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Discussion in 'Amps and Cabs [BG]' started by I.'.I.'.Nakoa, Apr 20, 2002.
I read that people use these.. what exactly do they do?
I Don't know what they do exactly in technical terms. I think they increase or decrease the time that certain frequencies are released according to how the knobs are adjusted. I use one and it is a very very clean sound. I would not advise getting one if you have a lot of fretnoise and finger noise coming from your bass. Unless you want to practice on your technique. I have to bring mine to every gig or the other guys don't like me for a couple sets.
yeah, it delays certain frequencies to make the bass seem deeper and the highs clearer. It makes your whole sound very high fidelity.
ok.. this is my best shot at the technical explination.
Lower frequencies take longer to produce than higher frequencies. Speakers aren't perfect, so when you hit a low note, the cone can't instantaneously jump out to where it's supposed to be, it has to accelerate toward that point, and that takes time... not a lot of time, but more time than it takes for a high note.
The result of this is that when you introduce a range of frequencies, (any one note you play is a whole collection of different frequencies), the low frequencies are made a very short time after the higher ones. Your brain doesn't register this as a delay, but as a "muddy" sound.
What a sonic maximizer does is slightly delay the higher notes so that they are made at exactly the same time as the lower ones. This is supposed to make a much more "clear" sound.
Does it work? I have no clue, i've never gotten to use one. But I've read the manuals and data seets and such, and i tihnk that they're very interesting. devices. If you get one let me know what it actually sounds like.
I couldn't explain it in technical terms... but when you play through one, and then turn it off, you realize how badly you want one!
I have a BBE 383 pre amp that has a Sonic Maximizer circuit in it. The processing clearly involves some EQ and delay; there might be some asymmetrical waveform shaping to generate some even-order harmonics but I can't say for sure without further investigation.
It's okayit seems to add a nice little boost in about the 1 to 2.5 kHz range, but the delay really bothered me because it added a sort of slapback echo to attacks. I would've rather had them put the money into improving the unit's compressor circuitry.
Lower frequencies take longer than higher frequencies to complete each cycle, not really to "produce." But that's what makes them low frequencies.
I'm not clear on what you're saying about speakers.
Muddy sound comes from having the lower frequencies too strong in relation to the higher ones. Temporal relationships between lows and highs don't affect "muddiness" or "clarity," as long as they're not way out of whack--like if you delayed the higher frequncies a couple seconds after the lows, it certainly would impair the clarity of the sound.
I've used one in the recording studio for several years now. BBE would have you believe that there's a whole lot going on under the hood of one of these processors, but they bassically have two knobs, one for high-end and one for low-end. Both knobs just clean up and accentuate their respective frequencies. We only use it in the studio as a last resort, in case something sounds so crappy that normal eq doesn't do anything for it. If you're having problems with these frequencies, I would recommend going to the source of the problem (bass, amp, strings, your fingers, etc.) instead of trying to dress up your sound with one of these boxes.
That is what i read while trying to find out what the BBE actually does.
My own inference is this.
Low frequencies require higher cone excursion than higher ones... higher cone excursion will take more time because of the inertia of the speaker etc.
higher frequencies don't have to move it as much so they come out sooner..
Please let me know if this reasoning is wrong. I'd hate to be misinformed.
There is a really good description of what is going on at the BBE website. www.bbesound.com , then go to Technology, then Overview. It seems to describe the whole process.
Pretty darn interesting!!
That part is correct.
That part isn't.
A speaker cone has inertia whether it is reproducing high frequencies or lows. However, higher frequencies requires more abrupt acceleration of the speaker cone, so inertia tends to have a more significant effect. In fact, a large cone can reach a frequency where the entire cone doesn't respond as one, so it starts to flex; this breakup dramatically decreases the acoustic output. That's why larger drivers are used for low frequencies and smaller ones for highs.
An amp with a reasonably high damping factor, connected through wire with very low resistance, will correct almost all of the motor effects of inertia--lag and overshoot--but it can't do anything about cone breakup.
Sound comes out of the speaker whenever its cone is moving at a high enough frequency to create sound, and high frequencies don't come out faster.
From the BBE website:
So according to them, i had it backwards.. Higher frequencies take longer to produce. Do you agree with this Bob, or are they selling snake oil?
I think their explanation has a distinct marketing touch to it.
But I wouldn't call it snake oil. It does alter the sound of a bass in a way that some would find pleasing, and you can adjust it, or at least you can on my pre. In that sense, I consider it more of an effect and not a correction for loudspeakers.
One thing I really appreciate about my BBE pre is that they put the schematics in the owner's manual. It makes it easier to plot out some mods to the compressor circuitry.
Vented boxes blur the sound by introducing increasing group delays as the frequency descends toward the cabinet tuning frequency. The worst delay occurs at the tuning frequency. Group delays higher than 24 msec are audibly sloppy and muddy at those frequencies. In contrast, sealed boxes are renowned for their tight bass because they have very low group delay, typically well under 7 msec.
With vented boxes, nearly all radiation comes from the port at the tuning frequency. Phase lag between the driver and the port is 90 degrees at resonance. This wouldn't be a problem if the driver was reproducing only sine waves, but it's not.
On scope traces, the 2nd harmonic is as strong as the fundamental, and sometimes stronger. The second harmonic of low B is 62 Hz, and well within the range of the woofer producing the fundamental. Played through a cab tuned at 31 Hz, the fundamental will be 90-degrees behind the 2nd harmonic (read: mud). This nasty trait cleans up as the frequency moves higher from the tuning frequency.
The trick is to find a driver that is optimally tuned below the lowest usable note of the cabinet. This keeps the muddy group delay problem away from the range of usable notes.
Thanks for the replies everyone! Ya'll have made it a litttle more clear what these do...