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Power Amp coloring tone

Discussion in 'Amps and Cabs [BG]' started by ChrisPbass, Sep 17, 2008.

  1. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    I just bought my 1st power amp so I could power 2 4ohm cabs and for other reasons.
    I used my eden wt-400 as the pre and ran into 2 cabs.

    .....I hate the way it sounds. I assumed that the power amp would be basically neutral but that is not the case at all. I don't mean that I don't -prefer- the tone I mean I hate it. The only way to make it listenable at ALL was to seriously cut the mids and treble. I have never heard so much treble coming out of these cabs. One cab is a 12 w/no tweeter and the other cab is a 2x10 and I had the tweeter almost all the way off. I'm wondering if I hooked it up wrong and am causing a phase issue. I'm only running the power amp at 35% or so. Could it be phase cancellation!? The cabs are stacked on top of each other.
    here's how I hooked it up

    http://www.talkbass.com/forum/showthread.php?t=470094 any help would be greatly appreciated.
  2. Vinny D

    Vinny D

    Jan 9, 2007
    Warwick, RI
    I have slaved Eden heads before into poweramps and have had no issues at all with the tone coming from them.
    As long as you are using the headphone out on the Eden head you are getting the preamp & EQ signal so that should be *your* sound getting sent to the external amplifier.
    Did you try another amplifier or have you used the poweramp in any other configuration to make sure it is operating properly?
  3. what power amp is it? Usually I run my power amps with no attenuation. The knob on front is not a gain knob, it attenuates, so running it open may have an effect.
  4. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    it's a Crown xs-500.
    I have no other power amp.

    I'm using a mono 1/4 split to 2 1/4s (a Y cable...) to go out of the headphone into both channels of the Crown. is that ok?
  5. Vinny D

    Vinny D

    Jan 9, 2007
    Warwick, RI
    Your connections are fine but have you tried connecting just one side of the poweramp (taking the *Y* cord out) and just trying one cab to see how that sounds?
  6. bongomania

    bongomania Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Technically the knob is both an attenuator and a gain knob. Your signal goes into the input buffer stage of the amp, then it goes through the attenuator pots which actually are for setting the level of the signal that has the gain applied to it. IOW it controls the gain by regulating the level of the signal coming from the power amp's first amplification stage.

    Unless the power amp is a total POS (or maybe a low-powered all-tube power rig), it should not be altering your tone that much. So I'd suspect a faulty connection to one or more speaker cabs, or a misunderstood setting on either the Eden or the power amp.
  7. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    I have not. I didn't know if that was OK or not. I'm very paranoid about destroying the amp!

    i'll give it a try tonight.
  8. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    Eden is run flat as can be, speakons work fine, y cable is new, and the 1/4 going from the Eden is fine. Power Amp is a Crown xs-500, which is by no means top of line, that wasn't, according to the seller, used much. It doesn't 'look' all that used. for whatever looks are worth. It has 2 volume knobs and a power switch.
    I'll just need to try the seperate channels tonight.
  9. If the headphone out is stereo, you may be shorting out one side of the headphone driver circuit. I don't know enough about Edens to know if this is a problem. I wouldn't think so, but you never know.
  10. Vinny D

    Vinny D

    Jan 9, 2007
    Warwick, RI
    The Eden headphone out does not need to be used with a stereo cable, it was designed to be used as a slave output and can use a mono cable
  11. Good to know - thanks Vinny.
  12. bassbrock


    Feb 20, 2007
    Callahan, FL
    What does your Eden sounds like when you plug a pair of headphones into the headphone output? Do you get the same trebly harshness that you describe is coming out of the power amp and speakers? Also, what type of 4-ohm speaker cabs are using?

    I haven't had specific experience with your Eden head into a power amp, but I have had extensive experience with various models and brands of power amps, from expensive to cheap. In all my experience, the power amps I've owned and/or used have never colored the tone in any audible way.
  13. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    I've never plugged in headphones. I'll try that tonight, maybe that's the problem.

    Avatar 2x10 and a Schroeder 1x12. both 4ohms and 500 watts. The whole chain is Eden wt-400, Crown XS-500 (500 watts at 4ohms per channel) and then the 2 cabs.
  14. anderbass


    Dec 20, 2005
    Phoenix. Az.
    Good suggestions already, also make sure those two cabs and each of their speaker cables are both wired in the same (+/-) phase as each other. If they're not, a large drop in bass response would be expected when using them together with any amp. (this would effectively over emphasize your high end response)

    Just to make absolute sure the Y-cord you were sold wasn't actually a mislabeled TRS (tip-ring-sleeve) type insert-cord thats intended for mixer inserts... Do all 3 of your Y-cords 1/4" plugs have the same standard TS (tip/sleeve) plug style just like a regular guitar cord has?
  15. SpankyPants

    SpankyPants That's Mr. SpankyPants to you.

    Aug 24, 2006
    Brooklyn, NY
    I know someone trying to sell an Eden WT1250 back in Baton Rouge if you want one.
  16. joegeezer


    Mar 9, 2005
    Northern Wisconsin
    Avatar Club#12 Eden Club Lucky# 13--USA Peavey Club#37 Carvin Club#5
    Thats how I run my rig, and thanks to Vinny, mine is right. I tried the wrong output to the amp at first. The headphone out jack worked like a dream. Hope you get the problem soon. When you do, you';ll love the sound you can get, that I'm sure of.
  17. I think the "Y" cable you have could be the problem. It'll be causing serious impedance changes to the signal the crown is seeing (your tone will be thinner with far less punch). Does you Crown have a mono bridging option? or a parallel input option?
  18. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    Crown sayeth that if I want to run from a mono source then I need to use a Y cord. The Y LOOKS like a regular instrument cable. I do have some other things I need to check but I'm going on vacation so It will have to wait.
    I'll post my results later.

    thanks for the help y'all. :hyper:
  19. ChrisPbass


    Jul 18, 2006
    Fairfax, VA
    Headphones - Eden sounds great
    channel 1, cab 1 - sounds like an Eden
    channel 2, cab 2 - sounds like an Eden

    that is with only one input. 2nd channel left empy and vice versa. I did try the different channels with both inputs the other day where I would turn down one channel and listen and the reverse the process. I didn't notice anything unusual but I wasn't listening for anything and I didn't spend much time on it.

    The Y cable looks just like 1/4 cable i'm using for inputs. SO...........:confused:
  20. Vinny D

    Vinny D

    Jan 9, 2007
    Warwick, RI
    It sounds like you have a phase issue, either the *Y* cable is wired incorrectly or one of your cabs is wired wrong internaly.

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