Audio Research D300 Power Amplifier Review

[milosz]

I think that the whole "low negative feedback" or even NO FEEDBACK thing is a marketing bullet-point aimed at high-end buyers who don't have a clue what feedback is, how it works, etc. They just "know" it's bad. After all how can negative feedback be GOOD if it's NEGATIVE?

I also think there's another more subtle reason for this. Seems some listeners PREFER a certain kind of coloration which is added by a certain distortion profile. It's one of things that makes the amplifier sound somewhat different from other amps. If all amps were like the Benchmark, they'd all sound the same for the most part. And many high-end buyers will listen to a product and end up believing that DIFFERENT is BETTER.

And maybe the distortion profile of this amp is meant to be similar to the euphonic distortion of Audio Research's tubed amps? I'd be curious to know if it has rather high-ish output source impedance, which would lend it more "tube character."

 

[pma]

Shall I start at A for Accuphase and go through the alphabet? Pretty much every power amp they produced from the late 1980s onwards would outperform by a wide margin this Audio Research.

Here's a few random (early 90s) Accuphase THD vs Po plots I posted in another thread:

And here is an independent measurement
https://www.stereophile.com/solidpoweramps/200accu/index.html

https://www.stereophile.com/content/accuphase-m-2000-monoblock-power-amplifier-measurements

As I wrote earlier in another thread, and we disagreed, I do not like if measurements are too much concentrated to 1kHz results. Yes, Accuphase is good at other frequencies as well. Another point - to me measurements to 8ohm load are close to useless. Almost no speaker impedance stays at 8ohm. Even 8ohm nominal impedance usually goes to 4ohm. Dips to 2 ohm or even below are not unusual. So, to me, this is much more informative

Fig.3 Accuphase M-2000, THD+noise (%) vs frequency at (from top to bottom at 6kHz): 4W into 2 ohms, balanced; 2W into 4 ohms, balanced; 2W into 4 ohms, unbalanced; 2.83V into simulated loudspeaker load, balanced; 1W into 8 ohms, unbalanced; and 1W into 8 ohms, balanced.
Read more at https://www.stereophile.com/content...er-amplifier-measurements#AD50LzVxcjkdjE20.99

 

[restorer-john]

"John Atkinson used the Miller Amplifier Profiler to examine the M-200's output power on a slow-duty-cycle 1kHz toneburst, which is more like a typical music waveform. The results are shown in fig.8. Specified at a continuous 250W into 8 ohms, the Accuphase actually didn't clip until 524W (black trace), with 1007W available into 4 ohms (red), 1938W (blue) (2ohms), and 3602W (green) (1 ohm)!"

 

[MetalheadRich]

With tons of GNFB -> very good specs. But sound, emotion, 3-D... ?

So what? There's no proven negative to large negative feedback.

 

[Ron Texas]

Ah yes, the drive over test will be the next big thing. I recommend using an F-150.

 

[anmpr1]

Ah yes, the drive over test will be the next big thing...

Fire. Have to do the fire test to make sure.

 

[martijn86]

All the lines fall on top of each other indicating the amp just doesn't care what frequency you feed it. It amplifies it, adds a heap of distortion and that is that. Makes you want to cry and celebrate at the same time!

It fails perfectly consistent.

 

[Newk Yuler]

Unless I'm mistaken this amp appears to have solid copper speaker terminals instead of the typical gold/nickle plated brass. That extra detail has always impressed me in audio equipment. I mean, it oxidizes but why use brass when copper is a much better conductor and it's what most interconnecting cables are made from?

For example, why not better use something like this for RCA connections?

http://www.audio-cmc.com/rca-jacks/rca-jacks-p_31.html

 

[LTig]

A lot of pictures of D200 model.

https://www.stereo.net.au/forums/to...0-power-amp-with-all-original-packing-manual/

Resized, clarified and optimized

View attachment 40822


http://www.audiocostruzioni.com/r_s...i/audio-research-d200/audio-research-d200.htm

View attachment 40818

NFB, only 21 dB

Exactly what the measurements predicted!

And no THD specs! One really has to read between the lines - even back then.

 

[restorer-john]

Fire. Have to do the fire test to make sure.

So Crown copied Marantz's 2270 ad...

 

[LTig]

So Crown copied Marantz's 2270 ad...

View attachment 40912

I'm rather inclined to disbelieve both stories. Intense heat in a fire or drowned with water for longer periods and still working to specs is quite unrelastic.

 

[restorer-john]

I'm rather inclined to disbelieve both stories.

I've always had my doubts over the Marantz ad. I went on a rant about it way back in this thread:

https://www.audiosciencereview.com/...age-of-japanese-audio.8108/page-2#post-207339

 

[Zaki Ghul]

I've got the C80/M80 pair from the Natural Sound series. I purchased them for a Christmas gift for my brother way back when they were a couple years old. I tried them out in my system at the time and it sounded very good. I told others about it, but you didn't run across them very often even then. They were rather inexpensive at the time too.

http://www.hifi-classic.net/review/yamaha-c-80-and-yamaha-m-80-463.html

View attachment 40833

Are you selling as a bundle or will you separate? I would be interested in the pre.

 

[Labjr]

What they don't tell you is that Marantz and Crown were the cause of the fire!

 

[pozz]

What they don't tell you is that Marantz and Crown were the cause of the fire!

That was actually my first impression... that it wasn't the electric organ, it was the Crown amp. Made for a confusing bit of advertising before I read it through to the end.

 

[Blumlein 88]

Are you selling as a bundle or will you separate? I would be interested in the pre.

Haven't decided yet. Send me a PM, and when I do I'll get in touch with you.

 

[martijn86]

And many high-end buyers will listen to a product and end up believing that DIFFERENT is BETTER.

To be fair, while maybe not the best measuring, the thing you like to listen to the most is the better fit for you. It's not like 'many high-end buyers' are idiots who buy the 'wrong' amplifier.

 

[milosz]

To be fair, while maybe not the best measuring, the thing you like to listen to the most is the better fit for you. It's not like 'many high-end buyers' are idiots who buy the 'wrong' amplifier.

I know quite a few high-end buyers who are idiots. If there weren't a lot of gullible people with more money than sense they'd never be able to sell those $1,000 interconnects and the $1,400 ethernet cables.

 

[anmpr1]

But Audio Research have always done their own thing, not bowing to fashion or style and they have a loyal following to this day. Personally, I'm glad they have survived and are still in business.

The fact that they are still in business tells you that they've done something right..., at least from a marketing standpoint. I think a lot of it must be attributed to 1) a solid dealer network, 2) likely good after the sell service, and 3) accommodating taste-makers in the high end press. Hard to argue with the first two criteria; the latter has been for them, however, dependent upon 'fashion and style'. But that is the same for any manufacturer playing the the 'high end' game, and Audio Research was playing it before there was officially a high-end, so if anyone knows how to do it, it is them.

A-R started out with some Dyna mods (at least that was the first I'd heard of them). The big turn was when Harry Pearson and, I believe, Gordon Holt fell in love with the SP3 preamplifier. That was also Peter Aczel's main preamp for a while--before Audio Critic, and before he left the glass audio scene. We recall how this was all at a time when tubes had mostly been forsaken by the mainstream. So, in that respect, what they were doing was surfing a 'tube renaissance' they pretty much single handedly created.

For a while the company auditioned their gear with associated Magneplanar speakers. At stores the two were inseparable, with dealers advising how you needed both in order to get the real magic. I don't really know how it was... maybe Audio Research was the Magnepan distributor.

Their solid state 'analog module' thing is best forgotten. For their part, I think they have forgotten that era in their early history. Much easier to replace a tube in an SP3a, than trying to find out whatever the company potted in that black brick. The critics didn't like it, so in order to cater to fashion and style Audio Research mostly went back to tubes.

A related anecdote. Peter Aczel's hybrid M300 pair 'blew up". In his own words: A short from the control grid screen in one of the 6550s's created some kind of avalanche effect that traveled upstream and took out all the FET's. The moral? There is no amount of unhappiness in this materialistic world that $9800.00. cannot buy.

 

[maty]

Now that nobody reads us, just to say that AR is the only thing that interests me are the tube (hybrid) preamps as the old Audio Research SP-15 (1988). It has a very good phono too.

http://www.audiocostruzioni.com/r_s/pre/audio-research-sp15/audio-research-sp15.htm
https://audioresearch.com/ar-package/sp15_manual-pdf/
https://www.hifiengine.com/manual_library/audio-research/sp-15.shtml
https://www.usaudiomart.com/details/649548871-audio-research-sp-15-hybrid-preamp/images/2381821/

https://tmraudio.com/components/pre...sp17-stereo-tube-preamplifier-sp-17-mm-phono/