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Old 7th July 2012, 12:17 PM   #1581
Salas is offline Salas  Greece
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Done. Now #1578 is the right one.
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Old 7th July 2012, 01:08 PM   #1582
nar is offline nar
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Quote:
Originally Posted by Salas View Post
Done. Now #1578 is the right one.
Dear Salas, thanks for this greatly appreciated.

I would love to try your shunt reg with Pearl II one day

For now I use UGS style power supply by CheefdeGaar. I can say it gives a better sound than previous onboard 78XX/79XX ... But shunt reg would give an even better sounding unit I guess

Best,

nAr
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Old 7th July 2012, 01:29 PM   #1583
Salas is offline Salas  Greece
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Can't say about Pearl's particular susceptibility to PSU types, having no direct experience in Pearl, but experimenting is the holly grail of DIY, so good luck. Always use oscilloscope to know that different supplies cooperate OK for clean rail results before comparing.
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Old 7th July 2012, 02:23 PM   #1584
Siberia is offline Siberia  Lithuania
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Added 1K to R9 in parallel. Q3 reads:

C 10.8; 10.9V
B 9.4; 9.3V
E 8.75; 8.65V

Looks like more in the ballpark?
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Old 7th July 2012, 03:46 PM   #1585
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Voltages across R21, R22, R23, R24 are:

L 69.4mV; 69,3mV; 69.8mV; 70.1mV
R 69.1mV; 69.6mV; 69.2mV; 69.8mV

Other voltages around the circuit are pretty close to Wayne's reference, the drain of Q4 with 20.5 instead of 21 being most "innacurate".

What is the safe margin for 0 DC point setting? While my DMM is set on averaging I manage to set it from 0 to 0.01V. How long I should watch the behaviour?
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Old 7th July 2012, 04:04 PM   #1586
nar is offline nar
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Quote:
Originally Posted by Siberia View Post
Added 1K to R9 in parallel. Q3 reads:

C 10.8; 10.9V
B 9.4; 9.3V
E 8.75; 8.65V

Looks like more in the ballpark?
Yes, ballpark

Quote:
Originally Posted by Siberia View Post
Voltages across R21, R22, R23, R24 are:

L 69.4mV; 69,3mV; 69.8mV; 70.1mV
R 69.1mV; 69.6mV; 69.2mV; 69.8mV

Other voltages around the circuit are pretty close to Wayne's reference, the drain of Q4 with 20.5 instead of 21 being most "innacurate".

What is the safe margin for 0 DC point setting? While my DMM is set on averaging I manage to set it from 0 to 0.01V. How long I should watch the behaviour?
It always wander a little. Wanders less when in enclosed box. Don't worry, as you have capacitors series with output. It won't cut too high in the output swing either. 50 mV +/- are not a crime

Nex thing, wire in / out and listen ?

Best,

nAr
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Old 7th July 2012, 04:33 PM   #1587
Siberia is offline Siberia  Lithuania
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Thanks. I have input jFets mounted on supports, just in case I would want to adjust for tighter quads. But I suppose my values are alright and there's no shuffle to be made?
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Old 7th July 2012, 04:35 PM   #1588
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Quote:
Originally Posted by Siberia View Post
Thanks. I have input jFets mounted on supports, just in case I would want to adjust for tighter quads. But I suppose my values are alright and there's no shuffle to be made?
I would say so

nAr
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Old 8th July 2012, 04:12 PM   #1589
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Default finally

It's up and spinning

Pheew, it took time this build! So, firstly, thanks all for the help provided. I wouldn't be listening to it at the moment without you, guys. Special thanks to AnaŽl and Salas.

I've spinned about 5 LPs until now. First impression, it sounds better by a notch to my previous RIAA. If it was mechanics, I would say somebody has tightened the screws in the system. And of course it's tomb silent. So in general let's say the state is more solid right now

Other benefits may appear after more listening. It could be, that my rig is not helping to hear the full potential at the moment too. But I have to say, at least to myself, that my comercial, "dwarf" in comparison GSP unit wasn't bad at all. It might have some tiny benefits even. But as I said, I should better listen more and compare.

My cartridge loading resistors are 47.5K and my cartridge loading spec. resistance is 47K. Hope there's no mismatch? I've also lowered gain. R16 is set to 47K. I had way too much of it when with 100K. I wonder if I can measure my gain somehow now? Maybe it can even be lower? Chance of oscillation?

I don't have C9 installed. Wonder if it was there for any reason at the beginning.

HFN test record says the system is in phase. I swapped +/- leads on both channels on the cartridge.

Crikey, it's hot down here. About 30 deg. C. inside. So both DCB1 heatsinks and Pearl negative one is sweating around 50C. Closer to the winter, I would love to hear if upping CCS helps.
Attached Images
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File Type: jpg Pearl II b.jpg (718.6 KB, 158 views)
File Type: jpg Pearl II c.jpg (789.9 KB, 159 views)
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Old 8th July 2012, 04:48 PM   #1590
nar is offline nar
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Hey, Nice setup dude
I can see "my" Allen minimalistic replicas running at the outputs

Good to hear no noise at all. Gain setting is also absolutely relevant.
47k5 as cartridge load is perfect, no need to think for a load mismatch compared to 47k value

Best,

nAr
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Last edited by nar; 8th July 2012 at 04:52 PM.
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