Re: Minimizing woofer dynamic compression (RBP??)

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In Reply to: Minimizing woofer dynamic compression (RBP??) posted by Duke on April 16, 2002 at 03:10:02:

Hi Duke!
I will cut and paste...if that is ok...
Q:. Other than efficiency, what factors make a significant difference as far as minimizing woofer dynamic compression? This will help me narrow down my woofer choices (specific recommendations enthusiastically appreciated).
* Look for a unit that has the least gap distance in the pole piece/magnet stucture and preferably a flat wire voice coil. Losses in the gap are a major concern for dynamic integrety. JBL professional woofers (2226H for a 15") would be a great choice...but follow the parameters for proper loading of that motor.
Q. 2. Do muliple woofers give you better dynamics than a single woofer of the same model? In this application size and maximum volume aren't really an issue, but best possible dynamics is.
* You will lower distortion with multiple woofers and increase dynamics. Distortion is lowered by having less cone motion of each woofer for a given output. Once most woofers move farther than an 1/8 inch on a half wave (1/4" peak to peak)...distortion from differential field bias is measurable and audible, not to mention "cone cry" and other moving part anomilies. I love 3 equal units in unequal enclosure sizes, close but not the same to spread out unwanted resonances over a broader band. Stay within the parameters of the driver. You can vary 20%, making the ideal one the one closest to ear leave at your seat, or focus position.
Q. 3. If multiple woofers are used, what's the best way to hook them up to minimize compression? For example, should two 8-ohm woofers be hooked up in series or in parallel? Should four 8-ohm woofers be hooked up in series, parallel, or series-parallel?
* Look at the system impedance you need for your amplifier. In horn loaded enclosures, I prefer to use 2 16ohm units in parallel to get 8 ohms. I did a Klipschorn bottom at 2 ohms once (dual voice coil single driver 4 ohms each coil in parallel and had great results because the amp I was using was comfortable with low DC resistance and the bass horn raises acoustic resistance appreciably. The above means that you can vary the final impedance to suit your amplifier power requirments...dampning, heat, drive current average...etc..

I go parallel before I go series in 95% of cases.
Choose your minimum DC resistance and wire according to number of drivers, parameters and amp choice. There is not "ideal impedance" other than a flat impedance curve...which is damn near unattainable, unless you go to resistive loading, and that will fuck up your dynamic integrety. (tradeoff again)
All designs are tradeoffs. You have to live with the ones that are acceptable for your application and desires.
Hope this helps.

Email is audiowkstation@aol.com if you want to get deeper.

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Follow Ups Full Thread

Topic - Minimizing woofer dynamic compression (RBP??) - Duke 03:10:02 04/16/02 (5)

Re: Minimizing woofer dynamic compression (RBP??) - RBP 22:23:32 04/18/02 (3)

What factors help to keep the impedance curve flat? - phenderson 18:03:18 04/21/02 (1)

re:many varables - RBP 16:54:41 04/22/02 (0)

Thank you again, RBP! - Duke 00:10:51 04/19/02 (0)

Re: Minimizing woofer dynamic compression (RBP??) - Bill Wassilak 08:27:41 04/16/02 (0)

Follow Ups

Re: Minimizing woofer dynamic compression (RBP??) - RBP 22:23:32 04/18/02 (3)

What factors help to keep the impedance curve flat? - phenderson 18:03:18 04/21/02 (1)

re:many varables - RBP 16:54:41 04/22/02 (0)

Thank you again, RBP! - Duke 00:10:51 04/19/02 (0)

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