Finished my SSMH build some month ago but forgot to post some feedback.
It was my first electronic build, a very instructing experience.
Below are some photos :
Since it was before Beezar kit reissue, this build is based on a Fred2004 PCB (many thanks to him & other contributors).
Some infos :
- It's a 12au7 version.
- My starting BOM was the one in this post : http://www.head-fi.org/t/664191/starving-student-pcbs/165#post_10256930
I made some changes like upgraded output capacitors.
Also, insulation pads for mosefts are not silicon stuff but aluminium oxyde. Anyway it works good, heatsinks are not too hot.
The 4 front LEDs were an attempt to add diode protection for the headphones but are currently disconnected.
- Drilling & adjusting the case can take the most time in the build
If you're working with Fred PCB, my advice is to select a larger case than the small Hammond one I selected : tube socket traces are not centered so I had to air wire the sockets to keep the things centered. Also, PCB was a bit larger than the case so I had to file & grind to slide all the stuff inside.
- After checking for DC at the jack & testing with cheap buds, I can say that this amp drives my Q701 nicely with plently of power (input resistors are 47k, pot 50k).
I had to ground the pot metal body to get rid of noise when touching the case.
Now amp is silent with full size headphones, but I get some noise floor when using <16ohm buds, don't know if I can solve this.
I'm using the 48V cisco PSU.