Behringer EP4000 input sensitivity question - AVS Forum
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post #1 of 8 Old 05-25-2013, 11:11 AM - Thread Starter
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I can only put 0.9 V RMS into the EP4000. I have an LMS-R 15" DVC I'm trying to drive with it. First question, running the EP4000 as 4 ohm bridged is the same thing as running it as 2 ohm stereo, correct? Does this mean the 0.9V RMS I give it can output 2025V RMS? P= (Vin*Vgain)^2/R = (0.9*50)^2/2 = 1012.5. So it gives 1012.5 Watts per channel, so in bridged it is doing 2025W? Can someone please tell me if this is correct?

Or is the amp power calculated based on a single 4 ohm load, so P = (0.9*50)^2/4 = 506.25.

If the latter is true, what can I do to get the Vin up to where it needs to be?
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post #2 of 8 Old 05-25-2013, 11:47 AM
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In the Bridged Mode, max possible power is 4X...
The Bridged Mode is actually a push-pull type configuration not stereo. However, actual power output will be determined by:
a. Specs for output devices
b. Power supply capability
c. Threshold settings for protection circuitry

Make sure that the amplifier was orignally designed for Bridged Mode operation, also note that the amplifier thinks it is operating into a 2 Ohm load and now all Speaker Out terminals (+, -) are above chassis ground. Whereas in a normal Unbridged Mode, the (-) Speaker Out is chassis ground.

Just my $0.02... wink.gif
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post #3 of 8 Old 05-25-2013, 12:21 PM - Thread Starter
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I think you misinterpreted what I'm asking. Basically all I want to know is what is the input voltage required of 4 ohm bridged to get approximately 1800 W of output power?

The amplifier is designed for bridged mode, and it's running it properly, it has been for a year now. I have seen the actual measurements I believe 4 ohm bridge can do something like 1920W, the manual says 2500W. I only need up to 1800W though as I'm on a 15A circuit 120V. I have all the settings on the amplifier right, the amplifier is not the problem. I'm just worried my input source can not do high enough RMS voltage output to get to the max power of the amplifier.
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post #4 of 8 Old 05-25-2013, 03:18 PM
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Nominal input voltage for rated output is 1V RMS...
Regarding the 15A, don't worry about that as the amplifier will never pull enough current playing music source material...
Also make sure the amplifier has @ least 3-4" of free-air clearance for the L/R sides and top cover..

Just my $0.02... 👍😉
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post #5 of 8 Old 05-25-2013, 03:28 PM - Thread Starter
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Quote:
Originally Posted by M Code View Post

Nominal input voltage for rated output is 1V RMS...
Regarding the 15A, don't worry about that as the amplifier will never pull enough current playing music source material...
Also make sure the amplifier has @ least 3-4" of free-air clearance for the L/R sides and top cover..

Just my $0.02... 👍😉

Yeah I have a lot of space around the amp. Where did you get the 1V input voltage or what math did you do? So is my 0.9V RMS max input voltage fine then?

It's a subwoofer amp mainly for movies so, I do need quite a bit of power.
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post #6 of 8 Old 05-27-2013, 07:17 AM - Thread Starter
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basically which math is correct:

4 ohm bridged mode:

1950 W = (V*2*50)^2/4

V = 0.88 V

OR

1950 W = (V*50)^2/4

V = 1.73 V

When bridging an amplifier, the voltage gets doubled, which is where the *2 comes from. So from this math the ep2500/4000 only needs 0.88V to reach it's max output on 4 ohm bridged. The measured power value is from here http://www.avsforum.com/t/855865/measuring-amplifiers/0_100#post_10755565

The *50 is from the 34 dB gain of the ep4000 amplifier. The /4 is from the 4 ohm load.
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post #7 of 8 Old 05-27-2013, 11:20 AM
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Quote:
Originally Posted by WagBoss View Post

basically which math is correct:

4 ohm bridged mode:

1950 W = (V*2*50)^2/4

V = 0.88 V

OR

1950 W = (V*50)^2/4

V = 1.73 V

When bridging an amplifier, the voltage gets doubled, which is where the *2 comes from. So from this math the ep2500/4000 only needs 0.88V to reach it's max output on 4 ohm bridged. The measured power value is from here http://www.avsforum.com/t/855865/measuring-amplifiers/0_100#post_10755565

The *50 is from the 34 dB gain of the ep4000 amplifier. The /4 is from the 4 ohm load.

INput sensitivity should be called out in the owner's manual specifications and I assume that's where the 1 volt came from.
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post #8 of 8 Old 05-27-2013, 11:26 AM - Thread Starter
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Quote:
Originally Posted by JHAz View Post

INput sensitivity should be called out in the owner's manual specifications and I assume that's where the 1 volt came from.

It does, but only for 8 ohm, and it says 1.23V

and just calculating it:

450 watts per channel

450=(v*50)^2/8
3600=(v*50)^2
60=v*50
v=6/5=1.2 V

and bridged (if my math is right for bridging)

1300=(v*50*2)/8
10400=(v*100)^2
102=100v
v=1.02V

bridged (if my math is wrong for bridging)

1300=(v*50)^2/8
10400=(v*50)^2
102=50v
v= 2.04V

I don't think it makes sense that it needs more voltage when bridged, it should need the same to quadruple the power, because bridging just takes the same input signal, and amplifies it, but inverts it so the combined total voltage output has double the peaks, which in turn quadruples the power because it's v^2
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