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Pars

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Everything posted by Pars

  1. The thread on diyaudio might be of interest to you re: OPA828 vs. OPA627. Schitt equipment seems to be well engineered and built, to very attractive price points. Unlike some others in heavy shilling/pimping these days 9<<cough>> Topping <<cough>> https://www.diyaudio.com/community/threads/opa828-opa2828-vs-opa627.400109/
  2. I've never built a T2, so take this with a grain of salt, but anytime I see DC levels bouncing all over the place, one of the first things I would suspect is oscillation somewhere.
  3. Will the 5V LT1021 work in shunt mode? I didn't think it did? Kerry posted a design using a MAX6138 reference which would do 5V back in 2018:
  4. That sounds reasonable in terms of the pots and their action. I couldn't comment on voltage before clipping, but I guess around 2.5Vac for a front end sounds reasonable. Kevin could probably tell you, or maybe the guy building the CFP3s on head-fi (sorry, forgot his name). Glad you found the problem with the opamp socket. That is a strange one.
  5. Are you asking about the bias for the ubal-bal tube stage or overall for the CFP2/CFP3? For the CFP2/3, it is generally 150mA, which is also what I run my DynaFET at. Not sure for the tube stage, sorry.
  6. Happy Birthday Jim! I hope you have a great one!
  7. 16.98V is about what you would get if you had R7 and R8 swapped. Check the positions on the board.
  8. RIP to your friend Jimmy, Brent.
  9. Just started watching this last night (s1e1). Enjoyed it, and will continue.
  10. Interesting. Where is a good source for forming taps?
  11. Happy Birthday and miss you Matt! RIP
  12. The standard audio grade from Toroidy is the same transformer; just not encapsulated. It is screened, etc. just like the supreme, and at least for mine, was half the cost. Mine only took about 4 weeks from order to delivery. I might consider the 100Vac transformer. You might need to deal with some extra heat, and ensure that component ratings are sufficient for that.
  13. I would check with Toroidy in Poland. I had a pair of 6 secondary 100VA transformers done and they were pretty reasonable. Dual primary, 4x24V and 2x8V for either 57 EUR for their standard audio grade or 107 EUR for the audio supreme grade (I went with the audio supreme). They could do your 90Vac and 8Vac with no problems. Shipping was a bit high as is to be expected, but they came in about the same delivered as SumR, who I wouldn't use now.
  14. I would guess that those are for turning on the opto coupler ( CPC1117NTR), same as the normal GRHV's have, for delay purposes. Haven't looked at the schematic for the 100, but for the normal GRHV, you have to apply a voltage to turn it on. You can leave the CPC1117 out if you don't need this feature. I probably wouldn't use mica insulators for something like this (aluminum oxide instead), but I know mica has been used throughout the years for HV applications.
  15. I do recall on the one CFP3 I worked on, half the LEDs were different, so I changed them all out for the correct ones. Later, the builder said he ran out of the normal ones and used what he had. Not the right move.
  16. https://www.mouser.com/ProductDetail/CK/7203SD9AQE?qs=G14F9ppgKfS26PW35gemkA%3D%3D
  17. Measure across 1 resistor only. Then across the other one. Yes the voltage will change as the amp warms up. Ideally, you would do this with the amp cased and having warmed up an hour or so. Some might go as far as having the top on (or partially on) when doing this as well. When I build one, it will run at 30V. I believe Dukei's do as well (at least the one I worked on was running 30V supplies).
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