Reply To: Class D for Sound Lab Speakers?

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    I’ve owned 3-SoundLab pairs, obviously at different times.

    Frist, I had Millennium-1’s and then M1-PX’s with the consummate backplates and currently, Majestic 845’s.

    I drove my original Millennium-1’s with a Mark Levinson 336 stereo amplifier. At that time and on the old SLOG forum, many were using tube amps, especially Wolcott’s and Atma-sphere’s. Thus, I wanted to try a tube amp and see what all the fuss was about.

    A local dealer had a used pair of CAT (Convergent Audio Technology) JL1 monoblocks – 100W/Ch. Those weighed in at just under 400lbs. Along with the CAT’s, the dealer had an audition pair of Parasound Halo JC1 monoblocks. I took both the CAT’s and Parasound’s home. I first inserted the Parasound’s. At less cost than my Levinson, the JC1’s were very similar to the Levinson 336. When I inserted the CAT’s, I was immediately bowled over. The CAT’s controlled the SoundLabs unlike the two solid state amps. Bass was better, SoundLab’s superb midrange was even better and the treble was great. I then thought what am I missing? The answer was nothing was missing! Everything I value was better, soundstage, harmonics, imaging, drive and control etc.

    A few years later, I had the opportunity to obtain CAT JL3’s with double the output tubes and 50 more watts/channel than my original JL1 CAT’s. They were better with my then Millennium SoundLabs in terms of a marginal higher output. But the overall sound was very similar between the 2-amps. With PX panels and the newest backplate’s, I’m sure JL1’s would now be sufficient.

    However, after developing significant spine and hip issues, the CAT’s became problematic. Because CAT’s owner Ken Stevens strives for utmost excellence, he chose to forego using actual fuses. Instead, he installed sacrificial resistors at each tube socket – 16 for the JL1’s and 32 for the JL3’s. I had several resistors blow while I owned the CAT’s. Each time, the 190lb. amps had to be flipped over on their tops and their bottom plate’s many screws removed. The blown resistor then needed to be de-soldered and a new one re-soldered. Not a terrible process for someone with a soldering iron and the physical capabilities to perform the function. But the process became one I could no longer perform.

    At 37lbs. each, robust and fused, I thought that the Atma-sphere MA1’s may be a good alternative to the CAT’s. My local dealer brought the MA1’s out for an in-home audition, along with Levinson and Pass Labs amps. The Pass was an A/B amp, at I believe 250-watts. Sonically, it wasn’t at all what I was used to. The Levinson was also around 250-watts and its protection circuits kicked-in. So, I didn’t get to hear much of it. But when the Atma-sphere’s were inserted, I had reproduction similar to my CAT’s. They may have a bit less bass wise, but they had a bit more detail (which was good) than the CAT’s. But the harmonics, imagining, soundstage and control were similar to the CAT’s. Hence, I chose to buy a new pair of MA1’s. I had no more sacrificial resistor concerns and no worries about repairing, lifting and moving 190lb. amplifiers. To the CAT’s credit however, much of the 190lbs. is due to CAT’s 55lb. proprietary transformers. My belief is that CAT push/pull amps (with a midrange SET purity) owe much of their superb capabilities to their proprietary transformers. As such, CAT’s are a supreme match for SoundLabs. And as you can tell, I hated to part with them. They’re that good with SoundLabs and I understand with many other speakers. In fact, I would imagine that CAT’s newer JL5 stereo amps would be a great match with S/L’s.

    With that said, many solid-state amplifiers of sufficient power will drive the SoundLabs well. I thought my Levinson and then the Parasound Halo’s did well, until I heard the CAT’s and tubes. At that point, everything was better. Bass was better and harmonics were better and as such, symphonic instruments sounded more like the real thing. Thus, with the CAT’s and Atma-sphere’s, I prefer tubes. If I never heard the difference, I would have been quite satisfied with the solid-state amplifiers I owned and tried. However, if you have a chance to audition CAT’s or Atma-sphere’s, you may well hear the plusses that prompted me to stick with these tube amplifiers.

    As a matter of fact, because of my physical limitations which even impact tube changing and rolling, I would like to find solid state amps that would equal the Atma-sphere’s. Forum member “ACHiPo” does own Atma-sphere’s and Benchmarks. He has made a comparison between the two.

    However, I would love to hear from other folks who have had the opportunity to compare Atma-sphere’s with for example: Pass A/B and Class A amps as well as other solid-state Class A/B, D & H amps.

    Some who run their system many hours per day, may choose solid state because of tube replacement issues. And although heat is not a problem with my Midwest, basement audio room, I can understand why some may have chosen solid state. But of supreme importance to me is not heat or tube maintenance, but the end result – i.e., from a purely sonic perspective, what solid-state amp will equal CAT or Atma-sphere tubes? If I move to solid state amps, I would like to do so laterally sound wise and not regret the move.