EP2500 Disappointment

[annunaki]

So I purchased a Beringer EP2500 to power my JL Audio 12W7 (currently in a sealed enclosure). I get it all hooked up and run a few tests with my signal generator and find out that the amplifier has a steep roll off at 30hz & down. I double check all of the settings and speak to some other owners and it seems I have a faulty infrasonic filter defeat switch.

I get another one from ZZsounds (Awesome Service!!!!) and I get the same issue. I cannot see how this amplifier is recommended for powering subs when it has no response below 30hz. Either there is some trick I am missing or Behringer has begun limiting the response on this amplifier below 30hz. I have tried a few different settings options on the amplifier and have not been able to remedy this problem. Above 30hz the amp performs like a champ.

The amplifier is also not stable enough in mono for the 3 ohm load this driver presents. The static DC resistance is quite high enough (3.6 or so I will take measurements again to confirm), it must have an impedance dip near 30 hz or below as the amplifer gets a bit crazy as the power demand increases.

I am currently using a RCA to 1/4" adaptor as I am waiting for balanced adaptors, so I do not know if that has anything to do with the problem.

I may have to find a new amplifier now for this driver

 

[avaserfi]

I have set up multiple EP2500s without this [or any] issue and have seen many measurements of people with DIY subwoofers that are powered with EP2500 that have no issue with a 30Hz roll off. Also, the measurements taken by Chasw98 from AVS of the EP2500 show it to be down by about 0.5dB at 20Hz and 1.3dB at 10Hz and stable down to two ohms with over 800 watts per channel. Please note that the EP2500 requires a 20 amp circuit to achieve such power output.

Is there anyway you could take a picture of the rear of your EP2500 so the settings as well as connections are visible? Also, what size enclosure is the JL 12W7 in? Are you equalizing the subwoofer to increase low end response counteracting the natural roll off of sealed alignments?

 

[annunaki]

I have set up multiple EP2500s without this [or any] issue and have seen many measurements of people with DIY subwoofers that are powered with EP2500 that have no issue with a 30Hz roll off. Also, the measurements taken by Chasw98 from AVS of the EP2500 show it to be down by about 0.5dB at 20Hz and 1.3dB at 10Hz and stable down to two ohms with over 800 watts per channel. Please note that the EP2500 requires a 20 amp circuit to achieve such power output.

Is there anyway you could take a picture of the rear of your EP2500 so the settings as well as connections are visible? Also, what size enclosure is the JL 12W7 in? Are you equalizing the subwoofer to increase low end response counteracting the natural roll off of sealed alignments?

I will see what I can do about pictures.

There is no response below 30hz. The enclosure would not matter as the woofer would still be moving like mad based upon the power output capability of the amplifier in question if it indeed had response below 30hz. The woofer barely moves.

The sub is in a sealed alignment with a .707 QTC of 2.25ft^3.

I do have it on a 15 amp circuit so that may be the reason for the clipping/stability issues. I will swap my circuit (after checking the wiring) to a 20 amp breaker.

 

[WmAx]

If the driver has a static DC resistance of 3.6 Ohms, it's not a 3 Ohm driver. It's an over 4 Ohm driver. The EP2500 has zero issue driving 4 Ohm speaker loads.

What do you mean the amp goes 'crazy'?

As for your your frequency response - did you manually sweep sine waves directlyi to it? Are you sure it's not the device FEEDING the EP2500 that is limiting low frequency output? I have never heard of, nor used an EP2500 with limited LF output. Haloeb recently bought an EP2500(and returned it after finding a great deal on two QSCs) and it worked down to 20Hz with attenuation, no problem. This was a recent model.

-Chris

 

[annunaki]

If the driver has a static DC resistance of 3.6 Ohms, it's not a 3 Ohm driver. It's an over 4 Ohm driver. The EP2500 has zero issue driving 4 Ohm speaker loads.

What do you mean the amp goes 'crazy'?

As for your your frequency response - did you manually sweep sine waves directlyi to it? Are you sure it's not the device FEEDING the EP2500 that is limiting low frequency output? I have never heard of, nor used an EP2500 with limited LF output. Haloeb recently bought an EP2500(and returned it after finding a great deal on two QSCs) and it worked down to 20Hz with attenuation, no problem. This was a recent model.

-Chris

I am running it through my Harman Kardon receiver. I had my SVS hooked up to it with no issues playing well below 20hz.

I have manually fed the amplifier with sine waves as well. I will do it again though just to confirm.

By the amplifier going "crazy" I meant that the clipping light flashes and it sounds highly distorted and power backs off. This may indeed be due to the fact that the amplifier is on a 15 amp circuit currently. Although, nothing else on the circuit suffers from it when this happens. Both amplifiers did this.

 

[mike c]

doesnt the EP2500 have some wrongly labelled dip switches at the back?
perhaps the low cutoff is wrongly labelled, can you try to flip that one and try with the sine waves again?

 

[annunaki]

doesnt the EP2500 have some wrongly labelled dip switches at the back?
perhaps the low cutoff is wrongly labelled, can you try to flip that one and try with the sine waves again?

I have tried the switches in both positions.

 

[Alex2507]

Is there any chance that they just sent your old one back to you?

 

[annunaki]

No, I actually have two amplifiers here right now.

In any case I got it working. My lights dim at high output, low frequency operation with no weird clipping issues. Not to mention the house starts making noises I am not used to

On the back of the amplifier they list correct mono operation. In the manual I believe it fails to mention some of the settings of the switches.

 

[mike c]

oh one more thing. where's the sealed 12w7 pics?

 

[Alex2507]

Considering that I'm relieved you must be stoked.

So what are ya gonna do with the 2nd amp?

 

[WmAx]

As I thought - user error.

Man, blaming the poor, innocent EP2500.....

-Chris

 

[fmw]

Please note that the EP2500 requires a 20 amp circuit to achieve such power output.

Perhaps at full power. You aren't going to use anywhere near full power in a home theater.

 

[mike c]

Perhaps at full power. You aren't going to use anywhere near full power in a home theater.

that would depend on the speaker. for this speaker, in this case, a subwoofer ... and at the said frequency, 800w for the W7 driver in a sealed enclosure isn't even pushing the driver, i think.

 

[avaserfi]

Perhaps at full power. You aren't going to use anywhere near full power in a home theater.

This is not necessarily the case. For example, consider the common occurrence of one building a small sealed enclosure with a linear, high excursion, driver and the intent to equalize for more low end gain. In such a case equalization of the low end will cause large increases in power requirements if clipping is to be avoided. Thus the amplifier will be used at full power or near it even in home theater or music use primarily during a transient scenes with high energy in the frequencies being boosted.

 

[Midcow2]

Almost a moot point -- How many sounds are lower than 30 Hz ?

So I purchased a Beringer EP2500 to power my JL Audio 12W7 (currently in a sealed enclosure). I get it all hooked up and run a few tests with my signal generator and find out that the amplifier has a steep roll off at 30hz & down. I double check all of the settings and speak to some other owners and it seems I have a faulty infrasonic filter defeat switch.

I get another one from ZZsounds (Awesome Service!!!!) and I get the same issue. I cannot see how this amplifier is recommended for powering subs when it has no response below 30hz. Either there is some trick I am missing or Behringer has begun limiting the response on this amplifier below 30hz. I have tried a few different settings options on the amplifier and have not been able to remedy this problem. Above 30hz the amp performs like a champ.

The amplifier is also not stable enough in mono for the 3 ohm load this driver presents. The static DC resistance is quite high enough (3.6 or so I will take measurements again to confirm), it must have an impedance dip near 30 hz or below as the amplifer gets a bit crazy as the power demand increases.

I am currently using a RCA to 1/4" adaptor as I am waiting for balanced adaptors, so I do not know if that has anything to do with the problem.

I may have to find a new amplifier now for this driver

Human hearing range is 20- 20K Hertz. So you are missing the frequencies from 20-30 Hertz. The ear itself does not respond to frequencies below 20 Hz, but these can be perceived via the body's sense of touch but you CAN FEEL THE VIBRATIONS. sk peoepl who have been through and explosion or earthquake.

Most amplifers make a trade-off. Lower frequencies require significantly more power. it is difficult to amplifier low frequencies, so much so that a separate patent has been awarded for low frequency amplification , United States Patent 1936597 .

The best way to obtain a lower frequency amplification is to use a capacitve coupled circuit.A capacitively-coupled amplifier circuit includes an amplifier for receiving an input signal via a coupling capacitance and for amplifying the input signal to produce an output signal. A resistor provides a bias voltage to the amplifier. The resistor is bootstrapped using positive feedback with a loop gain of slightly less than one. The bootstrapping causes an increase in the value of the resistor to lower the cut-in (pole) frequency of the amplifier. The bootstrapping or feedback circuit includes a roll-off (pole) at a frequency below the roll-off (pole) frequency of the amplifier. This prevents phase shift in the feedback loop from adversely effecting the high frequency response of the amplifier. The resulting amplifier circuit exhibits a wide passband and excellent low frequency response despite having a capacitively coupled input signal. However, in doing so you introduct an additional component that has untability of dieeelectric components over time. Addtionally ,the physical size of the the capcitors is very large.

The normal frequency ranges of different sound sources is shown below:

And since there are very few sounds lower than low, low pipe organ notes, most amplfiers do not tend to amplify the very,very low notes

 

[fmw]

This is not necessarily the case. For example, consider the common occurrence of one building a small sealed enclosure with a linear, high excursion, driver and the intent to equalize for more low end gain. In such a case equalization of the low end will cause large increases in power requirements if clipping is to be avoided. Thus the amplifier will be used at full power or near it even in home theater or music use primarily during a transient scenes with high energy in the frequencies being boosted.

Sorry, let me rephrase. Using an amplifier of that power at clipping level in a home theater would be so rare and unusual as to be a meaningless issue. Perhaps that's a more accurate statement.

 

[annunaki]

As I thought - user error.

Man, blaming the poor, innocent EP2500.....

-Chris

Come on now, even you have to admit Chris that the rear of the amplifer and the manual contradict themselves and are not extremely clear.

 

[annunaki]

Human hearing range is 20- 20K Hertz. So you are missing the frequencies from 20-30 Hertz. The ear itself does not respond to frequencies below 20 Hz, but these can be perceived via the body's sense of touch but you CAN FEEL THE VIBRATIONS. sk peoepl who have been through and explosion or earthquake.

Most amplifers make a trade-off. Lower frequencies require significantly more power. it is difficult to amplifier low frequencies, so much so that a separate patent has been awarded for low frequency amplification , United States Patent 1936597 .

The best way to obtain a lower frequency amplification is to use a capacitve coupled circuit.A capacitively-coupled amplifier circuit includes an amplifier for receiving an input signal via a coupling capacitance and for amplifying the input signal to produce an output signal. A resistor provides a bias voltage to the amplifier. The resistor is bootstrapped using positive feedback with a loop gain of slightly less than one. The bootstrapping causes an increase in the value of the resistor to lower the cut-in (pole) frequency of the amplifier. The bootstrapping or feedback circuit includes a roll-off (pole) at a frequency below the roll-off (pole) frequency of the amplifier. This prevents phase shift in the feedback loop from adversely effecting the high frequency response of the amplifier. The resulting amplifier circuit exhibits a wide passband and excellent low frequency response despite having a capacitively coupled input signal. However, in doing so you introduct an additional component that has untability of dieeelectric components over time. Addtionally ,the physical size of the the capcitors is very large.

The normal frequency ranges of different sound sources is shown below:

And since there are very few sounds lower than low, low pipe organ notes, most amplfiers do not tend to amplify the very,very low notes

I do plan to use a DCX 2496 to equalize LF response. I have also DBT my hearing to 17hz and up to about 17.5K. Car audio and other loud situations in my younger days has limited some of my upper end hearing response.

I have a lot of movies that play well down into the teens for LF response at a pretty significant margin. Granted you mainly feel those, but that is the point. I love it when the room pressurizes.

 

[annunaki]

This is not necessarily the case. For example, consider the common occurrence of one building a small sealed enclosure with a linear, high excursion, driver and the intent to equalize for more low end gain. In such a case equalization of the low end will cause large increases in power requirements if clipping is to be avoided. Thus the amplifier will be used at full power or near it even in home theater or music use primarily during a transient scenes with high energy in the frequencies being boosted.

To reiterate your point, once I receive the DCX 2496, I am positive I will have no issue clipping the EP2500 due to increased power demands with eq'ed response. The W7 drivers have extremely low power compression. In independent lab tests, the 12W7 driver required about 2500 watts rms just to cause it to reach 10% driver induced distortion. The RMS power rating is 750-1000.

For the 13W7, ith RMS burst tests, for measuring power compression and dynamic transient capablity, they were clipping their 10,000 watt test amplifier and had to rig two of them together. I believe it was Richard Clark or Tom Nousaine who did the testing on the 13W7.