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MartinLogan guts, all over the floor.

Sam Cogley said:
If this works, let me know. I have a dead, completely unobtainium Infinity Kappa EMIT-N car audio tweeter that needs a diaphragm. I keep an eye out for EMIT-Ns for sale, hoping a single will drift by. I don't want to talk about how long I've been looking.
Click to expand...

I did a Google to see what they looked like, & this guy popped up. It might be what you need.
https://www.ebay.com/itm/132712183258

I'm going to contact him about my tweeters. He may have a better way to do things than what I've come up with.
Good luck & have fun!
 
PhooBar said:
I did a Google to see what they looked like, & this guy popped up. It might be what you need.
https://www.ebay.com/itm/132712183258

I'm going to contact him about my tweeters. He may have a better way to do things than what I've come up with.
Good luck & have fun!
Click to expand...
Those appear to be a narrow version of the coil - this should help them have (much?) wider dispersion, but they are going to have different response and impedance, for sure.
 
sregor said:
@Bobbyd38 is a member here.
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Thank you for sharing that! I will be PM-ing him shortly.


NeilBEN said:
Those appear to be a narrow version of the coil - this should help them have (much?) wider dispersion, but they are going to have different response and impedance, for sure.
Click to expand...

This whole thing is an electro-planar learning exercise for me. I've drawn up several versions of the tweeter traces, some using three traces, spaced slightly further apart, instead of the original four. I'm also looking into making one with 30ga copper wire, instead of the printed foil. I just need to figure out how to make a jig that will hold them in place, while I bond them to the kapton.

Thermal specs for Kapton: (-196° to 400°C) [-320° to 752°F]

I've also picked up some mylar film that I'm going to try.
Thermal specs for mylar: (–70 to 150°C) [–94 to 302°F])

o7
 
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swechsler said:
Hmm, I have a pair of RSDS EMITs. How do the EMIT-Ns differ?
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I was having trouble placing the RSDS code, so I looked them up...if they're the same ones that I just found in an old US Audio Mart ad, I think they are the EMIT-Ns. There were two slightly different versions of the EMIT-N that had cosmetic differences in the frame and the bass-blocking crossovers, but I don't think there were any functional differences. Could you post a picture of them, preferably with a ruler next to one?

This 1992 document lists the Kappa EMIT-N and RSDS EMIT-N has having identical specs (at least for what's listed), except that the Kappa is listed as an "angled" mount while the RSDS is listed as "pointable." Neither is listed as flush-mount or convertible, though my Kappa set came with flush-mount housings as one of the mounting options.
https://worldradiohistory.com/hd2/I...o-IDX/IDX/90s/Audio-1992-05-OCR-Page-0101.pdf
 
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swechsler said:
OK, off-topic, but how in hell do you find links to individual pages of publications on that site? I always have to post a link to the entire issue and then tell people what page to look at.
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In this case, the pdf document was one page.
 
The operation was (finally) a success! But the patient looks ugly without clothes on.

First off, let me say that I have developed a real dislike for black plastic.
I don't know what the official name for these things is, but they suck.
This one is the sole, undamaged survivor.
a6I4zAXl.png

All the other ones were destroyed, or fell apart when I took the screws out.
dGoUuoSl.png

I tried several times to build up these screw-on points with epoxy putty, but the plastic underneath the epoxy kept breaking off when I re-assembled them.

Frustrating. Very frustrating.

So...
I made aluminum panels to replace the crappy plastic.
EzVidD3l.jpg

Stronger. Better. Free! These used to be block-off panels for computer racks.
noN3oN0l.jpg

It took about two hours to make replacements for both speakers.
I used tiny rubber washers under all the hardware.
3XLki59l.jpg

Everything just screws together, right over the aluminum. I didn't modify anything else to make them fit.
When they're together, you can't even tell that they've been fixed.
Q9Zwt3ll.jpg

Once I got them all put back together, I fired up the Marantz & did some A - B testing against my Infinity RS-5's & Definitive BP-6's.
qg2IWdtm.jpg
NnIISuLm.jpg

It wasn't much of a contest.
HOLY ****!
I'm not a big fan of hype, but I get the idea when people say that these Mosaics just "breathe music into the air".
Because that's what they do.
Loud, soft, jazz, rock, classical... Whatever I played through them, they sounded effortless.
Best positioning was about two feet away from the wall. Give 'em some space.
Amazing. Definitely worth the time & effort to save them.

And I've learned a few things, along the way.

Full disclosure: I gave up on trying to make replacement membranes for the burned-out tweeters. I found a company that can print the
conductor pattern onto kapton film, just like I wanted, but their minimum order was way outta my price range. I shoulda seen that coming.

@ TheMarco, You were right.
I ended up spending $80.oo on replacement tweeters from Parts Express. Worth it!

But...

I also learned a bit about planar magnetic speakers & how they fail.
Apparently the nickle plating on the magnets is a common problem.
Look here:
EusBglJm.jpg
YRXOvl6m.jpg

See the shiny bits, just inside the frame openings?
That's the nickle plating, flaking off of the magnets.
Conducive metal flakes, in a high magnetic field, in close proximity to electrical conductors. What could go wrong?
Remember the pics of my tweeters? I went back and checked the magnets in them.
There were several spots missing the plating. They matched up with the burned areas on the membranes.
I got a magnifier and some tweezers and picked out all the loose bits I could.
I should really take these apart & do a more thorough job of cleaning them up.
As it stands now, I know these speakers will eventually fail, I just don't know when.

If you ever have the opportunity to get a good look at some planar magnetic speakers, check the magnets.
Especially if you're thinking about buying them.

Would I buy these speakers again, knowing what I know now?
For $100, absolutely!
Would I spend more than that?
Not without a really close inspection.
Caveat Emptor.

Damn, they sound good!

Thanks for all the likes, links & suggestions!

Also:
Let me put in a good word for this thing.
msnZduCm.jpg

USB charging apex driver. Tiny, strong, but not strong enough to strip out most screws in plastic or wood.
If you're working on something that has a bunch of screws you need to dis- & re-assemble more than a few times, these are very helpful.
I found this one at the flea market.
Good luck & have fun!
 
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ABS plastic is NG - it is not strong, as you've seen, and it does resist resonating hardly at all. If there is room, it can be reinforced with fiberglass or fabric with glue.
 
the crumbly black plastic is a common fail issue in automotive interior panels. Same ABS plastic, and it cracks apart in the same way. The only thing that sort-of works to a limited degree is solvent welding. Can use the stuff for ABS plumbing pipe, or just acetone. It will melt the broken bits back together but it tends to just rip out a chunk around the repair.
 
GR Research also sells a variant of the BG Neo 3. It's the GR Neo 3. Danny Richie made design changes, to better suit his speaker line. These new Neo's use Kapton film as well.

GR Neo 3

Regardless, I'm glad to hear the speakers are working, and the OP is happy with them. And if there is interest in a HT set up, a Martin Logan Fresco would be a matching center speaker, since it uses the same mids and tweeters. The Fresco can be found fairly cheap on eBay (none mine).

Fresco
 
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