balanced/unbalanced preamplifier

Berry · 17th July 2008, 06:32 PM

What is the best schematic ?
If there are better one's please let me know. I wil use it for an aleph 5.

juma · 20th July 2008, 06:22 PM

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

leadbelly · 20th July 2008, 06:50 PM

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

Quote:

Originally posted by juma
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:

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.

juma · 20th July 2008, 10:09 PM

Quote:

Originally posted by leadbelly

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.

gregorx · 20th July 2008, 11:37 PM

Have you taken a look at these:
THAT1646

Berry · 21st July 2008, 06:07 PM

Thank you all !

The reason i do not use an Aleph pre is because it does not fit in the nad T162. The NAD tuner/preamp has no balanced output.
I can use the power supply of the NAD to drive an op-amp, to build an balanced output.

Berry · 21st July 2008, 08:09 PM

Last question,

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

juma · 22nd July 2008, 08:58 AM

http://www.diyaudio.com/forums/showt...26#post1563426

digi01 · 24th July 2008, 12:09 AM

i built the real thing.

bridge preamp

drv134 version

zang

Berry · 8th August 2008, 06:46 AM

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 ?

20th July 2008, 11:37 PM	#5
gregorx diyAudio Member Join Date: Jun 2003 Location: Columbus, Ohio USA	Have you taken a look at these: THAT1646 __________________ Language is a virus - William S. Burroughs

24th July 2008, 12:09 AM	#9
digi01 diyAudio Member Join Date: Mar 2003 Location: BEIJING	i built the real thing. bridge preamp drv134 version zang __________________ 2010 DIY ALBUM UPDATED UCPv1(preamp) & DUAL(power supply)

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20th July 2008, 06:22 PM	#2
juma diyAudio Member Join Date: Nov 2005 Location: Zemun	Berry, OpAmps are second choice parts for this job. To do it properly you need a fully differential amp (OPA1632,THS4131....)

21st July 2008, 06:07 PM	#6
Berry diyAudio Member Join Date: Apr 2004 Location: Netherlands	Thank you all ! The reason i do not use an Aleph pre is because it does not fit in the nad T162. The NAD tuner/preamp has no balanced output. I can use the power supply of the NAD to drive an op-amp, to build an balanced output.

22nd July 2008, 08:58 AM	#8
juma diyAudio Member Join Date: Nov 2005 Location: Zemun	http://www.diyaudio.com/forums/showt...26#post1563426

8th August 2008, 06:46 AM	#10
Berry diyAudio Member Join Date: Apr 2004 Location: Netherlands	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 ?

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