"Bob-Stanton" wrote in message
om
"Arny Krueger"

All you have to do is reduce distortion to the point where it is
inaudible. Easy enough to do in the 21st century - without active
crossovers.

Still, you haven't give us one example of a low cost amplifier with no
audible distortion.

And you haven't given us one example of a low cost amplifier with audible
distoriton when operated within its ratings.

Staying within an $800 budget is not tough.

Two, low cost, stereo amplifiers: $400
Passive electronic crossover: $ 20
Two Vifa woofers at $100 each: $200
Two Vifa TG 27 tweeters at $30 each: $ 60
Two old enclosures from a garage sale: $ 20

Total: $ 700

This isn't a system.

Right, it isn't a system, it's the parts for a system. Add DIY and you
have a system.

Doooh. No front end, no control.

IME, no. Either way, the best way is to optimize the driver & box
combination using Thiel/small parameters and verify with actual
measurements.

Most manufacturers of quality woofers provide T/S parameters and
leave the design up to the purchaser.

Manufactures give a "VB ltrs" spec. Isn't that the recommended box
volume?

Here's a sample set of data for a Vifa woofer from the
manufacturer's web site.

http://www.d-s-t.com/vifa/data/tc08sd49-04d.htm

Now maybe you can find Vb here, but I sure can't.

I have data sheets for Vifa woofers, that Madisound sent out. Each
data sheet *has* a recommended VB(Ltrs) for the woofer.

One can go to Google and type: "speaker calculator". It will come up
with Websites that offer free T/S box calculators. They are *very*
easy to use. Just type in four T/S parameters, and the calculator will
come up with the correct volume for the enclosure.


I can find Vas, but Vas isn't the same as recommended box size.
Recommended relationships between Vas, Vb and other parameters are
given he

http://www.diysubwoofers.org/sld/sealed1.htm


Zoebels are for people who don't get it.

I'm one who doesn't "get it".

How do they relate to a system with an electronic crossover?

Zoebels are not necessary for an electronic crossover system. (One of
the *advantages* of electronic crossoves.)

BTW *You didn't answer the question.* What do you have against
Zoebels?

They add complexity and parts, when the problem they propose to solve can be
addressed by other means or not at all.

BTW#2 Here's how to calculate the Zoebel, R and C values:

Rz = 1.25 * R (the voice coil, dc resistance.)
Cz (in uF) = 1000 * L (in mH)/(Rz*Rz)


Example Calculation:

(The L and R values are from the Vifa P13WH-00-08, 5' woofer)

R dc voice coil = 5.7 and L voice coil inductance = 1 mH.

Rz = 5.7 * 1.25 = 7.1 Ohms
Cz = (1000 * 1) / (7.1 * 7.1)= 19.8 uF

Again, Rolling your own loudspeakers and getting good results is far
from simple unless you stick to subwoofers. Doing a two-way
woofer/tweeter speaker system *right* is actually one of the tougher
technical chores around.

Again, I have to disagree with you.

Yes, it is somewhat difficult to design a two-way speaker system: if
you want to have a bass reflex enclosure, if you want to have a
complex crossover (such as a 4th order, Linkwitz-Riley), if you want
to add equalization networks (to make the response flat to 1 dB), if
you want to have a resistive terminal impedance, and if you want to
have good polar patterns at all frequencies.

But, using a *closed box driver*, and using an *electronic crossover*,
greatly simplifies the design. Simplifies it to the point where, a
home builder can make a good two-way speaker, fairly easily.

I wish.