your build looks fantastic!
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The onlu high impedance headphones I have are the HD600’s at the moment…and I have other amps that work well with them so I was considering selling it, but its such a nice simple straightforward amp…
I havent mucked with the output caps etc…the ones I have heard with high dollar boutique caps never really made that much of a diffrence to me but things like channel imbalance made me replace the stocl pot with a real ALPS…and its wonderful and its only a $20 item…and its the real thing not a chinese rip off.
The other update is one that cost 2 diodes that are soldered in near the IEC power jack. Real easy to do and all it does it shunts any possible incoming noise RFI etc to graound. In some environments people have phones, routers, pc’s etc near their listening stuff and it sometime causes some slight buzzing, noise etc…again simple, make real sense and works.
But if I eventually get other high impedance cans, ie 120+ ohms then I would just ahve to keep this amp.
And I am in the search for the next set and havent decided etc…
I had Beyer T1’s, T90’s etc and even the T1’s at 600 ohms worked well with the Crack.
Most every DIY project I have done 50+ have all worked the first time!!! One did not, and it was a really cramped, OPA1622 amp design called the “Crocodile”, and it has the latest smallest SMD parts and you cannot hand solder them, its all with a heat oven, or hot air gun ans solder paste…I fried a few parts not knowing this and it was a constant pain to remove and replace…I finally sent it to a friend who wanted to try to fix it!! Its still inoerative! (only cost $15 for the pcb and $50 parts)…oh well thats 49 _ and one -1.
Here it is with the transformer housing painted black:
The ALPS pot install…the pins on the ALPS are small and not recommended to solder directly to them. I have, but if your not experienced you can heat too much and damage the pot, without knowing it until its too late. A small pcb is available from a few sources for $1 or so, you solder to the pcb and wire in etc.
When you do this the pcb extends out about a 1/8 to 1/4" and you have to cut a slot in the wooden base to allow the whole unit to fit back in the base…simple wood tool, dremel etc…to make the notch.
I did not like many paint the etched baseplate, many do and they are really neat. I wanted the old school here is what the BH Crack looks like from Bottlehead.
Ok for now think I will fire it up and listen with the HD600’s this am!!
Alex
NOTE: Listening with the 600’s and Empire Brass, Baroque Music for Brass and Organ, “Trio for Oboe, violin & continuo in Bflat major (Six Trios No.1), TWV 42:B1: Sicilienne”…Fantastic!
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There is a wealth of information at the Bottlehead site…take a look at their forums and under the Crack thread there is a FAQ that has lots of good info on this amp.
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Nice man! I like the look, and thought behind it. I have a real Alps Blue Velvet, on my BHC and it is smooth as silk. I have seen pics of those fake Alps pots.
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I have rolled a dozen tubes in it and my gotos are the beautiful old RCA NOS 6AS7G!! The coke bottle RCA’s are just so neat looking to me!! ha!
When I first got the amp I bought several of these, some were very sensitive to mechanical vibrations, when i typed on the keyboard I could hear it in the amp! I have several RCA’s that are really solid and sent several back…
I have may other types and input tubes as well…5963’s, Bugle Boys etc…most all sound about the same…no real BIG difference and no need to spend $200 for a western electric tube at least thats my experience…
Great amp
Alex
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After many weeks/months of planning this out, researching options, gluing, sanding, dying, finishing,and various prep I finally got the exterior done. I went a very non-traditional route and colored my build rather than keep it a more classic woody look, I’m guessing this is fairly polarizing, but it will be a unique Crack for sure. Anyways, I’m looking forward to the electrics build phase and finishing this up soon.
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Looks cool, I like it. 
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Blue?! BLASPHEMY!!
But I like it.
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this is my poor man’s DNA amp
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Whoa - different but looks cool! Reminds me of those crazy bowling ball colors. @TylersEclectic inspiration for refinishing your OG crack base to look like this (but obviously purple!)?? What did you use to finish the top plate and transformer color? I hope you enjoy the electronics portion of the build, it goes by way faster than you’d expect! I have not been able to find a new project that was as fun as building the crack since I finished mine…
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Here is a fun pic of the BHC base @raindownthunda made and I bought off of him (it was his spare one)
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Hah yeah the bowling ball comparison makes sense now that I look at it that way. I really did want to keep some of the grain swirls coming through so it didn’t look plasticky. The finish is super smooth though, like a bowling ball. And the dyes I bought come in a kit to make any color, @TylersEclectic’s deep purple love would be easy to create. Another cool variation I considered was doing a shou sugi ban burnt look with different colored finishes.
I’m definitely excited about the electronics part, and I’m in no rush to crank this out so I’m enjoying taking my time and really putting the extra effort in. I’m going to try and do a really clean wiring install. I’ll definitely post up once the amp is done.
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I am looking forward to it! It was my first time ever really soldering anything so I want to do another one down the road… so I can have a cleaner build myself lol
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Oh yeah forgot to answer that question. I used Rustoleum Hammered Black spray paint. That was a really easy application and simple to do, I highly recommend it.
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Lovely colour and it’s something a little different too.
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I like it! That looks very unique, and the stain looks great!
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I did the same for mine but in copper!
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Alright ladies. Acquiring a already built crack soon. What’s a must have tube/s?
Comes with some upgraded ones. A Chatham 6080 and a Brimar CV4003, plus whatever stock tubes were.
Be running a Verite Open for the foreseeable future.
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Those are really good tubes you have there! However, the next level up, are the tubes listed below.
For driver tube, there is nothing better than the 7316 Long Plate Foil D Getter. For power tube, there is nothing better than the Bendix 6080wb slotted plate.
Also, for way less money and almost as good of sound for driver tube, look for a Sylvania 5814a triple mica short grey plate square getter.
Of course it depends on your DAC and headphones synergy, but the tubes I listed would work well in any scenario.
Happy Hunting!
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Bottlehead Tube Rolling Thread AT Bottlehead’s Forums
A great source for the search for the “elusive” perfect magical tube!!
Only 140 pages of tube “diving”…
:>)
Alex
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