Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Dr. Soot on March 26, 2023, 02:27:32 PM

Title: Upgrading/Rebuilding my Crack-some questions
Post by: Dr. Soot on March 26, 2023, 02:27:32 PM

Hello folks, so after the immense lessons I learned while installing the Speedball on my Crack, I have decided I want to start over.  I want to rebuild it better and cleaner, kinda like the 6 million dollar man, for those old enough to remember him.  I picked up a couple Audyn 100 uF 400 V caps to replace the Nichicon 100μF 160V capacitors. I read an article on Headphonesty where Doc B suggested this as a good upgrade.  Now I am wondering, is there an equally good upgrade option for the 220 uF 250 V caps on the transformer?  Additionally, any good upgrade options for the resistors?  Are those something that would make a difference?  I figure since I am rewiring it, might as well kick it up a notch while I am at it. 

Lastly, is the power switch an SPST? 

Many thanks!

Doctor Soot

Title: Re: Upgrading/Rebuilding my Crack-some questions
Post by: Paul Birkeland on March 26, 2023, 04:00:24 PM

For the 220uF/250V caps, the UCY caps from Nichicon are about the best rated caps I have found for that job.  There are lots of 220uF 250V caps at places like Parts Connexion that don't provide enough data to even take a wild stab at operational lifetime, so I'd avoid those.  The 270 ohm resistors in the power supply work better if they are inductive, so I wouldn't bother worrying about non-inductive resistors.

There are some good gains from using a stepped attenuator in place of the volume pot.

Title: Re: Upgrading/Rebuilding my Crack-some questions
Post by: hmbscott on March 26, 2023, 06:37:41 PM

I bypassed all my power supply caps with Dayton Audio DMPC-2.2 2.2uF 250V Polypropylene Capacitors ($2.22 ea). I have no idea if they make any difference to the sound, but presumably they can't hurt. They were kind of a pain in the ass to install though, because it's really tight around the transformer.

I also read that article where Doc recommended Audyn Q4 100uF, and installed those too. Again, I don't know if they made any difference, because that's where I started, I never used the stock caps. I will say that it sounds fantastic, but better? That I cannot say. I did have fun though, and that's got to count for something.

Title: Re: Upgrading/Rebuilding my Crack-some questions
Post by: Dr. Soot on March 28, 2023, 09:42:02 AM

If I was to install a stepped attenuator, should I try to match the same resistance as suggested?  100k or so?

Title: Re: Upgrading/Rebuilding my Crack-some questions
Post by: Paul Birkeland on March 28, 2023, 09:56:06 AM

Anything from about 25K-100K will work just fine.

Title: Re: Upgrading/Rebuilding my Crack-some questions
Post by: Dr. Soot on March 28, 2023, 11:15:39 AM

Awesome, thank you as always