Pars

Fired the first board up after rechecking all connections, and wiring the inputs to ground. I'm getting full voltage (806 Vdc) from O+ to O-. Nothing exploded or seems to be getting hot, though I didn't leave it on very long. Both LEDs are lit evenly on the board. All pots were centered when I built it, and other than the current source pots, which I had adjusted using Soren's method to ~17mA, haven't been touched yet. I know I've seen this problem in the thread somewhere, off to find it.

A couple of questions: For the balance adjustment, should you measure from O+ to O-? Or is this O+ to GND? I'm guessing the former. For the offset adjustment, I'm guessing O+ to GND (and also check O- to GND)? Also, how critical is it to GND out the I+ and I- (I don't have a pot wired in yet, but could jumper these). It isn't clear in Michael's pics where the blue wire is running to. I bought a 2nd meter (Brymen BM867) so could look at both the +/- offset at once. Thanks!

Links in the first post work for me...

Happy Birthday Dan!

Given that these are so far away from what you view as good sound, I don't think an overly warm tube amp will even revive these. With the price of these, I would return them while you still can. The measurements look pretty bad, even though I don't give ASR much credence.

Wire gauge: I'm wiring up the PSUs to the Carbon boards, but wanted to get an opinion on AWG to use. I had bought a bunch of 22ga teflon jacketed 600V wire from ebay seller skip malley. Since I don't think the HV supplies are sourcing much current, I think this should be fine but want to get any input if you think it is too light of gauge? Usually I've used 18 or 20 for other amps. Thanks.

Happy Birthday Al! I hope you have a great one!

Happy Birthday Colin!

I would check octopart.com and see if you can find any of the semis from a distributor. For the DN2540N3s the other part would be fine if it is the TO92 package you need, not TO220. For the MJW21194, I would look for the 21196 as well (higher rated). If you are in the US, I would use Antek transformers. Something like this: https://www.antekinc.com/as-1230-100va-30v-transformer/ Dual primaries, shielded. These work very well. They also have 28V or 24V if you want to drop that a bit. If you are in Europe, not sure what shipping would look like for these. Otherwise there are probably better options in Europe than buying transformers from Mouser.

Yes, I realized that when I looked at diya. Your screenshot was from there. I know they do have US stock on some stuff; wish they showed that more clearly.

Happy Birthday Steve!

I believe they are the cfp3smtsplit gerbers (Amp and Pre) on his site. If you read the thread, Kerry also did some spilt boards with more SMT on them (so probably smaller), but I don't think he released the Gerbers. Probably going to do a commercial product with his new company with those.

The thread for the CFA2 or 3 is here: Depending upon what you want, you could do either 4 CFA2 boards for balanced only, or do the CFA3 for the ability to run SE or balanced. For the CFA3, Kevin also did some split boards which separate the front end stuff from the amp guts and allow more flexibility in chassis layout. Personally, I have built Dynahi's and would recommend the CFA3 instead. I have only built a couple of CFA2 boards, but worked on one of Dukei's CFA3s for another HC user and really liked it. Something that was finally a bit better than my DynaFET. And done with currently available parts as well (other than Toshiba JFETs for the input).

Does the diyaudio store have the one you want? They have US stock, so should be cheaper.

Happy Birthday! Hope all is well!

RIP Raquel Welch. Damn was she hot... https://www.cnn.com/2023/02/15/entertainment/raquel-welch-death/index.html

I'd return them. Welcome to "high end" audio. I've never listened to the Atticus, or any other ZMF headphone. I know they have a good reputation, but what sounds good to one will vary for others. Don't buy expensive cables as they are generally snake oil, and as you note, no difference in sound. From your description, I don't think anything you might try (pads, cable, better amp, etc.) is going to get you where you want to go.

^ Yeah, I had thought of him as well. He hasn't been around here for quite awhile.

Wonder if the J.C. is John Curl? Have to poke around diya and see if there is anything there on this one.

Happy Birthday Jeff!

Happy Birthday Mike!

Happy Birthday!

Happy Belated Birthday Grahame!

Happy Birthday!

Happy Birthday!