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Peter Daniel 20th September 2009 05:36 PM

The Phono Stage
3 Attachment(s)
I'd like to present here a complete phono stage project. It's been greatly inspired by the original phono cube and if you are interested in the specs, they would be similar (not mentioning the schematic).

In my approach however, I'm using much better parts and much better power supplies. I also wanted to be able to fit everything in a simple 2x3 aluminum tubing enclosure, having the PS integrated with the preamp.

The end result is the phono stage that can compete with basically anything out there, it is so good.

Looking at the board, you may notice that it is same form factor as my both DACs, the size is 2.75 x 8.75"

Peter Daniel 20th September 2009 05:42 PM

3 Attachment(s)
The PS is +/-15V shunt type. It produces quite a lot of heat, and since I wanted to fit it inside aluminum tubing, I had to figure out a smart way for heatsinking. I managed to do that with special brackets that are attach to power devices first and then are bolted from enclosure bottom after the board is inserted.

Peter Daniel 20th September 2009 05:46 PM

3 Attachment(s)
The board sits on standoffs that are easy to install from both ends. Additional angles are used to secure front and rear panels.

Peter Daniel 20th September 2009 05:48 PM

4 Attachment(s)
The complete unit is very simple, yet quite functional.

Phono section schematic attached.

Peter Daniel 20th September 2009 07:48 PM

1 Attachment(s)
Attached is the schematic of a shunt regulator. I tested few other discreet regulator types with this circuit, but the one in attachment worked best.

The regulator can be separated form phono stage through a scoring line. It features completely independent grounds for both sides and can be suitable for many other applications. Of course I will be offering it separately as well. BOM coming soon.

Peter Daniel 20th September 2009 09:34 PM

2 Attachment(s)
Attached are BOM files for both circuits. They were compiled by one of the forum members who already got the boards. The actual cost and parts selection may still need adjustment, but for now, it gives some idea what's involved.

Peter Daniel 20th September 2009 10:01 PM

1 Attachment(s)
The shunt regulator is based on a regulator posted in this link:

I tried it after i was also testing other, similar regulator (as in attachment), as well ALWSR, and this regulator sounded substantially better. Now, that you mentioned it, I'll be curious to try it without a cap as well.

Peter Daniel 20th September 2009 10:08 PM

Another observation: while single regulator shared between two channels sounds fine, going dual mono brings quite noticeable improvement. I was also testing phono stage and regulators separated by 4ft cord and didn't notice any particular degradation. In that case you will need C11/C12 and C4/C5. When all together, C11/C12 can be omitted.

Toaster 24th September 2009 08:10 PM

Looks good. Will you be offering it as a kit or a board only Peter?

karma 25th September 2009 05:39 AM

nice work peter;) if theirs a kit im there. all your other kits still sound great:cool:

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