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Crack;Bottlehead OTL


ironbut
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Hi guys,

Got a Crack coming in as my first DIY build to write an article on. I'll do the basic build first, then the Speedball upgrade.

Then I'll no doubt re-read this thread and start making a friggen $1000 amp out of it with all the good ideas here.

Thanks for the great thread! No noise Head-Case FTMFW.

Not a Crack, just crack. Bottlehead is what got me completely in to DIY and tube audio, God bless 'em. Enjoy the ride, Tyll.

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Hi guys,

Got a Crack coming in as my first DIY build to write an article on. I'll do the basic build first, then the Speedball upgrade.

Then I'll no doubt re-read this thread and start making a friggen $1000 amp out of it with all the good ideas here.

Thanks for the great thread! No noise Head-Case FTMFW.

Hey Tyll,

don't forget about the Bottlehead forum. Tons of great info there too!

http://www.bottlehead.com/smf/index.php

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  • 2 months later...

another +1 on this amp.... It's really good for the money and very easy to put together. The steps are layed out and explained very well. So well in fact that I lett my 11 yo son solder a few joints and this has now peaked his interest in the DIY arts.

It sounds really good with my 250 ohm darth beyers. The sound quality was the same as some amp designs that I've thrown hundreds of dollars of caps at let alone the full cost of building them. I cant wait to try the speedball upgrade

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  • 5 months later...
  • 2 months later...

after a year or so with this amp, my cbs/hytron 5814a seems to have stopped wanting to play clean noise. too much static and warbly noises continuously. Reseating the tube would help for a minute but once the tube warmed up, the noise would come back. I don't want anything too expensive as I already have a slew of tubes for the amp but I loved the sound of the hytron. is there anything similar to the tube anyone can suggest? i will probably get one of the hytrons as they aren't too costly but something new/similar to try out would be reasonable.

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If it sounds like static and isn't the bubbly, popping sound (which is usually a tube gone gassy), it could just be the pins have corroded a bit.

One sure cure for that is to clean the pins with metal polish. I use my Dremel tool and Mother's Aluminum and Mag Polish (at any decent auto store). If you have a Dremel, cut a Q-Tip in half and insert it into the small mandrill chuck, dab a bit of Mother's on it and polish each pin for a few seconds. Clean the residue with a clean swab, put your favorite contact enhancer on (I use Pro Gold) and call it done.

In low noise applications (phono pre etc) you'll often get a few dB less noise and any contact related noise is histo'.

It's kind of a "poor man's" gold pin.

Oops,.. forgot to say to give a Mullard/Amperex 12au7 a try. Since you just need a single, you can get some pretty decent prices on them. A real smoothy.

Edited by ironbut
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I have both of the suggested ones. The bugle boy and the black plate mullard set me back a fair bit but the 421a and the 5814a seemed to sound the best - probably why they stayed in as a combo for over a year. I have the bugle boy in right now and its a very very clean sound. I don't want to call it clinical but it is colder than the hytron. Don't have a dremel tool but do have a drill. I'll see if I can hack up something from it. Or perhaps ask around my neighbors.

Might throw in some 5998 or a 6AS7 for a different flavor tonight since I changed the input tube too.

Needless to say a much cleaner sounding amp with the input tube replacement.

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  • 2 months later...

If you have a Dremel, cut a Q-Tip in half and insert it into the small mandrill chuck, dab a bit of Mother's on it and polish each pin for a few seconds. Clean the residue with a clean swab, put your favorite contact enhancer on (I use Pro Gold) and call it done.

Good stuff. I tried to find a way to do this without the Dremel, no dice. This is a "why didn't I think of that" technique. Excellent!
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  • 3 years later...

I hate to revive a zombie, but I finally had a chance to hear the Crack/HD600 paining. Wow! What an amazing value for the price.

It looks like Bottlehead has just launched an upgraded crack: http://bottlehead.com/product/crack-a-two-a/

I'm thinking the Crack-a-two-a will be a nice little project. I ordered a kit and I'm looking forward to breaking out the iron and getting to work.

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  • 1 month later...

Really fun little amp. I'm looking forward to getting to A/B it with an original Crack/Speedball.

It is amazing how different it sounds from the SuSy Dynalo. If I had to pick one, it'd be the Dynalo, but I don't and won't. It is a fantastic change of pace amp and makes super relaxing pairing with the HD650s.

tse3M5u.jpg

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  • Like 5
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  • 1 year later...
  • 3 weeks later...

since I've mostly listened to the Stax 009 system. It's time to find a new owner that will love this bottlehead crack2 atwoa as much as I do.

If you guys are interested in the full upgraded version of crack-atwoa... and also looks sexy like the one above, just PM me :) 

Thanks

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  • 10 months later...

Not trolling at all.

Considering they're all 12au7/6dj8/6sn7 driving a 6080 in otl, I thought they were a bit related, electrically, and was curious what the differences were.

I joined here hoping to pick up some diy amp building knowledge that isn't around anywhere else, and I didn't know where to start... 

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Ok, I'll take it easy on you.

No one but you knows which three amps you're trying to compare.  Naming manufacturers is not specific and technically, Pete's not a manufacturer.   He has, at times, produced commercial products under at least two names (Wheatfield and Apex) and has also published numerous DIY designs.  At least a couple use 6080 (or pin-similar) tubes on the output.  Woo has made so many amps I couldn't begin to guess which you're talking about but I don't have schematics for any of them.  I'm not going to give any thought to Darkvoice.\

Second point - if you want DIY advice that's fine.  Asking us to compare commercial designs isn't a great start.

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