Pearl 3 Burning Amp 2023

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@Wellerman
while I will probably use the on-board regulators for this Pearl I have other projects for which I am considering "super" regulation.
one of the features of these regs is the sense line which I always took to facilitate... potentially... distancing the regulator boards from the circuit whilst still realizing their full high level of performance. I'm not talking about putting the SRs in the remote PSU with the transformer or anything so extreme. But a couple of the (more fanciful) arrangements I've come up with for preamps would place the SRs in a separate compartment adjacent to the main circuit enclosure.
I wondered if you found this to be borne out in practice with your projects? How far away have you located the SR boards from the circuit and still been happy with the results?
 
@mhenschel
Actually this is the first time I'm using a super reg. I will place them in the same enclosure, close to the P3 boards, like on the photo. In my Pearl Two I replaced the 7x24's with discrete Sparkos regulators, as they were a drop in replacement and there was no space for a super reg in the P2 enclosure. I think I would always like to have the regs in the same enclosure as the boards they supply. Jan Didden spoke of shielding the sense wires, that might be wise if the regs are in their own enclosure.
 
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@Wellerman
a few things:
I would assume closer is better generally.
Isn't the second ground on the SR output for the shield specifically? not sure what value there is in connecting it as you've done in the test.
Are you configuring the pre-regulator as Jan et al did in the Audio Amateur articles or just a simple remote 317/337 reg? (which might make the most sense with a remote PSU box)
Are you devoting a transformer secondary to each leg ie. beginning to end separate channels?
 
And now for something completely different. Just finished my Pearl3 and it plays... But a couple of weird things going on I think.

1 Only error I am aware of sofar is that I managed to break the wire of the positive supply for one channel. Repaired it and voltages measure ok. Also bias is set at 4,9 mA
2 When I turn the power on the red leds on both boards keep turning on and off. When I then change channel on my preamp to phono the leds turn on permanently
3 When the interlinks are removed from the output cinch, the red leds immediately turn on when the power is turned on.

Is the above acceptable behaviour or is something REALLY WRONG..

4 There are loud pops and clicks when the turntable is connected, whether I play a record or not. Without the interlink from the turntable there is only some noise when the volume is at max. Will check the turntable for wiring errors. Was a bit noisy with the previous tube phono stage.

Thanks for advice and ideas on next steps...

Leo
 

6L6

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That’s not right.

The LED will blink on power-up, but should be stable after that, regardless of gain jumper position. Why this changes with your preamp selection is also odd.

Noise when connected to the turntable is likely the turntable or turntable wiring, however something else may be amiss.

You know the drill, please post a series of well-lit, in-focus photos. We need to see wiring and read resistors.
 
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When I tested my P3's board I observed when the P3 input is "overloaded" the red LED will "flicker" a bit.
I think that is natural if the output circuit clips. E.g. when I turned on the 1000 Hz test generator it takes a bit of time before it stabilizes. It has a small lamp to stabilize the voltage. If the input signal is at a level where the P3 output clips then the LED "flickers". So maybe check the input signal when this happens.
My theory is that the P3 clips when red LED "flickers".
 
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In short: it works, music comes out. Bit of hum with the ear to the speaker,
Optimally, use twisted pair between the SR and the P3, keep the leads as short as possible. (Always a nice idea to have a spool of CAT5 lying about as it gives you 4 twisted pairs).

If you are using one SR set per PCB, the "Sense+" and "Sense-" should go to pins 8 and 4 of U1.
 
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@jackinnj
Good to know. I did a quick review of Jan's info.
If we're using twisted pairs for the senses and using separate regulators for each channel perhaps run grounds to pin 3 of U1? Shield the wires as necessary, connecting at the SR ground?
And if the wiring is to be "as short as possible" (but no shorter) what is the longest the wires could be without wasting the effort of building these regulators? 6"? 9"?
 
@Wellerman
a few things:
I would assume closer is better generally.
Isn't the second ground on the SR output for the shield specifically? not sure what value there is in connecting it as you've done in the test.
Are you configuring the pre-regulator as Jan et al did in the Audio Amateur articles or just a simple remote 317/337 reg? (which might make the most sense with a remote PSU box)
Are you devoting a transformer secondary to each leg ie. beginning to end separate channels?
I 'm using a simple 317/317 pre reg as in the data sheet with protection diodes and adjust pin bypass cap. They regulate down to about 20.5V, the super reg takes it down to 15 (Jan Didden advised at least 5V surplus voltage). I will also add load resistors to draw some more current out of the regs to get Zout down (something Walt Jung mentioned in a post and deemed important).

I have one transformer as in the stock configuration; dual bridges, CRCRC. This has a common ground, the articles in The Audio Amateur advise to keep the ( pos and neg) grounds seperate and only connect them at the load. Don't know how to combine that with the stock design where the grounds connect together and to chassis in the PSU box.
 
Optimally, use twisted pair between the SR and the P3, keep the leads as short as possible. (Always a nice idea to have a spool of CAT5 lying about as it gives you 4 twisted pairs).

If you are using one SR set per PCB, the "Sense+" and "Sense-" should go to pins 8 and 4 of U1.
Don't know how much twisting I can do when the leads will stay onder 10 cm, but I can try. Soldering the sense wires directly to U1 (I'm using one SR set per channel) would require some careful soldering on the underside of the board, but I guess it can be done. Sense wires do not have to be very thick.
 
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@Wellerman
yeah... I've been asking how to rationalize the grounding with the Gary Galo raw supply scheme (whether with CRC or chokes). the SR input has separate returns to the supply and it seems consistent with the secondary and bridge for each rail.

at U1 there are pads for a regular DIP chip that must connect to the SMD pads, no? I would use those. handy.
 
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And now for something completely different. Just finished my Pearl3 and it plays... But a couple of weird things going on I think.

1 Only error I am aware of sofar is that I managed to break the wire of the positive supply for one channel. Repaired it and voltages measure ok. Also bias is set at 4,9 mA
2 When I turn the power on the red leds on both boards keep turning on and off. When I then change channel on my preamp to phono the leds turn on permanently
3 When the interlinks are removed from the output cinch, the red leds immediately turn on when the power is turned on.

Is the above acceptable behaviour or is something REALLY WRONG..

4 There are loud pops and clicks when the turntable is connected, whether I play a record or not. Without the interlink from the turntable there is only some noise when the volume is at max. Will check the turntable for wiring errors. Was a bit noisy with the previous tube phono stage.

Thanks for advice and ideas on next steps...

Leo
Could it be, that you have a tiny DC on output, and your preamp actually shorts/grounds the unselected inputs?
 
I ordered an enclosure from Modushop on Tuesday evening and it arrived here in Colorado this afternoon (Saturday)! Unbelievable, thanks Gianluca!
Just waiting on a fuse drawer. I had ordered the DD12.9111.1111 PEM from Mouser and it arrived without the fuse drawer. Let them know it was missing and they said it is not included and I had to order it separately so I did. Seems odd, I did not see any mention of it in the description?

This is the best phono stage I have ever had and I am playing a lot of records lately! I have not heard the Pearl 2 but someone mentioned earlier that it was more forgiving of poor recordings than the Pearl 3. While this may be true, I have not played a record with the Pearl 3 that needs to be forgiven.
 
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