What exactly is a Behringer Feedback Destroyer? (1 Viewer)

[Sundar Prasad]

Wayne,
I will have to disagree with this one too
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Actually, flat response is not the goal. Flat response sounds thin and unnatural. Highly regarded equalizer manufacturers like Ashly and AudioControl recommend a “house curve,” a uniform slope rising from the highest frequencies to the lowest, as the most natural sounding response
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I want to listen to what is on the recording. This means that I need to screw around with the original signal as little as possible apart from amplifying it. There is nothing wrong with applying some gradual boost to the low end - lots of people do. But then I am no longer hearing what the mastering engineer heard at the studio. The 'goal' is not really defined anyway. Some people prefer flat response (which is the most faithful to the content on the disc), while others prefer boosted low end, while some even boost/cut the high end.

 

[BruceD]

Sundar,
In most home listening rooms don't the bass frequencies automatically rise because of room gain?
Doesn't this also follow our ear's response curve [fletcher-munson(sp?)] to lower frequency sound? Doesn't that mean bass needs higher SPL to blend in correctly?
IMO, in order to perceive the music as more realistic, the lower frequencies should have a slight rise in SPL to seamlessly blend (fletcher-munson example above).
A parametric EQ lets you even out the bass peaks (cut) so you can actually hear the rest of the bass frequencies without single frequency boom dominating the bass volume.
I don't consider this altering the musical intent of the recording, but instead simply correcting my listening room's sonic characteristics.
bstan
[Edited last by BruceD on October 31, 2001 at 03:57 PM]

 

[Sundar Prasad]

Bruce,
You are right about everything you said - in fact I said nothing to the contrary. Room gain boosts lower frequencies while the ear's response drops off as one approaches 20 Hz. Low frequency equalization which achieves a flat response in the listening spot is a desirable thing and has nothing to do with the ear at all. This is usually done by using a microphone and associated hardware to determine which frequencies are being boosted/cancelled by room modes at the listening position. A combination of parametric eq. and relocation of the subwoofer (note I am talking of frequencies below 100 Hz or so) is then used to remove the humps and valleys in the frequency response. Once this is achieved, you are done.
However as Wayne suggested, some people go further and actually apply a gradually increasing boost toward the lower frequencies. In my opinion, this is more a matter of preference than accounting for the ear's diminishing response. Let me explain.
Consider a properly set up mixing booth in a studio. The mixing engineer is listening to either near-field monitors or other speakers when he/she is laying out the final 'sound' of the music that is being mixed down to 2 (or more) channels. If the physical space and hardware that this mixing engineer is using has been designed properly (including the choice/location/eq. of the speakers for monitoring), the frequency response at their listening position should be flat from 20 Hz to 20 kHz. Neither the booth nor the mixing electronics should add or subtract from the sound on the master tape.
With this setup, the engineer uses his/her ears and the mixing console to lay down what they think sounds good to them (and hopefully to their target audience). This process usually includes some equalization anyway. If it is assumed (and this may not necessarily be true) that their ear's low frequency response drops off in the same way as you the listener, then they are going to set the loudness of the low frequency part of the music to a level that they consider appropriate for them/you. At home, the only way you can hear what this engineer heard when doing the mix, is if the two main transfer functions involved in the process, namely the booth's frequency response at the engineer's seat, and the Fletcher Munsen curves for the engineer's ears, are reproduced in the same way.
I can do the former with some level of accuracy, i.e. make the response flat at my listening location at home. If this is achieved, and I still feel that the bass is too weak, then it means that either my ears are not as sensitive to low frequencies in comparison to the engineer's (his F-M curves are different) or that I simply prefer more bass than the engineer does. In either case, I am free to boost the low end to a level I feel is appropriate for my enjoyment. However, once I have done this, I have unflattened the freq. response of my system and am no longer reproducing the recording as it was laid down on the disc.
Hope this makes sense.

 

[BruceD]

Sundar,
Guess we are in total agreement with each other.
I do use MLS impulse response signals and FFT to create frequency response graphs from a calibtrated mic at my listening position. With real time graph generation, it is very easy to tune the parametric frequency and bandwidth cuts to smooth out the room response.
These graphs indicate a gradual rise in low frequency in-room response without any parametric boosting of the signal.
My main concern is to eliminate any low frequency spikes so I can get smooth bass response at all frequencies.
Bruce

 

[Wayne A. Pflughaupt]

Sundar,
It appears that I was less than succinct.
As Bruce noted, the house curve is already there, a function of the speaker’s inherent response characteristics and interaction with the room. If you have ever taken measurements of your system you know that dB readings at 400Hz are higher than at 10kHz, and readings at 60Hz are higher than at 400Hz, etc. Therefore the sound you are hearing at your listening position is not flat. Theoretically it was flat when it left the speaker, but it is not flat by the time it reaches your ears.
A lot of people, especially if they are new to room measurements and equalization, are distressed to see their readings are not flat. However, when they equalize for flat response at the listening position they find that the results are overly bright--very unpleasant, if not unlistenable.

The mixing engineer is listening to either near-field monitors or other speakers when he/she is laying out the final 'sound' of the music that is being mixed down to 2 (or more) channels. If the physical space and hardware that the mixing engineer is using has been designed properly (including the choice/location/eq. of the speakers for monitoring), the frequency response at their listening position should be flat from 20 Hz to 20 kHz.

Near-field monitors reduce room reflections due to their close proximity, but they do not escape interaction with the room. Furthermore, they are voiced and designed (in a general sense, via the use of wide-dispersion tweeters and other methods) to resemble the sound of regular speakers at a normal listening distance. Therefore, the house curve function applies to studio situations, too. Measured flat response in the studio sounds a bad as it does in the home. (In actuality, if the studio speakers exhibit truly flat response, the engineer will overcompensate. The result to the end user (that’s us) will be a product that is extremely and unnaturally bass-heavy.)
The same is true, even more so, with subs. I can’t count the number of threads I have seen where someone lamented, “My sub’s response is within 2dB from 100 to 25Hz, but it still sounds bad.”
As we know, most every sub will exhibit one or more response peaks, and eliminating them will result in an improvement. However, eliminating peaks may or may not result in listenable bass. For instance, if the sub is an 8 or 10 incher and the listening area is large, say 6000 cubic ft., the bass will sound anemic at all but low-to-moderate volumes. This is because the little sub does not have the power or extension to properly blend in and “hold up” its end of the house curve. Likewise, even an adequate sub for a given room may naturally roll out before response reaches 20Hz. If the goal is to achieve response and extension as good as the studio (hopefully) had, there is nothing wrong with “applying a gradually increasing boost toward the lower frequencies” (to borrow your words) in order to achieve that objective.
Actually, achieving a natural-sounding house curve is the best way to “listen to what is on the recording” and to “what the mastering engineer heard at the studio.” I used to equalize the bass on many recordings to make it to sound the way I wanted it to. Since I have achieved proper room response, I am confident I am hearing what was recorded, for better or worse.
Regards,
Wayne A. Pflughaupt
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