(Trivia question : What TV show did that line come from? You will show your age with the answer.)

Thought I would share my latest project, my son and I wired it up last weekend and it has been tweaked several times during the past few days.

http://www.quarter-wave.com/OB_Wings_Back.jpg

http://www.quarter-wave.com/OB_Wings_Out.jpg

This is an OB system (48" tall x 60" wide with the wings out) using either the Lowther PM2C, PM2A, or DX4 driver and two Dayton 15" high efficiency woofers (JBL 2226 clones) per side. I am using a DBX DriveRack PA digital crossover, the woofers roll off at 120 Hz 12 dB/octave and the Lowthers roll in at 120 Hz 24 dB/octave, and two Rotel RB-1080 200 watt amps.

All solid state and no passive BSC filter required. My calculations indicate the efficiency is about 98 dB/w/m and reasonably flat above 50 Hz. Decent bass into the 30 Hz range but no measurements yet to prove any of these numbers.

This is a very efficient system and even at fairly loud volumes the drivers barely move, you have to touch them to convince yourself they are connected. Great dynamics and bass. Best reproduction of a kick drum that I have heard from any of my own speaker designs, they can move a lot of air. Very similar sound to my Lowther ML TL design but with better bottom end, no big surprise I guess.

More details to come on my web site when I am done tweaking and find time to documented the project,

Martin

Hey, you coming to the Great Plains Audiofest this year? We'd all love to see you there!

Nudge, nudge, wink, wink.

I looked very hard at the JBLs, these Dayton drivers had identical specs right down to moving mass, BL, and efficiency for less than half the price. I think I got four drivers for the price of one JBL and the construction and consistency between units is very impressive. So for frequencies below 200 Hz, I did not feel I was loosing anything with the Daytons.

GPAF? Would love to come and hear eveything, meet the people on the forum, and discuss audio and music. But that is just too far from home at this time. Maybe someday but not this year.

Martin

"You may want to check out the Linkwitz web site."

I have visited Linkwitz web site in the past and read through the sections he has presented on his designs. He has a lot of interesting things to say and obviously is an expert in his field.

But as usual, I wanted to reinvent and try to learn everything for myself. I wrote the MathCad worksheets needed to design my OB system taking into account the driver parameters, the crossover (assumed active), the position and number of drivers on the baffle, the driver's directivity, the size and shape of the baffle, and the reflections with the floor. Spent a few months working on this and coming up with the design I built. Seems to work well and I am having a lot of fun adjusting the crossover to hear the effects.

This is an experiment and learning experience so we will see how long they last or how long my wife tolerates them.

Martin

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-080

I bought them a few years ago for a different project that did not get built. The T/S para,eters on the PE site have chnaged a little but not enough to matter.

Martin

Did you ever try an MTM instead of an TMM configuration?

I look forward to the writeup on this project......Colin