The "design" was just a pair of BUF-03s. Now, that's not damning with faint praise, the BUF-03 was a fine chip (though it runs WARM). And unless you do something stupid in the layout to make it hum, buzz, or oscillate, it will be totally transparent in the sense that you will not be able to distinguish output from input by ear alone.
SY said:
Wow. That's great -- perfection achieved here on earth. I guess all the amp designers can go home now, they're all obsolete.
I could be wrong as I must be somewhat dense in this regard. I haven't even found a lowly wire or metal film resistor that is "totally transparent". Your mileage may vary.
Now Chas, be nice!
Just as resistors and caps vary, so do ears....
You can do a lot worse than a BUF03 or BUF634, just as you can do a bit better. If the worst component he had in his system was a klone of the Aunt Corey's preamp direct coupled, it could be a pretty fair system!
Not everyone has an Ayre K5x preamp for comparison! How does one explain that an active preamp can sound better in the right system configurations than a passive preamp using Shallco based attenuators? But it's true....
~Jon
Just as resistors and caps vary, so do ears....
You can do a lot worse than a BUF03 or BUF634, just as you can do a bit better. If the worst component he had in his system was a klone of the Aunt Corey's preamp direct coupled, it could be a pretty fair system!
Not everyone has an Ayre K5x preamp for comparison! How does one explain that an active preamp can sound better in the right system configurations than a passive preamp using Shallco based attenuators? But it's true....
~Jon
Assertion is easy. Evidence is tougher. If you've got real evidence, JAES is waiting with bated breath. Showing up Lipshitz, Greiner, et al would be quite a coup, and would definitely not hurt your business
Obligatory Disclaimer: I am not in the business of selling boxes of gain claimed to "sound better" than normal, competent electronics.
So, you only want your boxes of gain to sound as good as "normal, competent electronics"?
What is that standard? Is that the standard set by all the marvelous $60 DVD players you can buy at CostCo, Wal-Mart, and Best Buy? Do enough listening, and you may change your mind.
I'm not in the business of selling any kind of boxes of gain; well, not these days. But time after time I have heard these differences between "competent" electronics and others- even when not expecting or wanting to!
And have concluded fairly often that "competent" electronics, as I think you define, are often not so good. Otherwise I would not have easily heard things I didn't like about one of my own first solid state amplifiers (which actually was sold in a commercial design) compared with a Conrad Johnson tube amplifier- even though my own design would put out over 100 watts at THD and IMD of 0.004% or less- in fact, lead dress of every production unit was checked using the distortion analyzer, to assure this level of performance. BTW, this was in the late 70's. And this was a so-called low TIM design, with an SR of > 100V/usec, using a JFET front end, and an emitter follower triple output stage (yes, based on the Bart Locanthi circuit). Fortunately, for me, I've learned a lot over the years, both on the bench and in listening. And my current designs sound a lot better than that late 70's era amplifier.
Curiously, an amplifier I did earlier in the 70's sounded better than the one described above, even though it didnt' measure as well in some conventional ways- in large measure because of the power supply and attention to components and their sound, I believe. That one would clean the clock of top of the line Luxman solid state amps, SAE, and even the 150 watt per channel Stax Class A. So, progress and learning are not always at an even pace, and one ignores lessons past learned at one's own risk.
And if all this stuff about "boxes of gain" is too annoying for you, Just try to design and build a really good interconnect or speaker cable some time....
Of course, you may be happy with some 12 AWG zip cord from Home depot. And while I can point to why the cables I use measure better at audio frequencies than zip cord speaker wires, I don't really know enough to think I can tell you why they sound better in the ways they do...
Regards,
Jon
Harmon said:
I built one years ago, still have the board lying around (all hardwired) but stole the power supply for something else. In an a/b test (level matched!) with a Sonic Frontiers SFL 2 preamp, we couldn't tell the difference. So I guess it was pretty good, considering the price difference.
I'm actually thinking of reviving the project, as right now I'm using a passive attenuator who's output impedence is too high, at worst case its 30kHz out and my amp is only 20kHz in! Other thought is a simple JFET buffer based on Borbely's writings, John Curl has confirmed that the design is very low distortion.
The Buf-03 does run hot, needs a heatsink, and it's long out of production.
RonS
The BUF634 is essentially a complementary diamond buffer with a variable biasing option. Internal topology is quite different from the BUF03. OTOH, you should be able to make a decent buffer/follower with it; it does require good local bypass for stability. I wouldn't recommend using it direct coupled at the output because it can have 20-30 mV of output offset, and fed into some power amps, that would cause problems (typical gain of 20 or more would result in half volt or more offset at the output of a DC coupled power amp. Yes, many power amps do have caps in the feedback loop and have unity gain at DC, but a significant number don't. I'd recommend using output coupling caps, follwed with a pull down (100K or so) to ground.
analog_sa said:
I have never used the BUF-03 but have used a BUF634 in two applications. First was as the output buffer on a Pioneer PD-91. It was a huge step up from the stock unit. I think Jam is sitting on the player now.
I later built a bufffer for a passive linestage using some. It was very nice, but nothing close to input = output. It was idled up to 10 ma or so. The sound was a little zingy, hifi-ish.
Went with a simple dc coupled fet buffer. Much more natural.
Some felt the 634 is better sounding than the 03. I should have picked some up back when they were available at Digikey and other suppliers to compare.
George
analog_sa said:
Was the fet buffer better in this respect?
No, maybe worse. But the effect of the fet buffer seemed to if anything to add warmth and make the mids richer. The BUF seemed to give the music a leaner sound.
Some ears and systems might find the BUF's are perfect, but in my system the fet buffer
I've built more than 20 of the BUF-03s in the past and they sound very, very good compared to any of the other buffers available at that time. They are still some of the most neutral sounding buffers I've used. Alas, they are long gone from production and have no current equal. The 634 is not the same at all and does not sound nearly as good IMO. The secret with the BUF-03s was the power supply had to be very stable and high current with no more than 15 volts a side. The BUF-03 liked to be hot to sound the best and was a class A device without any pullup. I'd love to find a new device that does the same thing.
well, FET my BUF
Folks that miss the BUF03 could always try making your own. It might be an interesting alternative to the various diamond buffer designs going on right now.
You can view the obsolete datasheet available still at Analog's website.
Here's the simplified schematic:
The real question is who will be first with the PC board?
Folks that miss the BUF03 could always try making your own. It might be an interesting alternative to the various diamond buffer designs going on right now.
You can view the obsolete datasheet available still at Analog's website.
Here's the simplified schematic:
The real question is who will be first with the PC board?
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