I still have some (very small) DC instability on the left channel at the output of the 2nd chip: I can get it to average close to zero, but it’s annoying me, as the right channel is rock solid. I rolled some chips in to see if it was that, but all they did was change the zero point, instability remains. Any other possible culprits?
I'm debating whether I should build a Salas UFSP or a Pete Millett LR. I don't think I'll be running MC anytime soon, simply because of the economics and relatively lower quality of the rest of my chain.
Is anyone having luck running a mid-fi MM cart, like an Ortofon OM series, into one of these?
Edit: the reason I ask is because of @Mark Tillotson's comments about the suitability of using AD757s, on the first page (post 7) of this thread
Is anyone having luck running a mid-fi MM cart, like an Ortofon OM series, into one of these?
Edit: the reason I ask is because of @Mark Tillotson's comments about the suitability of using AD757s, on the first page (post 7) of this thread
I agree with 6L6 of course… And I think that setting up LR for batt power is slick and educational… Salas is a different game there…. Have to build them both to know! Maybe LR first? I recall the cinemags taking a little time to get… not sure the status of an Ultra build… last I checked you had to get on the list for the next run of boards, and one is looking at 2 chassis for that build…
I also built both, the UFSP is very flexible, however you lose very little with the LR. I use my LR with a high output MC cartridge, in my case the key to both of these preamps was matching the cartridge to the load resistor.
Both of these preamps are rock steady after the adjustments, I liked the sound of the AD797 so much, I built a Hypnotize MC preamp using them.
When I built the LR, I had something wrong the first time around. There was hum in the single chassis setup that I could not get rid of. I tried every type of shielding out there but nothing worked. I finally built a second power supply in a separate chassis and the hum disappeared. One thing that I had done differently was to use an upgrade set of IC from Brown Dog. Actually they were not upgrade, being that it was the same 797 OPA. Funny thing was that they got even more hum than the originals.
That's pretty creative, nice work.
What are your impressions after listening to it?
Nice work. Your amplification sections look like they are transistors rather than op-amps...FETs I would imagine. Can you share your amplification circuits?
I am really on board with the idea of using discreet transistors in place of integrated circuits. That is one thing that stood out to me here. The best part though was the neatness of the wiring ground path. Sounds funny I guess but when neatness is attended to in a build, it inspires confidence.
Actually, I've figured out what those are - Staccato discrete op-amps. Not cheap.
https://staccatoaudio.com/portfolio_page/osh-s-open-sound-hybrid-single/