Reply To: Experience with amplifiers and Sound Lab speakers

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    I wrote the following observations on this subject on the Linn Forum (HiFiWigwam):

    Posted July 10 (edited)
    I usually drive my SoundLAB speakers (full range electrostatic) with two mono Audio Research VT-150 (vacuum tube) amplifiers but lately I also been trying a single stereo Linn KLOUT and I find it does an excellent job overall. The perspective and focus of that lens peering into the window of the music is quite different between the two of them but equally as enlightening. Each amplifier has its own presentation of the overall soundstage: but both are very pleasing to the listener via these ELS speakers (musically balanced and no crossovers with stellar phase and transient response).

    Applause to the KLOUT design team at Linn…..thirty years ago…

    Follow-up to my original post:

    Over the years I’ve owned Quad ELS (way back when…the metal grill black and gold versions, sometimes using four, two per side, at once); Acoustat 3 (transformerless ELS with their direct drive 6BH5 tube amps); the later Acoustat 4s (ELS, transformer coupled, just upgraded/refurbished transformers by Roy Esposito); Sound Lab A1s ELS (I had these for well over twenty years, Toroid 1 version, panels just shipped to back to the factory for service); and recently, I picked up a pair of Sound Lab ELS A3PX Toroid 2.

    The audible presentation I hear with the Sound Lab ELS that sets it apart from the others is when listening to source material with “real” stereo information captured…. (soundstage L-R, depth F-B etc…. vs. multi-mic pan pot location placing and artificial acoustics ie. electronic reverbs…. sadly (or not) the latter is what 99% or all recordings consist of…and of course there is no real “space” or “depth” even present on these recordings)… is the Sound Lab’s ability to present (recreate) the instruments in the acoustic space, ie. the room’s acoustic qualities and the musicians playing their instruments in that room.

    The recordings I use for this subjective analysis are recording I’ve made with a completely transformerless analog(ue) recording chain, capturing the information with a pair of (90-degree angled figure-eight) microphones and storing this information on audio tape running at 30 inches per second (Ampex ATR-100 direct into the recording amplifier electronics ie. no ATR I/O modules present). Absolute polarity is maintained throughout this recording system.

    Phonograph records (33 1/3 LPs on TELDEC vinyl) have been made from these same audio tape recordings so I have the LPs as a source for cartridge, arm, TT, RIAA phono preamplifier analysis. We all know about the phono cartridge’s inherent lack of separation always being an issue.

    I’ve made analog to digital versions of these same stereo tape recordings at various bit/sample rates. I’ve also made Red Book CDs at 44.1k 16 bit (direct from the master tapes w/o sample rate conversion) for standard CD player/DAC analysis.

    The music is performed by professional classical musicians from a large city symphony performing in ensembles, in acoustic spaces (small chapels etc.) complementary to the music.

    The Sound Lab A1’s …. (2350 square inches of radiating area with (my older pair are the version with) 90 degree full spectrum horizontal dispersion) and the A3PX’s (1800 square inches of radiating area with 45 degree full spectrum horizontal dispersion) …coherent phase (full range ie. crossoverless vs. multiple drivers with an attempt to fix the phase relationships/crossover points/crossover slopes etc.)… and LF to ultrasonic frequency response…essential to accurately presenting to the listener the sound of the instruments in the original room.

    The Sound Lab speakers with the Audio Research VT-150SE amplifiers (1994, mono, 130 watts +, I use the 8 ohm taps w/ the SLs) combination presents the musicians and their instruments in the room with a life-sized perspective. The Linn Klout (1992, 160 watts into 4 ohms) perspective is about 35% “smaller”.

    The subtilties of articulation in areas such as the bow against the viola’s strings; the finger’s of the harpist plucking the strings; the rich natural overtone structures of the violin, cello or the flute radiating into the room…these are the some of the most significant areas of differences between the two amplifiers. The ARC amplifiers (in this setting) exceed the Linn amplifier and contributes subjectively to a great sense of the “air” (in the room), the space between the instruments and the overall “size” of the soundscape. Remember, I was in the room making the recordings. I was there.

    The LF of the ARC amplifiers is powerful and deep (room acoustics) whereas the Klout is powerful and somewhat leaner in comparison. The impedance of the speakers (specification stated at 8 ohms) varies with frequency and the taps to the transformers on the ARC amplifiers vs. the Linn are a variable here. The impedance of SL ELS goes up in the LF (around 16 ohms?) and down in the HF (4 ohms?).

    By no means am I stating any judgements here. I have presented my method of listening and I’ve tried to report what I hear…subjectively…with these amplifiers driving the Sound Lab ELS speakers.

    And now, for something completely different…Four Klouts on Keltiks. Who cares about pan pots and artificial reverb units? Still astonishing to listen to popular studio recordings (and live) at realistic levels.