lookin for some literature

[Gatorfooseball08 2]

Ive been lurking around audio forums for awhile now trying to pick up as much technical info as I can to better understand the actual physics behind the audio design concepts. I understand the basic electrical principles and have a very limited knowledge on the physics behind acoustics from lurking here and my physics classes, but besides changing my major to acoustical engineering, i dnt think im going to be able to pick up the level of technical know-how that im looking for without some good reference literature. I was just wondering if some of the members here could throw out some titles that I could study to really start getting some in-depth knowledge of different designs and such. Any help would be greatly appreciated thanks

[sefugi 166]

Don't know if this might be helpful or not, got this link from a member here to do a little reading about AP enclosures which caught my interest. Few other pages of infomation. Can not say if the info is correct or not but thought I would pass it along.

http://www.teamaudionutz.com/tutorials

[Impious 1,476]

Loudspeaker Design Cookbook by Vance Dickason is pretty much the standard for an introduction to the more technical side of reference material. It's novice oriented but assumes you have a fundamental understanding to begin with.

[Impious 1,476]

Don't know if this might be helpful or not, got this link from a member here to do a little reading about AP enclosures which caught my interest. Few other pages of infomation. Can not say if the info is correct or not but thought I would pass it along.

http://www.teamaudionutz.com/tutorials

Steve's a smart guy, a fantastic installer and from all accounts a good tuner as well.

But, from interactions I've observed on the forums, not the most technical person in the hobby and one who also holds on to some popular snake-oil type myths. Though to his credit, he's willing to take advice and perform experiments to help find an answer to a debated question, which is much more than can be said from most. So this certainly isn't aimed at putting him down.

So, let's look quickly at the first page I clicked on: the DVC Subwoofers Page. I didn't read the page in detail, just skimmed, so I probably missed a lot of things. But just a couple comments that I caught on a glance:

"Parallel configurations also tend to RAISE the resonant frequency(Fs) of the woofer , most likely due to variances in inductance, Qes, or other parameters. "

First, Fs is a physical/mechanical parameter. It's mass on a spring, not related to the electrical side of the driver's operation.

What's the equation for Fs?

Fs = 1 / 2Pi * sqrt(Cms * Mms)

So the only parameters that are used to derive Fs are Cms, which is the compliance of the suspension, and Mms, which is the mass of the moving assembly plus acoustic load (i.e. the air). So, by changing the wiring of the driver is either the Cms or Mms of the driver going to change? No, they are not. You are going to have the same mass (Mms) on the same spring (Cms) regardless of how the driver is wired. Which means Fs is going to remain the same between both wiring configurations.

Second, is Qes going to change between series and parallel wiring as is apparently suggested in the above statement?

Qes = 2 * Pi * Fs * Mms * Re / BL^2

The short answer is no, it's not. Qes is going to be the same. Why? Well, look at the equation and figure out what's going to change. When you wire a driver in series, Re quadruples compared to parallel wiring and BL doubles compared to parallel wiring. Since Fs and Mms are going to be the same, we can ignore basically all of the equation except for Re and BL for this comparison. So let's just look at the "Re/BL^2" part of the equation. Since these two values are going to change proportionally to each other, the actual value of Qes is not going to change.

"Obviously, woofer sensitivity specs (db/1watt/1meter) will be least for the woofer in series, highest for the woofer in parallel, and mid-line for the single coil wiring."

Wrong. Sensitivity for parallel and series wiring will be identical. You calculate sensitivity with the formula:

Sensitivity (SPL) = 112 + 10*Log(9.64 * 10^(-10) * Fs^3 * Vas / Qes)

So which of those parameters is going to change between series and parallel wiring? The answer is, NONE. Fs and Qes we explained above, Vas isn't going to change since it's based on Cms and Sd (both of which will remain constant between series and parallel wiring). So what is going to change that will change the sensitivity of the driver between series and parallel wiring? Nothing.

Sensitivity would be lowest for a DVC driver with a single coil driven since you only have half of the motor force, so Qes doubles. It would, in fact, be 3db lower than the sensitivity of the driver with both coils driven (in either series or parallel wiring).

Anyways.....moral of the story is be careful what you read on the internet. And from reading a little more on that DVC page, there are a lot of comments that are either completely inaccurate or arguable at best. Like I said; Steve's a smart and talented guy who has contributed a lot to the hobby. I wouldn't, however, take everything he says as fact when it comes to the technical side of the hobby.

[Gatorfooseball08 2]

Thank you Impious, I'll see if I can find the Cookbook anywhere for a decent price