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Bottlehead Crack?

I have built several Bottlehead kits, some moded some not. My advice is to buy and build the Crack kit stock and use it for a while, then maybe change out some of the parts. Check out the Bottlehead forum and see what actual users have to say about the Crack. I have the SEX amp unmodded and it sounds fantastic. At $200 for a tube head amp is a great deal, I am not a headphone user.
 
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looks like a fun project at a reasonable price point to me.

well laid out instructions, very complete.

you could probably build a china made kit and get more "bang for buck" however I'd bet money you wouldn't be nearly as complete and you wouldn't have decent instructions either.

they also seem to have a good relationship with magnequest, which arguably means they use some reasonable iron occasionally. :)


I find it exciting to see any American company offer nice kits.
 
Give it a go.

You'll be thrilled the very first time you listen to it, and you put it together by yourself.

Check my signature.


Kim
 
Dread31,

My wife bought me the Crack kit for Christmas last year. I ordered the Speedball upgrade at the same time and built the amp with it from the start. It drives 600 ohm Beyer cans most excellently......I have this version of the 770s/880s/990s so know of what I speak.

It is a great first amp build!!! But, I would not want to tackle it as a first soldering project.....too many small bits and pieces for a beginner IMOH.
 
drtechno said:
the only reason I am a little harsh about them is people miss the point with these kits.

they are gear towards education. Not application.

I particularly get their stuff pushed my way by frustrated audiophiles that haven't been trained to solder, or construction techniques and it was all because of parts quality. Some of the cases, tthey did something wrong and I had to fix thier other gear because of the mistakes of the novice.
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Have you heard the Crack -w- Speedball driving some high impedance phones?
 
In November 2008 I was laid off, so with a lot of free time on my hands I decided to get a Bottlehead kit so I could start the learning process about how tube amps work. I chose the S.E.X. kit because as I was looking it was the best deal on the site. They raised the price $100 the month after I bought it.

I took my time building it and had a lot of fun doing it while learning a lot about how a SET amp works. I did not have to design it. I did not have to source the parts. The directions were very clear which allowed a complete novice the ability to build a tube amp and feel really good when it worked and sounded great.

Looking back and knowing what I know now I can say that the basic kit quality was good enough to produce a very fine amp. Of course Bottlehead could have sold it with the Magnequest iron and doubled the price. But the point is they are simply providing a simple platform to build a kit that can be heavily modified into an amp that any audiophool would be proud to own.

I would build the Crack in a heartbeat if I needed a good headphone amp.

BTW, I was only out of work for a month. I am lucky.
 
it's a decent amp. after all the upgrades, it's not so cheap though. i drove a pair of quite low impedance headphones with it and sounded fine. stock parts are very low quality. you might want to use something little better from the beginning.
 
gogofast said:
it's a decent amp. after all the upgrades, it's not so cheap though. i drove a pair of quite low impedance headphones with it and sounded fine. stock parts are very low quality. you might want to use something little better from the beginning.
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The Crack will not drive low impedance phones properly because it is output transformerless (OTL). Which Botthlehead amp are you speaking of?
 
BmWr75 said:
The Crack will not drive low impedance phones properly because it is output transformerless (OTL). Which Botthlehead amp are you speaking of?
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i sold mine because of that reason since most of my headphones are lower impedance. nevertheless, pair of AKG 701's sounded very nice through the crack. it was about the only amp that i could roll bunch of 6080 tubes salvaged from a few tektronix scopes.
 
Well, it'll have to wait a while now. My washing machine gave up the ghost today. Can't complain, it gave me 22 years, everyone retires sooner or later. Even clothes washers.

Anyhow, the new washer cost me $320 on sale. There went my budget for a headphone amp, plus a c-note. Maybe it could be my birthday gift to myself come March?

Dave
 
gogofast said:
i sold mine because of that reason since most of my headphones are lower impedance. nevertheless, pair of AKG 701's sounded very nice through the crack. it was about the only amp that i could roll bunch of 6080 tubes salvaged from a few tektronix scopes.
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62 ohm K701s sound pretty bad with my Crack amp. Per the Bottlehead website "Crack is an output transformerless amp designed specifically for running higher impedance (200 ohms or higher) headphones......".
 
BmWr75 said:
62 ohm K701s sound pretty bad with my Crack amp. Per the Bottlehead website "Crack is an output transformerless amp designed specifically for running higher impedance (200 ohms or higher) headphones......".
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i can only imagine how nicer it would've sounded with higher impedance phones.:sigh:
 
well, no because all my headphones I own are below 100 ohms.

I'm sure it works ok with high impedence headphones because the load is not working into the CCS as much.

For a more educated answer to why I'm not really fond of this amp is self bias was not recommended for the 6as7 and cathode bias via css is in the nonlinear region of the tube and results would differ between tube sections as well as tubes and especially with load.

ccs sort of fixes the nonlinear behavior of the tube (masks it by buffering the output).
but does so at a price of transient response because the circuit reacts to the changes current demand and the hysteresis of the ccs would cause a subtraction to slew rate dynamically.

but I'm sure the 300-500 ohm consumer headphones would probably work just fine.
I would use better parts to build with. As I'm sure they gone away from using cheap power transformers these last 10 years. And of course you are not going to find premium parts in a budget kit like this.
 
BmWr75 said:
Have you heard the Crack -w- Speedball driving some high impedance phones?
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@drtechno and I PMed on this topic and he has not listened to the Crack amp with 200+ ohm headphones for which it is designed.
 
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