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moe29 11th June 2003 03:35 AM

my SOZ with Regulated PSU...
2 Attachment(s)
I decided to try and build a regulated PSU for my SOZ after
reading the Zen Variations part 3. I figured the PSU line art
for the BOSOZ project would work fine, since the two circuits
are so similar. The two transformers i have are 250VA with
12 volt secondaries. The changes i made were upgraded bridges
(of course) C1, C2 are 10,000uf - R101 1500 ohms R102 221 ohms
per the Zen V3 schematic for a 10 watt SOZ. C103, C105
remained 10uf as in the BOSOZ circuit.

i'm getting 30 volts in to the PSU and approx 22 volts regulated

I haven't seen any other SOZs with a regulated PSU. I was just
wondering if i have enough capacatence at C1,C2. Should a
parallel some more 10,000 uf caps? or is enough, enough?

the picture below is the amp on the bench. the bridges will
be attached to the alluminum chasis when made. They were
getting quite hot on the small heatsinks shown after about
20 minutes. I seem to have enough heatsinking for the rest
of the circuit. I'm gessing approximately 8 to 9 watts.

Final chasis and finished pics soon.

this is a little premature, but big thanks to Mr. Pass for
sharing such great ideas with us. I wouldn't be dabling in
DIY if it weren't for him. Thanks to all the regulars on the
forum for your input and advice. special thanks to Pedro,
Grey Rollins (wish you were here) and Peter Daniel.

jam 11th June 2003 03:42 AM


Did the regulator help the sound?


moe29 11th June 2003 04:46 AM

spent tonight getting the DC offset down to under 50mv...

will do some actual listening tomorrow. It's just kind of
"thrown together" right now... will do quality final wiring
and such once chasis is finished.

the unregulated version was 5 watts with CLC filter. It was
dead quiet. no hum. sounded great. but could've used a
little more power.

JOE DIRTŪ 11th June 2003 05:05 AM

MOE looks like you have a start to a winner there....your caps will suffice....those are damn big heatsinks Bro


Mad_K 11th June 2003 05:29 AM

Good job! Looks very nice; let us know how you like it;)

Henrik 11th June 2003 06:28 AM

Nice work!

Regarding regulated PSU, take a look at my SOZ scematic, itīs the same PSU that I uses in my X-SOZ.
In the following posts there is some discussions on PSU capasitors.

Netlist 11th June 2003 07:15 AM

Nice job Moe,

Can't wait for that quality wire picture. ;)
Keep us informed.

/Hugo ;)

ThomasLMcLean 20th June 2003 03:41 PM


How did it all come out? Did the regulated power supply make a difference, and were you able to get more power?

I like the SOZ design and am interested in your results.



moe29 20th June 2003 06:31 PM


- I did get more power with the transformers i had on hand
by regulating the PSU. Originally i was building the amp as two
mono-blocks - with CLC unregulated PSU. The transformers are
250VA with 12 volt secondaries. I was getting approx. 15V rails.

Then i was reading the Zen V2 & 3 articles, and just on a whim
decided to try to build it a regulated power supply. So yes i'm
now getting more power - approx 22V rails... not quite the 10W
power supply noted in the Zen V3 article. I'm not sure, but i hope
the transformers are good enough at 250VA for this supply.

I would love to be able to tell you some more about the sound,
but i've only been able to listen to the amp as it was pictured -
on the test bed. I'm having trouble building the chasis and
finializing the project. I'm sure it will sound better sans alligator
clips and better grounding/shorter leads, etc.

But, i was happy with the sounds it was making, even in the
sorry state it's in right now! I am going to add a bit more
capacitance to the PSU. Maybe up to 40,000 uf for each phase.

I promise to give a how it sounds report when it's completed.
exscuse my early posting of the project, i guess i was just
excited that it worked! and had to share.

more soon,


ThomasLMcLean 20th June 2003 06:51 PM


Thanks for the report. Your excitement gets me going also. I like the SOZ design, and 10 to 15v watts would be about right for what I want to do. I am also consider current sources in place of one of the sets of resistors.

Again, thanks for the posts and we are looking forward to your next report.

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