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Best Op-amp for X-Fi Prelude/Meridian or socketed soundcard if using an amp is NONE

post #1 of 32
12/1/07 at 10:02pm
Thread Starter 
The Best Op-amp for your X-Fi Prelude/Meridian or socketed soundcard if using an amp is NO OPAMP. Simply bridge using a nice thin lead of wire pin's 3 and 5 in the dip socket, and be prepared for the cleanest, airiest, most detailed presentation your soundcard is capable of, inspired by PPL's best opamp for your ppa is no opamp thread here : http://www.head-fi.org/forums/f6/bes...op-amp-113776/
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post #2 of 32
12/2/07 at 12:16am
Is-it a popular tweek ? First time I hear that.

Are-you able to listen with your headphone on the soundcard after this mod or the level become too low for that ?
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post #3 of 32
12/2/07 at 2:00am
Thread Starter 
Probably not unless its some low impedence phones, like your sonys or grados, and most ear phones. If it was popular you'd know about it. i have my amp plugged into the sound card in this way.
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post #4 of 32
12/2/07 at 2:20am
any link on how to do the mod?
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post #5 of 32
12/2/07 at 5:54pm
Basing on an LM4562, pins 3 and 6 are non-inverting and inverting inputs (respectively) for channel A and channel B respectively. That leaves pins 2 and 5 for signals. Wouldn't the right and left outputs be out of phase with each other?
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post #6 of 32
1/1/08 at 12:08am
I am interested in trying this mod. I plan to attach a fully discrete headphone amp to the opamp by-passed output of the x-meridian. I think this will provide the cleanest and highest quality audio path possible.

Could anyone confirm which pins should be shortened?

Thanks!
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post #7 of 32
1/1/08 at 8:36am
Examining a dual opamp datasheet, the pin assignation is:

1: output A
2: inverting input A
3: non-inverting input A
4: V-
5: non-inverting input B
6: inverting input B
7: output B
8: V+

I have very little experience with electronics but, being a dual opamp processing two audio channels (A and B inputs, I assume), isn't it necessary to shortcut two pairs of pints?

I mean, A input (2 or 3) with A output (1) and B input (5 or 6) with B output (7).

Could anyone explain this? Which is the difference between the inverting and non-interting inputs?
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post #8 of 32
1/4/08 at 7:49pm
I found a similar mod to convert to "passive" the output card. It is applied over the bluegears b-enspirer, a c-media based card very similar to the x-meridian but without the socketed opamps (dacs are the same).

It is a little more radical, as it completely bypass the active output stage and pins out directly from the dac's output.

Some pictures in the author's web:

Picasa-Webalben - Klaus - Audio
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post #9 of 32
2/4/08 at 6:07am
has anyone else successfully done this mod?
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post #10 of 32
3/16/08 at 3:34am
Quote:
Originally Posted by stormcloud View Post
Basing on an LM4562, pins 3 and 6 are non-inverting and inverting inputs (respectively) for channel A and channel B respectively. That leaves pins 2 and 5 for signals. Wouldn't the right and left outputs be out of phase with each other?


You're right. The right channel is out of phase when you do it this way. Is there another way to bridge so they aren't out of phase? Audio sounds excellent this way except the right channel is messed up...
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post #11 of 32
3/16/08 at 3:53am
Woot. Hey. I discovered how to fix this following the datasheet. You need to bridge the 3rd and 5th plugs rather than the 3rd and 6th. Sounds fantastic this way.
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post #12 of 32
3/16/08 at 2:25pm
Wouldn't it make sense to bridge the input to the output (3 to 1)?
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post #13 of 32
3/16/08 at 10:46pm
I don't understand, is the purpose of this so that the port becomes a clean line out?

It has no line out? I was thinking about the Prelude but no line out is a worry... And I thought the DAC would be decent so it seems a waste going Prelude -> optical out -> dedicated DAC -> headphone amp...
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post #14 of 32
3/17/08 at 9:03pm
maybe the line out in the prelude is "variable out" instead of "fixed out".
If bit-perfect is activated I'm not sure it is important.

Correct me if I'm wrong.


note:
Prelude -> optical out -> dedicated DAC (Benchmark DAC1, Xeces ...) -> headphone amp...
Prelude (DAC +OPAMP) -> headphone amp

are the same. In both cases you have a OP AMP
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post #15 of 32
3/17/08 at 9:24pm
I think the OP is just getting at how to bypass the opamp on the card with the intention of impoving the quality assuming the downstream components can live with the loss of gain. I don't know if this has any merit or not, but it makes me curious.
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