Dette kan muligens interessere differensialforsterkerkonstruktørene:
Jeg digger:
Jeg digger:
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Whitepaper om Sotas nye phonoforsterkere
- Trådstarter Valentino
- Startdato
Noen her inne har vel sagt det samme i et år eller tre.
Sant nok.
Hi. I'm the "author" of the whitepaper and the designer of the SoTA Pyxi phono stage as a reduced "derivative" of a DIY design that I posted on DiyAudio and Audiokarma.
Sorry that this is in English. Although I had a girlfriend in Bergen 50 years ago my Norwegian isn't up to much.
I would appreciate any commentary on the contents of the Whitepaper. It was necessarily superficial, but was intended to create an exchange of ideas.
Sorry that this is in English. Although I had a girlfriend in Bergen 50 years ago my Norwegian isn't up to much.
I would appreciate any commentary on the contents of the Whitepaper. It was necessarily superficial, but was intended to create an exchange of ideas.
Hi and welcome to HFS!
Thanks for a use full white paper and nice work! Your findings on COG capacitors and elliptic warep-filter are interesting. Concerning A-weighted SN, are the measurements with maximum gain and referenced to 13 dBV out ?
Is this your the thread on diyAudio ?
https://www.diyaudio.com/community/...p-elliptic-filter-line-headphone-amps.362390/
Some of your ideas/findings are convergent with my own «tinkering» on phono-preamp design in this thread:
https://www.hifisentralen.no/forumet/threads/kjs-fjøsmekk-smdd-phonoforsterker.103465/
Its still work in «progress», where the «progress» is some what «relaxed».
Best regards/mvh
KJ
Yes, that was my thread. There are other threads on Audiokarma, where the design continued to evolve.
Ultra high spec. opamp MC/MM phono, warp "elliptic" filter, line, headphone amps. | Audiokarma Home Audio Stereo Discussion Forums
The S/N in the whitepaper is with all gain settings as the gain increments are applied after the RIAA deemphasis stage and the additional noise from the gain block is inconsequential.
The whitepaper is actually for the unreleased Acrux design, and the "rated" output for that is +10dBv, "balanced" or +4dBv, single ended. The S/N ratio is specified relative to that.
For the Pyxi the S/N ratio is specified at +5dBv output.
Unlike your approach, I am not a fan of transimpedance inputs for MC gain blocks. The idea of having the gain transfer function be a strong function of the cartridge/interconnect/input stage input impedance etc. is unappealing to me when equivalent noise, distortion, power supply rejection and signal bandwidth can be obtained using voltage gain only circuits which offer, in my opinion, more degrees of freedom in a sense.
The implementation also strongly depends on maintaining extremely high feedback factors up to and beyond the audio band limit, so only a limited set of opamps are acceptable.
Ultra high spec. opamp MC/MM phono, warp "elliptic" filter, line, headphone amps. | Audiokarma Home Audio Stereo Discussion Forums
The S/N in the whitepaper is with all gain settings as the gain increments are applied after the RIAA deemphasis stage and the additional noise from the gain block is inconsequential.
The whitepaper is actually for the unreleased Acrux design, and the "rated" output for that is +10dBv, "balanced" or +4dBv, single ended. The S/N ratio is specified relative to that.
For the Pyxi the S/N ratio is specified at +5dBv output.
Unlike your approach, I am not a fan of transimpedance inputs for MC gain blocks. The idea of having the gain transfer function be a strong function of the cartridge/interconnect/input stage input impedance etc. is unappealing to me when equivalent noise, distortion, power supply rejection and signal bandwidth can be obtained using voltage gain only circuits which offer, in my opinion, more degrees of freedom in a sense.
The implementation also strongly depends on maintaining extremely high feedback factors up to and beyond the audio band limit, so only a limited set of opamps are acceptable.
Sist redigert:
Thanks for the clarification and lots to read 
I totally agree that my approach, a differential transimpedance input stage for MC, is not a «universal solution». It’s «just» an old idea, inspired by variant of Marshall Leach’s common base head amp https://leachlegacy.ece.gatech.edu/headamp/, that I just had to realize.
mvh
KJ
I totally agree that my approach, a differential transimpedance input stage for MC, is not a «universal solution». It’s «just» an old idea, inspired by variant of Marshall Leach’s common base head amp https://leachlegacy.ece.gatech.edu/headamp/, that I just had to realize.
mvh
KJ
You might find this thread interesting.
The Leach moving coil pre-preamp | Audiokarma Home Audio Stereo Discussion Forums
I did a strip down of the Leach design, together with improvements and, I believe, a more coherent explanation of its operation and issues.
As I wrote " So the bottom line is that it seems to do as well as the sims suggested and that the good prof. Leach's description of how the circuit worked weren't exactly right and you managed to get some insight into that. All in all it seems to have been a useful exercise. Is there some other project that you are excited about now that this one is concluded? " . This resulted in Halfapt and I cooperating on the phono stage.
The Leach moving coil pre-preamp | Audiokarma Home Audio Stereo Discussion Forums
I did a strip down of the Leach design, together with improvements and, I believe, a more coherent explanation of its operation and issues.
As I wrote " So the bottom line is that it seems to do as well as the sims suggested and that the good prof. Leach's description of how the circuit worked weren't exactly right and you managed to get some insight into that. All in all it seems to have been a useful exercise. Is there some other project that you are excited about now that this one is concluded? " . This resulted in Halfapt and I cooperating on the phono stage.