bartelby Posted August 18, 2011 Share Posted August 18, 2011 So, I recently got an Ampeg PF-500 and during a band rehearsal it started to cut out. So I sent it back and get a replacement. The first test the second amp got was a gig and I performed marvellously! It also worked fine last week at a song writing session (no drummer) Then last night we had a full band rehearsal and again the amp started to cut out. So I got to thinking: In the rehearsal room I use a Peavey 410txf (4 ohm) cab. It's only rated to 350W so I make sure the volume is kept down. During the gig I was using 2 8ohm cabs. The amp has a thermal trip that will mute the output if it gets too hot. Last week the drummer was unavailable so we used the time to write a couple of new songs, so the volume was much lower. Last night, with the drummer there, the 3 times the sound dropped were when I started playing harder and the over all volume was higher. So my question is: Can running a single 4 ohm cab cause the amp to overheat and trip the thermal protection?, or does the amp have a problem developing? Thanks. Quote Link to comment Share on other sites More sharing options...
chris_b Posted August 18, 2011 Share Posted August 18, 2011 If the amp is cutting out with a thermal trip, and this is the second amp you’ve had with this problem, then I'd suspect user error! Have you restricted the airflow in any way? Put the amp in a case or bag? Quote Link to comment Share on other sites More sharing options...
bartelby Posted August 18, 2011 Author Share Posted August 18, 2011 [quote name='chris_b' post='1344024' date='Aug 18 2011, 08:59 AM']If the amp is cutting out with a thermal trip, and this is the second amp you’ve had with this problem, then I'd suspect user error! Have you restricted the airflow in any way? Put the amp in a case or bag?[/quote] I'm only guessing it's the thermal trip, but it's only a drop out for a second or so. I'd have thought heat issues would take longer to correct. Nope, the amp is just sat there, no bag/rack or any other obstruction. The fan works fine. Quote Link to comment Share on other sites More sharing options...
chris_b Posted August 18, 2011 Share Posted August 18, 2011 A thermal trip won’t reset until the temperature goes down and that will take a few minutes. If the sound is only dropping out for a few seconds I think this could be a problem with the amp. But it could also be a bad lead or a bad connection. I'd swap everything and take the amp off the cab. The vibrations might be causing the problem. If none of this works then I'd talk to the place that sold it to you. This might be part of a bad batch. Did they check the first amp you sent back, or did they just resell it? If they did check it, what did they find? Quote Link to comment Share on other sites More sharing options...
bartelby Posted August 18, 2011 Author Share Posted August 18, 2011 (edited) Next week I'll take my 2 8ohm cabs. If there's still a problem then it's going back and I'm not getting another. I got it through Digital Village. They said they'd get, the one I returned, sent back to Ampeg. Edited August 18, 2011 by bartelby Quote Link to comment Share on other sites More sharing options...
keving Posted August 18, 2011 Share Posted August 18, 2011 Does it only happen in the rehearsal space? Could it be a mains power issue? I've heard, but have never experienced, that these types of amps are a lot more sensitive to fluctuating power supply issues. Quote Link to comment Share on other sites More sharing options...
bartelby Posted August 18, 2011 Author Share Posted August 18, 2011 [quote name='keving' post='1344427' date='Aug 18 2011, 02:35 PM']Does it only happen in the rehearsal space? Could it be a mains power issue? I've heard, but have never experienced, that these types of amps are a lot more sensitive to fluctuating power supply issues.[/quote] Interesting you say that, my guitarist was saying last night he used to have an amp that would drop in volume if he played power cords. In the same room we use. Is there any solution to that? Quote Link to comment Share on other sites More sharing options...
Monckyman Posted August 18, 2011 Share Posted August 18, 2011 Try it through a UPS if you can borrow one. Have you tried it on a different power socket/different room? I`m presuming the gig was louder than the rehearsal vol but you used 2 cabs... Are you absolutely sure it`s not the cab with a loose cable? Quote Link to comment Share on other sites More sharing options...
bartelby Posted August 19, 2011 Author Share Posted August 19, 2011 [quote name='Monckyman' post='1344731' date='Aug 18 2011, 07:17 PM']Try it through a UPS if you can borrow one. Have you tried it on a different power socket/different room? I`m presuming the gig was louder than the rehearsal vol but you used 2 cabs... Are you absolutely sure it`s not the cab with a loose cable?[/quote] Not tried it through a different socket, but the way the room seems to be wired I doubt it would make a difference. The gig was louder and the cab in the rehearsal room worked fine with a MarkBass head and, when the Ampeg buggers up, a Peavey MkIII. Quote Link to comment Share on other sites More sharing options...
Lozz196 Posted August 19, 2011 Share Posted August 19, 2011 I`m not an electronics person by any chance, but it sounds to me like the amp really doesn`t like the Peavey cab. I don`t know why that would happen, if you`re not pushing it, but it seems to be that that is affecting it. Quote Link to comment Share on other sites More sharing options...
bartelby Posted August 24, 2011 Author Share Posted August 24, 2011 Took my 8ohm cabs to band rehearsal, that was actually a song writing session as the drummer couldn't make it, and playing with gain at 11'oclock and vol at 12 it was fine. Ran prefectly with no drop outs. Next week I'll take the cabs and see what happens at a higher volume... So, it's looking like it it doesn't like a 4 ohm cab. Quote Link to comment Share on other sites More sharing options...
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