Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: adamct on August 07, 2013, 06:07:54 AM
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I'm not sure I want to tackle this, but has anyone tried fully replacing the last cap in the power supply with a film cap? Was there a noticeable change in the sound? I currently have that cap bypassed with a ClarityCap ESA cap, but I'm wondering if it is worthwhile to fully replace it. I tend to think the answer is no, but..."Inquiring minds want to know!"
What is the value of that cap (I'm at work and don't have the manual at hand)? I think it is something like 220 or 250uf, is that right?
I believe Paul mentioned that if you want to replace it with a 100uf 250V cap, then you need to add a choke as well.
Does the same hold true if using a 200uf or 220uf cap? I've been looking at a Solen PB FastCap 220uf / 400 VDC, or a ClarityCap TC 220uf 700VDC. Anyone have any experience with either cap? I have to admit the giant ClarityCap TC caps with screw terminals instead of wire leads look pretty damn cool...
Best regards,
Adam
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Well first off did you like it when you bypassed the last cap? if yes then why not.
As a general rule, you can replace a electrolytic cap with a somewhat smaller film cap, how much smaller, is hard to say.
But the thought of adding a choke is appealing. How about something like 100uf-CX-7-100uf, I am just throwing these values out. Best to model it on PSUII.
That is if you take advise from a teenage girl 8)
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Well, sure, I love the sound with the last cap bypassed. But actually replacing the cap, instead of bypassing it, would be a much more involved (and expensive) operation, so I want to make sure it is worthwile before I undertake it.
I think Paul's point was that if you replace the electrolytic power supply cap with a smaller value film cap, then you need to add a choke. But in the example he used, he was referring to replacing the cap with a 100uf film cap. I'm trying to figure out whether the choke is still necessary if I were to go with a much bigger cap: 200 or 220uf, which I think is close to the value of the electrolytic, although I can't remember the exact value off-hand.
Thus far I've stayed away from adding a choke, just because I didn't want to deal with the added complexity.
And John, I'll take your advice even if you don't quite look like your avatar...
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Hey Adam - I say, if you can replace an electrolytic with a film cap of the same value - why not! - as long as the film cap can handle the voltage, and your wallet can handle the price!
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Eric,
A wise man once said:
"...this modding thing can get a bit crazy, its good to keep a level head about it. ... Its more about enjoying what you have. I wouldnt mod anything unless I felt I had a "reason" to. In other words, there is something that I would like to improve upon, and I'm motivated to solve that problem. Without identifying a problem, its a bit like shooting in the dark IMO."
;D ;)
I'm doing my damndest (spelling?) to keep a level head. I don't really have any complaints about my modded Crack, no problems or anything I want to improve upon. So I'm definitely shooting in the dark and would rather not go to the expense and hassle unless there is a reasonable prospect of success (meaning an audible improvement in sound).
Best,
Adam
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Eric,
A wise man once said:
"...this modding thing can get a bit crazy, its good to keep a level head about it. ... Its more about enjoying what you have. I wouldnt mod anything unless I felt I had a "reason" to. In other words, there is something that I would like to improve upon, and I'm motivated to solve that problem. Without identifying a problem, its a bit like shooting in the dark IMO."
;D ;)
I could not have said it better myself!
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LOL! Touch
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I don't have a crack but 220uf is a likely value. there would be no issue replacing it with a 200uf film of equal or better voltage rating.
My thought was, what is the cost of the big 200uf cap, compared to 2, 100uf caps, the choke is less then $20.
CLC with film caps is the way I am going with my SR-45 rebuild, I am thinking 100uf motor runs, got them already ;).
And you are right, that is kind of an old photo...John
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You mean I could use something like this (http://www.ebay.com/itm/CDJ-MKP-Polypropylene-Film-Motor-Start-up-Capacitor-450VAC-200uF-10-/321106640745?pt=LH_DefaultDomain_0&hash=item4ac3727f69)?
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I am not sure if I was clear. you can replace the last cap with whatever you have on hand within limits. Voltage limits.
Other than that it depends on how much hum you get, you won't hurt anything. 50uf is probably too low but hey, might work. Turn the vol up slowly and check for hum.
I am in the camp of the smallest best-est cap is the one for me.
Make no claim to being in the right camp...John
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You mean I could use something like this (http://www.ebay.com/itm/CDJ-MKP-Polypropylene-Film-Motor-Start-up-Capacitor-450VAC-200uF-10-/321106640745?pt=LH_DefaultDomain_0&hash=item4ac3727f69)?
Not sure. I look for motor RUN caps. This sort of thing. check e-bay
http://angela.com/angelaascoilcapacitor50uf515vdc.aspx
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Maybe I'll just get 12 of those and wire them into three sets of four...
Relax, I'm kidding. I wouldn't do that. Or would I?...... 8)
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The ASC and other motor run oil caps are great in the power supply.
They have fallen from favor lately because they do not command top dollar.
So sad...John
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In ebay search for "oil capacitor" and you will find all kinds. Larger values are getting harder to find.
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The actual first Crack that I ever built was back in 2004, and I used several motor run caps in the power supply. Ultimately I can recall that 100uf per section wasn't enough (I was using a CRC filter with a lot of resistance) I actually ended up with more like 400uf per section in the end, and the experience of these experiments was very educational.
PB
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I have experience with the Clarity TC caps. They do involve some rethinking when it comes to mounting them. And compared to the Panasonic electrolytics they replaced, there was a significant improvement in sound quality. The trade-off is size and cost.
I hear what you're saying about stabbing in the dark. Personally, I say stab away! Kill it! There's Grues in there!
Ok, seriously; this is part of the madness and enjoyment of this hobby. Experimenting! How boring was audio when you just bought stuff and listened to it?
SO boring!
So experiment away! You never know when a change will really make a difference until you try it yourself.
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Quite true Rob! The other side of the logic is that when you buy some nice caps etc. you can always use them for something. They won't go to waist!
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(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv213%2Fhighflyin9%2FDIY%2FSolen-Power-Update-2.jpg&hash=5b7026b03f809c3a571e9d0e377750f47894ed0d)
You can squeeze a 220uF Solen in there just barely :)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2F1.bp.blogspot.com%2F--9HVdXvbtAQ%2FUZZgOmW5W3I%2FAAAAAAAABeE%2FPY7KPn6N8P4%2Fs1600%2FFinished-Internals.jpg&hash=ebd29fd8db75d698eda86017f180f6d9d8c05191)
Or (3) 75uF caps in parallel in this custom chassis.
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Beautiful builds. What are the small red caps in the one with the big Solen? I assume you bypassed the other two power supply electrolytics?
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Hey erm where does the Choke go again if I were to put it into the circuit? I'm having trouble recalling which 270R was I supposed to replace with using the Triad C7X
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Beautiful builds. What are the small red caps in the one with the big Solen? I assume you bypassed the other two power supply electrolytics?
Thanks!. Yes, that was the purpose of the little red Audiofiler caps.
Nick, if you look at the photo above, you'll see the 159M choke on the left going up to the approximate area where the 270R resistor would have been.
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It looks like my choices are (1) going for 3 of the oilers from eBay (70uf each), (2) one of these (http://www.ebay.com/itm/CDJ-MKP-Polypropylene-Film-Motor-Start-up-Capacitor-450VAC-200uF-10-/321106640745?pt=LH_DefaultDomain_0&hash=item4ac3727f69), or (3) a Solen 220uf film cap. Frankly, 3 of the oilers off eBay would cost almost as much as the Solen, but would be much bulkier and require more wiring, so I'm inclined to skip them. Any thoughts on option #2?
Best,
Adam
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On the "OLD BOARD" there was something called a PDMPS, a third stage of filtering. It stood for Pseudo Dual Mono Power Supply. I did this with my FP 2 adding a couple of 100uF "Oilers" motor start caps. I just put another 1k resistor between the mono power supply output and the oilers. Then the two power supply rails went to the right and left channel.
It did improve the sound.
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IMO - i don't think you will notice a sound difference between film caps in the power supply. That would be a guess, but I'd do feel its worth going from electrolytic to film, even from just the peace of mind aspect.
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Hi Nick, the resistor in question would be the one that connects the 2 high voltage caps together...John
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Hi Adam
I use the 220 uF version of this cap:
http://www.partsconnexion.com/capacitor_film_clarity_tc.html
(Relatively) cheap and some peace of mind offered. Sonically satisfied, fiscally challenged.
Not a pretty solution, but it does the job.
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Yep, that's the other cap I was considering. But I wonder if the $11 film cap from eBay wouldn't be just as good when used in the power supply...
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Hey Adam - with large value film caps like that, in a power supply, I would go ahead and try the cheapest one you can find. No harm done. Its going to be really hard (expensive) to get any name boutique cap in those values. Money can go other places IMO.
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Hmmmm....at that price, maybe I'll replace all the power supply caps! :D
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Yes.. Large Caps Increase Your Manhood!
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Just bought 3 of the 200uf poly film caps off eBay. If MLB tested me right now, I would fail a doping test...my testosterone is off the charts!
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LoL!!! .. yep.. you are definitely hooked!
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Hmmmm....fools rush in.....
I just watched a video on the difference between start and run capacitors. The poly caps I bought are start capacitors. Am I correct that those are a no-no for use in the power supply, and likely to blow up in my face? :-\
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If it has a DC rating equal or greater than the stock cap you are fine.
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Therein lies the rub....I think it is rated for AC only...
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Typically the AC ratings for a cap are notably lower than the DC ratings. I'd imagine the manufacturer probably just didn't anticipate anyone dropping their cap into an amp ;)
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I think you are going to have to try it and see. If the caps don't destruct in the first 5 minutes they just might make it. For the test put jumpers on. Don't remove any other caps just put the new cap, only one, in parallel with the last cap. Put some paper under it in the odd chance that it lets go.
Then move forward with confidence.
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Check out this eBay listing (http://www.ebay.com/itm/251157598949?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649), then scroll down and watch the embedded video. How dangerous is it if a cap goes belly up?
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Interesting.. Now I know the difference between a "start" and "run" capacitor.
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Grainger,
Do you still think I should try it, or just chuck them in a drawer chalk it up to a learning experience?
I've already ordered two of the 100uf oiler "run" caps at the eBay link to use instead of the last power supply cap. Unless someone tells me they really think it is safe and/or worth experimenting with the poly "start" caps, I'll leave the other two electrolytics in the power supply as-is.
Best,
Adam
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I have a bad feeling about them but I have no personal data to back that up.
I can say that motor RUN caps, if not your holy grail. Work pretty well for me...John
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Adam,
Did the auction say "Motor Start" capacitor? What voltage rating did they have? What voltage will be on them?
I should point out that capacitors have a surge rating and a steady state rating. That is one of the differences between a start, which accounts for the surge, and run capacitor that is expected to be used in steady state AC applications. That also brings up that the demonstration was with AC, a power supply is DC.
So I'm still at the try it point.
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It said "motor start-up", not "run", and they are rated for 450 VAC.
Best,
Adam
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Also, I'm just wondering...in the video, they specifically said that motor start caps are only rated for AC. I took that to mean "don't use these for DC", not "the DC rating isn't specified" (which would imply that if you knew the DC rating, and they matched your purpose, they would be OK).
Is there a way to test these outside of the Crack? I've got a DC power supply. Actually several of them, but they are admittedly relatively low voltage (one goes up to 12 or 18V, the other is 34).
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Ok, rated for 450V AC can, but doesn't necessarily, mean 636V DC. Since we are talking about Crack here, the steady state DC is 170V. The AC from the power transformer is 150V but paralleled to give double the current capability.
I'm still at try one to see. Otherwise what are you going to do with it? Throw it away? Wouldn't you want to see if it explodes first? Protect your eyes and face.
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Otherwise what are you going to do with it? Throw it away? Wouldn't you want to see if it explodes first?
I'm pretty sure my mother warned me about guys like you! And I sense strong potential for you to be my wife's new best friend when she gets the payout on my life insurance policy...
I guess I'm OK testing them, but I would rather do it someplace away from the Crack...and my house...and my face, eyes and other body parts I've grown rather fond of...hmmmm.....
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I have a story about that... When I was playing around with the "secondary" crossover for my subwoofer, I was using one of the 220R 1/4 watt resistors from my stash to experiment running parallel with a 22uf cap to crossover about 40hz. The resistor didnt seem to get hot during normal low/medium level listening, so I left it there. One night we were watching a blu-ray that had some good explosions etc and there was a flash and a pop from the sub amp area. It was such a tiny resistor I really didnt care if it exploded like that. Kind of fun actually! - so I put another one in...
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LOL, too funny!
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I dind't seen anybody mention it, so I will say again that motor start capacitors have no place in any tube circuit (though I think they would be OK in a speaker crossover).
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I dind't seen anybody mention it, so I will say again that motor start capacitors have no place in any tube circuit (though I think they would be OK in a speaker crossover).
My wife is decidedly disappointed that I won't be trying Grainger's experiment. She was already looking for real estate in Monte Carlo...
Thanks for saving me from my foolish ways, Paul!
Adam
P.S. Eric, why are my estrogen levels suddenly rising?
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No worries Adam. At one point, I accidentally used a couple of motor start caps that weren't well labelled. Four of the twelve blew up all at once. I was running them with just under 200V DC total, across a string of four caps per bank that had 165V stamped on them.
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On the "OLD BOARD" there was something called a PDMPS, a third stage of filtering. It stood for Pseudo Dual Mono Power Supply. I did this with my FP 2 adding a couple of 100uF "Oilers" motor start caps. I just put another 1k resistor between the mono power supply output and the oilers. Then the two power supply rails went to the right and left channel.
It did improve the sound.
...'splain this more pleeze.
Is this something that would be suitable for the Crack? Or any other Bottlehead headphone amps?
Also, when I install the oilers in place of the last power supply cap, do I need to / should I install a bleeder resistor? If so, what values are recommended, and where do they go?
Best regards,
Adam
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Does the bleeder resistor get installed across the terminals on each cap? And I assume it should be fairly high value in order to dissipate charge quickly?
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Whoa, it's not a bleeder. Don't do this until you better understand what it is. The idea was from Paul Schwerman, aka Voltsecond. He simply split the single final filter cap into two, with one supplying each channel. The resistor was an additional "R" to create an additional pole ,i.e., RC, with the added cap. I imagine that there is a link to the original article somewhere.
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Sorry, I should have been clearer. I was combining two thoughts in one post. To clarify:
1. I was asking Grainger to explain his reference to the PDMPS.
2. I plan on installing two 100uf motor run caps in place of the last electrolytic in my Crack. I'm wondering whether I need to install a bleeder resistor for safety purposes.
Regards,
Adam
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Re: #1, above: Information on the PDMPS for the Foreplay is available here (http://www.siteswithstyle.com/VoltSecond/PDMPS/pseudo_dual_mono_foreplay.html).
So now I'm just looking for guidance on #2.
Thanks,
Adam
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The PDMPS is well explained in text and schematics here, it is VoltSecond's site:
http://www.siteswithstyle.com/VoltSecond/PDMPS/pseudo_dual_mono_foreplay.html
You turn a CRC filter into a CRCRC, with an additional RC for each of the channels. Hmm, that isn't clear. So the stock CRC stands. After which you attach two 1k ohm resistors. Each of those feed another 220uF cap, one end of each cap grounded, the other end attached to the 1k resistor and feeding the power supply for each channel. What it does is adds a third stage dedicated to each channel. It is a good thing if you also make the last cap a lower ESR cap. Motor Run and Film caps are good here. I am not looking at the schematic here but if the second stage Crack power supply cap is a 220uF you can add a film 150uF and it will make a positive difference.
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My 100uf oilers arrived today. It may be pure folly, but I have to admit that I find them SEXY!
Can anyone answer my question above? Should I install a bleeder resistor for these caps? If so, what value/kind of resistor, and where/how should I install them?
Best regards,
Adam
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The current bleeder will discharge all the power supply caps. It usually is a 249k Ohm resistor connected from somewhere in the CRC chain to ground.
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Thanks, Grainger. Can anyone tell me if this (http://www.elektronik.ropla.eu/pdf/stock/dokumentacja/ikar/1k5604%20lnf%20p3b-200-30%20pag%201%20of%202.pdf) is a metalized polypropylene cap suitable for use in the Crack's power supply? I think it is, but confirmation would be welcome...
Thanks!
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The cap has one terminal on one end, and two terminals on the other end. Do that mean anything?
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Well, I now know it is metalized polypropylene, and I know it is DC rated. I also know it is not a motor start cap. So the only open question is whether it matters that it has two terminals on one side...
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Hmmmm...could it be an HVAC cap? If so, any reason not to use one?
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That could be a terminal, or just a mounting stud, but the datasheet you linked to isn't very specific. It would seem reasonable that the bottom stud is not connected internally, especially since this is a motor run cap.
-PB
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Thanks. Here is a picture (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230968898220&ssPageName=ADME:X:RTQ:US:1123). I think I'll buy a couple and try them out...
Just to confirm: it is OK to replace the 220uf electrolytics in the power supply with 200uf film caps, right? Would a 250uf cap be better?
Best,
Adam
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The ebay listing says 420vDC but the data sheet says 420vAC. The data sheet says metalized but does not say what is metalized - polyester, polypropylene, dried snot, kleenex, who knows?! The maximum 5kHz frequency makes me suspect it might not be polypropylene - not clear why you "now know it is ..."?!
Sorry, I'm just a suspicious SOB. It's cheap, give it a try - the worst that can happen is a blown fuse, and a REAL Bottlehead buys them by the gross at Costco! :^)
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200uf should be close enough. The data sheet calls out a "Fixing stud"
fixing: Stud M 12 x 16 mm
Maximum torque (fixing) 10 Nm
Case Material :
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I found this data sheet (http://www.dacpol.eu/en/power-capacitors-142/product/capacitors-for-ac-filters-lnf-series), which shows they are polypropylene. I agree it is odd that the data sheet doesn't mention the DC rating, but the label on the cap itself does show a DC rating (you can see it if you enlarge the picture in the eBay listing). The seller confirmed that they aren't motor start caps.
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200uf should be close enough. The data sheet calls out a "Fixing stud"
fixing: Stud M 12 x 16 mm
Maximum torque (fixing) 10 Nm
Case Material :
Great. Thanks, John.
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Well, I've now got four of them on the way to me. Worst comes to worst, I can add them to my growing collection of unsuitable 200uf caps. I recently received a call from a dealer in Miami, who said he had an eccentric client with a pair of mint, 200uf metalized Kleenex caps available for the right price. Apparently these are fairly unusual, since they still have pieces of vintage snot on them. I'm afraid I won't be able to resist that siren song. The second mortgage on my house should be approved any day now, and then those caps WILL be mine!
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The data sheet says metalized but does not say what is metalized - polyester, polypropylene, dried snot, kleenex, who knows?! The maximum 5kHz frequency makes me suspect it might not be polypropylene - not clear why you "now know it is ..."?!
Hey PJ,
If I roll you some copper foil/kleenex caps and pot them in mineral oil, can I put them in your BeePre? ;)
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200uf should be close enough. The data sheet calls out a "Fixing stud"
That's what we call PB when he's doing repairs for customers.
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That's what we call PB when he's doing repairs for customers.
+1 ;D
Cheers,
Geary
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I still offer my, Earwax impregnated, Gum wrapper caps.
Available in copper or Spearmint...John
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So the 200uf Icar caps arrived today.
THEY.
ARE.
MASSIVE!!!
We will see how they perform, but they make me laugh just looking at them. Here is my question: the terminals are massive bolts with chunky nuts that screw onto them. I'm trying to envision myself soldering leads onto there, and I just don't see it happening. I've got to believe my soldering iron would just lie down and call "Uncle". Any advice? Should I try it anyway? Or do you think I can/should just wrap the stripped tip of the lead onto the terminal and cinch down the bolt? Is a physical connection enough here?
I'm cautious about attempting to solder leads on, as I don't want to get solder in the terminal threads and thereby render it impossible to screw a bolt on if I need to.
Pictures to follow when I get a chance...
Best,
Adam
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I'm cautious about attempting to solder leads on, as I don't want to get solder in the terminal threads and thereby render it impossible to screw a bolt on if I need to.
Try something like this.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi576.photobucket.com%2Falbums%2Fss207%2Fcorndog642%2FDynaco%2520ST35%2FIMG_7782_zps63cb086b.jpg&hash=d8f37d7339b78dc62009a1ca11dc0125da00e39b)
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I love that stuff! Big ass peaces of wire welded on. Solid!
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Rob
Just so I understand, what is the benefit of doing it that way? Isn't that essentially the equivalent of wrapping the lead directly around the terminal? The copper wire you soldered the leads to is just physically connected to the terminal right? Or have I misunderstood?
Thanks,
Adam
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It's not welded on. I took a piece of 16awg copper and made a ring terminal. Multiple ring terminal. So there.
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You guys do know that then make terminals, right? Look like washers with a solder tab on one side? There are some in our kits, for instance the safety ground lug. Hardware stores have them. :^)
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Yeah, but mine is made of 16awg OFC so it's better!!! Audiophile approved.
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Very funny, Mr. Joppa. ;)
But is that any better than just stripping 2-3 inches of insulation off the end of the lead, wrapping it around the terminal a couple times, and then cinching down the nut to hold everything in place?
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There are many ways to skin a cat.. In the end, you have to feel good about it! If I dont feel good about something, its only a matter of time before I tear it apart for no real good reason!
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But is that any better than just stripping 2-3 inches of insulation off the end of the lead, wrapping it around the terminal a couple times, and then cinching down the nut to hold everything in place?
Technically, no. But if I want to disconnect the wire I don't have to loosen the nut and unwrap it.
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Got it. Thanks!
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As promised (http://www.bottlehead.com/smf/index.php/topic,4744.new.html#new).
;)
Adam
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Go to your hardware store. Buy some ring terminals that will fit onto the studs. Crimp the wires onto them, solder over if you are as compulsive as I am. Then you have what you need.
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I think I'm going to try and mount the oilers upside down on the top of the chassis using brackets, and then attach the big blue caps at the back. The brackets I have are just slightly too big for the metal can oilers, so I need something to fill the gap that is preferably slightly "tacky" to avoid having the caps slide around. Something like a piece of bicycle inner tube would probably be ideal, but I happen to have a piece of styrofoam-like material that is the perfect thickness, density and degree of tackiness. It has a fairly small, regular and tight cell structure (it is a sheet of foam material that the oilers were wrapped in when they were shipped). Does anyone know whether this stuff is likely to degrade over time? I'm thinking about shrinkage, compression, brittleness, flaking, turning into goop, etc. I realize this is a wild shot in the dark, so I'm not really expecting anyone to know the answer to this.
Best regards,
Adam