Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: ALL212 on May 18, 2015, 03:37:45 PM

Title: Stock Crack vs. Modded Crack
Post by: ALL212 on May 18, 2015, 03:37:45 PM: I picked up Crack #2 during the recent sale and now have a 100% stock Crack to compare to my modded Crack. The modded Crack was my 1st BH kit and this new one is kit #7 so I've had some experience working under the hood and my wiring is much nicer. Senn HD650's are used for listening tests.

Modded crack changes:
Wiring - I like cloth wrapped solid core. Only on and directly around the transformer did I use original wire.
Attenuator is an Alps Blue
Input RCA's are Vampire
Input wiring from RCA's to attenuator is Cardas 2x24
2 of the PS caps are Rubicons, 1 is Nichicon
Last cap (Nichcon) is tipped with a 1uf Clarity PX cap
230 ohm resistor is replaced with C-7x choke
PS diodes replaced with Cree Shotkey diodes (not pictured)
Output caps are Clarity Cap PX
Speedball is installed
5998 tube in place of the 6080
5963 Rca long black plate in the 12AU7 spot
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_2862_zpsfbf0qsdd.jpg&hash=a9d1f47c1fa37659261924d67e18a22f3a2ec279) (http://s905.photobucket.com/user/all212212/media/DSC_2862_zpsfbf0qsdd.jpg.html)

Stock:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_3234_zpswchp4seq.jpg&hash=b644507ce4fdc8d2681dfaad9d704442e6d46012) (http://s905.photobucket.com/user/all212212/media/DSC_3234_zpswchp4seq.jpg.html)

I'm hoping to put the o'scope to these and see if I can spot waveform (AC and output) differences. Most immediate apparent difference is bass. The stock unit is very nice to listen to but the bass just jumps out at you on the modded one.
Title: Re: Stock Crack vs. Modded Crack
Post by: grausch on May 18, 2015, 11:39:28 PM: I am very interested to see how they will measure on the o'scope. Would also be very interested to see how both measure with the same tubes, i.e. 6080 and 12AU7 in both.

Once I get some time, I plan to spend some time listening to my Crack to get used to the sound signature again. Once that is done, I plan to start upgrading quite a few parts (err..more than quite a few actually). It would be great to see actual evidence that these do positively impact the performance of the amp.

Cheers,

Gunter
Title: Re: Stock Crack vs. Modded Crack
Post by: Doc B. on May 19, 2015, 05:53:36 AM: atomicbob has some measurements with different output caps in the Crack thread over on Head Fi.

https://www.head-fi.org/t/476650/crack-bottlehead-otl/6795#post_11509819 (https://www.head-fi.org/t/476650/crack-bottlehead-otl/6795#post_11509819)

I will add my usual comment that there is a law of diminishing returns on the addition of boutique parts. It would be wiser to spend $1200 on an amp kit with a more refined circuit design like Mainline than $1200 on gigantic caps from Ukrainian missile cruisers, spider silk insulated wire that has been passed over the thighs of 14 year old virgins and unobtainable tubes of questionable background for a Crack. However I also support the notion of one doing the experiments for their own edification. I waste money on stuff that doesn't improve things as much as the cost would imply as much as the next guy, though not so much in my audio gear these days as my other hobbies. My suggestion is to keep the spirit of the Crack in mind and make sure the mods you do are great bang for the buck.
Title: Re: Stock Crack vs. Modded Crack
Post by: grausch on May 20, 2015, 03:07:17 AM: Hi DocB,

Thank you for the link - do you think I should install some 470uf Rubycon caps in my Crack? ;) Even though I am kidding, part of me is seriously considering it.

Point taken on the diminishing returns and I agree with you on the Mainline. I should note that I really don't expect that much of an audible difference and I am usually quite sceptical that any upgrades will make much of a change in sound. However, as an electronics noob, I have learnt a great deal tinkering on the Crack and planning & researching future upgrades. My dad sure as hell never suspected that I would one day explain to him how a rectifier bridge works! I also have to note that the more I modify my Crack, the more I start to appreciate the original design. Everything is much better thought out than I originally suspected and to my ears the stock Crack sounded fantastic.

Still looking forward to see the results of the o'scope though...
Title: Re: Stock Crack vs. Modded Crack
Post by: Natural Sound on May 20, 2015, 05:14:33 AM: Quote from: Doc B. on May 19, 2015, 05:53:36 AM
gigantic caps from Ukrainian missile cruisers, spider silk insulated wire that has been passed over the thighs of 14 year old virgins

You owe me a keyboard. ;D
Title: Re: Stock Crack vs. Modded Crack
Post by: Alonzo on May 20, 2015, 06:34:16 AM: For a lot of us it's all about the chase. Actually doing hands on work is part of the fun and once the build is done you want to do more. Also it's easier to pay for a upgrade here and there than to kill the beer budget for a large purchase. Having a scope does well to track changes, some of the upgrades I've done really didn't show audible improvements (to me) but it's become a fun hobby (cough "obsession" cough).
Title: Re: Stock Crack vs. Modded Crack
Post by: Paul Birkeland on May 20, 2015, 06:52:45 AM: Quote from: grausch on May 20, 2015, 03:07:17 AM
Thank you for the link - do you think I should install some 470uf Rubycon caps in my Crack? ;) Even though I am kidding, part of me is seriously considering it.
There are some operational/safety concerns with putting more than 100uF per channel of coupling capacitors into the Crack, therefore we don't recommend it.
Title: Re: Stock Crack vs. Modded Crack
Post by: grausch on May 20, 2015, 07:43:54 AM: PB,

Thanks for the warning. I was considering them in the PS as per this thread (http://bottlehead.com/smf/index.php?topic=7950.0) and not as output caps.
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on May 21, 2015, 05:43:34 AM: Quote from: Doc B. on May 19, 2015, 05:53:36 AM

I will add my usual comment that there is a law of diminishing returns on the addition of boutique parts. It would be wiser to spend $1200 on an amp kit with a more refined circuit design like Mainline than $1200 on gigantic caps from Ukrainian missile cruisers, spider silk insulated wire that has been passed over the thighs of 14 year old virgins and unobtainable tubes of questionable background for a Crack. However I also support the notion of one doing the experiments for their own edification. I waste money on stuff that doesn't improve things as much as the cost would imply as much as the next guy, though not so much in my audio gear these days as my other hobbies. My suggestion is to keep the spirit of the Crack in mind and make sure the mods you do are great bang for the buck.

I find it much easier on my mental circuits and current budget to blow up my Crack and have to repair it than blow up a Mainline whilst playing with updates and wonder "how much to fix this"? As far as wisdom goes...discuss that with my wife, she has made observations over the years that may put any wisdom I might think I have in serious question. :o

I've built some kits and the directions are fantastic but I find myself wondering at the end of the build why does all this work. If I piece out a bit of it (power supply) I can work my way back into the circuit and have some understanding of what goes on in there as I do updates and mods. This power supply filtering is a great learning experience for me.

I also would want to buy a pair of expensive headphones to match the Mainline. I would always wonder if my HD650's would sound as good as HD800's so my budget feels safer at the Crack + updates level.

Might I also start a new thread with a "Doc Says" title and put your requirements for a good upgrade in there?
Doc says, "...gigantic caps from Ukrainian missile cruisers, spider silk insulated wire that has been passed over the thighs of 14 year old virgins and unobtainable tubes of questionable background..." would be a great upgrade to your Bottlehead Crack kits.
OK...maybe a bit out of context... ::)
Title: Re: Stock Crack vs. Modded Crack
Post by: Doc B. on May 21, 2015, 06:22:22 AM: Well I could probably be making a lot more money if I just put my scruples in the cabinet in the lab. Maybe our next product will be the audiophile grade clip leads we have been talking about for years. I have also wanted to make paper and wax capacitors with ear wax from mastering engineers. And I lose the argument to make a tube powered solder station every design meeting.

Maybe instead we will start a service of replacing the vacuum in your vacuum tubes with fresh vacuum every year. I've got bottles full of the stuff in my basement, some of it rare vintages. We could maybe even do transplants, like put 300B vacuum in EL34s.

"I started out with nothin', and I still got most of it left" -Seasick Steve
Title: Re: Stock Crack vs. Modded Crack
Post by: ZacharyP on May 21, 2015, 06:44:17 AM: Quote from: Doc B. on May 21, 2015, 06:22:22 AM

Maybe instead we will start a service of replacing the vacuum in your vacuum tubes with fresh vacuum every year. I've got bottles full of the stuff in my basement, some of it rare vintages. We could maybe even do transplants, like put 300B vacuum in EL34s.

"I started out with nothin', and I still got most of it left" -Seasick Steve

Best post all year :D

First bottlehead to build a tube powered soldering station wins...Doc's heart?
Title: Re: Stock Crack vs. Modded Crack
Post by: Strikkflypilot on May 21, 2015, 06:45:06 AM: Wouldn't recommend ear wax, Doc.
It's full of hair and epithelial surface cells.
Of course, there might be genres that would profit from it:)
Title: Re: Stock Crack vs. Modded Crack
Post by: Alonzo on May 21, 2015, 07:23:36 AM: Or a Jacob's Ladder power indicator, would put those wimpy vintage lights to shame...
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on May 21, 2015, 08:28:45 AM: Quote from: Doc B. on May 21, 2015, 06:22:22 AM
And I lose the argument to make a tube powered solder station every design meeting.

Maybe instead we will start a service of replacing the vacuum in your vacuum tubes with fresh vacuum every year. I've got bottles full of the stuff in my basement, some of it rare vintages. We could maybe even do transplants, like put 300B vacuum in EL34s.

"I started out with nothin', and I still got most of it left" -Seasick Steve

Not embarrassed or shy to say that I would pony up for a vacuum tube solder station right now! As long as I could upgrade the caps in it...

Vacuum tube vacuum replacement....I like that! ;D ;D ;D
Title: Re: Stock Crack vs. Modded Crack
Post by: SCompRacer on May 21, 2015, 09:32:22 AM: I'd be interested in a warmer summer sounding vacuum instead of a cold winter sounding vacuum.

Nice Crack builds Aaron!
Title: Re: Stock Crack vs. Modded Crack
Post by: Paul Birkeland on May 21, 2015, 11:06:22 AM: Quote from: ZacharyP on May 21, 2015, 06:44:17 AM
First bottlehead to build a tube powered soldering station wins...Doc's heart?
If you could build an all-tube soldering station with tube based temperature control, I'm quite confident that Doc B. would come up with some kind of ridiculous award.
Title: Re: Stock Crack vs. Modded Crack
Post by: 2wo on May 21, 2015, 06:00:47 PM: He threw that some years ago, don't think anyone bit...John
Title: Re: Stock Crack vs. Modded Crack
Post by: Doc B. on May 22, 2015, 06:17:03 AM: Actually one guy did. I think we worked out that the thyratron chosen might have been a little underpowered. Plus the guys all thought the thyratron control was useless without temp sensing and nobody wanted to work out that part of it.

This would be similar to my talking to John Swenson about an all tube DAC many years ago. Not tubes tacked onto a DAC chip, a real honest tube demux with tube flip flops running into a resistor ladder. John kinda won the argument against when we calculated something like 50 amps required just for all of the tube heaters and a full size equipment rack or two to hold all the parts.
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on May 24, 2015, 07:27:29 AM: Request for guidance:

I've got a Hitachi V222 20Mhz o'scope. I think what I'm looking for is possible differences in post power supply noise of the stock vs. modified Crack and then also any noise or "disturbances in the force" at the headphone outputs (I've no clue what to expect - maybe nothing...). I plan to use an app on my iPhone to generate wave forms to look at on the output.

What spots should I be poking the lead of the o'scope into to find such fun stuff. The output is obvious - I can handle that one ::)!

I think:
1) The 270k resistor in the PS as one spot.
2) Heaters come straight from the transformer so I wouldn't expect differences here.
3) At the headphone outputs.

Should power supply checks be done with a load or should that be part of my experience here? I can rig a resistor across the headphone jack to simulate that.

Any other places?
Title: Re: Stock Crack vs. Modded Crack
Post by: Paul Birkeland on May 24, 2015, 07:31:45 AM: Quote from: ALL212 on May 24, 2015, 07:27:29 AM
I think what I'm looking for is possible differences in post power supply noise of the stock vs. modified Crack
A lot of multimeters will measure AC voltage in the presence of DC, so you may not need the scope for that. Otherwise, you could measure across the 270K resistor.

Quote from: ALL212 on May 24, 2015, 07:27:29 AM
Should power supply checks be done with a load or should that be part of my experience here? I can rig a resistor across the rca terminals to simulate that.
You can do it with both, but I wouldn't expect too much difference at the power supply with loads. Since the headphone jack is the output, that is where you'll want to apply your loads.
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on May 24, 2015, 04:20:51 PM: Crack Stock:

I've used an app on my iphone to sweep from 200 to 20k. Output is take from the headphone jack, input at the RCA. Voltage's are matched.

I really expected to see a voltage drop or some distortion at the exteme's. Nothing - it looks fine end to end.

Video of it here.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2Fth_DSC_3241_zpsclsjomxb.mp4&hash=f993517ace27dc7afb920f31b4abbf85e878907c) (http://i905.photobucket.com/albums/ac253/all212212/DSC_3241_zpsclsjomxb.mp4)
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on May 26, 2015, 03:39:58 PM: I just have not the tools to do the measurements that would reveal the magic. I ran the same scan on the modified Crack with the same tubes and everything looked the same.

Going to close this project down before I blow something up and really regret my curiosity! :-\
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on June 11, 2015, 04:50:06 PM: Added speedball and instead of spending $$$ on some huge film caps for the outputs I tipped a pair of Nichicon electrolytics with some small Solens. Also threw a small film cap on the last power supply filter cap.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_3270_zpskrghjz3d.jpg&hash=905ee706a190aad72040b863f356499ce6bd5ff1) (http://s905.photobucket.com/user/all212212/media/DSC_3270_zpskrghjz3d.jpg.html)

This one is going on the chopping block - don't need two of 'em.
Title: Re: Stock Crack vs. Modded Crack
Post by: Grainger49 on June 11, 2015, 11:47:22 PM: Was this the "Stock" Crack to start with? What did the bypass caps do?
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on June 12, 2015, 01:05:00 AM: Yep, this was Mr. Stock a day ago.

I violated the Bottlehead policy of one thing at a time ....again.... so I'm not sure if the bypass caps help but my soul feels better now that I done did it. I have a box of orphaned parts and the Nichi's and Solens came from there so my immediate cost was some time and solder.

However, bass on this mod is much better. It wasn't noticeably thin on the stock unit unless I switched over to my modded Crack and then it was apparent that the bottom was shallow.

I know the Speedball assists in that area. The big Nichi's were sitting in a drawer next to the Solen's, my ADHD kicked in and BOOM - bigger caps with bypasses installed.

Reason for the upgrades is that I have a buyer - he wanted to know if I could touch it up and put the speedball in without spending the big bucks for those 100uf film caps. This is my attempt at that.

I gotta say again - it's so much fun putting power to these when you're done and finding out that it works. Then put the cans on your head and just sit back and say .....DAMN, that's nice!!!
Title: Re: Stock Crack vs. Modded Crack
Post by: Strikkflypilot on June 12, 2015, 08:24:57 AM: Beautiful looking job!
Title: Re: Stock Crack vs. Modded Crack
Post by: Deluk on June 13, 2015, 12:46:04 PM: Yes that looks "right" to my eyes. Can you give us the exact details of the Nichi's, Solens and the film cap please? My Crack/SB kit arrived a few days ago, so early days for me, but I like to have ideas.
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on June 13, 2015, 02:35:42 PM: Quote from: Deluk on June 13, 2015, 12:46:04 PM
Yes that looks "right" to my eyes. Can you give us the exact details of the Nichi's, Solens and the film cap please? My Crack/SB kit arrived a few days ago, so early days for me, but I like to have ideas.

Forgive me if I chuckle a bit on the "right" part and only for my own sake - I'm just winging it, but it did come out well. 8)

"Men" laws:
1) Bigger has to be better ;)
2) More is always better ;D
3) Adding "stuff" couldn't possibly cause a problem :-\
4) there is no rule 5 :o
6) Film beats Electrolytic (kinda like rock, paper, scissors, type of beat) ???
There are more but I think those are the three (read carefully - this is guy talk) that I adhered to on the tail end of this build.

The proper way of dealing with the electrolytic output caps would be to completely replace them with some mongo (remember Mongo? Knocked a horse out in Blazing Saddles?!) sized film caps that would make it near impossible to put the plate back in the base. I think Doc would say that the proper way would be to add the speedball and quit mucking things up. However, it is quite possible to double the cost of this headphone amp merely by the purchase of such beasts and that was not my intention. In this case a word foreign to me but occasionally referenced by my wife comes to mind...budget.

The stock output caps are 100uf, 65v, 85 degree caps - perfectly suited for the job at hand. Apply Rule 1 - I put in Nichicon PW 100uf, 450v, 105 degree caps - physically about 4 times the size of the originals. And I still did not feel complete. :-[ So I threw in some Solen 1.5 uf film caps in parallel to the replacement caps (see rule #2 and add rule #6). I did keep within the voltage range - I think those were 600v caps ::). This kept me from feeling guilty about not having film caps in the output. Based on those specs I believe the top plate will evaporate before any degradation of the replacement caps will occur.

The thought process behind carefully selecting these replacements had everything to do with what was left laying around after 10 years or so of changing "stuff".

In other threads (and on my own modified Crack) there are discussions on modding the power supply and one easy step is to add a film cap to the last electrolytic (and in some cases folks have applied rule #6 to the last electrolytic cap). What I added in there was a Dayton .01uf 400v cap left over from the Reduction build. See rule #3.

Bass definitely picked up - now, was that due to the speedball or my own carefully thought out and crafted advanced designs?

We may never know... ::)

Side note: I had some "fuzz" (distortion?) on upper bass and some vocals - just barely noticeable. I pulled the tubes from my first Crack (ok...that' really doesn't sound right) and "fuzz" disappeared. I rolled tubes for 24 hours and as a last test put the originals back in - "fuzz" either gone or reduced to unhearable levels. Maybe break in time should be applied.
Title: Re: Stock Crack vs. Modded Crack
Post by: Deluk on June 17, 2015, 10:03:00 AM: Thanks for the numbers. Are "men" allowed to think "small but perfectly formed"? Seems to describe Bottlehead watts for example. ;D
Title: Re: Stock Crack vs. Modded Crack
Post by: ALL212 on June 17, 2015, 01:27:05 PM: I believe that is a phrase straight out of the Bottlehead Club Handbook. Probably page 1. ;D