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^ Yep. I attached some pics below. The last one with the 4 caps in a row next to the heatsinks are the caps that are running at 40V in the schematic. They don't appear to have leaked from what I can see (a bit of flux on the right side). From my experiences working on my Rotel RCD991, boards of this vintage are pretty easy to work on, so other than disassembly/reassembly, this might not be that bad. The schematic/service manual seems to be missing sheets 12-14 of 16, and I note the volume control (black box) is not shown on these, unless I am missing it. It is supposed to be a 60 step, and I assumed relay based as the volume control itself feels like an encoder. I haven't taken the front panel apart yet (not sure that I will) to see if anything is hiding in there in terms of electrolytic caps. Also, I was looking the amp section schematic over. This appears to be DC coupled. In the snip below (sheet 10), shouldn't there be a V- connection (-24V) at the bottom? I only see 1 rail being used, but filter caps on what I think should be the neg rail...

I came home from out of state on Sunday and noticed my preamp display was awry (L-R arrows flashing, mute on, front panel non-responsive). Last night I took a look at it and it seemed to return to normal upon running signal thru it (CD->pre->headphone amp). This is a Classe CP-50, probably mid-90s vintage. From reading the owners manual, the display I was seeing is what is supposed to be there after a power outage, but I thought after 45 seconds or so it was supposed to go back to normal? At any rate, I have it open now and think I will recap it. Most, if not all original caps are Nichicon VX(M), 85C, standard series, 2000 hour life (from what I can tell). This thing is a cap farm . My goal is to a) match the original size/lead spacing if possible for good fit, b) long load life, c) 105C rating. Target cap for me where possible would be Panasonic FR. A few questions: Is Nippon Chemicon any good? The two main PSU caps are 2200uf/63V with 10mm lead spacing. The two I picked were Nippon Chemicon KYB (10000 hr) or Nichicon UPW (8000 hr). I can't find anything worth a shit that has 10mm lead spacing; these are 7.5mm. I'm also pretty sure they are not snap-in as they are Nich. VX. For the above, I have some Panasonic TSHA 4700uf/63V snap in at 10mm spacing. I could straighten the leads and file as necessary to fit. Is going up to 4700uf too much increase? Note the 35V caps in a 40V circuit... haven't measured yet to see if it really is 40V. I'll replace these with 50V Nichicon UPW I'll probably have more questions as I go on. This thing has a lot of premium parts in it, such as (10) 2SJ109BL, 2SK79/2SK216, etc. Sounds good as well. Probably not as good as the Aleph P I had, but good nonetheless. Classe CP-50-TM Service Manual.pdf

There is a 1K on the v1.10 board. Not on the schematic (hence the R? designation). There is also a 22pf cap on the board, also not on the schematic. These appear to be associated with the input as the 1K runs from the input connector and appears to connect to the 22pf. With Kevin's designs, you always go with the board markings

50VA would be fine, though I usually use the 100VA Antek transformers. This is team overkill, after all EDIT: I also ran the sim I have with 35VAC input, and used 4K/2K for R7/R8 for 30V out. The voltages across the 47uf caps was 9V for the first one and 10V for the second. The 10uf had ~16V on it. This is a sim, which may not match real life, but I would think it would be close to actual.

There is a dynamic CFA2/3 as well. Now for something completely different... Sent from my iPhone using Tapatalk

You should be good. I’ll have to look at the one in my DynaFET as it is +/-30V. I think 35V is as high as you can get for the 47uf. I’ll take a look in a sim and see what voltage these are on a 30V supply. Sent from my iPhone using Tapatalk

They are shown as B stock... not sure if that means much for these or not?

Redco.com Sent from my iPhone using Tapatalk

Got one put together, but having a strange problem with it. The output voltages seem fine (and stable). However on startup, D1 flashes and then goes dim. D9 is brighter than either of the negative channel LEDs (D2 or D8). The V drop across the 150R are 1.51V for R1 and 1.62V for R2. Other voltages appear to be approximately the same. I'll have to remeasure the drops across the LEDs. The zeners appear to be similar (~8.9V). Any initial thoughts? Components appear to be in the proper spots. Since I was in a rush to get these made (seeed 30% off), I also hadn't noticed some placement changes vs. the layouts from Kevin, particularly the LED placement is for D1 and D9 were reversed from Kevin's. I have made some changes in my diptrace files since I had these boards run to correct for that and label placements, etc. EDIT: Found/fixed. Somehow I had put a BC559 in in place of an MPSA92 (Q3). Must have gotten mixed in my bag of MPSA92s somehow and I didn't read the labels when building it. Works just fine now (DOH!) EDIT2: This one is for Diptrace users. When I went back into the schematic for this, after making some changes for the LED placement, and to add a pair of 220uf with 5mm LS in addition to the 7.5mm LS caps that were there (Silmics?), I found that the V- net had connected itself to the AGND net (no V- net present). Fortunately, this was not present in the board file I had run. How does this happen? And it wasn't easy/straight forward to fix.

I got a number of hits searching on “pcb busbar”, including this one on stackexchange: https://electronics.stackexchange.com/questions/59735/creating-a-high-current-bus-on-a-pcb (Sorry, Hand-typed, hopefully works. Also, I’ve been out of town and didn’t take a close look at your pics). Sent from my iPhone using Tapatalk

Happy belated birthday!

Happy Birthday!

Maybe just post them to the thread... Still not sure what all the interest is in this, but I confess to not having built one. The SS Dynalo is a better amp from what I understand. Or the CFP2... Sent from my iPhone using Tapatalk

Yes, dropping R14/R29 drops the bias level. Sorry for any confusion in past posts.

You should be OK, assuming you are using the right adapters (don't use the SA1349/SC33xx adapters!). There aren't really any voltages present there that would damage the JFETs, unless the Gate is wired incorrectly.

I probably got it backwards as from what I recall, the 402R biased it hotter than the 422R did. IThe 15mA or so came after it was running for at least 30 mins, more like an hour. Putting the heatsinks on should drop it a bit (couldn't measure, but based on overall current draw of the amp). EDIT: just played around in a spice model, and lowering the LED resistors (R1, R3) biases things hotter.

Yeah, I also like that one a lot. Not quite up to your guys levels, but my wife got me this for Christmas...

Happy Merry Birthday!

Do you mean the ACN (Analog Crossover Network)? That was the only thing even close that I found there...

2SJ109BLs are a tough ask (for genuine ones). You could use singles (2SJ74 or Linear equivalents), or the Linear duals with some lead manipulation. Maybe: https://www.diyaudio.com/forums/swap-meet/320192-toshiba-2sj109bl.html This guy... maybe: https://www.ebay.com/itm/Matched-quad-of-2SK389BL-2SJ109BL-100-original-and-genuine-Toshiba-015-idss9-9/282424664232?epid=593519663&hash=item41c1d260a8:g:2-oAAOSwuxFYtUc~:rk:3:pf:1&frcectupt=true

Happy Birthday Ken!!!

Tangent has an article on his site ( http:// tangentsoft.net/audio ) on building a load box. He used 33 and 330 ohms, but did mention 120 as a third option. Sent from my iPhone using Tapatalk

What they said regarding community participation. As for adding a headphone jack, you could simply wire a pair of RCA plugs to a jack (1/4” TRS). The L+ would go to the Tip contact of the jack, the R+ to the Ring contact, and the Gnd to the Sleeve. If you have room on the faceplate for the jack, wiring it internally would be a nice plus. Not sure how good it would sound, so going the cable route would probably be advised until you determine that. I would also measure the DC offset (L+ to Gnd, R+ to Gnd) before plugging any phones in. 10% distortion at 1000Hz? That is pretty awful if accurate. Sent from my iPhone using Tapatalk

It appears that the 750R / 511R voltage divider feeding the opamp is what sets the gain, but I didn’t find a formula for calculating the output voltage. One guy dropped his to 19V by paralleling a 2k resistor with the 511R. https://www.diyaudio.com/forums/headphone-systems/109618-krell-ksa5-10.html#post5190186 Sent from my iPhone using Tapatalk

Why? 1 to 2 volts is a pretty minimal change. Sent from my iPhone using Tapatalk