Would u choose Buf634T?

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Hi!
Didn't get that much on searching so....


Just wonder what ur opinions are on Buf634T? I will use it as a output buffer in a closed loop circuit (in a headphone amp).

It doesn't seems to be popular on some headphone - forums , therefore I felt that I must ask u people here...and yes I know that Carlos seems happy with it, but how about the rest of u?

And, doesn't Mark Levinson use it in their dac's?

I feel that it can't be that bad but it cost a lot..however it's nice to hear so many opinions that's possible before deciding on the pcb-layout...

Thanx!

________________________

/Peder
 
PederBass said:
Just wonder what ur opinions are on Buf634T? I will use it as a output buffer in a closed loop circuit (in a headphone amp).

It doesn't seems to be popular on some headphone - forums , therefore I felt that I must ask u people here...and yes I know that Carlos seems happy with it, but how about the rest of u?
I at least am very pleased with BUF634 and the "F" model (SMD, TO220). Together with OPA627, AD8610 and OPA134 I think it's an excellent combination. I have also tested the buffer in "medium speed" and "high speed" without any big differences. Medium speed is to have 3.9 kohms from BW pin to V-.

Picture here
 
"Note that this buffer is an industrial part and the sound quality has nothing to do with it's price. It has to do with demand from the industry and how hard it's to make."

Yes, I totally agree about that soundquality has nothing to do with price, just ment that high price would be a negative factor when u choose ur amp...:)

So ur happy with then? Have u compared it to other buffers, like those Intersil HA-5002 or HA-5033 buffers?


/Peder
 
You can try to get samples, cost you nothing but you can also build a diamond buffer quite easily with very good results. Check my designs for inspiration. All of these are "high speed, low distortion versions" with cascodes but you can make it. QRV-03 is made of ordinary parts and the other two are made of SMD parts.

QRV03
QRV05
QRV06

Good reading can befound here
http://www.elecdesign.com/Globals/PlanetEE/Content/2800.html
http://www.linear.com/prod/datasheet.html?datasheet=315
http://www.national.com/an/AN/AN-227.pdf
http://focus.ti.com/lit/an/sboa071/sboa071.pdf
 
I had compared this type with similar discrete one ( something as Jung's diamond buffer ). Both was connected to feedback loop of opamp ( OPA 134, OPA 627 ), both was set up to the same BW ( 1 MHz ), both had the same load impedance ( 50 Ohm ). I bias of 634 was 15 mA, discrete was cca 25 mA. In discrete was used normal cheap transistors ( BC 546 / BC 556, BD 139 / BD 140 ), not any " exotic " high speed types. And results ? Discrete win " two horse lenhg " in all aspects, mainly in much more firm bass. Interesting of this solution is also price - it is ten times lower ;).
 
Keep goin :)

Thanx guys!
This info is really interesting to me, especially that part about a discrete solution...
Been studying that - but it seems that u have to match most of the transistors quite good - to get good values in output offset and noise, right or wrong? Otherwise I feel that a discrete solutions very often is much better than a ic-one.

But keep goin...would appreciate more opinions..:)


/Peder
 
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