Unity Horn Project Progress

[Sheldon]

Finally got all the pieces and constructed the enclosures. The horn was Nick Mckinney's last unit. He supplied the horn, passive crossover components for the horn, and the mid drivers. I'm using TAD 2001 for the tweeters. The bass unit is a 15" Lambda TDX Apollo and the sub is a 12" Lambda TDX faraday motor with two 15" PR's at about 1500g each. The sub enclosure is about 2.5 cu ft (around 32L). As you can see from the pics, the bass is a sort of modified open baffle, or a short U-frame.

My ultimate plan is to have 4 channels of amplification per side. Because the horn crossover can be made phase correct, I will probably do that as an active line level crossover. The crossover to the bass and to the sub will be with FIR filters. I will do equalization with the FIR as well, much as discribed in this thread by John Hancock: first pics of the new speaks

I may do it by PC, but I'm leaning toward DEQX for now, as I'm not sure I want to deal with the steeper learning curve of the PC approach.

Here's the front view.

[Sheldon]

And the rear:

Oh, and you can't see it here, but I modified the entry holes for the mids, as suggested by John. That largely removed a resonance peak at around 2000 that was there with the larger holes.

[Sheldon]

Here' s the passive crossover for the mid/tweet that Nick sent with the horn. I may use a passive here for a while, while I build the amps. I did some measurements and had a surprising finding. The tweeter run full range had the expected profile. It rolled off around 250hz, IIRC, and above about 2500 rolled off at 6db. With the crossover, it rolled off around 1200 on the lower end and, with the shelving high pass, had less roll off up high. The surprise was that there was a lot of lower frequency stuff in the spectrum that did not appear without the crossover. Why would that be. I'll try to post some spectra, if I can figure out how to record them from LspCAD (Just MLS). The program has an export function, but I can't find the images.

Sheldon

[mwmkravchenko]

Green with envy.

Mark

[Cal Weldon]

Very nice Sheldon. I especially like the finish on the drones, using the cut out for the cover piece. Really nice touch.

[lcsegeng]

Hi Sheldon,

Good to see you got all your drivers from Nick and have assembled your speakers. I was one of about four of us that were very anxious if we would ever see our drivers from Nick. My system is complete now and I am quite satisfied with the results. I think Stryke Audio has taken over the Lambda line. Have you heard anything on this.

Regarding the xover, I went with a 3 channel XM44 Marchand electronic xover and works very nice. They also have a 4 channel available.

[Sheldon]

Thanks guys,

Originally posted by Cal Weldon
I especially like the finish on the drones, using the cut out for the cover piece.

Laminating the veneer (Koa) is not much fun, but it looks very nice, so I wanted to cover as much as I could. I laminated the cut-outs to a 1/8" (3mm) thick piece of high density fiberboard, then attached that with double sided mounting tape.

Originally posted by lcsegeng
Hi Sheldon,

Good to see you got all your drivers from Nick and have assembled your speakers. I was one of about four of us that were very anxious if we would ever see our drivers from Nick. My system is complete now and I am quite satisfied with the results. I think Stryke Audio has taken over the Lambda line. Have you heard anything on this.

Regarding the xover, I went with a 3 channel XM44 Marchand electronic xover and works very nice. They also have a 4 channel available.

Thanks for the info. Are your crossovers speaker level or line level on the horn? Orders and freq.?

Yes, Acoustic Elegance (formerly Stryke) did purchase Nick's remaining stock of parts and is making some of the Lambda drivers. I got the 12"er from John J.. That took a while too, as he had his own string of setbacks to sort out. Seems like he might be back on track now. I had originally planned to make a 75L box with just the one 15" and the PR's. But playing around I decided I liked the open backed woofer a little better, so divided the box in two and added the 12" to cover below about 50. In theory, the OB woofer might give me a little better match in directivity for the horn.

Sheldon

[Cal Weldon]

Originally posted by Sheldon
then attached that with double sided mounting tape.

Not wood glue? Hope they stay in place for you. Not sure I would trust the tape.

[Sheldon]

Originally posted by Cal Weldon


Not wood glue? Hope they stay in place for you. Not sure I would trust the tape.

We'll see. No harm, no foul, if the tape doesn't hold up. However, these kind of tapes come in all sorts of grades. Body panels, etc.., to many automobiles are held on this way. Some grades are as tough as most glues, and more flexible. The stuff I used is a medium strength polyester foam tape.

Sheldon

[Sheldon]

Originally posted by Sheldon
The surprise was that there was a lot of lower frequency stuff in the spectrum that did not appear without the crossover.
Sheldon

Nevermind that one. Turns out it was a problem with my measurement system, caused by poor connection. No such behavior on retest.

Sheldon