Pars

Oops, nm, misread. Carry on

The ones in the BOM are what is needed. I use Schottkys because I believe that they induce less switching noise. The GRLV is very well protected against diode switching noise, so I don't know whether they actually help in this case. I couldn't see anything on my scope when looking at them, but I might not know what to look for and I certainly don't have access to a screen room. I don't know what you are talking about in your last sentence. Sent from my iPhone using Tapatalk

These weren't the devices that I got from you, but the ones that I had in there. Yours are matched very well. I just haven't brought myself to use them yet Sent from my iPhone using Tapatalk

Glad to hear that you are healing well Steve! Sent from my iPhone using Tapatalk

Some posts regarding lower voltages. I would think that the 10V LT1021 reference and 9.1V zeners should be OK for the 12/15 and definitely the 18V you were thinking about, but don't know for sure on the 12V. BTW, you can buy the LT1021 directly from Linear at a lower price, but only worth it if you are buying several. When I was testing mine with a 24-26V transformer on a variac, it was regulating at 20V output down to around 18Vac input, a bit lower (17.9Vac). I wound up using the Antec 20V 520 transformer and it is working fine, and running at around 44C on the pass transistors powering an SS dynalo.

Yet again... RIP George M

Happy Birthday Ric!

But... But... But... Those aren't Oyaide! I assume you have 20A wiring/breaker as well? And agree regarding Decora. Always interesting to see what you are up to; like the Pass phono as well above.

Yes, I don't think that anyone got theirs working. Pretty large GB as well, so kinda surprising. I thought that luvdunhill had his working earlier in the thread, but I think not. As for using a ferrite bead for this, would it replace the gate stopper, go in series with it, or? I do have some ferrite beads like these.

Happy Birthday Ken!

Spent some time reading the build thread (and rubbing salt in old wounds I had seen or had the T2 thread pointed out back then, and tried larger gate stoppers at that point with no luck. After re-reading that thread, I'm not going to continue doing anything with these.

Sorry, it was in the group buy thread. Also he mentioned that R1 and R3 should be 422 ohms, not 402. I got my Dynalo all back up and running, offset dialed in, GRLV. Listening, it sounds very good. I can't tell if it sounds better than it did with the sigma22; I think so but going from memory. I also had found that I had miswired the switch I use for SE->BAL input; it had left the - input floating when in SE mode, so I corrected that. Flipping back and forth, I couldn't tell any difference. Might have to actually listen to this with balanced in one of these days, if I can get my XLRs back from my son

Very cool, thank Kevin!

Thanks! Yes, I was going thru the DynaFET build thread and looked at the T2 thread (finding Craig's post regarding going with 750R), but hadn't run across that post yet. I looked at the board I was tweaking and it does have 47R on it, but on the back side, directly on the gate pins. I have some 750R and will see what happens with those. I'm trying to reacquaint myself with the jumpers and feedback choices, and have to dig the rest of it out, including schematics. It always bothers me when I can't get something to work, but don't have the background that some such as Craig do

Nope, though I haven't touched these in quite some time and can't remember what all I did. I think I might have tried lower resistance gate stoppers? I'll try to take a look, and go thru the T2 thread. Sent from my iPhone using Tapatalk

The LTST-C170CKT that he switched to a few posts ago is 1.8V Vf. The ones normally used are 1.7V, not 2.1V.

Still playing around with my dynalo, now with the GRLV at +/- 20V and finding some interesting things (at least to me). Mine is using 2SJ74/2SK170BL input JFETs. I had noticed that the balance between the + and - sides of each of the boards was off about 1mA. I determined that the JFET combos were mismatched, and got that corrected. One board has Idss of around 8.4-8.5mA while the other is 6.7-6.8. The higher Idss board has bias ~ 0.5mA higher than the one with the lower Idss JFETs, which makes sense. Using some JFETs that are matched (octal), they are both even, which also makes sense. Using bias resistors of 261R, after about 1/2 hour, bias is at 13.5 mA. I don't currently have an IR thermometer (Santa?), but nothing feels hot, just barely warm, including the GRLV pass transistors. just for fun, since I don't have any THAT340s, I put some 2SA970/2SC2240 BLs in (accounting for the pinout diff of E-C-B vs. the THAT E-B-C), I was seeing the same bias currents on the one channel that I tried these in as I had with the FET input. The BJTs had hFE of ~530, vs the 100 or so for the THAT chips, so the hFE doesn't seem to make a lot of difference. In my previous post, I had noted that bias resistors of 277 gave ~16mA; it was actually up to 17 mA once I let it run in for quite awhile. Kerry sent me his ltspice file for this (thanks Kerry!), but so far I haven't been able to get it to even come close to real world currents; it is running 4.7mA or lower. I'm pretty new to spice models though. It appears that his BJT models came from Fairchild, and have a strange hFE (BF?) of 12.16K. Real world on these is more in the 300 range for mine. If I modify that parameter, the output stage Ie current drops to 3mA or less. I was hoping to use this to narrow down the bias resistors, as the 301R I had in there would have hit 20mA. Sorry for the tl;dr, but just thought I would post this. I would guess with the mini that it will be toss it together with no matching. The BJTs in mine are matched pretty well, as I had 100 of each.

My Rotel RCD-855 (modded) is a TDA1541A-based player. I've also built Pedja Rogic's DAC and liked it, but didn't really use it much. Jim (morphsci) has it now. This DAC is the predecessor of the AYA DACs. I have at least a couple of spare chips as well. The 1998 Taiwan chips are supposedly the best ones (go figure). Check https://www.audialonline.com/topics/tda1541a-and-model-s-usb-part-4-tda1541a-grades-and-series/ for more info on the grades (than I ever knew). Apparently many of the std. A grade chips measure so close (or as good or better than) that it isn't worth paying the exorbitant pricing people are charging for crown chips.

Could you: move the power on LED and the 2K resistors leave the mounting holes in the same places, but extend the board out a bit to allow moving the output connector(s) out a touch, allowing for a couple of them also, is anyone actually using the adjustment pots? with good gain resistor measurement, you can get the output voltages quite tight without them (my board is a previous version without them). This would free up considerable real estate. Just some thoughts. 2x18ga wires into a Phoenix block isn't much fun, and I don't think the Molex SPOX connectors I prefer using would accept more than 1 wire per terminal either, though I haven't tried it yet.

Any ideas as to why no one could get these working? I know with the SS Dynahi around now, why bother. I was thinking about recouping some parts from the pair of boards I have built up.

Could I request that a second set of output terminals be added to the next revision? This would make things easier when feeding more than one board. Sent from my iPhone using Tapatalk

You can probably bend more than once, but take care. Note that I haven't used one of these pots before, so I can't be certain. I would nonetheless plan out how you wanted to do it carefully first. You would probably need to put the pot as far forward as possible and mimic the position of the Alpha pot, so the nut and nose fit thru the front panel in the same position as an Alpha. Looking at a PCB and the one 601 pot I have, it looks doable. Pay attention to the Alpha pinout regarding the loudness tap row, and maybe coat that row's solder pads with something non-conductive to ensure no short to it.

The leads on the TKD 601s are quite long... might be able to do some creative lead bending, use of teflon tubing?

Cute! Good chains too (KMC). Switched to those from SRAM. Did it come with some of the Two Brothers also?

I don't think the TKDs are the right pots for the mini dynalo? I thought that only took the Alpha pot?