Need a crossover for my new 400 lb center channel speaker...

**analog addict** · July 30th, 2012, 11:47 PM

I pullked the 1005b/288b off the shelf where it had been sitting. When I originally unpacked and tested this one, it sounded distorted. I put it away and didn't screw with it, and was hoping it was just some dirt in the gap/'phragm.

The raw material complete with 50+ years of dust.

Here's a surprise - a loading cap. The screws on the cap all had that little "snap" to them when loosened, making me pretty confident that no one had been in this driver before.

Show me the money! A pristine 288b diaphragm. I didn't see the model number, but I've not found a model number listed for the 288b 'phragms. A pair of 20221s for the 288c went for over $600 on E-Pray last fall, and this one's in better condition than those - not that I'm ever going to sell....

I gently blew out the driver itself and was rewarded with a noticeable puff of dust. I carefully reassembled it, plopped a 7 uF capacitance in series with the + lead, and carefully applied some low wattage music.

Success! The distortion I once heard is gone. So I should be in good shape for Pano this weekend. Oh yeah, DCR on this guy is 14.2 ohms, so it's a real 20-24 ohm 'phragm.

**Alien_Shore** · July 31st, 2012, 08:33 PM

Killer old gear.
Man cave.
Judas Priest vinyl.
This thread just keeps getting better and better!

**analog addict** · August 1st, 2012, 11:32 PM

Almost have the mancave redone...

**Panomaniac** · August 2nd, 2012, 04:48 PM

Cool! I like the new arrangement. I wonder if that thing should go on its side?

**analog addict** · August 2nd, 2012, 06:40 PM

Originally Posted by Panomaniac

Cool! I like the new arrangement. I wonder if that thing should go on its side?

Hard to ever put wings on it if it's lying on it's side.....

**analog addict** · August 5th, 2012, 11:08 PM

Here's some of Panomaniac's work....

and here's a hashed together working unit to use while I await the results of his work...

**Panomaniac** · August 6th, 2012, 11:00 AM

We had a great time last night, A.A. is always a great host and everyone had a blast. We did have some trouble concentrating on the audio, as Olympic Beach Volleyball was on the TV (sound off). :cool
I think we came up with a pretty good crossover by measurement and by ear. It was nice to have some trained listeners there to verify the sound of things. The crossover turned out to be 3rd order electrical with the horn reversed (IIRC). Acoustically the crossover point is circa 770Hz, but I don't remember the electrical points. It's what sounded best.
I'll get some measurement graphs and other info up ASAP - tonight I hope.

EDIT: Oh yeah, the traces you see above are impedance plots for the dual woofers and the horn+driver.