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
I'm a huge ARC fan as well. Hopefully, they make it right over time. Get back to 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.
Gpgr4blu ... couldn't agree more. We may be recycling the same inside news from the same person that the GS line is targeted for the Chinese/Asian market, but I heard that bit of information too. I still find it hard to understand ARC's pricing/value proposition for the GS line. Short of a major "Ref 10" type redo, which is based on the 40th Anniversary linestage on steroids, I just don't get it.

IMO, I would not part with the kinda cash ARC is asking for the GS line, even if it could levitate spoons and bend them in mid-air.
P.S. Correction to my post to Jasper. What I should have said is that the output voltage variation (not power) is tightest off the 4 ohm tap and therefore the amp performs more solid state like ... that is like a constant voltage source. This corresponds to the fact that the output impedance (about .6 ohms) of the 4 ohm tap is the lowest of the 3 taps.

So, if the ML speakers were voiced to be driven by a low output impedance SS amp, the 4 ohm tap might (??) produce the flattest frequency response, assuming the MLs spec flat as a threshold matter.

But having said that, as Al said, the ultimate output may sound better at a higher ohm tap based on listener preferences (i.e., preferred acoustic coloration) and/or the impedance match (or maybe better said, mismatch) of the amp and speakers especially if the amp is called upon to produce large amounts of power.

As Al said, generally, most amps are not called on to deliver huge amounts of power in the treble frequencies.

In the end, go with what ever sounds best.

BIF
Thank you Gentlemen, as I posted above, I do like to run this combination counterintuitive to received wisdom. For your info a link to some test measurements taken during the HiFi World review ~

http://www.hi-fiworld.co.uk/index.php/loudspeakers/65-reviews/252-martin-logan-clx.html?start=2

Jasper.
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?