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Power amp comparisons: Belles, Exposure, Linn, PS Audio (LONG!)

Discussion in 'audio' started by Bob Edwards, May 23, 2020.

  1. Bob Edwards

    Bob Edwards pfm Member

    First off - pardon the length!

    With the C19 pandemic ongoing, I had the chance to play with my hifi - both in terms of listening to music and experimenting with some components. I had started with an eye toward upgrading my speakers - I had used a pair of Linn Helix 2s with the ku-stone stands for something like 15 years, and always enjoyed them. They communicate music well, even if I can list out their faults. And they were always good enough to let me hear differences from one component to the next. In their place I now have Monitor Audio Gold GX300s, which were a rather spectacular leap forward (as you'd hope and expect!).

    The GX300s did, however, show that my power amp, an Exposure XXVIII (28), might be a bit underpowered (more on that later). So I started thinking about power amplifiers that might work well. Through a set of circumstances I won't bore anyone with, I wound up with a Linn Klout, a pair of PS Audio M700s (PS Audio is based in the town next to mine), and a Belles 350A Reference (with the "soft start" circuit).

    Sources were an Exposure 3010S2 CD player, a Naim nDAC (later with a Teddy Pardo TeddyXPS), a Linn Karik III (mainly used as a transport), and, briefly, a Mark Levinson 31.5/30.6 transport/DAC that a good friend has and let me borrow. Preamp was mainly an Exposure 3010S2, I also used a conrad-johnson PF2-L, and, also briefly, an Audio Research LS17SE.

    The room is difficult, as it is effectively my entire townhouse - there is no effective separation from the main level to the upstairs, and a thin door is all that separates the main level from the stairs leading to the finished basement. That was part of what led me to look for speakers that could better load the space - the Helix 2s just couldn't do it.

    Anyway, on to the amps.

    I'll start with the Exposure, as I've owned it for a while now after having the Exposure stack see off (what a fantastic expression - I wish more Americans could understand British English!) a Naim stack. The 28 provides 70 watts per channel into 8 ohms; no 4 ohm rating is provided. It is a dual mono design, with a (fairly large) transformer for each channel, which accounts for much of its 24 lb (11 kg) weight.

    Musically, the Exposure is very good. It's easy to follow most instrumental and musical lines, whether on something like Lyle Lovett's cover of "Bears" on "Step Inside This House," or REM's "I Believe" on "Life's Rich Pageant," or Ulrich Schnauss and Mark Peters' "There's Always Tomorrow." The 28 has a balance and inner drive that allows the music to drive itself forward without sounding bright or forward itself. It also does a (surprisingly to me) good job of image placement and depth (particularly obvious with the ARC LS17SE). There is one fly in the ointment, however - the 28 does not seem to have enough power reserve to drive the GX300s to their full potential. It almost literally sounds like it is running out of breath (or 'puff') on notes that have a sustain or long decay. It's particularly noticeable on music like Reiner's Beethoven 5 with the CSO and on different tracks on the Lyle Lovett album mentioned above, to say nothing of more electronic music like the Schnauss/Peters album, or Mickey Hart's Planet Drum. Just another example of the need to system and room match.

    Next up was the Linn Klout. One of the classic "oldie but goodie" amps. The Klout, compared to the Exposure, didn't run out of breath, but it also didn't sound as engaging. Relative to the other amps, it sounded a bit dark. I don't want to overstate that, because it was not dull or shut-in sounding, just not as informative with cymbals, triangles, violins, etc. (I should note that the Klout would almost certainly benefit from recapping, as it dates to the mid 90s by serial number). Overall, a reasonably good sounding amp (and solidly built!), but it was not as engaging and interesting (to me) as the 28.

    The next amps to arrive were the PS Audio M700s. A rather different approach to amplification, and much newer than any of the other amps, the M700s provide 350 watts per channel and use Class D amplification. Frankly, I don't care what "class" an amplifier is - I've heard amps from different classes sound great and terrible, so I think it's more down to execution than class. Overall, the M700s sounded terrific. They are lively, balanced, and do a good job of letting the music speak for itself. They also recreated the biggest soundstage of the four amps here, and did a solid job of placing performers on the stage (where the music and recording allowed for it). The M700s also initially sounded like they had the best bass extension and grip, although the longer I listened the less I thought that - like the Exposure, but to a much lesser degree, it sounded like the M700s didn't have quite as much sustain as the Klout or the Belles. Out of the four, the M700s provided the best "hifi" and were quite good musically.

    Finally, I wound up acquiring a Belles 350A Reference. It's something of a classic American "high end" amp, like the Levinsons, Krells, and Rowlands of yore. Weighing ~65 lbs (or 30 kg), it weighs as much as one of my speakers. Rated at 250 watts per channel into 8 ohms, and 500 into 4 ohms, it's the biggest/heaviest amp I tried. Musically, it does a good job of separating musical and instrumental lines - it's probably the best of the four. It also has excellent extension and grip in the bass, which helps to separate different low-pitch instruments - the Belles makes it easy to hear different drums vs upright bass vs electric bass, etc. It also does a good job of separating instruments in space (again, when the music and recording allow). And the Belles does the best of the four in providing solidity - the character doesn't change as volume increases or decreases, and it does not sound like it ever runs out of breath (or 'puff' - another wonderful example of British English). Another way to put it would be to say that the Belles has the most 'authority' of the four.

    I've since sold the Klout and returned the M700s, alternating between the Exposure 28 and the Belles. Yes, it's a pain in the neck switching between them.

    After all of that, what I would LOVE to find is an amp that combines the liveliness, drive, and inner balance of the Exposure with the authority of the Belles. I may try a pair of Exposure 3010S2 monos, as Tony Brady has said they'll sound much better than the 28. I also briefly tried a Krell KST100, but was underwhelmed and sent it back. I am open to other suggestions - bring them on!
  2. Yomanze

    Yomanze pfm Member

    Bob Edwards likes this.
  3. Charlie_1

    Charlie_1 pfm Member

    Thanks for sharing your impressions Bob.

    I've not listened to an old Exposure pre/power for about 30 years. I was going to buy a pair (following a couple of dems) but then heard an LP12 with Kans and just had to have them (despite not owning any LPs) and had to settle for the Exposure XV integrated instead. That system provided about 15 years of happy listening.

    The only thought that struck me is that I doubt you're getting the best out of any of these amps. For example, I bet the Klout would sound a lot better with a Kairn, early 90s spec LP12 and some Linn speakers from that era. All too often, equipment like this doesn't mix too well. I find that even vintage Naim amps tend to sound best with their natural partner rather than a model launched several years later. Not saying it's impossible to find good matches outside of this but I think you'd have to be quite lucky.
    Bob Edwards likes this.
  4. Gervais Cote

    Gervais Cote Predator

    If I was in your situation, I would give a listen to these, in order of preference :

    Boulder, don’t know what model but I know they have beefy ones ! Dynamic and very defined bass is there.

    Pass Lab : They also have many powerful models, all the ones I heard were very musical.

    Classe Audio DR25 : They can sometimes be found at a rather low price but may need servicing. Often under rated IMO.

    Both the Boulder and Pass Lab might be expansive though........unless you find a bargain !
    Bob Edwards likes this.
  5. Cereal Killer

    Cereal Killer 432 Point5

    Bob Edwards and Salamander like this.
  6. Bob Edwards

    Bob Edwards pfm Member

    All - Thank you for your suggestions - please keep them coming!

    The Belles is sold (amazingly quickly!) and I should have a pair of 3010S2 monos coming.

    @Yomanze - thank you - LFD looks like a terrific suggestion. The only issue is that I only see integrateds available in the US. And while I'm sure I'll rejoin the integrated ranks someday, it probably won't be for a while.

    @Charlie_1 - I have no doubt you're correct re not getting the very best out of the amps; save perhaps the Exposure (as it was paired with an Exposure pre and CD). The character differences remained (at least with my speakers), and part of my goal was to just have some fun with it all.

    @Gervais Cote - I live down the road from Boulder, and have heard them here and there - very good sounding, but quite a bit past my target budget range (about $3k USD). Ditto Pass - very good sounding, but expensive and I'd prefer to stay away from Class A amps - too much heat, not very "green," etc. That was part of the appeal of the PS Audio M700s.

    Classe - That is a great suggestion - I had a DR9 years and years ago which was pretty good.

    Will update with the 3010S2s (and anything else I pick up) once they arrive
    clap likes this.
  7. Gervais Cote

    Gervais Cote Predator

    Okay, knowing now you are in the U.S., I may have another suggestion.
    A Krell amplifier from the 90’s, 100 watts or more per channel into 8 ohms might be of interest and affordable.
    I listened to these as well and I remember very clearly that the treble was perfect, not only good, just perfect.
    The bass was maybe a bit slow for my taste but I listened to it on large speakers (Kef something, with a 10 inch woofer?) so maybe that was the reason why.
    Bob Edwards likes this.
  8. Salamander

    Salamander pfm Member

    I will second Cereal Killer's post, Audionet's Amp 1 V2, is a fantastic amplifier, bettered much more expensive amps in my brother's system. Unfortunately it led him down the road to ruin having recently purchased a Audionet Humboldt. :)
    Rana, Bob Edwards and jan tomczak like this.
  9. Olsen

    Olsen pfm Member

    Did Audionet survive their restructural crisis last year ?
  10. Cereal Killer

    Cereal Killer 432 Point5

    Yes, and came back stronger. The new 'Ultimate' and 'Scientist' products has been selling really well according to the Kevin and FiAudio. There's even been rumours of a new DNA model.
    Salamanders brother can vouch for being part of that recent support :D

    Bob Edwards and jan tomczak like this.
  11. Hiesteem

    Hiesteem pfm Member

    I agree with Charlie1, about system synergy being important. I found a type of sound I like, which compliments through the system, a long time ago.
    I like the Exposure amps, delivery. If this is the sound signature you like, then that for me, would be a safe way to go. When we swop out a component it changes the whole sonic picture/delivery.
    Having said that, I will indulge, as I am in the german amp flavour, which offers something different in my opinion.
    They always have power and authority to drive speakers.
    Audionet major on detail and power. I also like Trigon, they have great integrateds, Trigon Exact, and Exceed, both will drive anything, again detailed and a revealing sound signature.
    I use Restek amps myself.I Saw a Restek Fantasy integrated on ebay recently. £600, ridiculous amount of power and will drive anything.
    Bob Edwards likes this.
  12. hifinutt

    hifinutt hifinutt

    Bob Edwards likes this.
  13. hifinutt

    hifinutt hifinutt

    After all of that, what I would LOVE to find is an amp that combines the liveliness, drive, and inner balance of the Exposure with the authority of the Belles. I may try a pair of Exposure 3010S2 monos, as Tony Brady has said they'll sound much better than the 28.

    I might suggest a sugden a21se or sugden Ia4 may well do that . so would a grandinote proemio and grandinote silva power amp which are pretty awesome , the pre amp has incredible resolution and bass .

    Bob Edwards likes this.
  14. Yomanze

    Yomanze pfm Member

    Bob, I do have a feeling that the 3010s2s might be just what you’re looking for. I have owned the smaller 2010S, and still own an old Exposure IV, lovely amps. Let us know how you get on. :)
    Bob Edwards likes this.
  15. Bob Edwards

    Bob Edwards pfm Member

    Thank you all!

    The 3010S2 monos arrived today, and even though they have only been powered up for a few hours, they're the best match to speaker, system, and room (already broken in, as they're pre-owned).

    Will post more later once they're fully warmed up and I've had a chance to play more music through them.
    BlueYeti, Yomanze, Salamander and 2 others like this.
  16. Hiesteem

    Hiesteem pfm Member

    Look forward to hearing your experience with the exposure mono's Bob. I liked their tonal texture through the mid's, and grip in lower frequencies, when I listened to them at the Bristol show in February.
    Wilson and Bob Edwards like this.
  17. Yomanze

    Yomanze pfm Member

    I think "tonal texture" is a really good way of describing what Exposure amps manage to retain. A lot of amps fall down here.
    Wilson, Hiesteem and Bob Edwards like this.
  18. Mr Underhill

    Mr Underhill pfm Member

    Hi Bob,

    Thanks for your thoughts and observations, very interesting. I have a healthy respect for Belles and came very close to swapping out my then power amp, an EAR534, for the Belles Class A power amp; managed to fight off the curiosity - for once. Shame about the PS Audios, I enjoy Paul's videos! System synergy is a bit of a bugger - but as you like the Exposure the new boxes may well fit like an old glove. look forward to your continuing adventures!

    Wilson and Bob Edwards like this.
  19. beammeup

    beammeup pfm Member

    I would always try a Croft power amp (or 2 perhaps in your case) - they are far more powerful and gutsy than their wattage implies.
  20. Bairnstorm

    Bairnstorm pfm Member

    If you are in the States I would try a VTL ST150.

    I had Studio 20's with a ST85 and they were very good with a lovely technicolor sound but ran out of puff a bit.

    With your GX300's and being 6 ohm the 150's should work well.

    I also found speaker positioning quite important. Get them right and big bass get them wrong and a bit too trebly. I am sure you already have that sorted.

    I tried Croft with them and they weren't very good.

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