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Noisy headphone amp in SWR Grand Prix

Discussion in 'Amps and Cabs [BG]' started by alexclaber, Oct 22, 2003.


  1. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I've had my (ex-demo) GP for ages but never really needed to use the headphone output on it. I remember trying it out years ago and thinking that it was really noisy and bad sounding but I didn't worry about it because it was a superfluous feature back then. I'm now starting to think it could be useful and am wondering what could be up with it. It hisses like hell, has very little gain, sounds somewhat distorted and very lacking in bottom. Fundamentally, it's crap.

    What could this be?

    Alex
     
  2. miccheck1516

    miccheck1516 Guest

    Feb 15, 2003
    Ireland
    are you using good quality headphones? crap headphones=crap sound
     
  3. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Yes - £50 Sennheiser closed back ones. It's not the tone that suggests there's a problem, it's the enormous amount of noise despite my bass being very quiet and the preamp itself being very quiet.

    Alex
     
  4. wyrtti

    wyrtti Supporting Member

    Oct 24, 2000
    Helsinki, Finland
    I have the same "problem". My Grand Prix has a horrible headphone amp, tons of hiss. I remember trying some other SWR amps headphone-part and it was just the same.

    I solved my problem by always having a little Behringer mixer around for the DI-signal.

    But, now that you remind me of it, it IS a drag.

    If this is a common problem with SWR, maybe we should start complaining? :)
     
  5. monkfill

    monkfill

    Jan 1, 2003
    Kansas City
    My GP has a noisy headphone amp as well . . .

    Isn't the GP the only SWR product with a headphone amp? In that case, complaining wouldn't do much good, since they are a few years out of production.
     
  6. mthoople

    mthoople

    Nov 1, 2001
    Denver, CO
    The GP IS the only SWR product with a headphone amp. The other SWR amps that have headphone outputs use signal from the power amp to drive the headphones. The GP uses a low-power stereo IC power amp just for the headphones; its the source of the noise.

    Matt
     
  7. wyrtti

    wyrtti Supporting Member

    Oct 24, 2000
    Helsinki, Finland
    Ahhh, I could have sworn that my old Workingman's 10 had a headphone connector.

    I guess this is what the years and mileage do to one's memory-circuits.

    But anyway, the headphone connection on the GP hisses, as we've established. Tough luck for us.
     
  8. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Is there any chance that the IC in mine could be knackered - I mean, there's noise and there's NOISE (mine's got the latter). I find it hard to believe that SWR would put such a poor headphone amp in what was their 'state of the art' preamp!

    Can you run headphones off one of the other line outs or would their low impedance draw more current than the output can supply?

    Alex
     
  9. chucko58

    chucko58

    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    No, they all do that. It appears the headphone output was an afterthought on the Grand Prix.

    The latter. Don't try hooking up a headphone to one of the line-level outs, you could smoke a chip.
     
  10. mthoople

    mthoople

    Nov 1, 2001
    Denver, CO
    wyrtti,

    What I meant was that the GP is the only SWR product with a headphone AMP. Any SWR product with a power amp uses that to drive the headphones. Since the GP doesn't have a power amp, it uses a very noisy amp to drive the headphone output.

    Matt
     
  11. fretlessrock

    fretlessrock Supporting Member

    Aug 8, 2002
    Corrupticut
    I had a GP and the headphone out was hissy on that one as well. I use a raven PHA-1 and it has spoiled me for pretty much any other headphone amp. It is too bad that Rabe couldn't have been involved in making the GP headphone circuit. I have to assume that he wasn't involved because his standard of work is so high on his other designs from the same era. I could be wrong and it is an anomaly...
     
  12. droskobass

    droskobass

    Oct 8, 2007
    Montreal, Canada
    Former Part-Time, Non-Commission Employee MOOG Audio
    Resurrecting this thread from the dead, is there an IC upgrade that could clean up the headphone out? has anyone solved this issue?

    The headphone out on my Groove Tubes preamp (also SWR Made) is 10,000% quieter that the one in my Grand Prix.