Pars

So I guess that GRLV board I sent Justin went to good use

I would hope this would give the climate deniers a pause for thought...

Never cased it.

We've gotten snow here in Chicago area twice this week (including Thursday night). I can deal with this kind of snow: a) don't have to go anywhere, and b) it doesn't stick to sidewalks and driveways, so don't have to do a damn thing about it

I think you'll like this once completed!

Not necessarily. First, it sounds like you are trying to measure these at too low of current. Look at the datasheet. The min hFe for the MJF15030/15031 is 40mA. They should ideally be matched at about the current they are going to run at, if possible,

RIP Brian Dennehy... https://www.cnn.com/2020/04/16/entertainment/brian-dennehy-dead/index.html

Happy Birthday!

One could ask why you are building a hi-powered amp for an easy to drive phone? Maybe an SS Dynalo would have been a better choice?

Interesting. Where you have the temp probe was always the hottest area when I was using an IR gun. Maybe a bit further left. Any reason you didn't populate the rail caps (above the right heatsink)?

I don't think you're going to get any closer than that

Sorry, just seeing this now. Not sure, but that sounds about right. See attached for the BOM I have for each. In the GRLV BOM, ignore the Schottky rectifiers (yellow shading). I only see an R21 500R resistor feeding the + input of the - rail opamp on the GRLV. All of the pots are labeled RV# in the schematic that I have. goldenreference LV schematic.pdf GR HV BOM_Sep26.xlsx Steve, I hadn't read that regarding a 4.5 digit DMM, but I would assume you would be able to see something? I've never used the trimpots for adjusting the voltages (I usually use either matched resistors using my HP bench meter, or 0.1% resistors and live with the results.) GR LV BOM_Sep26.xls

Happy Birthday!

I took it as room treatment, as that is what Michael does (did?).

Have just gotten the Project setup, thru my new untested (and in typical Pars tradition, uncased as of yet) Salas phono stage. I have to check the arm setup, but powered it all on and couldn't detect any noise or hum (yet). I've done some reading on the Project and in addition to the sorbothane washers, apparently there is a damping trough for these arms that is ~$200 ish and seems to be very promising. I was reading a very interesting thread on diyaudio last night regarding a guy building what looks to be an interesting tonearm, which is pivoted but provides perfectly tangential tracking: https://www.diyaudio.com/forums/analogue-source/327684-revolutionary-pivoting-tangential-tone-arm.html

^ Oooh, with a heapin' helpin' of Blose!

Curious... did you ever successfully install a couple of these regs on those 3oz boards? I know a couple of people did, but I never did get one to work. Ground planes with 1/3 to 1/2 of the pins tied to ground on these little parts seems to be to be somewhat challenging.

Nice mallet! And the table and bench are absolutely gorgeous! Great job all!

Kerry, Since many (most?) used Amb external regulators instead of the onboard, most would not be able to access the enable pins/function of the regs. Just a thought.

Thanks Kerry. I'm not interested in redoing mine. As long as I am aware of it, its fine

Congrats! When you saw the offset spike, were you checking the single-ended output (L+ or R+ to gnd)? If you look at the balanced offset (L+ to L- or same for R channel), you won't see this. It is something I noticed awhile back and is caused by the Meanwell bricks not coming up at the same time on power-on. Balanced phones should be fine (common mode or balanced offset won't spike). I would not leave single-ended phones connected on either power up or power down.

Yes. If you have the volume pot in, just turn it down all the way and that is good enough.

That is channel to gnd DC offset? The +/- offset pretty much takes care of itself. I wouldn't mess around too much with the 2 trimpots by the 255R's. From what I found, you can chase your tail trying to get it closer and closer and then wind up with one of them at a near dead short and things go south quickly from there. The differences you are seeing are probably transistor variances. The resistors from the BOM are all 0.1%, so should be fairly close. The ones I built, I got offset dialed into +/-2mV without the servos in.

340mV is rather high for a mini (17mA). What does your DC offset look like without the servo opamps in? I would check the bias across every 20R resistor for starters. Reset all trimpots to midpoint (with an ohmeter) and go from there. The 2 pots by the 255R bias resistors can cause some wonkiness if you go too far in the adjustment of them (same with the full size amps).