Behringer Feedback Destroyer PRO DSP1124P

[jeffsg4mac]

Jeff, that is equivalent to a 1/6th octave analysis. You can not accurately measure and compensate Q, frequency and gain with that resolution. High Q anomolies will be missed by this coarse analysis. If you were to measure the response using a higher number of sample points, you could achieve much better correction(s). To correct optimally using that coarse of measurement in the bass range would be co-incidence, or no high Q problems existed in your circumstance in the first place.

-Chris

Sure one could get a more precise and dedicated RTA, but you will also need a computer as well. Now we are talking about money. for under 400 bucks it does the job. The average room only has 1 or 2 peaks in the bass range of most subs so that sort of accuracy is just not needed to get a good sounding sub. Sorry but it just isn't. Sure I could tweak it more accurately with more points, would I hear the difference? maybe, maybe not. I got rid of the offending peak and thats what is important. The DEQ 2496 will fill the need of achiveing a good bass response in a home theater setup and it does it with out breaking your wallet and making your wife mad. Besides, using the other model without any RTA is shooting blind in the dark. That makes no sense.

 

[WmAx]

Sure one could get a more precise and dedicated RTA, but you will also need a computer as well. Now we are talking about money. for under 400 bucks it does the job. The average room only has 1 or 2 peaks in the bass range of most subs so that sort of accuracy is just not needed to get a good sounding sub. Sorry but it just isn't. Sure I could tweak it more accurately with more points, would I hear the difference? maybe, maybe not. I got rid of the offending peak and thats what is important. The DEQ 2496 will fill the need of achiveing a good bass response in a home theater setup and it does it with out breaking your wallet and making your wife mad. Besides, using the other model without any RTA is shooting blind in the dark. That makes no sense.

Just for reference here in this thread, here is a a quick plot I processed that demonstrates the issue(s) being discussed. Blue is a 1/60th sampling of a room's response. Red is at 1/6th octave sampling(equivalent to the RTA on the DEQ2496).

-Chris

 

[jeffsg4mac]

Thanks Chris for proving my point. 1/6th would be accurate enough to bring down the offending peaks. You cant do anything with the nulls. You bring down that peak at 25 and then the one at 55 and that is about the best your going to do anyway. That other one might come down a tad when you bring the other two down, depending Q's set. The DEQ 2496's RTA is more accurate than the red line you have there anyway. No need of 1/60th resolution to calibrate a sub. 1/10th octave would be plenty.

Behringer says " Ultra high-resolution 61-band real-time FFT Analyzer with additional auto EQ function for room and loudspeaker equalization"

Your saying that it is not high-res?

 

[WmAx]

Thanks Chris for proving my point. 1/6th would be accurate enough to bring down the offending peaks.

I'll focus on just peaks, becuase you are make a point about peaks.

In this example, 1/6th octave.....

-Could not determine the frequency, Q or amplitude of the 25Hz peak.

-Could not identify the 37 Hz peak as existing.

-Could not determine the Q or amplitude of the 54 Hz peak.

-Could not identify the 93 Hz peak as existing.

-Could not identify the 117 Hz peak as existing.

The DEQ 2496's RTA is more accurate than the red line you have there anyway. No need of 1/60th resolution to calibrate a sub. 1/10th is plenty.

Indeed, you are correct. My analysis was working with even numbers, so I rounded to 20 sample points between 20-200Hz. The DEQ2496 samples at 21 points between 20-200Hz. However, this is not enough difference to amount to any difference.

-Chris

 

[jeffsg4mac]

Chris, I think maybe your missing something on how the Behringer RTA works, 61 bands does not mean it is only sampling 61 points. Do you think if played a tone that does not correspond exactly with one of the labled bands that I would not see a response on the bar graph. It does not work that way. I would see those peaks and achieve a flatter response than what you are saying I would. I would have to play around with q's until I nailed it but The Behringer RTA would get it. I have a fairly flat response and I did it with this unit. Maybe you should play around with one instead of guessing what it does and printing out charts. My rooms response is nothing like that chart.

 

[WmAx]

Chris, I think maybe your missing something on how the Behringer RTA works, 61 bands does not mean it is only sampling 61 points.

Do you think if played a tone that does not correspond exactly with one of the labled bands that I would not see a response on the bar graph. It does not work that way.

The RTA uses averaged co-ordinates that are measured via a FFT process. The response from the DEQ would look slighlty different from the discrete samples that I have shown, but not by very much. It can not resolve any accurate information to program an accurate filter, nor can it resolve high Q problems. It can illustrate a coarse picture of what is going on, relying on trial, error and some luck to fine tune the filters to an approximate value.

Maybe you should play around with one instead of guessing what it does and printing out charts. My rooms response is nothing like that chart.

That is not your room, obviously. So your room response would not look like that. But according to what you have stated so far, I can only conclude that you don't actually know what your room response looks like.

-Chris

 

[jeffsg4mac]

I can only conclude that you don't actually know what your room response looks like.

-Chris

Did I not say I checked my response with tones? Did I not say I was pretty flat from 27 to 80, +/- 3db or so with the exception of the nulls? I know exactly what my rooms response is.

We are getting way off the point here anyway. The question Phil asked was should he get the feedback Destroyer PRO DSP1124P and the answer would be yes if he has already has an RTA and no if he does not. The DEQ 2496 would be a better choice. You over analyzed this to a point it did not need to go. The DEQ 2496 is a good choice without spending a ton of money to help tame ones subwoofers response. With a little trial and error and some tweaking you can significantly improve how your system sounds with it. That makes it worth the money. If one wants to get another RTA at some point and try to tweak it even further that would be an option too. They may find they don't need it though. The PEQ section in the 2496 is top notch and easy to use. One thing is for sure, without any RTA or some way to measure the rooms response a PEQ or GEQ is useless and you would end up doing more harm than good. I hope we can agree on at least that point. Jeesh

 

[WmAx]

Did I not say I checked my response with tones? Did I not say I was pretty flat from 27 to 80, +/- 3db or so with the exception of the nulls? I know exactly what my rooms response is.

To be fair, you did not specify what increments between that range you used.

We are getting way off the point here anyway. The question Phil asked was should he get the feedback Destroyer PRO DSP1124P and the answer would be yes if he has already has an RTA and no if he does not. The DEQ 2496 would be a better choice.

One can purchase an inexpensive mic preamp, an accurate measurement microphone(which one has to purchase to use the DEQ's RTA) and use freeware or shareware to measure the response of the room and then use any parametric equalizer accurately. My issue was that as a cost factor, the DEQ is not offering as precision a measurement ability as can be had for less, when using the FBD even when including the extra part that you need(mic pre-amp). This is assuming that cost is an issue(person wants to spend least amount for parts) and that the additionaly complexity of setting up the software is not a put off for said person. For simplification of the process, I will agree that the DEQ is definately the best choice to measure the room's low frequency response(at the cost of accuracy).

You over analyzed this to a point it did not need to go.

Sorry. I tend to do that.

The DEQ 2496 is a good choice without spending a ton of money to help tame ones subwoofers response.

Yes, the DEQ2496 is an excellent equalizer.

One thing is for sure, without any RTA or some way to measure the rooms response a PEQ or GEQ is useless and you would end up doing more harm than good. I hope we can agree on at least that point. Jeesh

Yes, of course I agree.

-Chris

 

[rolyasm]

Okay,
So I am in a little bit of the same position. I am building a sub under my riser and so I have no ability to move it around. I am planning on equalization. I DO have an SPL meter and really don't plan on equalizing my mains, unless there is some major problem with them. So just the sub, I hope. I have a lap top I can bring into the room. What items and programs are you suggesting I get to 1)check my room's response 2)equalize the sub. I don't mind spending money for something far superior, but if it is about sixes, I naturally prefer the cheaper method. I actually would like a good program that I could use on my computer so I can save charts and print them for all the experts here to look at and give advice. Not sure what sound card I have, but it is adequate for most things. I do have RCA and Mic inputs. I can give you specifics if that would help. Thanks
Roly

 

[WmAx]

Okay,
So I am in a little bit of the same position. I am building a sub under my riser and so I have no ability to move it around. I am planning on equalization. I DO have an SPL meter and really don't plan on equalizing my mains, unless there is some major problem with them. So just the sub, I hope. I have a lap top I can bring into the room. What items and programs are you suggesting I get to 1)check my room's response 2)equalize the sub. I don't mind spending money for something far superior, but if it is about sixes, I naturally prefer the cheaper method. I actually would like a good program that I could use on my computer so I can save charts and print them for all the experts here to look at and give advice. Not sure what sound card I have, but it is adequate for most things. I do have RCA and Mic inputs. I can give you specifics if that would help. Thanks
Roly

You can use a freeware program such as [1] Speaker Workshop(can be very difficult to use, as sometimes set-up/configuration can be problematic and it may have the most un-userfriendly interface possible, but it is a very powerful program, but some beyond basic knowledge may be required to properly set-up and use this program) . [2] RMAA can perform accurate frequency sweeps, but lacks ability to do any time-domain based analysis. Time based analysis will become relevant for >60Hz response characteristics where the average size room begins to act as a non-minimum phase system in respect to low frequency response. [3] ETF is the ideal(standardized, and easy to use) room analysis program, but it is not freeware($150).

For hardware, an accurate microphone such as the [4]Behringer ECM8000 and a phantom powered microphone pre-amplifier are required. A small [5]mixer will work fine and provide other various uses as well. If your SPL meter has an output you can use this for bass analysis input to your soundcard in place of a microphone and mic-pre, but it will not be accurate in the uppermidrange and treble.

[1] http://www.speakerworkshop.com/

[2] http://www.rightmark.org/

[3] http://www.etfacoustic.com/

[4] http://www.zzounds.com/item--BEHECM8000

[5] http://www.zzounds.com/item--BEHUB802

 

[rolyasm]

WmAx:
Thanks for the advice and links. Looking at the Beh. UB802 Input Mixer, I can't imagine I would ever use all of the stuff on there. What other things can I do with it, and is it worth the $15.00 over the UB502? Using these things I imagine the BFD 1124 would be the option I would choose. Is this also your opinion? thanks.
Roly

 

[WmAx]

WmAx:
Thanks for the advice and links. Looking at the Beh. UB802 Input Mixer, I can't imagine I would ever use all of the stuff on there. What other things can I do with it, and is it worth the $15.00 over the UB502? Using these things I imagine the BFD 1124 would be the option I would choose. Is this also your opinion? thanks.
Roly

The UB502 does not have phantom power, therefor it will not allow the measurement microphone to function. You can use the UB802 for recording, measurements(obviously) or use it as a very high quality headphone amplifier(if you ever get or have already, high quality headphones, many such models may not operate at sufficient SPL on a computer's soundcard output). If you would use one of these extra functions, I have no idea, but it's a good microphone preamplifier for your purposes. The BFD is a fine solution for low frequency modification. Note: The BFD is a pro unit, and the output levels are at pro voltage levels. This may cause noise insertion that is somewhat audible on your consumer equipment(that works at much lower voltage). In order to eliminate possible noise or clipping issues, you can insert a voltage-divider(basicly a potentiometer) between the output of the BFD and input of the amplifier. This is as simple as breaking out a solder iron, cutting up a cable and inserting the potentiometer in the middle. If this is not clear, I can go into specific details for you in PM.

-Chris

 

[genesound]

Note: The BFD is a pro unit, and the output levels are at pro voltage levels. This may cause noise insertion that is somewhat audible on your consumer equipment(that works at much lower voltage). In order to eliminate possible noise or clipping issues, you can insert a voltage-divider(basicly a potentiometer) between the output of the BFD and input of the amplifier. This is as simple as breaking out a solder iron, cutting up a cable and inserting the potentiometer in the middle. If this is not clear, I can go into specific details for you in PM.

-Chris

Strange, my BFD has +4/-10 dBv switches on it for both inputs and outputs. -10 is fine for consumer stuff, low noise and adequate headroom.

 

[WmAx]

Strange, my BFD has +4/-10 dBv switches on it for both inputs and outputs. -10 is fine for consumer stuff, low noise and adequate headroom.

That is fortunate, then, and makes the product that much easier to use. I had forgot that this product has this selectable feature. Many of their products lack this feature. Thank you for the reminder.

-Chris