• Disclaimer: This Vendor's Forum is a paid-for commercial area. Unlike the rest of diyAudio, the Vendor has complete control of what may or may not be posted in this forum. If you wish to discuss technical matters outside the bounds of what is permitted by the Vendor, please use the non-commercial areas of diyAudio to do so.

The Phono Stage

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"
 

Attachments

  • Phono1.jpg
    Phono1.jpg
    192.3 KB · Views: 13,304
  • Phono2.jpg
    Phono2.jpg
    193.9 KB · Views: 12,641
  • Phono3.jpg
    Phono3.jpg
    176.4 KB · Views: 12,185
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.
 

Attachments

  • Bracket2.jpg
    Bracket2.jpg
    187.5 KB · Views: 2,675
  • Bracket1.jpg
    Bracket1.jpg
    185.8 KB · Views: 11,210
  • Bracket.jpg
    Bracket.jpg
    143.5 KB · Views: 11,687
Last edited:
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.
 

Attachments

  • Shunt regulator.pdf
    155.7 KB · Views: 3,945
Last edited:

Attachments

  • shunt reg1.jpg
    shunt reg1.jpg
    21.8 KB · Views: 4,522
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.
 
Hm,

good to freak out PA....and now for the relevant part:

Nice work! I remember TL suggesting something very similar. Maybe he knows something....but I guess, your work is very similar to the 47 RIAA.

That said, what about including some SMD pads for OPA627/637 on the pcb?

J511 and the MJE1530x are the hard to find parts elsewere...any substitutes?

LG Carsten