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Audio Research GS150 Musings

Good day my fellow ARC Agaricus Bisporus.

In light of the relative ambivalence that seems to have descended upon ARC's latest, and Should we to believe the "word' on the street, greatest stereo amplifier, I thought that I would initiate this thread for the most part as a vehicle whereby any early adopters of this particular model might comment upon their considerations of the amplifier thus far, and hopefully utilize the same, as a place where they may log their considerations as they journey through the Roller Coaster ride that is ARC break in.

I hope that I will be excused for the somewhat laxidaisic cut n pasting that follows, however I plead the 'Humungous Hangover' defence!

" For my part I have listened to the same GS150 at 60 hours, then with 166 hours on the clock, and whilst there were signs of an opening up in the midrange, I felt the amplifier to to be rather 'Tight', and still a Tad constrained in some areas of tonality, texture and harmonics, particularly on acoustic strings.

Whilst considering comment made thus far in respect of the KT150, I was expecting to be impressed with the lower registers, even at this point in what can be something of a roller coaster ride where break in of ARC is concerned, however this particular GS is still quite some way off, in reproducing the gravitas evident in for example, Der Ring des Nibelungen, as imparted by my Ref150 even at 300 hours on the clock.

However! Even at this early juncture, It is in the upper mid-range, ascending, where the GS has ,for me, impressed the most. The retrieval of filagre micro detail is quite excellent, the GS seeming to impart additional 'air' and light with an effortless extension to the very upper registers. Smooth, clean and accurate, whilst remaining quite organic and utterly convincing in nature.

Jasper."
tsushima1
bifwynne
2,206 posts
 
Jasper, I'd appreciate Al's thoughts, but looking at the impedance graph of the ML's, they look like a giant capacitor. Notably, in the all critical power region (50 to 750Hz), impedance is quite high.

The graph is hard to read, but it looks like impedance is between 10 to 15 ohms in the frequency spectrum where the amp is called on to deliver power. It wouldn't surprise me that you like the sonics off the 16 ohm taps. As suggested, you might want to try the other taps to see which taps sound best.

For example, you might find bass to be tighter and punchier if you use the 8 ohm taps ... I expect a high DF. The 4 ohm taps might give you the tightest bass and the high end might be less bright

Al, any comments?
almarg's avatar
almarg
9,670 posts
 
Jasper, thanks for providing the link. Bruce, yes an electrostatic element can very reasonably be thought of as a giant capacitor, although the resulting impedance variation as a function of frequency will be modified by the step-up transformer that is usually used to drive the element.

I wouldn't expect a great deal of variation in bass response to result from differences in impedance interactions between the different output taps and the speaker's impedance vs. frequency characteristics, though. The reason being that the relatively low output impedance of all of the taps on the Ref150 (for a tube amp) results in all of those output impedances being much lower than the speaker impedance at low frequencies. So with respect to the effects of impedance interactions I would expect the most notable differences among the three taps to occur at higher frequencies, where amplifier output impedance becomes increasingly significant in relation to speaker impedance.

Also, of course, the concepts of bass damping and woofer control that come into play with dynamic speakers are essentially inapplicable to electrostatics.

Although it seems possible that the distortion characteristics of the amplifier could be significantly affected at low frequencies as a function of which tap is used. John Atkinson noted in his measurements that "over most of the audioband, and when the load impedance is very much higher than the transformer-tap value, the Ref150 offers low distortion." Although it should be noted that that comment was based on measurements performed at power levels of just a few watts or less, and it could be a different story at power levels approaching the amp's maximum.

Best regards,
-- Al
knghifi
1,668 posts
 
01-03-15: Gpgr4blu
I'm a huge ARC fan as well. Hopefully, they make it right over time. Get back to superior engineering at a reasonable price.
ARC IS producing superior engineering at a reasonable price.

If ARC has decided to make its products look better for the Chinese market, it can be done with a reasonable (1 to 2k) price increase so as not to lose its base here in the US.
DISAGREE! ARC should charge what the market bears. Passion alone doesn't pay the bills.
fsonicsmith's avatar
fsonicsmith
987 posts
 
"So is the GS150 really just a
REF150 with new looks? �As with
many designs from Audio Research,
the GS150 is an evolutionary step
from the REF150�, explained
Warren. �For while the two amplifiers
share many common aspects, **there
have been numerous parts and
layout changes which affect the
sound.**"

The question that I BELIEVE up until has not been answered definitively is whether there is any difference between the Ref150SE and the GS150 other than the latter's fancier case/meters. One poster in another thread suggested based upon a magazine review that the GS150 "blows the Ref 150 out of the water" (which I doubt) but what about the GS150 vs. the Ref150SE? Does the extra money buy a better circuit layout or parts inside? So as a registered ARC owner, I just emailed ARC that exact question last evening and just got this response;  "they are sonically the same." If you watch Mike Fremers two videos on Youtube of the ARC factory tour, there's a short section/exchange in which Warren Gehl says he uses the Ref150SE as his benchmark for subjective listening checks on all outgoing amps (unless I misunderstood the exchange and video).That explains that. I love the looks of the GS150-more than the staid looks of the Ref150SE. But is it worth the extra dough for the bling? Is ARC's Italian ownership going a bit over the line in making ARC gear resemble the stablemate McIntosh kit without the McIntosh blue meters? I have to wonder but again, I would take the beautiful GS150 any day of the week and Sunday too if they were close in price. I am biased-I just bought a dealer demo Ref150SE to go along with a brand new Ref 6 to replace a 25 year old tubed preamp and a 12 year old VS110. I'm happy but poorer! I have a fluke meter for my VS110 so I'm set in that respect.
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