stuckinthepod Posted February 24, 2022 Share Posted February 24, 2022 I've recently bought a RM Evo 2 112 cab. It is rated at 300w at 8ohms. I have been running at Ampeg Portaflex 350 which delivers 250w at 8ohm in to it. The ampeg has been cutting out and last practice there was an electric short burning smell from the Ampeg as it cut out and I switched it off sharpish. The Ampeg thankfully still works fine and has always performed well with a bigger 410 400watt rated 8ohm cab and zero issue. Is the issue that the cab is not correctly rated or is the Ampeg overloading? Any help appreciated ? Quote Link to comment Share on other sites More sharing options...
Lozz196 Posted February 24, 2022 Share Posted February 24, 2022 I had this with the second PF500 I had, happened on the first time I used it (connected to a Barefaced Compact & Midget so not an issue re the cabs). That was my journey with the PF range over, shame really as the first one I had was great, no issues at all. Quote Link to comment Share on other sites More sharing options...
nikon F Posted February 25, 2022 Share Posted February 25, 2022 have you looked inside the RM cab ? Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted February 25, 2022 Share Posted February 25, 2022 Your Ampeg has just about bit the dust. Aka one foot in the grave. Aka on its last legs. I reckon a fault in the cab would have sent the sound bad before the amp quit. Quid pro quo, the amp went toaster mode of its own accord. It's a mystery to me how it reset and continues operating after letting out magic smoke. Quote Link to comment Share on other sites More sharing options...
stuckinthepod Posted February 25, 2022 Author Share Posted February 25, 2022 Thanks all. I'm going to get the cab looked at before I use it again. Its a mystery how the Ampeg is still going but I've lost confidence in it. I've got a gig coming up and can't risk it. I've bought a TC BQ500 Thrust instead which seems to be just the ticket. Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted February 25, 2022 Share Posted February 25, 2022 The other possibility is the burning smell actually came from the cab. It's certainly possible to toast a higher rated cab with a lower rated amp by making it all go as loud as possible. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted February 25, 2022 Share Posted February 25, 2022 First of all the cab is correctly rated. It should be fine with your amp. if all else is well. Secondly unless the speaker cab is shorting out it is unlikely that the cab ort he speaker lead (which you might want to check) is responsible. The amp should turn itself off if there were anything wrong without causing problems other than temporary silence. There shouldn't be a smell of burning which is more likely to be an indicator of a failed or failing component inside the amp. if the amp is now working then all that has happened is that the protection circuits have taken over and switched the amp off for you, removing the power and letting the amp cool down has allowed it to re-set. It may be something as simple as a faulty joint sparking but something is wrong and I'd get somebody competent to have a look. Good Luck 2 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted February 27, 2022 Share Posted February 27, 2022 The cable you are using to connect the amp and cab is a SPEAKER cable and not a coax instrument cable yes? Quote Link to comment Share on other sites More sharing options...
stuckinthepod Posted February 28, 2022 Author Share Posted February 28, 2022 It was the cab. Opened it up and burning smell present inside. Cab just makes a quiet, buzzy sound now, it is most definitely dead. I'm returning it for a refund. Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted February 28, 2022 Share Posted February 28, 2022 250W into a single 12 is looking for trouble especially with a bass! Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted February 28, 2022 Share Posted February 28, 2022 58 minutes ago, stuckinthepod said: It was the cab. Opened it up and burning smell present inside. Cab just makes a quiet, buzzy sound now, it is most definitely dead. I'm returning it for a refund. I wouldn't be too sure about that. Burning up a cab is usually user error, even if it is initiated by unrealistic marketing expectations and a lack of background knowledge. When you turn up and it doesn't get louder you should turn it down some. If you don't it will heat up and can burn up if you lay into the bass for too long. If it ever seems quieter but you turn up some more that is when you burn it. The getting quieter is the driver motor getting hot and increasing resistance. Turning up instead of down makes a runaway condition where the increased voltage makes it hotter still and soon it is very very quiet. Ratings are only a very rough guide to selection for purpose. 3 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted March 14, 2022 Share Posted March 14, 2022 So how did this situation evolve? Inquiring minds need to know. 2 Quote Link to comment Share on other sites More sharing options...
stuckinthepod Posted March 15, 2022 Author Share Posted March 15, 2022 On 28/02/2022 at 19:09, BassmanPaul said: 250W into a single 12 is looking for trouble especially with a bass! Yes lesson learned there I guess. In short cab went. Ampeg is fine and still working and I'm now using 410 cabs Quote Link to comment Share on other sites More sharing options...
stuckinthepod Posted March 15, 2022 Author Share Posted March 15, 2022 On 28/02/2022 at 19:10, Downunderwonder said: I wouldn't be too sure about that. Burning up a cab is usually user error, even if it is initiated by unrealistic marketing expectations and a lack of background knowledge. When you turn up and it doesn't get louder you should turn it down some. If you don't it will heat up and can burn up if you lay into the bass for too long. If it ever seems quieter but you turn up some more that is when you burn it. The getting quieter is the driver motor getting hot and increasing resistance. Turning up instead of down makes a runaway condition where the increased voltage makes it hotter still and soon it is very very quiet. Ratings are only a very rough guide to selection for purpose. Ratings are only a very rough guide to selection for purpose. So it would seem! Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted March 20, 2022 Share Posted March 20, 2022 Did they refund you for the cabinet you blew? Quote Link to comment Share on other sites More sharing options...
agedhorse Posted March 22, 2022 Share Posted March 22, 2022 Is the 300 watts in the marketing material "RMS" or "program" (2x the RMS value) or "peak" (4x the RMS value)? The details are important. 2 Quote Link to comment Share on other sites More sharing options...
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