Pars

Well, went ahead and put the output devices (2 pairs) in and fired it up. Seems to work. Had 2 DMMs, one on each J/K source resistors. Started out at 1.05Vdc (500mA), and was dropping. I only left it on for ~30 secs (2 x) and they had dropped into the 800mV range, but that is still 400+ mA. Did not try adjusting VR3 yet, as this seems to be too high. VR3 was set to max resistance, but I will verify this. It is bolted to a heatsink (hifi2000 pesante dissipante). The dynahi angle brackets I have do not go completely under the TO-220 tab (1x1" angle). 1x1.25" would be better. Thoughts?

double post

The TO92 dual heatsinks came from Marc (from a diyaudio group buy I believe). No, it was pretty easy to insert them with the Arctic Silver... just messy. Marc: do you think I would be better off to just put all the FETs in? As for the "Vbe multiplier" (have to look that up), I just need to ensure that i have adequate adjustment range? Per our conversations, I have 20K R17/18, a 3.3K R62, and a 20K pot currently. Oh, BTW, do you have any extra FETs?

I like using Amb's adjustment procedure. Used it on the Dynahi and it worked well. http://www.head-fi.org/forum/thread/165788/dynahi-dc-offset-adjustment#post_1960704

Making progress. One board done other than the output devices, the other almost at this point as well. Fire in the hole this week sometime Will only be 1/2 populated on the outputs. Will probably begin testing with a single pair.

Also seems to lose track of some read items. My setting are set for Show me all content that I have not read... Some items that I have read reappear on subsequent visits.

It appears that what it is doing is putting up individual instances of the thread for each unread message that there is in the thread. If there are 2, you get the thread appearing twice, etc. At least that is what looks to be happening.

Looks nice Kerry. What layout software are you using? My only comments would relate to pad sizing, particularly for the TO220 devices. I much prefer the larger elongated pads for these as they seem to help regarding rework if needed.

HTFU...

probably "8" followed by ")"?

Yeah, I like the screw mount heatsinks a lot better than the pin mount ones. I would imagine getting those out of a tight space would be teh suck.

Yep, great news Reks! And good luck on the position Dan!

Did some reading on headwize, so the max resistance sets the lowest biasing; decreasing this increases the bias current... DOH OK, got my 50 each 'O' A1145/C2705s from Mouser and did some matching last nite (oh fun ). They were pretty consistent but not matching well between NPN/PNPs. The NPNs ran from about 95 to 114 hfe, while the PNPs were from 118 to 155, with all but 6 at 140+. Device classification range is from 80 to 160 for the 'O' devices. I do have some 'Y' devices with hfes in the 150 range for the NPNs (not enough, but some), so I may use this approach for anything deemed critical. Speaking of which, are there any areas where the devices should be matched well? Output FETs obviously, and the 2SK/2SJ parts should be as well. I mocked this up on the schematic indicating areas where matching might be important. Any comments?

Happy Birthday Mike! Trip to FFF today? Have a great one!

Sorry about the snow guys... its currently -6° F here, light wind so not too bad. At least the sun is out

I immediately thought that M-80s might be fun...

Didn't read your welcome pm, did you?

I currently have my setting on "Show me all content I haven't read". When I do a View New Content, I get the same thread appearing more than once. I'm up to 2 pages now, but probably the same 12-15 threads in it...

Private Messaging: No Sent items folder?No message receipts?I know, bitch bitch...

Yep. Thanks Todd.

So by maximum value, you mean highest resistance? Should I replace the 20K resistors with 10K? For initial startup, should I reduce the resistance (pot) somewhat until I can monitor it (and increase)? Is the consensus for 1/2 populated output stage current to have a target of 75mA? 150mA? Or something in between?

I just used the Delete Cookies and logged back in. Same behavior as before.

Same since 8:00 am CST (first time I was on today). Advanced search doesn't help because it expects a keyword.

Yes, I agree, but I do not know where the 1W recommendation came from. It isn't noted in Kevin's hand-drawn schematic, and in Jacob's (j4cbo) first pass BOM spreadsheet, they are shown as RN55s or 1/4W PRPs.