Posted by Adrian Mack [ 203.190.195.81 ] on March 31, 2004 at 05:58:14:
In Reply to: help on Beyma 12 posted by adkins on March 31, 2004 at 05:16:59:
G'day Adkins
Sorry for not replying to email.
By the way, each time you've given different T/S specs for the G320. I gave you a box reccomendation over the email for this driver awhile ago, but calculated with the other set of T/S specs you gave me. This is actually the 3rd set of T/S data you've given for this same driver...... are you absolutely sure that these are the correct TS parameters now?
The very low Qts of the driver unfortunately makes any box volume at all have a cutoff above 100Hz.
> This driver also shows a major hump in the lower bass around 70-
> 90hz I think, maybe this driver is designed to run above 200hz?
Thats about right. If its peaking at 70-90Hz its because you've oversized the box in attempt to gain a lower F3 frequency. It is not something I would do, as peaks are unwanted for one thing, and transient response becomes poor.
I'd suggest another driver be choosen instead. Earlier, you gave me some T/S specs for the G320 over the email. They are different from the ones you have posted here. Using the previous T/S data you gave me, it modelled up well and I suggested that you can use this driver. But now, assuming that those T/S specs were wrong and the ones you have just posted are correct, I do not suggest you use this driver at all because it does not suit your application.
> Is it o.k. to use the 18" driver all the way upto 200hz or maybe
> even 300hz? Will doing this require much more power from my
> subwoofer amplifier or limit its lower freq. extension? Or degrade
> the sound in any way?
As we aleady discussed, you'll be having the 18" driver in a seperate cabinet as a subwoofer. Crossover must be kept at 100Hz or preferably lower, with at least 4th order filter slope to ensure that it's pretty much non-directional.
If you did cross at 300Hz, not only would it quite distinctly seem like a seperate source from the rest of the system, but theres a huge chance frequency response will be highly non-uniform/irregular as well. I'm sure I've discussed to you before about phase and diffraction stuff, quite a lot, so you should pretty much know this by now.
Adrian
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