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

**aditya** · July 29th, 2012, 01:42 AM

Originally Posted by Panomaniac

You really need to measure the actual impedance for a good crossover. I'll get over there as soon as I can to measure for you. Might bring a digital x-over so we can play.

Maybe this coming Friday or Saturday?

I have a feeling that we are heading for a good thread on the 210s here. Pano is great in the "systematic reporting back" area. His thread here on the A7s was one of the best. Right now I am just eagerly waiting to see lots of graph-ridden posts, more so b'coz of these particular 515s.

**analog addict** · July 29th, 2012, 01:44 AM

Originally Posted by Panomaniac

You really need to measure the actual impedance for a good crossover. I'll get over there as soon as I can to measure for you. Might bring a digital x-over so we can play.

Maybe this coming Friday or Saturday?

Friday night is VIP night at the Beer Bourbon and Barbeque Fest across town, and I was lucky enough to score a half price ticket. Sat is a possibility though...
Meanwhile, back at the ranch....

Oh yeah, I measured the DCR on the 515's, both were in the 9 ohm range, and about 4.6 when paralleled. I'm betting these were closer to 16 ohms. Also, I have this bad boy on a couple of dollies now, and have cleared out my whole main system in preparation for working/final placement.

**aditya** · July 29th, 2012, 02:19 AM

Many thanks AA for the magnificent pic of the 515s. They seem to be in very good condition. Regarding the 9 ohms DC value, it sounds more like a 12 ohm version of the 515. However it does not matter much, as I am sure they will excel at the job they were meant for.

**analog addict** · July 29th, 2012, 11:25 PM

Originally Posted by aditya

Many thanks AA for the magnificent pic of the 515s. They seem to be in very good condition. Regarding the 9 ohms DC value, it sounds more like a 12 ohm version of the 515. However it does not matter much, as I am sure they will excel at the job they were meant for.

As you can see, they're marked as 20 ohm. What they really are is a good question....

A couple more pix...

Guess I should break out the real camera and get some better quality pix.

**aditya** · July 30th, 2012, 01:34 AM

Yes, you are right. Your latest pic sure says them to be of the 20 ohms types, but the DC values are way off !
May be its time for the experts to chime in.

**Panomaniac** · July 30th, 2012, 05:22 PM

I'll post actual impedance curves once I've been back over to A.A's Saturday or Sunday would be good for me.

**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.