"BEAR" wrote in message
...
Don Gortemiller wrote:

Check out this link to nelson Pass's DIY site.
http://www.passdiy.com/speakers.htm

A very interesting big transmission line.

Well, imho, not so very interesting.

Here's why.

First, Pass uses no less than TWO 21" pro sound woofers, with an Fs of
25Hz,
per channel.

Then he loads them into what is simply a very large long tube. The result
is
not tuned particularly. So, he has to EQ the whole thing to get the
response flat.
In effect throwing out the relative sensitivity (two 96dB woofies in
parallel -
presumably getting 102dB/1w/1m/4 ohms) to achieve a "flat response."

The filter he calls for is a 2nd order LP @ 20 Hz!

One has to ask, would the effect be much different if he merely built what
has been so popular here, what-it-called? The EBS alignment? And, a
much smaller box.

Ok, so you might like the long delayed LF coming out of those smokestacks
in your listening room, I dunno.

Note also, the end of the pipes are actually 2 feet from what is basically
a large
conic horn section - the peaked inside of the roof. Gain from this is
possible too.

Then he goes and plays them with 4,000 w/ch amps! Yeah, ok.

As noted, check Martin King's method, I think it is likely superior.

_-_-bear

So far as I know Augpurger's work is currently the best and most definitive
on TL's which is why i recomended it.
I know of nobody who has done more to refine TL theory.