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Problems with Ampeg SVT-4PRO... huge!

Discussion in 'Amps and Cabs [BG]' started by jayce, May 31, 2005.


  1. jayce

    jayce

    May 31, 2005
    Here's the thing... something about my set up/rehersal space causes it to overheat easily and go into safe mode. I've tried everything to keep it cool, but to no avail. I think a major factor is that my cab doesn't offer a heavy enough load to suck up all those watts. I dunno and I can't find anyone who can figure it out. I just don't want to worry about it cutting out when I really need it. I even took it into an amp tech in LA; he found everything intact and functioning as it should.

    I have tried connecting it to my classic ampeg 8x10 in mono and stereo and it still does it. Could be a problem with my cabinet? It hasn't been altered in any way. I am out of ideas. I tries hard wiring pre amps to power amps with patch cables, using the mute graphic eq selector... EVERYTHING.

    Does anyone have a clue and if not would anyone want it?
     
  2. PICK

    PICK

    Jan 27, 2002
    Sydney, Australia
    I would suggest thats it probably more of a problem with the amp. I cant really see a cabinet causing an amp to go into safe mode. Regardless of how much power a cabinet "Soaks up" from the amp it shoudlnt happen. If anything the amp would be less likely to go into safe mode if its using less power. Regardless of the cabinets "Power rating" the amp will still use the same amount of power. Get the amp checked out.
     
  3. r379

    r379

    Jul 28, 2004
    Dallas, Texas
    I seem to recall a recent thread in which this was discussed. Do you have the amp in a rack case? Apparently the amp has it's vents in the side (IIRC) and if it's in a case it doesn't vent well.
     
  4. Thats right, most (if not all) of the ampeg rack mounted heads have side mounted fans, some cases dont have enough space for adequite air flow
     
  5. NCorder

    NCorder Smoke-free since 4/3/05

    Dec 26, 2002
    Dayton, OH
    I had an rackmounted Ampeg B2R for over 3 years that took lots of abuse, and constantly connected to a 4 ohm cab that never once overheated. Though, its fan was rear-mounted instead of side-mounted as suggested above. Are your cabinet(s) below minimum ohm impendence? If your amp is good down to 4 ohms, connecting 2 4-ohm cabs (or 1 2-ohm)might cause it to kick into fault/protect mode.
     
  6. Ah crap sorry, i forgot there were other rack mounts, i think the pro series have mainly fans at the side and so does my SVT II

    my bad
     
  7. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    How's the cabling there. Make sure its UNshielded speaker cable and not "instrument" cable. If the shielding of an instrument cable melts when using it as a speaker cable, it can and will send an amp into protect mode . . . if you're lucky . . .
     
  8. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    First of all, yes it is side vented. No nothing needs to "suck up all those watts". If a tech thinks it is working, maybe it really is..........

    Second, some questions:

    How do you know it is *overheating*, as opposed to some other thing happening?
    (The same light comes on regardless, so there isn't an "overheat" light. And in protect mode of any sort, the fan normally goes to maximum speed, so it is possible to mis-interpret short circuit protection as overheating, I suppose.)

    How fast does it do whatever it does?

    Will it do whatever it does when just sitting there "on"?

    Does the fan speed increase slowly, or does it just suddenly go to full speed?

    Do you have reasonable venting if its in a rack?

    Have you tried other cables?
    (a short or other problem with the cable will make it go into protection, naturally)
     
  9. jayce

    jayce

    May 31, 2005
    I'm totally aware of everything you guys have said. My cab is 2x8 ohms stereo or 4 ohms mono and its wired correctly. Not modified in the least.

    I noticed the vents are on the side... So I tried taking it out so it could get more air. It still cuts output after 15 or so minutes. I even got an external personal fan to move the air in the area. Could the fan be failing/or lacking sufficient power. Its a total bitch.

    And good luck contacting Ampeg. Although friendly and helpful, they are impossible to get a hold of.

    I suspect that its just overheating issues because the amp is technically sound. How can I keep it even cooler?
     
  10. KPJ

    KPJ

    Oct 2, 2001
    Methuen, MA USA
     
  11. Sounds more to me like a problem with the A/C power in your rehearsal space.
     
  12. jayce

    jayce

    May 31, 2005
    Sorry I look like a total moron. I wrote that from my handheld wireless and it didn't show all of the posts. I take the Ampeg thing back... But ok let me read the ones I missed.
     
  13. r379

    r379

    Jul 28, 2004
    Dallas, Texas
    You can call Ampeg on the phone and they'll be glad to help. I've talked to them several times and they've been great.
     
  14. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    While you are reading other posts, please also look at the questions I asked.... and hopefully answer them.

    Information is power........ and at the moment it will probably lead to advice.......
     
  15. jayce

    jayce

    May 31, 2005
    Thanks to Jerrold and everyone else. I appreciate all of your help thus far.

    Ok...
    How do you know it is *overheating*, as opposed to some other thing happening?
    (The same light comes on regardless, so there isn't an "overheat" light. And in protect mode of any sort, the fan normally goes to maximum speed, so it is possible to mis-interpret short circuit protection as overheating, I suppose.)

    Well, I don't know for certain. I hear fan irregularities. It will go full speed then click off. And come back and click on and off again. I know there isn't a "overheat light" what i meant is that even when there is no output, I play my bass and the peak and limiter lights blink normally. whick i assume means that its getting a signal.
    How fast does it do whatever it does?
    after 15 minutes of playing.
    Will it do whatever it does when just sitting there "on"?
    I don't think so. I've been able to leave it on for an hour and then play it. But once it does cut output, I leave it alone and I hear the fan clicking and sometimes sound will come out of the speakers.
    Does the fan speed increase slowly, or does it just suddenly go to full speed?
    Sometimes it sort of revs up and slows down. Typically it sounds normal right when I turn it on.
    Do you have reasonable venting if its in a rack?
    I think so, but I took it out and it still does it.
    Have you tried other cables?
    (a short or other problem with the cable will make it go into protection, naturally)

    What should I have and how should it be plugged into the cabinet (inputs/outputs)? I have the SVT-810E.

    Thanks again you guys!
     
  16. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Ok, I think we have narrowed it down a bit.

    If we can't solve it here, you may have to take it to the tech and demonstrate the problem. It's always easier on the spot, and it makes sure the tech understands that there really IS a problem, so a "no fault found" isn't gonna work......

    Anyhow.....

    Could be overheating, which might mean the fan driver circuit is squirrelly for some reason (bad connection possible). If whatever air is coming from vent is really hot, that is likely. Could also be loose connection elsewhere.

    Could be a DC on output condition, which would turn off the sound also. That would probably be due to a loose connection somewhere.

    Could be from running hooked up mono bridge but set to stereo....that will also make trouble, but generally starts right away as soon as you play loud. I will assume this is not the problem....

    Yes, it even could be an AC power problem, but I doubt it.


    What hookup ought to be.....

    If you hook up in stereo mode, a Speakon wired 1+ 1- at the amp end is needed, plugged into correct channel (same for biamp mode with separate speakers). Mode should be "stereo" (switch just to right of speaker connections) Speaker can be anything down to 2 ohms.

    If you run mono bridge, speakon should be wired 1+ 2+ at amp end. Mode should be set to "mono bridge". Speaker should be 4 ohms or greater.

    Manual, if you don't have it, is available as a PDF on the Ampeg site. There are wiring examples, explanation of all controls, etc.

    Hopefully it is under warranty still.......
     
  17. Masher88

    Masher88 Believe in absurdities and you commit atrocities

    May 7, 2005
    Cleveland, OH
    The Amp only breaks when you play through it? What about if you unplug the speaker cable and just turn the amp on. Will it meltdown with no speaker connected? Try all different cables...instrument and speaker cables. Even try a different bass. try to omit as many variables as possible. Good Luck!
     
  18. jayce

    jayce

    May 31, 2005
    Well, next I am gonna make sure that I have the right pin configuration for the speakons... Does there need to be a specific pin configuration on the cab end? other than that I am gonna trouble shoot some more and let you know. With this head and cabinet, is it better to play in stereo or mono? Does it make a difference?
     
  19. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Speakon pinning should match what the speaker needs. Usually that is 1+1-.

    As far as usage, with "A" cabinet, as in one, bridge mono is probably best, as you get all the power capability that you can.

    Otherwise, stereo could be best if you have several 4 ohm cabs, because the channels can drive 2 ohms, but bridge mode cannot.

    If you for some reason do not want a lot of power, using a single (or both) channel in stereo mode will reduce the max power capability per speaker. Maybe you have a nice sounding vintage cab, and don't want to damage it, etc.
     
  20. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    Thought: Are we CERTAIN that the cabinet hasn't been rewired/miswired to be of a lower impedance than expected? Can't hurt to plug a meter to the cab and check. Cheap meters are available at any Radioshack for about $12, and if you don't damage the packaging, they have a very liberal return policy if you don't want to keep it.

    If the impedance of the cab is too low for the amp, then the amp WOULD shut down, or fry before it does. Odds are the Ampeg would shut down first to protect itself.