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Troubleshooting something totally bizarre
- Thread starter JimmyM
- Start date
I found the impedance curves in mag #4, nothing strange to see.
The impedance minimum is aprox 7.5 ohms, nothing critical about that. One pair should be no problem for the amp.
Maybe one of the transistors is bad.......
The impedance minimum is aprox 7.5 ohms, nothing critical about that. One pair should be no problem for the amp.
Maybe one of the transistors is bad.......
well, this put me over...i'm headed to rs to get a meter. maybe while i'm gone someone can tell me what the hell to do with it when i get back 
Start stabbing the probes in random places until you find something that doesn't seem right 
.
Ok, not really. Measure the DC resistance of the cabs. IIRC, 8 ohm cabs come out to ABOUT 6 ohms.
.Ok, not really. Measure the DC resistance of the cabs. IIRC, 8 ohm cabs come out to ABOUT 6 ohms.
ok, just measured each cab separately and together and also plugged into the head, and everything seems to be normal. each cab measured 7.something, and together they measured about 3.7 or 8. so i guess we can rule out impedance.
- Dec 18, 2000
- 13,201
- 340
- Disclosures
- greenboy designs: fEARful, bassic, dually, crazy88 etc
DCR from a multimeter ain't really saying much anyway.
Some of the "difficult load" things I've seen anecdotally aren't always about minimal values alone either.
Some of the "difficult load" things I've seen anecdotally aren't always about minimal values alone either.
so why did i just buy this meter?
Because now you know that at least the impedance at DC is approximately what it should be... You just don't know what it is anywhere else.
I think someone asked earlier whether the problem occurred at all frequencies above a certain volume, or just in certain frequency bands. I guess if the latter were true that wouldn't rule out an impedance issue, but it might mean something as simple as a fragile connection.
For all the good press you give them, I hope Ampeg sorts you out with a new rig!
Good luck, man.
For all the good press you give them, I hope Ampeg sorts you out with a new rig!
Good luck, man.
oh, must have missed that...it's on the lower notes, and it gets worse when i crank low end or turn up louder. going to call ampeg again now.
edit: ampeg ts said it's a bizarre problem they never saw it before either, but they're pretty sure it's in the head somewhere, so it sounds like they're going to work out details on a head swap and get back to me. first time dealing with ampeg cs, and i must say they've been pretty great so far. can't ask for more than that.
edit: ampeg ts said it's a bizarre problem they never saw it before either, but they're pretty sure it's in the head somewhere, so it sounds like they're going to work out details on a head swap and get back to me. first time dealing with ampeg cs, and i must say they've been pretty great so far. can't ask for more than that.
Good -- keep us posted, and I hope they're still your favourite amps after the call!
This amp has a switch mode power supply? If it does I'm wondering if the regulation of the supplies is collapsing under heavy load. I think the amp is faulty even if it just has a problem with the AV cabinets.
lol! yeah, i think they will be
it all works...it just doesn't work together in this one specific combination.
well it worked fine with two 8 ohm b-15 cabs and my 4 ohm svt 810. but they agree with you that it's in the head.
just did...
b-15 cab: 6.8-7 (they both have delta 15a's so i just measured one)
810: 3.7-4
Given that the 3 setups have comparable DC impedances, it seems odd that the problem should only occur with the 210AVs and still be thought to be in the head. Of course, I am far from expert in these matters...
