Experience with amplifiers and Sound Lab speakers

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    • #1182
      chungjh
      Participant

      That has been my experience with Benchmark. It punches way above its weight. Details, dynamics.. But it is not for you if you like warm sound.

    • #1180
      ACHiPo
      Participant

      After a little more than 3 weeks with the Benchmark AHBP amps I’ve decided to keep them in addition to my MA1s. The Benchmarks bring added dynamics on complex material while still delivering emotionally engaging musicality. There is still something special about AtmaSpheres, and I will keep them in rotation, especially for cold weather.

      • #1181
        drbond
        Participant

        @ACHiPo
        What are the relative strengths and weaknesses overall that you have found with the Benchmark AHBP amplifiers?
        Thanks.

        • #1183
          ACHiPo
          Participant

          @drbond The Benchmarks deliver punch without grit, glare, or grain. They are dynamic, musical, and emotionally engaging. Oh, and they aren’t space heaters.

          It’s amazing to me that even they run out of gas well before 100 dB. I really think something like an MA2 or MA3, or 600.8 is needed to achieve realistic spls with Sound Labs.

          • This reply was modified 5 months ago by ACHiPo.
    • #1171
      hpfish10
      Participant

      Drbond, I noticed you sold your AS MA1 mono amp, so which amp do you use now to drive your SL?

      • #1172
        drbond
        Participant

        @hpfish10

        Yes, I sold my Atma-Sphere MA-1 amplifiers. As it turned out, I didn’t have a great match between my passive pre-amplifier and the MA-1’s, as the MA-1’s need alot of voltage (3V) to push them to their fullest. Solo acoustic music sounded fantastic regardless, but more complex pieces seemed rather condensed and muffled. Since then, I have tried three or four other amplifiers, all of which have had their strengths and weaknesses, as outlined in previous posts. Currently, I’m using Ypsilon Hyperion hybrid amplifiers to drive the Sound Lab speakers. My opinion that has developed is that the more power you can give the speakers, the better (200-400WPC).

    • #1112
      WillB
      Participant

      Yeah, I got that.

      “Used”: There is a pair of VT150 (not SE) for $5k. I’m guessing an SE version would be around $7k.

      “Used” REF150SE probably around $7-8.5k

    • #1111
      Ralph
      Participant

      As I observed earlier, my price comparison was inflation adjusted. There’s nearly twenty years between them.

    • #1110
      WillB
      Participant

      The Ref150SE was $15k.
      The VT150SE was $16k for a pair.

    • #1109
      WillB
      Participant

      Yeah, and one less transformer.

    • #1107
      Ralph
      Participant

      Will,

      I’d say that’s a win for an amplifier with half the weight, size, number of tubes and costs slightly more than half in inflation adjusted dollars that sounds roughly equivalent. 🙂

    • #1105
      WillB
      Participant

      I’ve been trying/using an Audio Research Reference 150SE stereo amplifier that uses eight (four per channel) of the (relatively new designed) KT-150 power tubes (150W pc) and the input tubes are four 6H30s. The tubes are new and matched from Audio Research. It has tubes (two 6550s) in the power supply regulation. Power supply energy storage: 1040 joules for two channels.

      The SL A3PX speakers sound excellent when driven by it.

      Surprisingly or not, it is not “better” (whatever that means) than the two Audio Research VT-150SE mono amplifiers I’ve been using for the past twenty-five years on SoundLab speakers.

      The VT-150SEs also are rated at 150W pc but uses eight (four per channel/amplifier) of the 6550 power tubes and four (two per amplifier) 6922 input tubes. It also use tubes (two 6550s) in the power supply regulation. Power supply energy storage: 420 joules for each channel/amplifier.

      When comparing the VT-150SEs on SoundLab A3PX ELS, the Reference 150SE tonal balance is slightly leaner (taut) upper bass and slightly more forward upper mid-range, using the 8 ohm taps on the amplifiers. Speakers are set flat (0) with treble at 1-2 o’clock.

      It has only been a few days of comparison listening and switching so I’ll continue…

      • This reply was modified 7 months, 1 week ago by WillB.
      • #1108
        WillB
        Participant

        Correction:
        I incorrectly stated that the Ref150SE has 6550s in the regulation. It does not. Their Ref6 preamps do.

    • #1093
      D10
      Participant

      Great looking room Ralph and excellent speakers position! My friend also has VTL MB450 and loves this combination …

    • #1072
      Massimo Stefanizzi
      Participant

      Congratulations Ralph!
      🤩🤩🤩👍🥂

    • #1069
      Ralph
      Participant

      I’ve been very happy using VTL MB-450 mono tube amps with my U-1PX speakers. They match well with the modest impedance curve of the updated backplates that is tube friendly.

      Maybe when playing extremely dynamic content like Stravinsky’s Rite of Spring I would like to use a pair of their big brothers, the Siegfried. 🙂

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    • #1037
      drbond
      Participant

      Massimo,

      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!

    • #1036
      Massimo Stefanizzi
      Participant

      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
      Massimo

    • #1035
      drbond
      Participant

      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!

    • #1033
      drbond
      Participant

      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.

    • #1018
      MikeB
      Participant

      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.

    • #1013
      drbond
      Participant

      @MikeB

      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.

      Thanks.

    • #1012
      MikeB
      Participant

      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.

    • #1011
      John V
      Participant

      @chungjh

      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

      John

    • #1010
      chungjh
      Participant

      @Massimo

      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.

    • #1006
      drbond
      Participant

      @chungjh

      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 10 months, 4 weeks ago by drbond.
      • This reply was modified 10 months, 4 weeks ago by drbond.
    • #1005
      chungjh
      Participant

      @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.

    • #1002
      drbond
      Participant

      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.

    • #978
      Dizzie
      Participant

      Any experience with a Krell K-300i integrated?

    • #974
      Dizzie
      Participant

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

    • #970
      WillB
      Participant

      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.

      Sincerely,

    • #968
      drbond
      Participant

      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.

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