Experience with amplifiers and Sound Lab speakers

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    • #968

      While the combinations of cables, source, pre-amplifier, and amplifier play a composite role in producing the musical sound, I would like to open this thread to discuss peoples’ experiences with various amplifiers and their Sound Lab speakers.

      I think it would be important to comment at least on the type of music being played, and size of ensemble when commenting, among other things.

      Personally, I’m thinking that I need to have at least two different amplifiers on hand, depending on the type of music that I am playing, as neither of the three amplifiers that I’ve tried are best for all types of music. Each amplifier has its strength and weakness, which is probably what other people have found also.

      Perhaps, it would also be interesting to hear what other people have tried, and definitely did not work.

    • #970

      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.


    • #974

      Anybody try McIntosh amplifiers or integrated amplifiers with autoformers and 3 output taps?

    • #978

      Any experience with a Krell K-300i integrated?

    • #1002

      Two of my three amplifiers are Atma-Sphere MA-1, and Conrad Johnson LP140M. Both sound great for different pieces.

      Nothing beats the Atma-Sphere for solo instrumental works, or duets/sonatas for two instruments. While the Atma-Sphere is exceptional for the aforementioned pieces, the presentation of bass/tympani is slightly muted.

      The Conrad Johnson is slightly colored in presentation, but sounds very musical, and is the most relaxing to listen to. It has a stronger bass representation, and is a very good all-around amplifier: it’s not a delicate or transparent with solo-instruments as the A-S is, but with more complex orchestral pieces, it does a better job of piecing the dynamics of the instruments together.

    • #1005

      @drbond, I tried LP140M on my M545 and I got only the faintest of sound. I thought there was a mismatch of some kind and returned it. Now I wonder if the amp was just faulty.

      I heard AHB2 amp from Benchmark is amazing, but only 100W. Is it possible to bi-amp Sound Lab speakers? I know it is not setup for that as is.

    • #1006


      Yes, there was obviously a problem with your amplifiers. Even a 50W amplifier can sound decent on Sound Labs. The CJ LP140M’s you tested probably had bad tubes. The CJ LP140M can take either 6550 or KT88 tubes. I have preferred both over each other at different times over the past five years of ownership. Also, don’t forget about the driver tubes, which are 6922. I’ve switched those out as well, but haven’t evaluated the effect of those tubes to any significant degree.

      No, you can’t bi-amp Sound Labs, as they come from the factory.

      • This reply was modified 2 months, 3 weeks ago by drbond.
      • This reply was modified 2 months, 3 weeks ago by drbond.
    • #1010


      Yes, you can bridge AHB2 but they halve the impedance and this gets to be a problem at HF when the impedance dips down to 2 ohms.

    • #1011
      John V


      The factory does offer a bi-amp option.
      Your current backplates can be retrofitted if desired.
      I would email Roger for instructions. If your a bit handy
      it’s actually fairly easy to do yourself. I did this
      myself for my U890’s


    • #1012

      I readily acknowledge that different amplifiers sound differently and have various pluses and minuses, but doesn’t each and every piece of hardware in our systems do likewise? Having two or several different amplifiers to play differing types of music or to fit our mood at the time, would be a real treat. But once amplifier rolling is begun, should or would this concept end there?

      There is no one best component, including our beloved SoundLabs. Every audio component in our rig has its strengths and weaknesses. That is, we may believe that one component’s voicing may sound better with one type of music than another, which may depend upon our mood at the time or not etc.

      It is difficult and costly enough to select and then mix and match each component in our systems, let alone trying to pick multiple components to fit a music type, or our moods etc. Where would the mixing and matching as in sliding in/out multiple amps, pre-amps, cables, speakers, turntables, tonearms, cartridges, tubes racks, footers and DAC’s end?

      I often thought that if money and space were no object, it would be handy to have a room with a high ceiling and a motorized cable and pulley system installed to raise and lower equipment. I could raise an amplifier, a speaker etc. and lower another for a music type. Or do the same for a pre-amp, DAC, turntable etc. But at what point do we just determine that what we have is good enough and simply listen to the music we love? In fact, speaking of music, sometimes I find it a tad bit difficult to pick what music I want to listen to and when. After doing so, would I then want to choose which DAC, amp, cable, I would like to listen to that music? For the most part, I think not.

      Nevertheless, having two different amps to listen to (as some here are fortunate to have) would be a treat, somewhat like selecting a varietal and then bottle of wine. But invariably after many different tastings, I tend to pick favorites and generally stick with them. For me, the same holds true with my music playback system. Even if I were able to easily move and connect equipment, which I am not, I don’t really want to drive myself crazier by having multiple components in place waiting to be used, like many audio stores do. Would I like it, especially if it were easy and doable? Yeah, I think so. But I fear that novelty would wane, leaving something else in its wake to look forward to, collect, or do.

    • #1013


      Yes, I think we all recognize that all components contribute to the sound, but this thread is supposed to be about individuals’ experiences with different amplfiiers. We’d love to hear your positive contribution about your opinion of your amplifier of choice.


    • #1018

      For some reason, posting links to the following threads hasn’t worked the two times that I have tried. So I will post their titles instead:

      1) Best amp/preamp to go with SL?
      2) Atma-Sphere MA1 3.2 vs Pass XA60.8 amp

      There are interesting and informative comments about several amplifiers in these threads, including several that I made about my SoundLab amplifier sojourn.

      Hence, there was no need to reiterate my same comments herein and I responded to the premise of amplifier rolling (if you will). Having more than one amplifier would be a luxury both fiscally and physically. But I certainly can’t fault the premise, if one has the wherewithal and desire to switch now and again, for whatever reason.

    • #1033

      Listening to the Lamm M2.2’s tonight, one thing is very clear: these amplifiers are superb masters at separating complex orchestral pieces. There is marked clarity and detail, and an immense sound stage, with each instrument precisely imaged.

      These are hybrid amplifiers, with 3 stages, producing 220 WPC into 8 ohms.

      The sound is much sharper and clearer using Mogami Gold XLR cables over the Cardas Golden Reference RCA cables, which sound slightly warmer, but more muffled, and less defined.

    • #1035

      Holy bat smokes!

      I just plugged in a 1986 vintage Krell KSA-100, which is class A, and the sound is rather remarkable!

      It just seems to have a great balance between clarity and warmth, but is completely SS.

      I’ll need to keep these amplifiers for a while!

    • #1036
      Massimo Stefanizzi

      Hi drbond

      thank you very much for sharing your experience!
      Your positive impression does not surprise me, I also had a Krell KSA-80 (1989) for a couple of year driving Audiostatics. Excellent dynamic and bass extension but not the last word in terms of sound tage and timbre.
      Unfortunately very old models like do not have balanced inputs.
      I would love to continue reading your comments and listening impressions comparing Lamm and Krell.

      Best regards

    • #1037


      I am very impressed with the Krell KSA-100. I have two stereo amplifiers that I use as monoblocks, so my impression might differ slightly than if someone simply had one stereo amplifier.

      The Krell has great air and space around the instruments, and does offer a very nice sound stage. It has a rich, warm sound, with a musical presentation. Vocals are very clear, as well as bells, brass, and percussion.

      You identified the major weakness of the Krell: its timbre. There is only slight distortion to the string instruments, which cause them to sound only slightly synthetic. Occasional wind instruments, like the oboe, would sound tinny (although most wind/brass was excellently portrayed). One last weakness of the Krell is its lack of delicacy: it has less decay/fade on the sounds.

      By comparison, using the same RCA cables, the Lamm M2.2 is clearer and warmer with more dynamism, and separation of the instruments. It offers a more lively presentation with cleaner and clearer brass/wind instruments, with no tinny sounds.

      The Lamm M2.2 with the XLR is another notch or two above the Lamm with the RCA.

      Overall, I would be very content with the Krell KSA-100, and you wouldn’t miss anything musically, nor would you see how things could sound much better than with the Krell. . . but then you listen to the Lamm, and they do!

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