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Behringer Inuke LF performance with low impedance load

post #1 of 70
Thread Starter 
I am not sure if this was discussed before.

apparently the amp does not maintain full output at low frequencies with 4 and 2 ohm load.

http://www.diyaudio.com/forums/class-d/213071-behringer-inuke-nu3000-measurements.html#post3036619

Quote:
Out of curiosity, I tested voltage and continuous power output for 20hz & 10Hz.

With no load:
20Hz = 49Vrms
10Hz = 44Vrms

With 8 ohm load:
20Hz = 282 Wrms
10Hz = 230 Wrms

With 4 ohm load:
20Hz = 475 Wrms (< 10 seconds)

After about 10 seconds, the power output dropped back to 280Wrms.
Based on this, I skipped the 10Hz and 2ohm testing.

what do you think about this? big deal?
post #2 of 70
is this max output without clipping...or is it comparing output achieved with a calibrated/similar input level? If it's the latter, this could simply be the natural roll off of something in the signal chain. Remember, these are pro audio amps. Pro audio doesn't usually do much under 30 or 40 Hz, let alone 10.
post #3 of 70
interesting.

could heat build-up in your test rig have influenced the results?
post #4 of 70
Mister mister. . . we build D class amp for you. Couldn't help it but I remember Ray at Linear Power getting heckled at the last SEMA show and posting about it in a car audio forum. It's just a off the wall comment that stuck with me smile.gif.

Yeah aahemmm not enough balls in D class amps I've seen. I think the same was found in Crown K series being weak sauce in the lower freqs power falls off quickly. LG uses a special class TD their own version of D class which apparently is totally different. Guess stick with G/H or LG clone IMO.
post #5 of 70
Thread Starter 
Quote:
Originally Posted by vitaminbass View Post

is this max output without clipping...or is it comparing output achieved with a calibrated/similar input level? If it's the latter, this could simply be the natural roll off of something in the signal chain. Remember, these are pro audio amps. Pro audio doesn't usually do much under 30 or 40 Hz, let alone 10.

It is max output before clipping. The drop looks like the limiter kicked in. I suspect if the amp was driven a little short of the max it would have maintained the output. That's what the other test found

http://forum.speakerplans.com/behringer-inuke-nu6000-vs-kam-kxd7200-bench-tested_topic69202.html

It's for NU6000 so only 8 and 4 Ohm loads were tested. They found that for bass duty it can maintain approx 1.8kW @ 4 ohm where as for the mains it can do approx 200W more
post #6 of 70
from what i have read, 1800 watts stereo at 4 Ohms seems to be what everyone has always said it can do as far as bass duty. seems good to me
post #7 of 70
Thread Starter 
Quote:
Originally Posted by brian6751 View Post

from what i have read, 1800 watts stereo at 4 Ohms seems to be what everyone has always said it can do as far as bass duty. seems good to me
right.
in fairness though, 1.8kW result was based on the 31Hz test.
I could not find any more tests for 20Hz and 10Hz.
post #8 of 70
I just bought one, and measured it quite extensively before bringing it to use.
For the price it is a very powerful amp, and good enough for its intended purpose.

Here is what I found:

Behringer i3000 Vrms Vp Vpp P 8 P 4
Null 1KHz 51,50 72,83 145,66 331,53 663,06
Null 20Hz 48,30 68,31 136,61 291,61 583,22
Null 14Hz 47,50 67,18 134,35 282,03 564,06
Max 4R 1KHz 49,00 69,30 138,59 300,13 600,25
Max 4R 20Hz 47,40 67,03 134,07 280,85 561,69
Max 4R 14Hz 46,80 66,19 132,37 273,78 547,56

No 2ohm measurements, and I see that I have no measurement data for 10Hz, which indicates that it was not very fond of very low frequencies.
post #9 of 70
Thread Starter 
This is great stuff, thank you.

just to make sure I understand the numbers, it looks like you you had two types of tests, each ran at 1kHz, 20Hz and 14Hz. the last two numbers in each row seem to correspond to the power output measured at 8 and 4 Ohm respectively. The rest of the numbers are the voltage measurements (rms, peak and peak to peak).

Is this about right? If so, what are the two tests ("null" and "max 4R")? also, are the results for both channels driven?

thank you very much.


Quote:
Originally Posted by Okv View Post

I just bought one, and measured it quite extensively before bringing it to use.
For the price it is a very powerful amp, and good enough for its intended purpose.

Here is what I found:

Behringer i3000 Vrms Vp Vpp P 8 P 4
Null 1KHz 51,50 72,83 145,66 331,53 663,06
Null 20Hz 48,30 68,31 136,61 291,61 583,22
Null 14Hz 47,50 67,18 134,35 282,03 564,06
Max 4R 1KHz 49,00 69,30 138,59 300,13 600,25
Max 4R 20Hz 47,40 67,03 134,07 280,85 561,69
Max 4R 14Hz 46,80 66,19 132,37 273,78 547,56

No 2ohm measurements, and I see that I have no measurement data for 10Hz, which indicates that it was not very fond of very low frequencies.
post #10 of 70
I should have made some effort to format these numbers a little better, see if this is easier to read:

Behringer iNuke 3000 output power:
Load and freq Vrms P 8ohm P 4ohm
No load 1KHz 51,50 331,53 663,06
No load 20Hz 48,30 291,61 583,22
No load 14Hz 47,50 282,03 564,06
Max 8R 1KHz 51,00 325,13 650,25
Max 8R 20Hz 48,00 288,00 576,00
Max 8R 14Hz 47,60 283,22 566,44
Max 4R 1KHz 49,00 300,13 600,25
Max 4R 20Hz 47,40 280,85 561,69
Max 4R 14Hz 46,80 273,78 547,56


Measured by measuring output voltage, at the different frequencies, with different loads.
The P 8 and P 4 columns are calculated power output into respective loads if the amplifier outputs the measured voltage.
In very short intervals (i.e. peak transients) output power may be slightly higher than these static measurements indicate, but not by much, the output voltage is not likely to be higher than measured with no load.
Time interval of measurement is 2-4s burst.
Steady state output of very long intervals are not interesting for music/film use.
The amplifiers seems to have no problem running music or similar signals in to two 4 ohm subs, one on each output channel, running at max level.

I did not measure 2 channels simultaneously. If the psu is shared for both channels, the output power may be lower. To verify this, just check to see if there are two smps psu circuits inside.

Note that the iNuke has a built-in limiter that reduces the signal level in a way so that it will never clip the signal into square-waves like usual, so it is not immediately obvious by looking at the signal to determine that the maximum level is reached.

Lower output <<20Hz, as long as it does not freak out totally, is not a big problem as I see it, most drivers will be excursion limited at <<20Hz, so this may actually just help to make life a little easier for the driver.
This may be a limitation with inefficient, long-stroke drivers in small sealed boxes - the solution is of course to avoid such designs.
Also, keep in mind power is only 0.4dB down from 1KHz to 14Hz in 4ohm.
post #11 of 70
Thread Starter 
Thank you very much! It looks like there is no reason to upgrade from my Inuke yet.

So what happened when you tried the 10Hz tests?
Have you attempted to measure with 2 ohm load?
post #12 of 70
nice work okv. thanks for sharing your findings!
post #13 of 70
Quote:
Originally Posted by vitaminbass View Post

Pro audio doesn't usually do much under 30 or 40 Hz, let alone 10.

Ummm no,


My Marathon 5050 is flat to 5hz, bosso verified that with his setup.
http://www.avsforum.com/t/1335979/ma5050-or-inuke-for-lms5400#post_20458345

Someone also benched an ep2500 and found just a little roll off at 5-10hz. I know chucky's testing showed that it put out 2kw.





The advantage of the class D's is that they are lighter weight and don't waste power to heat. The lab;s have a tracking technology that can easily adjust to the transient dips and peaks. I would like to try one of the clones but don't want one of them to burn my house down and be unable to to claim insurance.
post #14 of 70
I saw no real limits when I ran mine bridged into an 8-ohm load running sine wave sweeps while testing the lilwrecker.
At the highest level sweep, it appears that I found the limits of my driver, my amp, and the soundcard, all at the same time. I can live with that.

At low volumes, it doesn't appear to roll off too badly. I can not test at war-volume as I don't have a large resistive load yet.

Before you freak, note the scale. The divisions are 0.5 dB (but the dB are not calibrated to anything meaningful here). I'm also reporting data down below my usual 10 Hz limit. This was run into a 4-ohm 120W resistor.



The only issue I have with my iNuke 3000DSP is the lack of any DSP functionality below 20 Hz. My subs need a slightly lower highpass than that....
post #15 of 70
Thread Starter 
Quote:
Originally Posted by lilmike View Post

I saw no real limits when I ran mine bridged into an 8-ohm load running sine wave sweeps while testing the lilwrecker.
At the highest level sweep, it appears that I found the limits of my driver, my amp, and the soundcard, all at the same time. I can live with that.

At low volumes, it doesn't appear to roll off too badly. I can not test at war-volume as I don't have a large resistive load yet.

Before you freak, note the scale. The divisions are 0.5 dB (but the dB are not calibrated to anything meaningful here). I'm also reporting data down below my usual 10 Hz limit. This was run into a 4-ohm 120W resistor.



The only issue I have with my iNuke 3000DSP is the lack of any DSP functionality below 20 Hz. My subs need a slightly lower highpass than that....

your measurements seem in line with Okv's - approx. 0.5 dB roll off in mid teens.

regarding the high pass below 20Hz: have you tried a combination of PEQ boost and HPF in the 20Hz region? you can get the resulting curve virtually indistinguishable from a 15Hz HPF.
post #16 of 70
Not yet. Thanks for the tip though. I only need a couple Hz, cause I am losing 2 dB of usable output at the low corner with a 20 Hz highpass.

I still need to complete the subs in question and get some better measurements of what I have created.
Then I'll worry about proper highpassing and getting them properly equalized in room.
post #17 of 70
"The only issue I have with my iNuke 3000DSP is the lack of any DSP functionality below 20 Hz. My subs need a slightly lower highpass than that...."

i believe that you can "wing it" with a combination of a 2nd order high pass and a low shelf with *negative* gain.

a second order high pass filter set to 20hz will have a -3db point at 20hz and will be down -12db at 10hz.

a high shelf 12db/octave (hs12) set to 20HZ will have a +3db point at 20hz and will be up +9db at 10hz.

together, these two filter produce the same thing as a second order high pass filter set to 10hz.

of course, you don't have to use 20hz for a 10hz net, you can set both filters for 30hz in order to achieve a 15hz high pass net.

the only downside is that the noise floor will be higher, which may not be a problem.
post #18 of 70
here is a picture of the filters.

divide the frequencies by 10, i.e. 100hz in the picture is 10hz. winisd gets screwed up with filters down under a few hz.

yellow line is a second order high pass filter at 200hz.

red line is 12db/oct high shelf filter at 200hz with -12 gain.

green line is the net of the two filters--a second order high pass filter at 100hz.

post #19 of 70
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

here is a picture of the filters.

divide the frequencies by 10, i.e. 100hz in the picture is 10hz. winisd gets screwed up with filters down under a few hz.

yellow line is a second order high pass filter at 200hz.

red line is 12db/oct high shelf filter at 200hz with -12 gain.

green line is the net of the two filters--a second order high pass filter at 100hz.


i cannot find shelf filter options in WinISD. how did you get it done?
post #20 of 70
"i cannot find shelf filter options in WinISD. how did you get it done?"

hehe...i'm not telling.

just kidding. too much *mucking* around with winisd. :-)

1. make a sealed cab with any driver it doesn't matter.

2. set inductance (le) for the driver to zero so there is no top end rolloff.

3. enter a linkwitz transform with fp = to 1.0 hz. this should give you a perfectly flat response.

4. enter a second linkwitz transform with f0 = high corner (200hz in this case), fp = low corner (100hz in this case), q0 and qp = 0.707.
post #21 of 70
Quote:
Originally Posted by zheka View Post

Thank you very much! It looks like there is no reason to upgrade from my Inuke yet.

So what happened when you tried the 10Hz tests?
Have you attempted to measure with 2 ohm load?

I have no documentation for 10Hz, and I know I did not test 2 ohm.
I never intended to power more than 2 subs from it, but now it seems I will likely try it with 4 subs.
Also, refer to the Diyaudio-measurements, they may be more valid for 2 channels operation.

Distortion is very low at 400Hz.
At lower frequencies, the distortion rises significantly, but is still around 0.1% (measured well below max output, around -6dB), the problem is the spectral content, rather nasty.
Distortion is lower at lower power levels, and also when putting out 500W in to those subwoofers the distortion from the house easily masks both the distortion from the sub and the amplifier.
post #22 of 70
Quote:
Originally Posted by lilmike View Post

...
The only issue I have with my iNuke 3000DSP is the lack of any DSP functionality below 20 Hz. My subs need a slightly lower highpass than that....

It has dynamic eq filters, could it be possible to use those instead of an ordinary hpf?
The purpose is to limit the output from the amp at very low frequencies, how you do it should not be that important, as long as the drivers survive.

I am using a MiniDSP, I do not have the iNuke dsp version.
post #23 of 70
Quote:
Originally Posted by Okv View Post

It has dynamic eq filters, could it be possible to use those instead of an ordinary hpf?
The purpose is to limit the output from the amp at very low frequencies, how you do it should not be that important, as long as the drivers survive.

I am using a MiniDSP, I do not have the iNuke dsp version.

Hmmm, that is an interesting idea. I will look into this.

It appears that a dynamic limiter on top of an "adjusted" highpass with either Peq or an LT might be the ticket. Thank you all for the suggestions.

Hopefully I'll have a chance to try this out tomorrow.
post #24 of 70
hpf at around 30 hz then boost centered at around 20 hz and play with the q. Or can use two narrower para eqs (such as one at 20, one at 25) if too lumpy for your tastes wit just one. That's how I plan to set up my F20
post #25 of 70
Quote:
Originally Posted by stgdz View Post

Ummm no,
My Marathon 5050 is flat to 5hz, bosso verified that with his setup.
http://www.avsforum.com/t/1335979/ma5050-or-inuke-for-lms5400#post_20458345
Someone also benched an ep2500 and found just a little roll off at 5-10hz. I know chucky's testing showed that it put out 2kw.
The advantage of the class D's is that they are lighter weight and don't waste power to heat. The lab;s have a tracking technology that can easily adjust to the transient dips and peaks. I would like to try one of the clones but don't want one of them to burn my house down and be unable to to claim insurance.

sorry...my intent wasn't very clear. What I meant was, pro audio output is typically not that low...hence the built in hpf on man pro audio amps. Go see a local band at a nightclub, if they have strong output at 40 Hz they are actually digging pretty deep. As a result, when the equipment is engineered, there isn't much focus on filters and performance at very low frequencies, and in some cases there is a capacitor (or equivalent) in there somewhere with the intent of blocking the signal as things approach DC....and not a lot of concern if this also attenuates 5 Hz or 10 Hz in the process. Not the case here evidently, just wanted to explain myself better.

I would speculate that since a tiny fraction of these amps (pick one of those discussed) end up for home audio use, if the output is flat to 5 or 10 it's either by accident or to make the brochurre specs look good...not because the designers are worried about the home theater crowd buying their product
post #26 of 70
I do agree one of the drawbacks would be the sub 20hz adjustability , but for the price you cant really complain. I run a LMS-R 12in off a 3000dsp without a highpass and it seems to do just fine. I have it bridged and it can give the sub a run for its money. Now if someone wanted to drive a huge 18in power house, you might want to reconsider. Without any load i measured 99v in bridge mode at -5db input with a 30hz sine.
post #27 of 70
Quote:
Originally Posted by lilmike View Post

Hmmm, that is an interesting idea. I will look into this.

It appears that a dynamic limiter on top of an "adjusted" highpass with either Peq or an LT might be the ticket. Thank you all for the suggestions.

Hopefully I'll have a chance to try this out tomorrow.

You know you can download the dsp application from the Behringer site?
It allows you to have a look at the possibilities, even without the amp.

The dynamic eq looks like it may be a good option for a hpf.
You can not set a true high-pass, only shelf, but I think that would be sufficient.

Someone must try this out and try to kill some long-throw drivers, long-throw is kind of out of fashion this year anyway.
post #28 of 70
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

"i cannot find shelf filter options in WinISD. how did you get it done?"

hehe...i'm not telling.

just kidding. too much *mucking* around with winisd. :-)

1. make a sealed cab with any driver it doesn't matter.

2. set inductance (le) for the driver to zero so there is no top end rolloff.

3. enter a linkwitz transform with fp = to 1.0 hz. this should give you a perfectly flat response.

4. enter a second linkwitz transform with f0 = high corner (200hz in this case), fp = low corner (100hz in this case), q0 and qp = 0.707.

thank you.
so this is how to make the yellow line on your chart. but what's the trick for emulating shelf filters in winisd in general? is the point #4 above all that is needed for 12dB slope/12db gain shelves - Q0 and Qp set to 0.707 and F0,Fp are 1 octave apart ? how does one emulate different gain and slope settings?


thank you
post #29 of 70
Thread Starter 
Quote:
Originally Posted by Okv View Post

You know you can download the dsp application from the Behringer site?
It allows you to have a look at the possibilities, even without the amp.

The dynamic eq looks like it may be a good option for a hpf.
You can not set a true high-pass, only shelf, but I think that would be sufficient.

Someone must try this out and try to kill some long-throw drivers, long-throw is kind of out of fashion this year anyway.

Interesting. So the idea is to set a negative gain low shelf filter at 20Hz, but only engage it after certain loudness threshold is reached. Is this about right?
post #30 of 70
Yes, this will limit the output at very low frequencies, and thus hopefully prevent over-excursion.
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