Pearl Two

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Siberia

Siberia

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Joined 2011
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ra7 said:
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'll be the first to participate in the ceremony then:)


nar said:
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 :rolleyes:

Best,

nAr
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Great explanations, Anaël. 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? :magnify:
 
PierreQuiRoule

PierreQuiRoule

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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
 
PierreQuiRoule

PierreQuiRoule

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Siberia said:
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.
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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
 
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Siberia

Siberia

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Joined 2011
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PierreQuiRoule said:
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
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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...
 
nar

nar

Member
Joined 2002
Siberia said:
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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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 :D

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

Best,

nAr
 
nar

nar

Member
Joined 2002
Sorry to bump again ... edit feature is now by time disabled so I can't edit previous post ...

I have finished the Pearl II psu_upgrade. Here is the link to the SkyDrive folder :)

http://sdrv.ms/NjYDbs

Those are UGS 24V psus, one for each channel.
I added some 3n3 X2 type (250/275V Panasonic he he) capacitors for mains filtering under the boards.
Mains wiring is done with solid code silvered copper ptfe insulated.
Power AC outlet is an ElecAudio rhodium plated.
An umbilical brings the voltages to Pearl II chassis.
The internal 78XX/79XX of Pearl II board have been removed & bypassed by small value resistors.

For now I'm very happy with the result !!! :)

Best,

nAr
 
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nar

nar

Member
Joined 2002
Wellerman said:
Impressive, most impressive.

Could you describe the audible improvements you are hearing?
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Soundstaging is definitely better. Dual mono xformers and regs seem to enhance stereo imaging and percieved sense of depth in recordings.

Whole spectrum is richer, bass has full subjective extension and swing now, it slams better than with the previous integrated 78XX/79XX

Sound is unveiled, detailed and non aggressive. Some "calm" presentation seem to emanate from recordings.

That permits to listen to the music better, without irritating sonics defects that can be troublesome (like you know you feel bad, without knowing why) :p

For the I/O I chose from the beginning low mass RCA plugs and a Wire Wrap Wire minimalistic design by Allen. So the conductors are single core copper www 0,254mm dia. with kynar insulation.

The cart outputs out of the TD and is wired to Pearl II this way. No shield, so far no noise. Then between Pearl II out and my UGS pre, same wiring scheme.

This can be tad tedious to hear, but I believe sound is directly impacted with interconnects(and speaker wires). So, the more transparent (less mass) it is, the best it is to judge about the psu upgrade sonic benefits.

I also believe PSU is for about 50% in final sound result :)

Now, the next thing would be to upgrade both cart (Ortofon MC3 turbo) and TT (vintage Revox B795 in perfect shape). Which I will do, when I can ;)

Best,

nAr
 
nar

nar

Member
Joined 2002
Wellerman said:
I plan on starting my Pearl project this fall or winter (parts already "in da house"). Due to money constraints I plan on building it on perf board. Would this seriously harm sound quality, and if so, why?
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It wouldn't, but I recommend you use same layout as Wayne did on the PassDiy boards.
Lack of ground planes might add sensitivity to noise on those small levels. You can still add them by cutting them off from thin copper foils and solder them in place :cool:

Best,

nAr
 
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