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My Ampeg head is nuts and my speaker is lighting up!?!?

Discussion in 'Amps and Cabs [BG]' started by wonderboy, Apr 27, 2003.


  1. wonderboy

    wonderboy

    Oct 27, 2002
    i know there was a thread about this in the past. but i didn't want to look for it.

    so i am at rehearsal today, and i have an ampeg svt4pro (about 6 months new straight from factory) and an ampeg bxt410hlf (new as well), and in the middle of a song randomly, a loud crunchy noise comes and then my speakers light up! this happened repeatedly so i had to call it quits for the day. what is the solution and cause of this problem? what do to need to do? the head has not been abused one bit. it came out of the box, and straight into a rack and has never been dropped or anything. i have baby'ed it from day one!

    any insight from those who have experienced this problem would be greatly appreciated!
     
  2. PICK

    PICK

    Jan 27, 2002
    Sydney, Australia
    Sounds like you got too much current going into the tweeter. Turn the tweeter attenuator down (Should be a dial on the back of the cab near where you plug the head into the cab).
    The cab is lighting up because there is a fuse in there that sacrifices itself for the sake of the tweeter. When too much current tries to go to the tweeter, the fuse (basically a light globe) catches it and lights up which uses up the excess current and effectively stops the extra current from getting to the tweeter and frying it. Its alot cheaper, and easier, to replace a little globe than it is to replace the tweeter.
    If, when you play the rig again, notice a loss of highend then i would think that you have blown the fuse and it will need to be replaced. The speaker will still work but the tweeter will be useless until the fuse is replaced. If the highs are still there then the fuse will probably be ok, just turn it down. You may have too much highend dialled in on the amp too.
     
  3. wonderboy

    wonderboy

    Oct 27, 2002
    any other suggestions?
     
  4. Mickey Shane

    Mickey Shane what goes here?

    Feb 23, 2003
    Denton, Texas
    You've got too much meat for your potatos wonderboy. Pick is spot on in his analysis and suggestions. You have attained maximum volume for your rig (great equipment by the way).

    You are the proud owner of a head that is capable of producing 1600W, and a cab that can handle 600W continuous. You didn't say what ohm cab you have and what modus operandi you are using for the amp, but there's no need to get into serious math. Look at the two numbers and you will see why you can't play above 5 1/2 on the master volume. That's where I have blown a tweet with 800W cont. handling. Since then I have added another 800W cab. I played on 7 the other night with the L-pads turned down to 1 (most tweets are 50-100W).

    If you want to run bridged-mono on that head and play on 9, you will need to have 4 cabs like the one you have now.

    $$$$$$ That is probably not what you wanted to hear.

    So, fix the tweet fuse (if necessary) and remember that you have volume limitations inherent to your setup.
     
  5. Another, more likely, possibility is that the amp has faulted and is dropping DC at its output. A fault would explain a strange noise out of nowhere and SVT IV Pro's are known to do this. BTW, the amp is rated at 1200 watts PEAK at 1600 Watts at 4 ohms bridged.

    Given Ampeg's penchant for overrating their s/s amps, it's probably good for about 800 clean watts at 4 ohms bridged which isn't going to cause a noise in a 600 watt cab, just gradually burn out the coils. The funny noise indicates a problem with the amp.

    Also, the master volume control of an amp is NOT a power attenuator, it is simply a gain control. Turning it to 5 and 1/2 does NOT limit the output power. The "speaker fuse" on the horn IS a lightbulb. High frequency AC or DC voltage will cause it to light; that's why they're used to protect horns and tweeters.
     
  6. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Far be it for me to second guess PSG but I'd like to add some food for thought. Is is possible that the noise he's talking about is just a severely compressed version of the note he's playing. I notice with my Nemisis cab that the light bulb seems to compress the notes if a horrible, crackly kind of way...... i upgraded the horn and problem solved.
     
  7. Mickey Shane

    Mickey Shane what goes here?

    Feb 23, 2003
    Denton, Texas
    PBG, it's pretty obvious that you don't own a Pro SVT-4 Ampeg head. There are serious problems that arise from trying to provide cabs for this monster.

    My post is from experience. You playin' one?
     
  8. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Actually he does use an SVT though I can remember which). From memory, he even modified it to make it better.
     
  9. You got that right. After fixing several of them and the crap I went through with my old SVT 3 Pro, I refuse to use an SLM Ampeg product. I used to work for a warranty repair center for SLM (Crate, Ampeg, Audio Centron), so I venture I MIGHT know what I'm talking about. I also used to work at GC, so I got to try several others that were not broken and it was patently obvious that Ampeg is VERY liberal in its power ratings.

    I never got to measure one that was not in for repair but all the ones that came across the bench went out at 800 watts MAX bridged at low freqs after repair and they did not sound any different than the ones that hadn't been fixed. Both put out the same volume through the same cabs.

    Shouldn't be. You don't see similar experiences from other people using power amps of 2 and 3 kw because this is NOT a problem related to overpowering the cabs, IME(xperience), it's a problem with the amp. Overpowering a cab doesn't usually produce audible distortion until the coils deform from the excess heat and start rubbing, which would NOT light the horn protection bulb.

    No. I like an amp I can trust.
     
  10. wonderboy

    wonderboy

    Oct 27, 2002
    the crunchy noise, is DEFINITELY NOT a noise of a note! i am not an idiot. it was like my head was possessed making my cab light up and "scream" randomly. it was not because i was playing notes at all. i am aware that i probably should get a few of those bulbs and replace the one that's in there now after all this. is it safe to say it is solely a head issue? has this happened to any of you before?
     
  11. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Sorry dude I wasn't implying that you're an idiot. Not at all. But with this additional info it now seems certain that PBG was right and your head has a problem. Hey at least we've covered all bases (no punn intended).
     
  12. wonderboy

    wonderboy

    Oct 27, 2002
    being that it is a fairly NEW head. what would you suggest i do? what would you do in this situation? send to ampeg to have fixed, or get a new rig all together, or have them send me a brand new head?
     
  13. What kind of problems?

    Also, PBG is too modest. He's got amps that even some well-informed gurus swear don't exist. So a 4pro is not a stretch.

    I'm not trying to be jerky. It's just that PBG has been sharing loads of helpful Ampeg info here for years.
     
  14. Mickey Shane

    Mickey Shane what goes here?

    Feb 23, 2003
    Denton, Texas
    Well, I thought that I was having a similar experience with my svt4, but I was getting awful schreeching sounds while playing at a fairly loud volume (a horn had blown). If yours is doing it at idle, PBG is probably right and you should get your head repaired.

    I have more questions than answers about bass amps. I'll start a new thread, instead of asking questions in this one.
     
  15. It has nothing to do with watts I think, After I so.ld my ampeg svt3 (lack of hi-end)
    I bought a Hartke 3500 Ha wich gave much more tranparency and brightness, and my ampeg svt410 hlf was lighting up like crazy, constantly.

    And now I bought a EBS TD650 and the problem is solved!??

    While the EBS has much more power than the Hartke?!!
     
  16. wonderboy

    wonderboy

    Oct 27, 2002
    bump