Audio Research Vs115

There are no reliability issues with that amp that I am aware of.

My VS115 is one of the earlier ones with the 6550's. At some point I will upgrade the tubes to KT120's. I've also blown one of the resistors in the amp. I ended up replacing the resistor myself--it's a 10 minute job if you know how to solder. Apparently this is a common problem.

Other than that, I love this amp. When I put it in my system, it totally changed the sound of my system in the area of midrange accuracy, imaging, and 3-dimensional soundstaging. I was using Classe solid state electronics before.

Compared to some tube amps, this is a very wideband amp. With laboratory test equipment I have measured its frequency response into an actual loudspeaker load as flat out to 20 kHz and -3 dB at 50 kHz. This probably helps account for why this amp does not sound rolled off in the highs and has very good detail.

I also have an LS-27 and Reference CD-7, so you can see I am sold on ARC.

Jake, what loudspeaker did you use when you tested the VS-115's FR? Also, what output taps did you use?

Bifwynne - The speakers under test were Thiel CS2.3 driven from the 4 ohm tap. The CS2.3 are a notoriously difficult load for amplifiers, with large swings in impedance over frequency and a minimum impedance of 2 ohms. However, the Thiels and the VS115 match up extremely well, far better than with solid state amps. I currently have the Sonus Faber Cremona M and get pretty much the same results with the VS115.

@Jake, your results line up with the test results from Stereophile and Soundstage I posted above. Did you also have a chance to near-field mic the actual SPL outputs of the Theils. That would seem to be the ultimate test.

I switched over to the 4 ohm tap and am getting used to it. Very different acoustic presentation, probably because the 8 ohm taps has a higher output impedance than the 4 ohm tap, ergo permitting a touch more output variation in the high impedance parts of my speakers, mainly the 2.2K to 4K Hz region of the freq. band. Per Atkinson at Stereophile, the SPL variation is almost half.