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Discussion Starter #1
I have a Behringer Feedback destroyer that I use for EQuing only the subwoofer. I use ETF for measurements and a Marchand XM9L crossover instead of the Lexicon MC-1's built-in crossover.


I noticed that the clip light "Red" in the Behringer comes up during heavy bass scenes (Tree Beard in LOTR, Darla scene in Nemo, etc). The Behringer manual says that the clip light indicates "Digital Distortion". I know I can avoid this by reducing the LFE level further but it is already turned very low compared to the mains. I can go lower, but then I have to increase the sub's gain. In way I am concerned about an imbalance that may result with very low LFE line level and high subwoofer gain.


Question,

Is the Rane PE-17 a purely analog EQ? Is an analog EQ more immune to distortion (the equivalent of digital distortion in the Behringer) ?


I have read multiple times in this forum that the A to D and D to A converion in the Behringer is a non-issue for LFE because the DAC and ADC do not adversely affect the sonics in this frequency. Maybe true, but wouldn't an entirely analog EQ be better if one is willing to compromise on the fine level of precision that the digital EQ would give?



An observation..

I use an RME Digi96/PAD professional sound card for 2-channel stereo. The DACs in this sound card are stunningly good in their sonics. WIth my bottlhead pre-amp, I set the level in the RME user interface to 0dB (Line Level) and do not use the volume control slider for attenuation while listening in stereo. However, when I was using the Lexicon's CD inputs (before I built the bottlehead), I observed the clip light in the Lexicon light up when the RME was set to 0dB. Obviously, the Lexicon converts A -> D and again D-> A to do DSP in the digital domain, similar to the Behringer input and output stages.


This makes me wonder, if all these digital equipment are subject to digital distortion when operated at reference level or beyond (I am talking about the scenario I mentinoned, and this is not a staementthat applies to all domains of digital processing). Since I have the bottlehead now, I am not concerned about the 2-channel setup because volume control is done in the analog domain.


Please post your thoughts, especially related to Rane PE-17 vs the Behringer.

Thanks,

-Jai
 

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Quote:
I noticed that the clip light "Red" in the Behringer comes up during heavy bass scenes ... In way I am concerned about an imbalance that may result with very low LFE line level and high subwoofer gain.
If the light's just quickly flickering on and off every now and then, no big deal. If it's staying on for several seconds at a time, do whatever you need to do to stop the Behringer from being overdriven.
Quote:
Maybe true, but wouldn't an entirely analog EQ be better if one is willing to compromise on the fine level of precision that the digital EQ would give?
I have a Symetrix 551, it's a VERY good analog EQ (it's easily as good as the Rane). I also have a BFD. There is no audible difference between the two when EQing my IB subs. Note that it takes test equipment to make sure that analog EQ's are properly set. You can't trust the little dials...
Quote:
if all these digital equipment are subject to digital distortion when operated at reference level or beyond...
Overdriving digital equipment should be avoided at all costs.
 

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Overdriving digital equipment should be avoided at all costs.

>>>>>>>>


I am not really up on the Berhinger Feedback Destroyer , what do you mean by this? Does the EQ indroduce some ugly noises to you amplifer if overdriver or what? How would one avoid this?


I was considering trying one out so I would like to know.
 

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Discussion Starter #4
Quote:
Originally posted by Thomas-W
If the light's just quickly flickering on and off every now and then, no big deal.


Note that it takes test equipment to make sure that analog EQ's are properly set. You can't trust the little dials...


Overdriving digital equipment should be avoided at all costs.
The lights quickly flicker on Bass Heavy Scenes....but those are the very scenes with incredible effects that good subs are built for. I wouldn't mind investing on a better EQ to get the maximum out of the sub with minimal distortion.


The ETF software curves can easily detech if the analog EQ is properly set.


What kind of detrimental effects can a digital distortion (clip) cause?


Thanks,

-Jai
 

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Turning the LFE gain lower and compensating by turning the gain up on the sub is the best way to match it up. It won't hurt anything and will probably lower the noise floor.
 

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Quote:
Originally posted by Thomas-W
...

Overdriving digital equipment should be avoided at all costs.
Actually, "overdriving" in digital domain only means that it reached its maximum level. No harm at all, it just won't increase its output signal if input goes even higher.

I would decrease the gain on the BFD and increase it on the subwoofer like Az Barber suggested. Of course recalibrate your setup.


Kirill
 

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"Actually, "overdriving" in digital domain only means that it reached its maximum level. No harm at all, it just won't increase its output signal if input goes even higher."


Seems to me that after D/A the waveform looks just like (and in fact is at this point) a clipped analog signal with the potential driver damage that implies.
 

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Discussion Starter #8
I tried recalibrating my system and as I expected with increase in subwoofer gain (now at 4/8 i.e, 1/2) I can hear hum when I am near the sub. The hum is not too loud and I can barely hear it in the listening position. Earlier, it was dead quiet from the listening position when the gain was at 1.5/8. Will try a few more tweaks and see what happens. I hate it when it clips because I know I am losing an extra punch that I would otherwise have.

Thanks,

-Jai
 

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The hum is probably a ground loop. Do you have cable? Do you already have a ground loop isolator on your cable?


If not, something like this will likely remove the hum. (You can experiment by unhooking the cable and see if the hum goes away)

http://www.elect-spec.com/video.htm


Radio Snack also carries a similar product.
 

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With professional gear, there is a larger range of gain and output capability. As such, you can overdrive inputs, and set gains excessively high. I believe there is an input gain setting for the BFD, be sure to play with that as well as the other gains. You do not want to EVER see the red lights come on. If you are looking to upgrade, check out QSC's DSP-4.
 

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Quote:
Originally posted by jmcomp124


Question,

Is the Rane PE-17 a purely analog EQ? Is an analog EQ more immune to distortion (the equivalent of digital distortion in the Behringer) ?



-Jai


I would like to know this as well because I am considering buying one of these for taming my Contrabass.
 

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Quote:
Originally posted by Az Barber
Turning the LFE gain lower and compensating by turning the gain up on the sub is the best way to match it up. It won't hurt anything and will probably lower the noise floor.
Listen to Az Barber


he is correct on this one. Turning down the line gain and turning up the gain on the sub actually DOES lower the noise floor.
 
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