the_equalizer
1000+ Head-Fier
- Joined
- Jul 5, 2009
- Posts
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- 70
Well I finally built a 12au7 version of this amp, I have been watching this thread for a long time.
My brother turned me onto this project and he had built one with the pcb board and is really happy with it. I too purchased a pcb, but once I started looking for a suitable enclosure I changed my mind and went for a point to point build.
What I came up with is shown in my avatar. I can't upload photos yet, since my account is too new. I will post more when I can. The box is from a Kenwood CB-44 Dual Amp Balancer I found at a local PC recycle center and the heat sinks are just clamp-on style CPU heatsinks mounted to the sides of the box. The volume pot was already a 50k and the power switch made a perfect location for the 1/8" headphone jacks. The box is very tight and the way it opens makes it somewhat difficult to keep some of the leads short. I know the heatsinks may work better if turned 90deg, but there is plenty of heat rejection and I feel it looks much better this way. Another really cool thing about this case is that the volume knob has a lit ring around it that will work as a power indicator.
Using all of the optional components, I found the gain was too high when I use my Shure SE315s and an iPod dock outs as a source. I removed the cathode caps and upped the input resistors to 500k and it seems to be working much better. After removing the cathode caps to floor noise is much less, though there is still a little there.
This was a very cool project, thanks to all who made it possible.
Great to hear you had fun and enjoy your new amp. The gain is hard to control indeed. I've been thinking about experimenting and adding a little bit of global negative feedback, as some builders in the thread mentioned they had done it and it had worked wonders. You might consider doing the same to help tame this little beast.
By the way, as some posters say: pictures of your amp or it didn't happen.
cheers!