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Power amp clipping

CBBass123

CBBass123

Oct 18, 2005
599
181
Texas
#1
Hey guys, sorry if in wrong section. I have a current problem with our behringer ep4000 sub amp. Channel 1 seems to be clipping like crazy with distortion when a moderately low signal is sent to it. It only clips when a speaker is plugged in. No speaker connected and it doesn't clip. Normal yellow likes come on. Channel 2 runs perfect with and without speaker connected. No clipping whats so ever. Chan 1 clips with and without clip limiter engaged. I am also running same signal source to both channels in parallel input mode. I also tried stereo mode but same conclusion. Ch1 clips, ch2 perfect. What could it be? I checked inside and gave a fresh slight coat solder on speaker board. Not sure where else to look.

Thanks,

C.B.
 
#2
Hi C.B.

Very common failure mode with A/B PP amps.

If You look at the output signal on an o'scope, you'll most likely see that either side of the signal hits a "rail" as soon as a little bit of signal is applied.
IMLE it's often on the power level where the transition to class B starts.

Depending on the topology, it's either the power semiconductors, or the driver circuit that has bitten the dust.

Either way, definitely tech time.

Regards
Sam
 
#5
no behringer product is worth fixing. replace it with something (from QSC IMO due to a 6yr warranty and reliable amp and $$$) that is rated to handle your subwoofer. and don't fall for the marketing with your amp replacement, ie EP4000 isn't a 4000w amp, unless you run it at 2ohms bridged (which you won't). you want to look at the p/channel specs at 8ohms if you are running a single speaker sub, or at 4ohms for any dual speaker sub. however to make 100% certaintly of the impedance level you obviously must consult the manufacturer specs on their website/manual.
 
#6
Personal opinions on Behringer products are often polarised. I had a EP2500 for a while and it was reliable, sold it to a work colleague who ended up abusing it more than I ever did and it seemed good for them too. Sometimes you get a dud, sometimes the model design is a dud but that is not always the case with Behringer (in my opinion). I would side with t-bird that something has gone wrong with some components, perhaps the bias circuitry has died causing lots of crossover distortion?

I do agree that the 4000W is a bit optimistic as I doubt a 110V wall socket would allow 40 amps current draw. Looking at the specs in the manual, it only states that is 'Peak' power in to a 4 ohm load. RMS is 2500W into 4 ohms with no mention of 2 ohm loads for bridge mode. In short ignore peak power claims and stick with RMS.

Check with a reputable tech and get a quote first. If it costs more than getting a new amp then replace. I would agree with Big Daws that QSC is a good brand but there are many out there as well as many forum discussions as to which is the best.
 
#7
Hi.

CBBass123 said:
Thanks for your reply Sam
Click to expand...

You're welcome.

CBBass123 said:
Is it worth fixing it rather than purchasing a different one.
Click to expand...

If it's just the driver section acting up, definitely worth fixing IMO, if it's the output devices, probably not.

The biggest problem with anything B related is that most of the techs AFAIK price the diagnose reflecting their dislike to the brand.
The diagnose can then be more $/€ than the same amp from the CL.

The "Behringer" schematics also tend to be harder to find than the ones for quality brands, but the EP series topology is ancient, any tech worth his/her salt will be able to diagnose it.

I usually run such amps with only the working channel, sometimes I remove the faulty module, sometimes just defeat the module and and mark the inputs & outputs.

The power supply is designed to be able to run only one amp at full swing, so using just one channel actually improves the low end reproduction tremendously.

Regards
Sam
 
#8
Thanks guys,

Ya I had a QSC RMX1450 back in the day when I played bass and abused the crap out of it and it never let me down. I'll let my buddy know my findings from here. He didn't wanna fork up for a new one but I as well sort of have a dislike towards behringer as I had two different bands have a mixer failure during live shows. One was effects going out and making loud alien noises and the other mic pres going out.

Thanks for your help.
 
#11
Dear CBBass123,

We do indeed offer a 3 year limited warranty, as of 2012, if you registered your gear when purchased. However, either way, please get in touch with our Care department at [email protected] and they will be more than happy to help you out!


Best regards,
Sean Fairchild
Specialist, Channel Marketing Prosumer Division
MUSIC Group
BEHRINGER
 

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