balanced/unbalanced preamplifier

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First of all, this is the wrong forum for this thread. It should be in SS or Pass labs.

juma said:
OpAmps are second choice parts for this job. To do it properly you need a fully differential amp (OPA1632,THS4131....)

AFAIK, using a diff opamp will actually make a very mediocre phase splitter.

The best topology for phase splitting with opamps is this:
An externally hosted image should be here but it was not working when we last tested it.


Which is what the inside of a DRV13x chip looks like.

HOWEVER, it is silly to use an opamp to do the splitting for an Aleph IMHO. The Aleph frontend should do a better job of phase splitting itself. If you absolutely need more gain I suggest you look at a discrete phase splitter.
 
leadbelly said:

AFAIK, using a diff opamp will actually make a very mediocre phase splitter.
The best topology for phase splitting with opamps is this:
http://sound.westhost.com/p87-f3.gif
Which is what the inside of a DRV13x chip looks like.

Try to compare directly (sound-wise) DRV134 to OPA1632 and you'll easily comprehend that DRV134 is by far inferior circuit.
I'm not willing to start a debate on this - just delivering commonly known fact.
 
Last question,

Is this the circuit to use to go from unbalanced to balanced ?
 

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Berry said:
I build the drv134 version, the problem that i have more noise than sound ?

The Amp for wich i will use it, is an aleph 5. When i put 2 capacitors in the + and the -, the noise dissapear.

Why is it not possible to drive the aleph direct by the drv134 ?


I cant see why you cant drive Aleph 5 or any other power amplifier
directly from DRV134.

About putting caps, I suppose you mean SERIES Output caps.
When you have not a stable DC output 0 Volt level (some dc-offset)
you may need output caps to get it to work well.

You can try without caps, and try different levels sound output
while measure any DC-Voltage at those two DRV134 outputs.
If you get any substancial DC-Offset output,
you should use Output caps.
 
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