BUF634 vs HA5002 buffers in headphone amp ?

[gurevise]

Guys,
What are your thoughts on these two buffers ?
I see that HA5002 is used a lot in headphone amps.
What about BUF634 ? It has a nice specs, at least on paper.
Is HA5002 really much better sounding IC then BUF634 ?
Let me know what you think. Thanks

BUF634 is easity available from digikey.com
HA5002 is harder to source.

Thanks
Sergey

[mlloyd1]

I just ordered some from Arrow Electronics

mlloyd1

[john curl]

If you really want quality, just make a discrete push-pull class A buffer from Fets or bipolar devices. The only other alternative is tubes. Trust me. ;-)

[PMA]

Originally posted by john curl
If you really want quality, just make a discrete push-pull class A buffer from Fets or bipolar devices. The only other alternative is tubes. Trust me. ;-)

There might be more kinds of "trust" .
I have the best experience with BUF634T, both parameters and sonic quality (you can visit my www to see an example of a circuit design). I am very sure that it is practically impossible to reach the same parameters by several discrete transistors, monolithic technology is superb for this purpose. The speed, thermal junction between components, repeatability ... And with BUF634 inside feedback loop you are able to reach THD of 0.0001% with OPA627, for example. You'll hear the result when listening to great philharmonic orchestra, violin, organ, trumpets ...

[jean-paul]

Don't trust your website, the link on your www site to the audio-buffer is broken.

At the moment it is:

file:///C:/Dokumenty/HIGHEND/MAC_hifi_publish/pokusny/buffer_en.html

This one works:

http://www.pha.inecnet.cz/macura/buffer_en.html

I would take advice of John Curl serious. He has some experience with preamps to say the least.

[analog_sa]

have the best experience with BUF634T, both parameters and sonic quality (you can visit my www to see an example of a circuit design). I am very sure that it is practically impossible to reach the same parameters by several discrete transistors, monolithic technology is superb for this purpose. The speed, thermal junction between components, repeatability ... And with BUF634 inside feedback loop you are able to reach THD of 0.0001% with OPA627, for example. You'll hear the result when listening to great philharmonic orchestra, violin, organ, trumpets ...

I have only used the dip BUF634 and have been consistently underwhelmed. As i don't care one bit about thd, the zeroes fail to impress me. Outside fb loop i find the sound pathetic; inside it's much better but you can always hear the presense of the BUF and not necessarily in a pleasant way. I haven't touched opamps for more than 10 years and only recently spent some time investigating how far have the little chips progressed. Well, in some respects the best are now truly better than the 5534 - a good design conveys a degree of a sense of space, delicacy and PRAT, but in respect of genuine, lifelike, startling dynamics they still have a long, long way to match the sonics of discretes, be that valves or SS. For the record my experiments have included a phono in which a opa637 is followed by a buf634 driving a fb type riaa network and a opa627 with a buf634 as a line stage.

cheers
peter

[PMA]

Originally posted by jean-paul
Don't trust your website, the link on your www site to the audio-buffer is broken.

You are right, thank you very much. I have just repaired it.

Pavel

[PMA]

Originally posted by analog_sa


As i don't care one bit about thd, the zeroes fail to impress me. Outside fb loop i find the sound pathetic; inside it's much better but you can always hear the presense of the BUF and not necessarily in a pleasant way.

Hi Peter,

yes, low thd is not the only sufficient parameter , but necessary (in case that the whole audio chain is perfect , otherwise it may emphasize another flaws). From my experience - low THD, IMD and perfectly stable design (to any load - this must be measured) are absolutely necessary in case that I want to listen to all the details of symphonic orchestra. Valves are fine for a jazz quartet or single saxophone, but I do not prefer to hear new colorations. Valve itself is further musical instrument in the audio chain

Pavel

[analog_sa]

Valves are fine for a jazz quartet or single saxophone, but I do not prefer to hear new colorations. Valve itself is further musical instrument in the audio chain

Valves require an incredible amount of care to sound good with complex music. In my experience each amplification stage has to have its own independent power supply, or at least dedicated regulator. The results can be truly rewarding but there is a price to be paid in size and weight. Of course microphony is another curse... To my ears, though, valves ultimately win as far as dynamic expression is concerned.
Have you compared the sonics of the dip BUF634 to BUF634T? Is there a substantial difference (assuming both are driving easy loads, far from max current)?

cheers
peter

[PMA]

Originally posted by analog_sa



Have you compared the sonics of the dip BUF634 to BUF634T? Is there a substantial difference (assuming both are driving easy loads, far from max current)?

cheers
peter

Nice post, peter. Regarding BUF634 in DIP-8 and BUF634T in TO220-5, I did not have chance to compare them. My choice was the BUF634T from the simple reason - in my buffer application I use the coax. cable terminated at both ends by 50 Ohms, i.e. 100 Ohms load for the buffer. This, especially terminating resistor (R12 in the Audio Buffer schematics) has brought dramatical improvement of the whole soundstage. Any hint of grain or harsh is over.

Pavel