EPX4000 Shutting down @1370W/4Ohm bridged ... really really bad

[Mauro Munzi]

Hello,
I bought this unit (S1102249ABB) a little more than 1 year ago and I'm using it to drive a 12" mid bass unit rated 500RMS/1000 Max.
In this days I measured its power ratings using my "real" test scenario; 3m cable from the wall outlet to a power strip on the rack and then a 1m power cord to connect the amplifier.I'm using 4 x 2Ohm 50W Arcol resistors in series for each channel (so 200W per channel) , which are able to handle an overload of 5x their rating with the test procedure I'm using. The test consists in running a 3s On and 18s Fff 100Hz sin wave; the amplifier delivered around 450W RMS @8Ohm and around 740W RMS @4Ohm. Because I'm not able to do the 2Ohm test, due to the combination of the resistors, for which however I was expecting 1000W RMS per channel, I did the 4Ohm bridged test.
With a big surprise the amplifier was not able to go over 74V RMS on 4Ohm, which translate into 1370W, because as you try to go further the amplifier goes into protection ...
I tried also with a 100ms On and 1s cycle but nothing change.
This happens also with the amplifier completely cold.
At that level the main dropped from around 235 to 227...
My impression is that there is something wrong in the protection regulation cuircuitery and/or something wrong with the unit.

[Glenn Slater]

Hello Mauro,

Sorry to hear that your EPX4000 is not performing properly. Please contact (44) 1562 732290 in Europe.for repairs.

Best Regards,

[Mauro Munzi]

Hello,
this morning I recabled my resistors and was able to test the unit with 1 channel driven at 2Ohm; with the usual On/Off period I use, the amplifer was able to deliver 84V RMS on that load, which translate into around 1150W (1channel, 2Ohm).
But after 5/6 cycles the amplifier turned off again (with the clip leds on for the whole protection duration).
So it seems that there are some issues on the power supply, or the power supply is not able to sustain the whole power the amplifier board is capable of. The air coming from the front intake was warm with the fan still blowing at tthe same speed as cold.

I don't want to spend several ten of euros (compared to the price I payed) for shipping, and getting back, the unit to the service center; could you submit this issue to some engineer in order to try to uderstand what the problem is?

[Mauro Munzi]

Hello,
on one of the power connectors there is an explicit reference to names like PS-LIMIT and PS-OFF connection ... the PS-LIMIT connection seems to be interesting (power supply limit? oh my God...). look at the attached image.
supply.jpg
Is it possible to have the schematic of the EPX4000 in order to check for the correct values on the PS-LIMIT, PS-OFF and PS-MUTE connections?
They all go to the power board

[Mauro Munzi]

It seems the attachement had problems
supply.jpg

[Glenn Slater]

Thanks for taking the time to send us the pic. This is really something that our service technicians must resolve for you.

For technical and warranty support for your BEHRINGER product, the best way to contact us is through our CARE department.

You can contact us by phone at (44) 1562 732290 in Europe.

You can also contact our CARE department via email at care@music-group.com. We try to respond to every email within 24-48 hours, but please be patient if it takes longer due to the volume of emails we receive