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Power amp for Isobariks

Discussion in 'audio' started by monstermoo, Jun 15, 2011.

  1. monstermoo

    monstermoo Active Member

    I use an LK280+spark and an LK275 to power my Isobariks (bi-amped), but I find the sound a little bit 'dry' and harsh at the top end.

    I'd like something with more 'boogey' factor and rythm.

    I'm thinking of selling these and buying either another power amp or an integrated amp.

    I'm thinking a budget of £600 - £700, and am quite happy to consider pre-owned and expect that is where the true vfm is to be found.

    I also currently use a Beresford Caiman as a DAC/volume control and would expect better results when using the fixed line outs rather than the variable ones if the amp was to be integrated with its own volume control.

    Any recommendations?
  2. Gaius

    Gaius Trade: Stiletto by Tangerine

    Naim Nap 250 would be the kiddy, especially the Chrome Bumper model.
  3. Robert

    Robert Tapehead

    Swapping the power amp isn't going to make an audible difference to the top end.
    Top end level and quality are governed by the amplifier response and how much distortion is present on the signal. Just about any linear power amplifier able to drive the Isobarik will be flat to 20kHz and low enough in terms of distortion (all distortions) to sound very alike.

    You can use a Naim power amp, preferably with a Naim pre in front as this sets the bandwidth, and it will likely sound a little different to the Linn. Subtle though and you might not notice it. Older Naims have 0.3 Ohms output impedance. That means that the response of the speaker will be modified slightly, mostly in the bass and around crossover points - though don't get excited as we're talking around 1dB max, though that is audible in most cases.

    I wouldn't feed a Dac straight into an older NAP, certainly without knowing exactly what that dac is doing at ultrasonic frequencies.
  4. monstermoo

    monstermoo Active Member

    Thanks for the suggestion.

    I'm not too keen on the Nap 250 or other Naim amps really, due to all the extra 'bolt ons' that are often needed such as seperate PS, Naim pre-amps for total system reliability, cabling etc. etc. Seems to get very expensive, very quickly.

    Any other suggestions?
  5. monstermoo

    monstermoo Active Member

    Sorry Robert, just read your post. So, do you feel that the amplifier plays a negligible part on the 'sound' as a whole or just the higher frequencies?

    I'm playing my music through an apple airport express to stream Apple lossless files which have been ripped from off-the-shelf CD's, or I play the CD's through my blu-ray DVD player. Though I'm condering an upgrade at this end, either a better streamer such as Linn DS or a better dedicated CD player.

    Perhaps this is where I need to concentrate my efforts instead?
  6. misterc6

    misterc6 Wasted and wounded, it ain’t what the moon did

    Or a well sorted NAP160, or a pair of NAP110/140 monos maybe?
  7. DavidS

    DavidS pfm Member

    A bit left field but there is a Crown K2 pa amp in the for sale section , this will give your bricks plenty of juice !


  8. IWC Doppel

    IWC Doppel pfm Member

    I think a 250 CB is a good suggestion. I also think an older muscle Musical Fidelity would be interesting like an A370 or something. Or somemting old from Meridian ?

    Don't listen to anyone whe says power amplifies make no audible difference to the sound....... I suspect most have not experimented with power amps like those who know this is not the case :confused:
  9. per flemming

    per flemming Registered User

    I would get a Kairn for first try
  10. colasblue

    colasblue pfm Member

    Krell KSA 50
  11. Gaius

    Gaius Trade: Stiletto by Tangerine

    Yes this is now what I use.

    Awesome power amp.
  12. david ellwood

    david ellwood Kirabosi Kognoscente

    i am surprised that you are getting harsh treble with lk280/lk2-75 amps.

    what is the rest of the system?

    the obvious way forward would be to get another lk280 and go active.

    it might be worthwhile to recap your crossovers and/or the amps.

    The lk series amps are certainly not harsh and if your system is exhibiting this trait the problem is either a fault or elsewhere.
  13. monstermoo

    monstermoo Active Member

    Thanks David, that's an interesting point.

    My system is early Isobariks which have been modified so they can be run fully active - (each driver has it's own set of banana plugs). There are then 2 external crossovers per speaker - 1 for the front drivers and 1 for the back bass and top drivers.
    These are fed by the LK280+spark and the LK2-75 (vertical arrangement), which are themselves fed by a Beresford Caiman via the variable outputs.
    Into the Caiman I have Apple Airport Express via optical Toslink which stream music via Itunes from my laptop. When I'm not doing that, there is my Sony Blu-ray player which is connected to the Beresford by a digital coax. cable.

    Speaker cable is Linn K20.

    Another trait I'm getting is that the music somehow feels 'remote' and with vocals occasionally sounding as if they are at the 'back of the music' if that makes sense, rather than up front....?

    Speakers are positioned in alcoves either side of the fire place.
  14. YNWOAN

    YNWOAN 100% Analogue

    135's end of story (one pair, or three pairs - six pack :))
  15. Robert

    Robert Tapehead

    Won't alter perceived harshness, might make a very small change to the overall sound balance if you switch to a Naim due to the higher output impedance working with what is regarded as a difficult speaker load.

    David's idea of adding another Linn power amp and going active is probably what I'd do with Isobariks - far better than any passive drive no matter what amplifier.

    If you want an all in one box solution, try a cambridge 840A/2.
    I think you can still get them on 30 day approval terms.

    Eek! - get them out of alcoves if you possibly can.
    The improvement will be truly dramatic and utterly trump any change to the electronics.
  16. per flemming

    per flemming Registered User


    No idea going active with a laptop as source

    Try a Kairn/Ikemi to narrow down issues
  17. Nik

    Nik pfm Member

    I'm surprised too. I found the 280 to be "thinner" and "brighter" sounding than the 275 but neither was "harsh". Someone suggested a Naim 250, and that will sound harsh compared with the Linns, and so will the MF suggested by someone else. Any chance you could borrow a Kairn + Klout for a comparison?

    How does what you have now compare with either amp used alone?
  18. monstermoo

    monstermoo Active Member

    It was quite some time ago that I tried this, but from memory there wasn't a huge amount of difference. The 2-75 on its own was perhaps a bit darker sounding if that makes sense, but essentially the main difference is a little more control - less 'squeezed'.

    We once tried my brothers Yaquin tube amp and that sounded a lot warmer, less thin and with a stronger sounding bass. BUT, at high volumes it did seem a bit wobbly with less grip. Still, we'd never listen at those volumes realistically.
  19. dave

    dave Plywood King

    My NAP 250 never sounded harsh compared to my LK-280 but that was with Kabers. If anything the 250 was warmer, more dynamic and in control during loud passages.
  20. MVV

    MVV pfm Member

    My 250 (olive) did sound harsh and crude in the treble. ( 52/LP12 Ekos Lingo Akiva) I could not cure it in six years and £'s of trying so the Briks went. Looking back I wish I'd tried one of the more powerful Linn power amps (or Linn active) but I was a totally blinkered Naimee at the time.

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