newbie: diy Speakers (Research Mode)

[thomas2717]

Hello:

I just started researching about building speakers and am finding a wealth of information on this site. The many speaker builds of shackters just amazes me!

I have newbie question on using multiple Tweeters in a single configuration i.e., I have seen designs like MTM, TMM etc., but the ones I have come across so far are limited to 1 tweeter & 1 or more woofer or midranges.

Is there a reason for this? Or could you kindly point me to some resources where I can learn more about such issues?

Thanks for your patience.

[BoomieMCT]

Multiple tweeters can cause something called "comb filtering effect" where basically the outputs of the offset tweeters interfere with each other and cause bad things. Woofers will do it too but the longer the wavelength (lower the frequency) the less driver offset will matter.

I have seen a few commercial designs with multiple tweeters and I remain skeptical about them (line arrays and dipole tweeters excluded).

[Geoff Gunnell]

In residential designs, intelligent choice of drivers and crossovers generally results in the mid-woofs and/or woofers reaching their limits first on standard program material -- so there's usually no need to go away from a single point source for the highest frequencies (with the exceptions noted above).

[DasBot]

You might want to pick up the LoudSpeaker Cookbook, on sale right now for $11 from Madisound. (6th ed). This will give you loads of information on the compromises you feel comfortable with. Most boil down to budget so don't be afraid to go cheap. One of my favorite subs only costs $15 and people are always amazed.

[BoomieMCT]

DasBot wrote:

One of my favorite subs only costs $15 and people are always amazed.

I've got to hear more about this!

[DasBot]

Pyramid car woofer. It says, "DUAL CHANNEL SUB" on the front. Retails for around $25.. Doubt they even make it any longer. Pyramid changes up much of their line. I have it in a ported 1.5cf box with passive coils for low pass. High pass is taken care of by a pair of Lightning Audio 6x9's in MDF boxes. (The boxes cost more than the speakers). I just have a single 200uf cap on each and an old Nikko amp running the deal. I only blew one during some showing off and that one lasted 5 years. I've had this one for 4 years now and still sounds great. Picture of the bench
http://img3.freeimagehosting.net/ima...612567f411.jpg

[looneybomber]

Geoff Gunnell wrote:

In residential designs, intelligent choice of drivers and crossovers generally results in the mid-woofs and/or woofers reaching their limits first on standard program material -- so there's usually no need to go away from a single point source for the highest frequencies (with the exceptions noted above).

I would completely disagree, but I guess you did throw in a qualitative limiter; "Intelligent choice". Without defining what that specifically means, in a speaker design, the tweeter will be the weak link since you can't use multiple tweeters, except in a line array. Because of that, a single dome tweeter will limit output to the 112-115db range, where as it's possible to have woofers capable of delivering 130db+. Ribbon tweeters and planars will bump that output up a bit, as will compression drivers.