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Old 31st May 2007, 03:47 AM   #21
Daveis is offline Daveis  United States
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Default Re: Op-amp viewpoints welcome !

Quote:
Originally posted by sandyK
Nightcap

If you want more information on op-amp "rolling" and subjective reports on the effect of using different types of op-amps. Have a look at the Rock Grotto Audio Forum. They have tested most of the better opamps in various types of equipment.
SandyK

http://rockgrotto.proboards39.com/index.cgi
Which forum at rockgrotto are you seeing this in?

Is there a quick synopsis of subjective opamp comparisons you could repeat here?
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Old 31st May 2007, 03:52 AM   #22
sandyK is offline sandyK  Australia
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Default Op-amp viewpoints welcome

Chris (and anyone else interested in soundcard mods)
Have a look at the attached link.
They are using the LM4562. I opted for the OPA2134 as a more conservative option, as I have found that the LM4562 can sometimes seem a little overpowering. Also, the X-Fi card is often reported to have stability problems. I already have a very high resolution headphone amplifier using the 8066 and 2SC5171/2SA1930 O/P stage with a JLH PSU addon .
I didn't want to overdo it. I have seen other reports critical of some of the modifications ,particularly the suggested filter capacitor replacement, and suggesting that short circuiting the marked capacitors is incorrect , as they don't appear to be in that part of the circuit.The SOIC OPA2134 is a little smaller than the original generic I.C. and precise placement is necessary. It will fit O.K. though. I don't have any apparent noise problems. My younger friends say it is quiet.
I have connected the earth of the headphone amplifier to the case of the PC to remove a minor hum loop problem.

SandyK

http://www.head-fi.org/forums/showthread.php?t=229350
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Old 31st May 2007, 04:04 AM   #23
sandyK is offline sandyK  Australia
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Default Op-amps viewpoints welcome

Daveis
They are scattered right through the forum, particularly in the headphone area. There does not appear to be any opamp tested that seems ideal for every type of equipment.This is also my experience.
So there is no specific list. Googling the forum (bottom of their page) should give some results.
However, some of the more specific equipment types are restricted to member only viewing, the same as non members can't always access some stuff here.
Pink Floyd is the man with a vast knowledge on this area,(as well as many other areas) and his views are respected in the industry.
SandyK
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Old 31st May 2007, 04:37 PM   #24
anatech is offline anatech  Canada
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Hi Sandy,
Perfect! Thank you.

I haven't read anything on the subject as yet. I have a lot of reading to do. I was thinking of using a metal shield on both sides of the card. I'l try to look at the datasheets for the CS4398(?). I will find my target card and confirm the chip number before I start.

I'm thinking that if the caps are in a high impedance circuit, the 1uF Wima caps may be sufficient for replacement. We'll see.

-Chris
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Old 10th June 2007, 12:12 PM   #25
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@sandyK

If you read through that headfi thread you linked, re modding the X-Fi, they do clear up that those caps are the correct ones to bypass IIRC.

Replacing the power cap... makes not a spot of difference audio-wise - seems to be purely for longevity purposes. I understand the jamicons aren't the best.

I have an X-Meridian, with LM4562s and the dc protection caps jumpered.
Some guys have made similar mods in terms of the main power supply cap, noting no difference.

Changing the individual opamp + dac power supply caps with bigger ones has been reported to improve dynamics.
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Old 10th June 2007, 12:40 PM   #26
sandyK is offline sandyK  Australia
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Default Op amp viewpoints welcome

I got the other information from a completely different website just before I replaced the L+R I.C. Apparently the X-FI cards can be very temperamental . I have also read such posts on the Creative website forum some time ago. I had stored the mod file some time ago, and there was no clarification about those caps to bypass at the time.
Regarding extra dynamics, I think that I have just about all the dynamics I can handle. My PC headphone amplifier is a modified Silicon Chip headphone amplifier from their Studio Series Preamplifier, but is using an AD8066 driving 2SC5171 and
2SA 1930 O/P devices. Much of the material I listen to is downloaded LPCM promo Music Videos. It is a shame that the CD releases are usually nowhere near the standard of some of the promos.

SandyK
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