small piece of acrylic with a simple cut pattern like that - around £10 or 12 if I remember correctly.
obviously if my wiring had turned into too much of a horror-show I might have just used a piece of wood with vents instead :)
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Great job!!!
Nice looking build, now you can relax and listen and enjoy!!
I just took mine apart to get ready to speedball it!!
Look forward to a more detailed review on how it sounds over the next week or so....
A simple amp that does very, very well with high impeadance cans!!
Alex
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The base looks lovely, you can tell you spent some time sanding and prepping it :)
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Super job Jeb congratulations on being up and running. I really like the acrylic base you had made. Any chance you can forward on the link to the supplier and adobe file I fancy getting one made for my Crack.
Ps the HD650 clamping pressure eases up with use, if you wanted to speed up the wearing in you could leave them lightly clamped to a few books when not in use.
Enjoy your Crack
Cheers
Jamie
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Excellent work Jeb, the base & bottom cover are really nicely done. Now on to some tube rolling & of course, Speedball! ;D
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adydula thanks - all your help was invaluable. I'll really look forward to your thoughts on the speedball installation and effect. I'm already thinking about it too so i'll be interested to hear how easy it is to get popped in. I did have a quick look at a few pics and I wondered about fitting one of the stand-offs since where it goes looks like a real nest of wires on mine!
mcandmar - also thank you. Yes I was pleased with the base - alder isn't something I've seen very often at all here and I really liked the look of it so I wanted to keep it natural looking as possible. Doc said they used to use a Satin water based and had gotten good results. I did spend far too long sanding it ...obsessively. I spent a long time on the case - partly because I was nervous about beginning the build :)
Chris - thanks - speedball seems inevitable doesn't it?! Crack is a gateway amp!
Jamie - glad to hear that about the 650s i think I will try and stretch them out a little over-night - they've come alive on the Crack.
The online laser-cut people are called razorLAB. I actually did the case-work a long time ago (procrastinated about doing the wiring...) so my adobe trial is long expired but I do have the final razorlab template I uploaded for cutting - It's not a file-type I can attach here (an .eps ) But if you would like it please shoot me a PM and I can email it to you. I measured it for my crack base and it's 142mm x 245mm.
I checked my invoice and the standard Acrylic piece they sold (384 x 384mm) was £5, out of that I got two bases cut (in case I then messed up drilling the holes for the spike feet...which I did)- cutting cost for that was £8. The annoyance is delivery - £10. & + VAT on top so I guess it does all add up in the end.
One cheaper alternative I thought about was just getting a piece of acrylic from any of the online "cut-to-size" companies, then drilling lots of holes for vents in an nice arrangement. I used 3mm acrylic - and while it's not really flimsy, you wouldn't want to press on it too hard when picking up the amp for example. If your Crack case/feet can accommodate 5mm thick base then I think that would be quite a bit stronger and also look cooler!
Jeb.
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Jeb,
I got the speedball in the mail yesterday and was out of town. I got up early this am and it took 3 hours of populating the three small pc boards and all the parts. Its installed and all the voltages are fine and I have played some music but cant really listen carefully...we have a hardwood floor installer here and its really LOUD!! LOL. But it worked the first time.
The mechanical plastic standoffs to which the boards attach and mount to need some careful moving of some wires a small amount to get them screwed to the existing screws....have to be careful, some as most of the wires seem to be a bit longer than really needed and they are pretty "stiff" and if you move them with pliers etc to get them away from the screw needed for the plastic standoffs you can move some of the tube socket terminals and may short out something. Just take a look on what might need re-positioning and be careful not to short anything.
The teflon wire is a smaller gauge and quite "slippery" to handle,,,,lol....it works fine but its a pain to me to work with.
IF you have never worked with transistors, these are small and when soldering I am careful not to solder all three leads (EBC) at the same time. I solder one lead and go around and solder others and come back and do the second lead etc...it prevents too much heat being applied to a small silicon based device..just a precaution I have always used over the years.
Its a real simple build, some of the labels on the small pc boards are a little hard to read, but the speedball manual is great as usual and easy to figure out...
As soon as the floor pounding is done in a few hours I will let you know how I feel it sounds etc...
Congrats again on your build!!!
Alex
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Jeb,
Finally quiet.....one word its "superb".....
I am a pretty objective guy...with my T90's and this upgrade I cant honestly see how it can get any better...
Listening to all my stuff again and its indeed still magic +.
The upgrade to me cant hurt what the crack is, its just better....soundstage etc...all those superlatives etc..
I got in on the $20 deal here and for that price its a real no-brainer....
Best $20 I have spent in this hobby in a long time!
Alex
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Nicely done Alex - you didn't hang about did you!
Very pleased to hear you feel it brings positives with no downsides. I'm thoroughly enjoying the Crack - being really objective about this amp is pretty difficult because I found it so much about the experience as much as the sound.. but i'm always open to sonic improvements and superlatives...so I'm keen on the Speedball. I think i'll place an order.
I've taken on-board your tips and experience fitting it - i'll definitely need to do a bit of re-arranging for the stand-offs by the looks of it. Obviously i've never done soldering to a board like that so perhaps while waiting I could pick up some cheap components and a board and practice a little to minimise risk of me frying anything.
I looked at the pics - do the capacitors near the 6080 socket just get bent out of the way ? i'm wondering if I left the leads long enough.
Congrats on your new new amp: Speedball fitted & new hardwood floors - life is good :)
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Yes the caps will bend right over so the board can mount on the standoffs, they touch the bottom of the board somewhat but no issues there.
I had my crack running for a few weeks before I decided to do the speedball, the price was right and hey soldering is always fun to me! LOL.
I think the low bass notes, kick drums, bass and tympani are just so superb now....who knows....the idea behind a constant current source has its benefits, sonically oeprating in the linear range and power supply isolation should be a better all around technical scenario...it sure doesnt hurt the crack in anyway IMO. I dont think anything has gone negative at all.
Cosmetically it starts to get crowded inside...more stuff and wires!!
Enjoy your crack for awhile and then you will have a good comparison to the sound quality etc.
oh...no we stayed and watched the floor guys OMG it was noisy!! Its done!!
Alex
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Excellent!
I am awaiting a speedball kit & will enjoy the stock Crack in the meantime. Pretty excited. Excited about the bottlehead baseball cap I ordered too. I heard it improves the soundstage - but that's unconfirmed ;)
Have fun with your new kit.
Jeb.
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Thanks!
I have been swapping tubes in and out and having some fun with that, the tubes I got are really good to me, but I found several fairly inexpensive tubes to play within my budget...and most of them sound just as good!!
Let us know when your ready to Speedball!!
Alex
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Will do - I think it may be a little while before I receive my kit. I totally agree about tubes - I've done a bit of rolling in other amps (12AU7s mainly) and although some of the *best* (whatever that means) tubes can command quite high prices, inexpensive tubes that really deliver and offer great bang for buck have always given me the most satisfaction.
One thing I'm finding with the Crack is how little I need to turn the volume knob to get to my ideal listening level - if 0 is at about 7 O'clock, I only need to go to just between 8 O'clock and 9 O'clock. I'm using a player on my computer that fixes the volume sent to the DAC (Rega DAC) and it seems to do this at max or near max (80%) - It was my understanding that this was the "correct" thing to do. Are there any benefits/disadvantages to changing things so I can reduce the computer volume and so have the volume pot on the Crack in a more open position? To be clear, despite not really having anything to play with with the volume pot - I don't have a problem with the sound I'm getting - i'm not hearing any imbalance and everything seems dead-quiet, but then I don't know any different at this point.
I see in the Crack FAQ it suggest adding some 75K resistors for both the red and white wires where they enter the volume pot, and a 33K resistor between each of the outer lugs - but I just wondered what the benefits were to a more open volume position and if i'd just be trying to solve something that isn't a problem anyway. I also see lots of people upgrade their volume pots. I'm open to doing that but probably somewhat nervous to go "off-piste" from the manual at this point!
Jeb.
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Ha...funny I just posted a new thread on this topic.
I had the same experience and added the voltage divider network of the two 75K/33K resisitors etc and it works well to allow more adjustment on the volume control...
With speedball I am back to noticing the volume is now at a lower mechanical postion 9 o'clock or there abouts..
So I think the gain with the speedball might have increased, I think that PB or Doc will respond with a change in the resistor values...I would be afraid to add these etc....no real issue that I can see..maybe some "johnson noise" added etc...
I agree on the price of tubes, some are absolutely out of this world....its more important to me to know the circuitry and what effect it has on the audio signal and circuits have more of a pronounced affect of things than changing tubes to me.
I have 7 power tubes and they all work well, spend too much time rolling to find that thing that eludes us!!! LOL. I have my wife change tubes on me and not tell me whats installed and I have tried to pick one over the other!!! I could not!!!
Time for more coffee and just enjoy the music!!
Alex
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Great - yes enjoy!
I'll wait and see what recommendation you are given and maybe I can skip straight to that solution at the same time that I install the Speedball.
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Jeb, your volume control action is Crack FAQ #3. Check the sticky. I prefer to use a greater range on the volume control as it allows me to set a more precise volume level.
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Thank you Grainger - that makes sense and it sounds good to me to have more range. I'll look into getting those resistors. I've been looking on the forums but I guess I do have a quick questions:
- I'm not sure I will but If I did fancy replacing the volume pot while I'm at it does a pot with a different impedance effect the resistors needed as per Crack FAQ 3 ?
Thank you in advance. Really enjoying the Crack and the hd650 clamping force is indeed letting-up with use!
Jeb.
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I went down the resistor route with my Crack and it works well. A little later on I decided to try fitting a stepped attenuator (100k valab ladder type) after a little use the range seemed greater and decided I didn't need the resistors any more and later removed them. They are easy to fit and try and just as quick and easy to remove.
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Hi Jamie...
I got a reply from PB to add 33K's in parallel with the 33Ks already installed.
I listened for several hours yesterday and for some reason it seems back to ok for me??? Strange...
I know source material hasa a replay gain factor and if I listen to stuff with a lower or positve replay gain I have more than enough volume control rotation...as the gain goes high in the negative direction I dont have to turn up the volume much like not past 9oclock...
So maybe after this I will just leave it as is for a few weeks and listen and then decide to leave it as is, add or pull out what I already have.
Alex
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Cool - Jamie, Alex - i'll look to adding some of those resistors at the same time as speed ball and maybe a different volume pot down the line!
Since I'm so new to this going to keep it stock + speedball first and make sure I can get all of that working first as suggested.
But...having said that I do like to plan ahead so if I did want to try cap upgrades down the line will I curse myself later on if I don't think about it now by figuring out some mounting options + holes and putting the stock output capacitors on fly leads to make it easier for myself later, or is it all easily do-able later on? It looks like some of those terminals might be difficult to get to post speedball.
Also Jamie - would you have any personal recommendations for caps that are not overly big, easy to fit, available in the UK and you feel offer a nice improvement?. I don't mind spending a bit - I think the Crack will take pride of place for the foreseeable!
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Cool - Jamie, Alex - i'll look to adding some of those resistors at the same time as speed ball and maybe a different volume pot down the line!
Since I'm so new to this going to keep it stock + speedball first and make sure I can get all of that working first as suggested.
But...having said that I do like to plan ahead so if I did want to try cap upgrades down the line will I curse myself later on if I don't think about it now by figuring out some mounting options + holes and putting the stock output capacitors on fly leads to make it easier for myself later, or is it all easily do-able later on? It looks like some of those terminals might be difficult to get to post speedball.
Also Jamie - would you have any personal recommendations for caps that are not overly big, easy to fit, available in the UK and you feel offer a nice improvement?. I don't mind spending a bit - I think the Crack will take pride of place for the foreseeable!
PMed you
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Hi guys - bear with me - need to ask a couple of real noob questions about doing the Crack FAQ No.3 resistance modification:
1) never bought resistors before , so many types, prices etc - just these ones will be okay and consistent with the quality of everything else? - http://www.maplin.co.uk/p/metal-film-06w-33k-ohm-resistor-m33k (http://www.maplin.co.uk/p/metal-film-06w-33k-ohm-resistor-m33k)
2) so looking at the sketch of the pot I attached I understand I attach 1 x 75k resistor between the red wire and pot lug A and 1 x 75k resistor between the white wire and pot lug B. But I'm confused about which lugs the 33k resistors go between? One between lugs A and E, one between lugs B and F ?
Sorry this is probably quite lame but I guess I'm not very good without pictures. :-\ Thanks! :)
Jeb
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Those resistors are fine (if a bit expensive, normally you can get them for very little).
Not sure which way you've drawn the pot, but if that's looking at it from the RCA jack side, then yes that's correct.
Just to confirm: the 75k resistors go between the wires that come from the RCA jacks & go to the outer lugs of the volume pot: one for red, one for white. You can add these at the RCA jack end or at the volume pot end.
The 33k resistors go between the outer lugs of the volume (not the centre lugs), top & bottom. That is, the lugs where the red & white wires from the RCA jacks connect & ground, the 2 lugs with the black wires attached (closest to the 12AU7).
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I'm not sure I got the Mouser UK site, although I clicked on that link. Here is my search. I believe you have the right type and power rating (very low) you need.
http://www.mouser.com/Passive-Components/Resistors/Film-Resistors/_/N-7gz3w?P=1yzekiaZ1z0z819Z1yzaok0
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Thanks Chris - I should have just used a photo! I have attached one to this message just to be a bit clearer but I think I have understood you correctly.
1 x 75K between Red RCA wire and A
1 X 75K between White RCA wire and B
1 x 33k between A & E
1 x 33k between B and F.
when I first read the FAQ somehow I got confused. I am still learning my way as to the "why" of everything.
May I ask in very basic terms why it is necessary to have these 33K resistors going to ground as well as the 75k ones on the red and white cables?
PS. Grainger thanks for info about resistors I'll grab a few. When I first did an online search some exotic ones were going for 4 or £5 each or more... Some metal film, some carbon. I guess these are "audiophile" resistors? the descriptions often talked about them having a certain "sound" be it warm or transparent or "dry". I guess things like this are considered pretty dubious or else just not critical in this application.
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Jeb......I asked the same question in another thread here are the resistors I used...very cheap and metal film from www.mouser.com
http://bottlehead.com/smf/index.php?topic=8151.0
Mouser #: 71-RL20S-G-33K
Mfr. #: RL20S333GB14
Desc.: Metal Film Resistors - Through Hole1/2watt 33Kohms 2%
2 $0.32 $0.64
Mouser #: 594-SFR16S0007502FR5
Mfr. #: SFR16S0007502FR500
Desc.: Metal Film Resistors - Through Hole1/2watt 75Kohms 1%
Here is a pix of them before I cleaned them up to test:
Alex
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Cheers - thanks for the thread link - I didn't realise all this had already happened in a parallel universe... :) I need to be better with the search function! in your pic Is there a reason why the resistors going across the middles are much bigger than the other ones even though they are 33k and the others are 75k ?
Alex You build looks nice and shiny and clean!!!... and with the speedball just tempting coming into view in the corner!
It's great to see a picture, it really helps - that's why the bottlehead manual is so good I think. While I wait for things to arrive I was watching some vids on soldering and I was wondering about what is the accepted method of joining a resistor to a piece of wire - from your pic it looks like you create a loop or hook on the wire end and then you can wrap the resistor lead around it as if it were a terminal, then just join to the volume terminal as normal.
the heatshrink suggested on your thread is a good idea too - I will get some.
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Hi Jeb...
There is no apparent reason as to why the resistors are different sizes that are apparent to me.
That said, both are rated at 1/2 watt more than whats needed and I chose tolerances of 1% and 2%, I couldnt find both at the same tolerance.
This may be why they are different physical sizes.
You can tack solder them on the pot terminals or try to wrap them around the terminals and solder but the joint is getting large here...
I have no issues with "tack" soldering if done well....there isnt any movement or strain on them.
One side of the pot outer terminals are already joined together so you could twist the 33ks together and solder to the inner most top terminal then each of the other leads of them
to the top and bottom outer pot terminal.
I elected to put the smaller 75 K resistors near the pot and away from the RCA jacks...read somewhere that this was the preferred method.
To neaten it up you can use heatshrink, solder the leads inline with the wire and attach and solder to a terminal and then slide the heatshrink over once cooled and shrink to make a
nice neat installation.
If u do use heatshrink, remember to put it on before you solder!!! LOL done that before....
I have done a lot of listening.....my wife thinks way too much!! Ha!!
The speedball kit makes things just a little nicer...
I dont think I am going to add the other resistors now as PB indicated I think that most of what I listen to is allowing me to go from 9 o'clock to 1 o'clock with plenty of enough
drive and volume...
So we are now a happy camper!!
Alex
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A happy camper, pleased to hear it! Those are great and welcome soldering tips, as ever, thank you.
I know what you mean about logging some serious listening time. It's like I heard Doc say, it really does sound better when you build it yourself!
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Resistors come in all sorts of different sizes, even with the same power rating.
I don't recommend Mouser, you have to order a minimum amount to get free shipping. In the UK, you can use RS Components, free next day delivery whatever amount you order, you just need to create an account (very easy).
Here's a sample of resistors: http://uk.rs-online.com/web/c/passive-components/fixed-resistors/through-hole-fixed-resistors/?applied-dimensions=,4294466702,4294882859 (http://uk.rs-online.com/web/c/passive-components/fixed-resistors/through-hole-fixed-resistors/?applied-dimensions=,4294466702,4294882859)
As you can see, just a few pence each, much better than Maplin's price! They do often come in packs, so you have to order a pack of 10 for example, just to get one. Some others don't, like the Vishay RN55 or RN60 which are very good resistors & used by Bottlehead in some kits.
The heat shrink is a good idea, another alternative is teflon (PTFE) tubing slipped over the leads.
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Chris - RS components looks great! Thanks for the tip.
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There is no apparent reason as to why the resistors are different sizes that are apparent to me.
One resistor is a mil-spec 1/2W and the other is a consumer grade 1/2W.
We find it safer to treat everything like a consumer grade resistor, just to avoid confusion. In this particular implementation, I might pay a little more for a higher power resistor just to get beefier lead wires.
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Yup one is a mil spec but both are rated at 1/2 watt power.
I agree getting resistors that are low noise and with larger diameter leads is nice in this application.
Alex
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Hello again guys!
Well 6 months on from finishing my Crack build, I've just started to begin the Speedball installation and am hoping for a bit of help and encouragement again!
I'm doing the main board and It's going OK (I think so far) but definitely finding soldering the PCB challenging because I've never done it before. At first I had trouble getting a nice concave solder joint or creating bridges between the transistor leads. I've reheated or completely redone almost all of the joints to the best of my ability and wondered if you guys could just take a glance at it to see if I'm doing okay or anything looks suspicious? I'd prefer to get it right or get some pointers before proceeding with the others.
One thing I've found is that even if I get what seems like a nice concave joint on the the bottom of the board, when I flip it over I will sometimes get a little ball or blob on the top side. I understand from reading around that this would perhaps be caused by too much heat and/or solder. If nothing is bridged on the top side, is it okay to leave these or do they indicate a bad joint throughout that pad?
Here's a couple of pics of the bottom of the board and one of the top showing a little bit of solder balling on the transistor lead - on close inspection, nothing is bridged. I have used a bit of cleaner to remove flux residue from the bottom of the PCB so its easier to see.
Any comments or pointers? Much appreciated!
James
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Those look just fine. The trick is to make sure the wire and the pad are both in contact with the iron tip, not just the wire.
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Nice-one, thank you for the tip Doc - I will proceed !
Cheers
James
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Okay maybe I spoke too soon... so I think I have damaged or melted one of the pads on the board.
There was one joint on one of the small resistors where I just couldn't get the solder to stick to anything but the resistor lead. I reheated and sucked up the solder to see what was going on and there doesn't seem to be a pad any more (see pic). Perhaps it lifted and I sucked it up? Ugh...
At this point would I need to order a new board?
I'm sure I'll get there in the end!
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Looks like there is just enough plated trace left directly under the lead to be able solder to. You can also take an xacto knife and carefully scrape off the green mask on the trace near where the pad was, to give you a little more surface to solder the end of the lead to.
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Okay Cool, sounds good. I'll give that a go tomorrow. Thank you once again.
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Hey Jeb!!
Congrats on working in the speedball upgrade.
Scraping the green stuff off a little to get more area of that trace to solder is a good idea, simple easy does it...
Cant wait to hear your comments about the upgrade!
Alex
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Cheers Alex!
I did just that - it was quite straightforward to expose a little area of the trace with a knife and it seems to have produced a good joint - from what I can tell at least! I was disappointed to mess up the pad but it's also good to learn a new technique if such a problem arises and to know there are ways around things with PCB work.
I'm quite pressed for time to devote to it at the moment but have finished the main board. Aiming to finish the others and get it wired in next week. I'm probably the slowest bottlehead builder yet... ;)
One basic question for what's coming up in the manual - After assembly of the PCBs, when actually wiring the boards into the Crack circuit, the hook-up wire is passed through the holes from underneath the boards, so I presume that means you carefully solder the pads on the top of the boards this time- correct? But using the same technique, pass the wire through, then bend it flat to the board to keep it in place, and be extra careful not to melt any nearby components?
I do like the PCB work so far- it's different and does require an extra degree of care and precision with the iron - but definitely satisfying and looks very cool. I'm sure it's pretty straightforward for you!
Hope you're still enjoying your amp too!
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One basic question for what's coming up in the manual - After assembly of the PCBs, when actually wiring the boards into the Crack circuit, the hook-up wire is passed through the holes from underneath the boards, so I presume that means you carefully solder the pads on the top of the boards this time- correct? But using the same technique, pass the wire through, then bend it flat to the board to keep it in place, and be extra careful not to melt any nearby components?
Yes, that's correct, although don't bend it 'flat' to the board. The wire should pass through the pad, then just bend the exposed end slightly to make a good contact with the pad & it will stay in place for soldering.
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Thanks Chris - will do!
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Jeb,
Yes thats pretty much it. Fairly easy to solder. If i remember following the wire lengths and being careful to attach the wires in the correct places is important. Check and work carefully.
I am still enjoying the amp. I have been busy and just completed another totally DIY amp, all solid state, came out nice. I will pm you a link to look at.
Alex
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Hi Guys,
Just a quick update: I just finished the smaller boards and got everything wired in. Tested well so just fired her up! Of course I doubted myself at every step of the way..lol.. but so far so good and it sounds really EXCELLENT!
In terms of sound there are quite a few areas of improvements I'm noticing - but in the bigger picture I would liken it to something slightly blurry having been brought into much tighter focus. I'm not sure if its because the staging has increased in width and depth or if it's just the greater resolution but the whole experience feels grander and more refined to me. One other area I would mention especially is the bass, which is exhibiting improved depth and definition, which is particularly noticeable vs the stock sound that I've been used to for the last 6 months.
The build was good fun and nicely challenging. For a beginner I would say it is really spot-on in terms of the learning curve from the skills I learned from the stock build. The manual/photos are excellent just as before. My PCB soldering skills definitely improved by the time I got to the smaller boards and I had bettered my technique and developed a bit more confidence in what I was doing. I suppose if I were doing it again I might have bought a blank practice board and got my eye in on that with some cheap components first before hitting the main board - but it didn't really matter in the end.
Once again, a big thank you to everyone here for their help and to also everyone at Bottlehead HQ for doing what they do!
Cheers!
James
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Hey Jeb!!
Congratulations on your upgrade and I am glad you like the sound. Its hard to tell the differences with all the variables involved. But technically its a better amp with the upgrade which should help.
It would be nice to have two identical amps side by side one with and one without to do a AB listening comparison.
To me it definitely did not hurt the sound quality at all. Its just different to me in a good way.
As you know I really like building stuff as well and cant resist upgrades and fiddling around with the stuff!
Been thinking of getting a fancy volume pot, stepped type to install....
Enjoy!
Alex
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Thanks Alex -
I agree - the tinkering is a lot of fun. I decided to strike while the iron was hot so I've also popped in a new pot (not stepped), power supply choke and film output caps in the last few days. I also bypassed the last PS cap with a small 2.2uF film cap. All challenging & a really great experience for me in terms of thinking outside of the manual a little bit.
To be honest I never really had any problem at all with the stock pot, but I do feel the better pot I have (TKD) is somehow a bit cleaner and less rough. The TKD feels incredibly silky so the user experience is really nice, that's for certain. Quite ridiculous when you think about the price in relation to the cost of the amp though of course. I also padded the pot with the resistors, as you did a while ago, which is GREAT as I have much more usable range on the dial now.
Crack is addictive.
Definitely post an update if you go ahead with the stepped attenuator!