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Ampeg SVT 4 pro crossover problems

Discussion in 'Amps and Cabs [BG]' started by fordkh, Sep 27, 2009.


  1. fordkh

    fordkh

    Sep 27, 2009
    I own a fairly new but often used Ampeg SVT 4 PRO. I have it paired with a markbass traveler 2x10 and markbass traveler 1x15 set up in bi-amp mode. Recently the 2x10 has lost all tone unless the crossover on the SVT is turned down to around 100 hz. Could the upper end pre amp have gone out while the lower end pre amp is still working? Any advice would be helpful.

    Thanks

    FordKH
     
  2. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    it's the same preamp, followed by a crossover that directly drives the low and high output jacks, which you patch into the power amps.

    Try reversing the patching, see if teh problem follows the amp, or follows your patch wire, or is always associate with the output. That will tell you what is out.

    The high and low come from one crossover circuit, so I would be surprised if it would work at all if there were a problem in the crossover. The 210 might get full range if the crossover were bad.
     
  3. fordkh

    fordkh

    Sep 27, 2009
    Yeah I tried today reverse wiring everything one at a time. The problem, if there is one, is definitely in the crossover. Anything coming out of the high output is striped of any kind of decent sound when the crossover is turned past 200 hz. Is this normal? Should I get it checked out by an Ampeg dealer?

    Thanks

    FordKH
     
  4. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    I am not sure what you mean by 'stripped of any decent sound".

    When you run with a crossover, you are no longer interested in the sound from each cabinet alone, but the way the two co-ordinate. Either one may sound horrible alone, but the combination should be fine.

    If the crossover is working, you should get whatever you dial up. If that doesn't work for your cabinet, maybe the biamp isn't the answer for that combination of cabinets, or maybe you DO need different settings.

    Most folks probably do cross over a bit lower than 200, just so they can use a good LF for lows and assign everything else to the HF cabinet. 10" speakers are fine at 150 hz etc.

    Why do you think there is a defect in the crossover as opposed to a frequency that isn't good for the cab?
     
  5. DBTOYS

    DBTOYS

    Sep 22, 2009
    Bend Oregon
    What kind of cables are you running
     
  6. fordkh

    fordkh

    Sep 27, 2009
    The decent sound I was speaking of was a more full sounding high frequency. I understand that they should sound strange when played alone but I though the high sounded especially hollow and brittle, as if all the mids were cut along with the highs in the HF output.

    I also noticed that I am getting quite a loud buzz from the HF output. I was at first attributing this to some grounding issues because the venue I play at regularly has notoriously dirty power. However when messing with the high and low outputs, I realized the HF output is the only one with the buzz. Is this still a grounding issue or is it something strange with the output?

    The cables are name brand 3 ft speaker cables in the patch, 6ft speak on cables in the outputs, and a 8ft tweed livewire cable out of the bass.

    Thanks for all your advice so far!

    FordKH
     
  7. Dino@Ampeg

    Dino@Ampeg

    Mar 27, 2008
    Global Product Specialist - Ampeg
    If I may chime in here too.....
    First off everything that Jerrold suggested is spot on.
    However, you should be using shielded, instrument patch cables when patching for biamp. Not unshielded speaker cables. This may be part of the buzz you're getting in the HF.
     
  8. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    The buzz is one thing......... the other thing might be a phase reversal in one cab. That may make the crossover sound weird, with a "hole" right at crossover.

    if you put both cabs side by side, and get your ears level with them, so that one cab is mostly in left ear, and the other mostly in your right ear.....then play softly.

    if they are correctly phased, the sound will seem to come from in front of you.

    If NOT, the sound will seem to be split to the two sides. it's very hard to describe, but that is how it always sounds to me.

    As for the buzz, naturally the right cable works better. But have you moved the cables around? They can pick up hum from equipment. A phase problem can also cause buzz to be made louder, but it won't CAUSE buzz.

    or, just use signal cable..... much much better than before, likely. But surprising that only one does it.

    The cables can also be bad. Swap low and high cables, see if the buzz follows the cable or the channel.

    Jacks can have a grounding problem, like being loose/bad solder.

    Once you figure it isn't the amp, go get some decent patch cables.
     
  9. DBTOYS

    DBTOYS

    Sep 22, 2009
    Bend Oregon
    same with dino you need a shielded {guitar cable} running the bi amp part of the ampeg then speaker cables to the speakers
     

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