Has anyone: unbalanced to balanced linestage /w BUF634? - diyAudio
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Old 22nd December 2006, 07:22 AM   #1
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Question Has anyone: unbalanced to balanced linestage /w BUF634?

Balanced stages seem popular these days, so i am tinkering with the idea, but i have not put in any serious calculator time on it yet. i imagine that I am looking for something simple and clean, maybe an opamp differential splitter feeding two BUF634 into an XLR output?? Anyone else toy with the idea?
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Old 22nd December 2006, 08:49 AM   #2
PMA is offline PMA  Europe
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3 years ago, I designed my pre standard amplifier with both single-ended and balanced outputs supported by BUF634T buffers.
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Old 22nd December 2006, 06:16 PM   #3
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Quote:
Originally posted by PMA
3 years ago, I designed my pre standard amplifier with both single-ended and balanced outputs supported by BUF634T buffers.

How did the BUF634work out? Are you still using them?
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Old 22nd December 2006, 06:25 PM   #4
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Default Re: Has anyone: unbalanced to balanced linestage /w BUF634?

Quote:
Originally posted by aletheian
Balanced stages seem popular these days, so i am tinkering with the idea, but i have not put in any serious calculator time on it yet. i imagine that I am looking for something simple and clean, maybe an opamp differential splitter feeding two BUF634 into an XLR output?? Anyone else toy with the idea?
Hard to beat a transformer for simple and clean.

CineMag's CMOB-4 would give you a balanced output without all the ancillary circuitry and they're only about $25 a pop in high nickel.

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Old 23rd December 2006, 06:38 AM   #5
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Quote:
Originally posted by aletheian



How did the BUF634work out? Are you still using them?
Yes. I do, and it works extremely well. As a hint, you can see the Audio Buffer on my web.

We compared it to transformer output, and prefered the BUF stage. Of course it is not the "true" balanced output, if you short one of the outputs the second does not double. But we compared it sonically, and the BUF beated transformers.

Contrary to Steve, I do not like transformers at all.
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Old 23rd December 2006, 06:41 AM   #6
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Quote:
Originally posted by PMA
We compared it to transformer output, and prefered the BUF stage. Of course it is not the "true" balanced output, if you short one of the outputs the second does not double. But we compared it sonically, and the BUF beated transformers.
If you don't mind my asking, what output trasnformers did you use and what was the circuit they were used in?

Quote:
Contrary to Steve, I do not like transformers at all.
And they don't like you either. So NYAH!

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Old 23rd December 2006, 07:17 AM   #7
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Steve,
you would not know them, as they are produced here. Very similar parameters to corresponding Jensen link transformers. I do not remember type numbers, it was 2 years ago.
For me, the biggest issues are sensitivity to external magnetic fields (heard), a lot of HF noise (measured, IMHO responsible for worsen sound) and higher LF distortion, possibly LF saturation at high voltage levels. That is why I do not like them.

Cheers,
Pavel
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Old 23rd December 2006, 09:56 AM   #8
Pasul is offline Pasul  Czech Republic
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Hello Mr.PMA,
I have question for you.I want use your buffer in DAC and do little test(measure).And my question is which version is best for you?50 Ohm at output and 50 Ohm in cable too.Or without 50 Ohm in cable.And what this alternation do with sound?I remember you tested this.I hope so...

I look on PCB and this I must make alone.And you now why.
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Old 23rd December 2006, 10:50 AM   #9
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You can try 2 versions:

1) R10=50 ohm (serial), R12=50 ohm (terminator)

2) R10=5 ohm (serial), R12=infinity (open end), then gain would be +2 / beware of next stage possible clipping

After doing your listening test you can tell me which one you prefer.
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Old 23rd December 2006, 11:55 AM   #10
Pasul is offline Pasul  Czech Republic
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I remember this discussion between you and OPA.And I now your choice.There is much difference in sound?And last time you promise new DAC.Which buffer you plan use?I think Mark Levinson use same topology (OPA627+BUF634) and this player is not bad.

Of course I show you my DPS and tell you which output configuration is best for me.
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