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Sorry to all injured HCers, and glad you didn't get injured in the fender bender CD44hi! I guess I am at home for a week or so following a strange week and sucky weekend in the hospital. It started out with me noticing double vision when looking left. Woke up on Saturday with double vision everywhere. Went to urgent care, who ran a CT scan which showed nothing. Then to the hospital where I spent Saturday and most of Sunday. Full head MRI there, again, clean. Diagnosed as 3rd cranial nerve palsy by neurologist, confirmed by ophthalmologist today. Should take care of itself in a couple of weeks, maybe less. I guess at my age, what they find in the scans, etc. could always be bad, so counting my blessings there. Heal up HC!

What 3D package are you doing those in Justin? I was messing around trying to figure out how to do voltage switching with 2 transformers, 1 using a relay to switch on (ala Amb e24), but handling voltage switching for 120/240. Does the below schematic look feasible?

Sure, I'd be up for that.

Note that the pinout for the 2SA1349/2SC3381 does not line up with the 2SJ109/2SK389 devices, even though they are the same package. So that adapter will work for the bipolars, but not for the JFETs.

I’d looked there 2 or more years ago. I’m probably just not remembering it correctly, but it wasn’t an Adcom. Thanks for the suggestion though! Sent from my iPhone using Tapatalk

Cool, and thanks! Sent from my iPhone using Tapatalk

No. I'm pretty sure it was Apogee, but it has been awhile. I think I do (or my brother did) have an Adcom around.

cspirou: Any idea on when you might move ahead on this? Also, will the vendor provide a proto case or sample? Not sure if they do this or not. Sent from my iPhone using Tapatalk

As you may have already discerned, this board doesn't have many fans of Cavalli. That said, at least from what appears to be the Eagle board file you posted in your link, IG connects to a rather large ground plane on the top of the board (there is a 2nd ground plane for OG?). The common junction between R1L and R1R appears to also connect to IG, right by the IG pad. If you have a DVM, you could verify this. There is probably shit all over the board that is connected to this ground plane and could be used to connect IG from the pot to. And no on your screw idea... IG has to connect to the board as reference for the input section.

Happy Birthday Jeff! Sent from my iPhone using Tapatalk

I’d check, but those you should be able to do the drive and memory yourself. Judging from my 2012, they aren’t too bad to work on. So get what you want for processor but limit the rest. I’d take a look at iFixit for instructions, and look at OWC for pci SSDs. Not sure if Samsung is offering those yet or not. Crucial, etc. for RAM. Sent from my iPhone using Tapatalk

At home, supposed to have 150Mbps

For the CFP you need one board per channel, so 2 for a stereo SE, 4 for balanced.

This is the link to board files: https://drive.google.com/drive/folders/0B_iJFfZStuVhSE5nOHBVdTByR1k This is the CFP2 (single ended) and CFP3 t(balanced) thread (Kevin or someone correct if this is wrong): There should be a BOM posted in the thread, though with the recent update for current mirrors in the feedback loop, it probably needs some adjustment. If you can't find one, I know I have one here somewhere.

Hmm, must have forgotten to post the follow-on. The 402R resistors got me pretty much where I wanted to be (262mV, or 13mA). Temps didn't seem to go up much when running it for half an hour or so. On the first bank, I tried a THAT chip instead of the FETs and no effect on bias. Used hot air to remove the 2 over by the Meanwell and got them done without hitting that. Used an iron for the soldering. So now I need to order more 402R as well.

I would think so. That is in the upper half at least of the range for B devices.

Noted. If going to the 402Rs doesn't get me where I want to be, I may replace the LEDs with the Bivars that RudeWolf had in his BOM (1.9V). I had also forgotten to order the 0R resistors for the servos, so will solder on resistor leads until I get some. I was disturbed to see how many items in my spreadsheet I forgot to order, even though I had built a separate tab which was a copy for importing into Mouser for the order. I went thru the order and removed backordered items, so that may be why (I forgot to find alternate source). Oh well

^ Here is the original post on that. Measuring mine, I'm seeing 1.64V across the LEDs (LTST-C170CKT). I believe 1.7V is the design spec? 1.06V across the 422Rs Vbe for each of the transistors by the LEDs seems low at 0.53V. I let it run 45 minutes or longer. Bias voltage across 20Rs was up to 220mV, so 11mA. I think I will start by replacing the 422Rs with 402Rs. I don't really want to increase the bias resistors above 255R, but trying to balance sound with heat. This is in open air, and it is winter in Chicago, and in the basement. I was seeing device temps around 60C, a bit higher in spots (IR measured). I do have my full size amp downstairs to compare to as well.

Same serial number and all? Agreed, wanker tech...

I think Kerry’s original post was in the group buy thread (possibly deleted now?). At any rate I quoted it in this post. Sent from my iPhone using Tapatalk

The input transistors shouldn’t effect the bias current. My full size is also using JFETs (Toshiba). I thought the 422R had to do with the LEDs having a higher Vf than the original 1.7V used in the full size versions... Sent from my iPhone using Tapatalk

I was going to suggest the Gilmore CFP2. If going balanced I would front it with a ubal-bal board for flexibility in input choices. Cheap, easy to build, and very good compared to the other suggestions. Use the golden reference PSU and you’ll be, well, golden. Sent from my iPhone using Tapatalk

Well the issue is the low bias current. 170mV is only 8.5mA. Target was 15mA. The bias resistors are 255R. I’m running 261R on my full size and getting north of 17mA on that (same PSU voltage). After seeing the posts on here of people having to dial these back with 240R, 220R, etc. I was expecting higher. I’ll look at it some more. And those are Linear LSK489/LSJ689 on some adapters I did. Sent from my iPhone using Tapatalk

Got the first of the 3 minis finished more or less (less case, etc.). Had it running on AC for about 5 mins or so. 255R bias resistors, +/-20V PSU... I'm only seeing around 170mV across the 20R resistors. Low, and seems strange with others getting 18mA with 220R, etc. As for adjustment (offset), I used the pots by the LEDs to get the offset between +/- for that channel centered around ground, then had dialed the individual offsets in using the other 2 pots. Anyone have a different adjustment method? I may play with the pot by the LEDs and see if that does anything to the bias current or not.

I suppose chassis ground would be to code, though from what I have seen no one who had built/cased one did that. Were you going to put holes in the bottom panel for feet? You could use the one closest to the IEC to run a ground wire. Make sure there isn't any interference from anything on the amp board. The RCAs (and the Neutriks) can be tapped. I just tapped an RCA for M3, and would think 4-40 would work as well. I prefer your v1 lettering above as well. EDIT: for grounding, the IEC has 2 mounting holes in the rear panel, which appear they require a screw/nut. As long as the screw contacts bare metal, those would work for the case grounding as well.