I have a subwoofer from the 1980s. It is an open baffle subwoofer called the Enigma subwoofer. The subwoofer has 4 15" subwoofers in a 2x2 dipole array. It can really put out the bass (claimed response down to +- 3db down to 20hz). The subwoofer came with an active eq unit. I am reaching out to someone who knows the DEQ2496 intimately to determine if I can duplicate what the active eq unit with the DEQ2496 or something similar before I buy it.
The active eq did the following:
a) high pass filter 18db/octave
b) low pass filter 18db/octave
c) 6db/octave boost down to resonance frequency of the speaker to compensate for the rolloff due to open baffle
d) I believe the low pass filter is set at 100hz
e) I don't know the fs of the speaker but at some point I will measure it. Right now I am just trying to determine if the active eq could be duplicated using a newer device such as the DEQ2496 (or miniDSP).
Thank you for anyone who can give me input.
Regards,
gwho
The active eq did the following:
a) high pass filter 18db/octave
b) low pass filter 18db/octave
c) 6db/octave boost down to resonance frequency of the speaker to compensate for the rolloff due to open baffle
d) I believe the low pass filter is set at 100hz
e) I don't know the fs of the speaker but at some point I will measure it. Right now I am just trying to determine if the active eq could be duplicated using a newer device such as the DEQ2496 (or miniDSP).
Thank you for anyone who can give me input.
Regards,
gwho
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Are you bi- or multi-amped now? After going to the new approach you will be.
I've always felt it was critical for open baffle woofers (or any woofer that doesn't have a sealed box behind it) to have very sharp rumble filtering like 36 or more dB/8ave with a knee, in your case, maybe at 23 Hz.
Not hard to do with parts but simpler if you have DSP available, I suppose.
I've fooled with open drivers some over the years. Seems wildly natural to let drivers roam box free. I think the sound is good, without denying the obvious wave cancellation facts.
My impression is that big difference between theory and what sounds best. Like all theory, very simplified and, in the case of open drivers, reduced to the most rudimentary calculation of high-school geometry combined with wave lengths.... Not that anybody can address features of your room and ambiance issues, but that's my point.
Ben
I've always felt it was critical for open baffle woofers (or any woofer that doesn't have a sealed box behind it) to have very sharp rumble filtering like 36 or more dB/8ave with a knee, in your case, maybe at 23 Hz.
Not hard to do with parts but simpler if you have DSP available, I suppose.
I've fooled with open drivers some over the years. Seems wildly natural to let drivers roam box free. I think the sound is good, without denying the obvious wave cancellation facts.
My impression is that big difference between theory and what sounds best. Like all theory, very simplified and, in the case of open drivers, reduced to the most rudimentary calculation of high-school geometry combined with wave lengths.... Not that anybody can address features of your room and ambiance issues, but that's my point.
Ben
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This is a stand alone dipole subwoofer so it has its own separate amplifier. I'm trying to duplicate the active equalizer as my unit does not function anymore. I guess the miniDSP is my best bet. Do you know if the miniDSP can mix the stereo signal to extract the bass? I'm not much of a speaker expert but what you said sounds correct. You want to have massive attenuation at or below the fs of the speaker (I believe).
Thanks,
gwho
Thanks,
gwho
I'd start by running sound level freq sweeps through the amp connected to the sub in your room. And maybe finding the best location in the room.
Who knows what the curve looks like to start with? Then take it from there.
Amazing what you can do with a Radio Shack sound level meter connected to the free-ware REW software.
Ben
Who knows what the curve looks like to start with? Then take it from there.
Amazing what you can do with a Radio Shack sound level meter connected to the free-ware REW software.
Ben
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