Vinyl Asylum

"Output decoupling"?

24.27.41.140

Triode_Kingdom

In Reply to: RE: Phono stage kit posted by Alex M on August 24, 2025 at 10:44:26

I think avoiding the Elekit for the reasons you've cited will raise your cost, but not the sound quality. Do you have a schematic for the PS-3250 that would allow some discussion regarding the topology? I only build with tubes, but my experience with solid stage design goes back several decades.

Follow Ups:

RE: "Output decoupling"? - Tre' 06:50:05 08/25/25 (5)
When you run an op-amp (at least some op-amps) from a single ended supply, instead of a +/- supply, half of the supply voltage shows up at the output and you have to use a coupling cap to block that DC

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
- OK, but that's not "decoupling" - Triode_Kingdom 16:44:59 08/26/25 (2)
  The capacitor in series with the output would be a coupling cap . A decoupling cap would be one of those used to bypass AC to ground at the VCC and/or VSS terminals.
  All this aside, the Elekit PS-3250 page states the following:
  A positve and negative voltage generating circuit is on-board for the power unit, and high quality sound and wide dynamic range are secured by supplying +/- 15V for OPamp .
  This would appear to contradict the OP's understanding of the unit.
  
  Edits: 08/26/25 08/26/25
  - RE: OK, but that's not "decoupling" - Alex M 00:25:22 08/27/25 (1)
    My typo - of course I meant "coupling".
    
    Alex
    - RE: OK, but that's not "decoupling" - Triode_Kingdom 09:33:21 08/29/25 (0)
      Right, but it seems you have also misunderstood the topology of the Elekit. The supply isn't single ended, according to the manufacturer.
      
      There's also the ZinAmp, which is available both kit and assembled. The company is in UK, so no import duties. I doubt this is superior to the Elekit, but I don't have access to a schematic for either, so impossible to compare.
      
      ZinAmp Phono (Open in New Window)
- RE: "Output decoupling"? - Alex M 12:25:14 08/25/25 (1)
  Precisely that. A single rail circuit requires a coupling cap at the output, which in this instance is either an electrolytic or a relatively bulky film cap. I am looking for a compact enclosure, and that makes the latter choice impractical.
  
  Alex
  - RE: "Output decoupling"? - Tre' 08:29:19 08/26/25 (0)
    I power my op-amps with one of these. It's overkill for sure but it works great.
    Tre'
    Have Fun and Enjoy the Music
    "Still Working the Problem"
    
    Edits: 08/30/25

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