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Old 11th July 2012, 07:34 PM   #1621
Siberia is offline Siberia  Lithuania
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Quote:
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I think nar deserves some kind of award here... for helping out so many people in this thread! Good work!
I'll be the first to participate in the ceremony then


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Originally Posted by nar View Post
Gain figure of 1st stage is roughly 35dB gain
Losses in passive RIAA about 20 dB
2nd Stage gain as per schematic is (R16+R14)/R14 as non inverting opamp
Per schematic x 101 times so, about 40 dB

Total Pearl gain by default 55 dB

To get 40 dB total gain for Pearl II you need to reduce 2nd stage gain to 25 dB or so (= increase feedback !!!)

R16 can be lowered, but you change Cx adjustment too I guess
Passing R16 to 20k gives you : (20+1)/1 = 21 times or 20 log21 = 26,4 dB


Another option is to change R14 value, with a 5k you get

(100K+5K)/5K = 21 times or 20 log21 = 26,4 dB

Ball park maybe

Best,

nAr
Great explanations, AnaŽl. I'll keep them in mind or even better noted, as I tend to forget things.

Coming back to GURU, I think I'm too new for searching for the grail. If I knew how the system or my vinyl rig sounds correctly, I would go and search for that ultimate position, which defies all the measurements and logic. But after spending some hours on it, all I can tell, is that I can't tell when it's better or worse, so I stick to default for the time.

And lastly, what's that tail in your picture?
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Old 11th July 2012, 07:49 PM   #1622
6L6 is offline 6L6  United States
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I think nar deserves some kind of award here... for helping out so many people in this thread! Good work!
I agree! Cheers!
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Old 11th July 2012, 10:11 PM   #1623
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Did some quick listening on a mac and with ear buds. Not on the main rig. So in less than ideal conditions.

I too, prefer the files ending with "2". The difference seemed to be more obvious in the first file. I would describe it as 'musical engagement'. In other words, file 2 made me forget to analyze and wanting to listen to the end of the wave file. When analyzing, I found the slurs to be clearer.

Pierre
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Old 11th July 2012, 10:14 PM   #1624
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I think nar deserves some kind of award here... for helping out so many people in this thread! Good work!
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I agree! Cheers!

YES !
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Old 11th July 2012, 10:25 PM   #1625
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Back to PEARL II, I'm thinking weather some more precise R matching, different caps or getting closer voltage values to Wayne's would benefit? In other words, is there's anything left to tune? Or perhaps it's too silly, as my current rig wouldn't be able to carry out the differences.
Good luck... I replaced the output caps (C8 and C13) by North Creek Music metallized polyprops film caps (the Zens) and frankly I don't know if I can hear a difference. Those SILMIC II are pretty sweet. Wayne knows what he is doing.

Since I added the Pearl 2 in my system, it is the MC cartridge and VPI table that have become the limiting factors. Changing VTF or VTA has a greater impact on the sound than the above caps substitution in the Pearl 2. Or perhaps it is the vinyl itself that has become the limiting element.

Oh. But changing the gain of the Pearl 2 does change its character a bit. I like it better with less gain (more feedback) alas I need the gain for the low output MC. Haven't played with the supplies like nAr has. Still, I feel no urge to mod the stock design. (Except I might try better resistors to load the cartridge). Anyways, hope this helps.

Pierre

Last edited by PierreQuiRoule; 11th July 2012 at 10:29 PM.
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Old 12th July 2012, 07:49 AM   #1626
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I hope to hear something from Wayne on the topic of gain settings. The manual writeup on acquiring more gain, but not down. I'm still looking for the best and surest way to get 40db.
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Old 12th July 2012, 08:11 AM   #1627
nar is offline nar
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Haven't played with the supplies like nAr has. Still, I feel no urge to mod the stock design.
Pierre
Will post pics when finished UGS style or shunt regs, nice options to upgrade the 7XXX regulators for sure

Best,

nAr
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Old 12th July 2012, 09:43 AM   #1628
Siberia is offline Siberia  Lithuania
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Quote:
Originally Posted by PierreQuiRoule View Post
Good luck... I replaced the output caps (C8 and C13) by North Creek Music metallized polyprops film caps (the Zens) and frankly I don't know if I can hear a difference. Those SILMIC II are pretty sweet. Wayne knows what he is doing.

Since I added the Pearl 2 in my system, it is the MC cartridge and VPI table that have become the limiting factors. Changing VTF or VTA has a greater impact on the sound than the above caps substitution in the Pearl 2. Or perhaps it is the vinyl itself that has become the limiting element.

Oh. But changing the gain of the Pearl 2 does change its character a bit. I like it better with less gain (more feedback) alas I need the gain for the low output MC. Haven't played with the supplies like nAr has. Still, I feel no urge to mod the stock design. (Except I might try better resistors to load the cartridge). Anyways, hope this helps.

Pierre
Thanks for listening to the files. I've got this Nichicon on output bypassed with Vishay MKP. What kind of loading resistors are you thinking of? I dream of VPI TTs. They are more easily found on your side of the pond, it seems.

More feedback and changing character, hmmmm...
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Old 12th July 2012, 10:25 AM   #1629
nar is offline nar
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Originally Posted by Siberia View Post
Thanks for listening to the files. I've got this Nichicon on output bypassed with Vishay MKP. What kind of loading resistors are you thinking of? I dream of VPI TTs. They are more easily found on your side of the pond, it seems.

More feedback and changing character, hmmmm...
I also have the Nichicon Muse at the output as coupling capacitor, I bypassed with a Panasonic MKT but will likely use some spare Wima MKP spares instead

Load resistor is a standard 47k Dale RN55C if I remember. My cart Ortofon mc3turbo is happy with that loading for now

Best,

nAr
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Old 12th July 2012, 10:38 PM   #1630
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What kind of loading resistors are you thinking of?
Dale CMF-60.
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