OTL Asylum

Posted by Grant (M) on August 20, 2005 at 12:25:49

I recently received my MA2mk2.3's back from Atma-sphere after having undergone an output resistor modification. Although I had always been very pleased with the MA2's performance, they, like all other amps I have owned, had a 'signature' sound that was unique. In brief, they had a very immediate, wide-open dynamic performance that was unlike other tube amps I have owned and evaluated. Also, I would say that they had a very slight upper-mid emphasis and an extended treble that demanded attention be paid to upstream electronics and cabling. Also, as is true of some other OTL's, they had exceptional delineation of fine detail and three-dimensional imaging that made them a worthwhile purchase. They have remained my references for two plus years.

My expectations for the output resistor mod were modest, at best, but I was curious to see if I could tell the difference. In short, the change was absolutely astonishing. First and foremost was an obvious improvement in the layering of harmonic texture. Musical overtones took on an immediate richness, definition and full body that had not been resolved by the amps before. The very slight emphasis in the upper mid vanished, replaced with the most natural rendering of piano and female voice that I've ever heard. All this while maintaining the extreme phase and time coherence which drew me to purchase them in the first place.

Detail within the sound-stage became immediately more evident and three dimensional. I have literally heard small but relevant musical detail on recordings for the first time. Pitch definition, especially through the lower mid and upper bass tightened noticeably, exposing more third-order harmonic detail. I think the subtraction of a few minor characteristics with the resistor change has exposed capabilities of these amps that one must hear to believe. I don't recall the cost exactly but know it was under $1k, which given their retail cost and the resulting improvement, was an enormous bargain.

I hadn't seen any comments on it thus far, so thought I share my .02