Infinity Quantum 4 Mids and EMIT Tweeter woes

Jeff Church

New Member
Just picked up a pair of Quantum 4. Pretty much a basket case. One Watkins woofer reads properly on both sides, the other only on the 2-ohm side. Both need re-foaming. Neither the mids or EMITs read anything at all. I noticed on one of the EMITs the reason - the ribbon layer of the EMIT "sandwich" is missing. Good news is the cabinets are in good shape and I have one broken grille to use as a template.

So, I'm looking for sources for replacement or repairing the Mids and EMITs. Well, there's no repairing one of the EMITs as the ribbon is completely missing. I could handle the re-foam of the Watkins but would be appreciative of sources for the re-foam surrounds and a potential way to fix the one 4-ohm side that's not providing readings.
 

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Watkins or MillerSound could probably fix the woofer, MillerSound the mids as well.
The EMITs MIGHT (sounds like the one does for sure) need new diaphragms, hard to find. Replacement EMITs, mids, and woofers show up on ebay.
Or subscribe here at AK ($25) and put a want to buy ad in Barter Town which is the only place that buying and selling is allowed.
Good luck, hope you get them up and running.

EDIT 4+ years later... AVA (Bobby D) designed and manufactures new diaphragms. At the time I made this post in 2017 NOS EMIT diaphragms were indeed hard to find.
 
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Unless you want to find the correct woofer on eBay (small magnet variety Watkins) then go with Millersound as goodolpg stated. You could fool with the bad woofer and look for something obvious as a broken wire. Try getting impedance under the dust cap. Is the vc frozen?
The mids may be repaired but looks like someone may have tried already. Goods ones come up on eBay now and then, I've just bought bad ones in the passed and fixed them using this method http://audiokarma.org/forums/index....quantum-midrange-repair-with-pictures.398687/.
Emits can be soured on eBay or you can try another diaphragm from the newer round emits. I used one from the older ones into a round one but not the other way around.
Well worth the money if you plan to keep them however if you are fixing them to flip don't expect to get much. They are real good performers with a stout amp.. I bought mine at the same time I rebuilt a pair of dq10's and they are long gone...the Quantum 4 still in the rotation.
Jim.
IMG_0257.JPG
 
Nice speakers! Watkins woofers, EMIT tweeters, mirrored cabinets, and real wood veneer!

Most of the tweeter diaphragms are interchangeable and are very common, that won't be a problem.

The mid domes are harder to find and therefore more expensive, expect to pay $70-100 for a working dome. Buying a broken one and fixing it yourself is another option, or you could have it professionally repaired, I think Miller Sound will do it for you.

The woofer might be a simple fix but if the coil is open, you will have to have it rebuilt, Watkins is still in business and can fix yours or sell you a new one.

Join Audiokarma for access to Barter Town for the best deals on replacement parts!
 
OK, here's what I've done since my last post and reading your suggestions (thanks, BTW):

- I've ordered new surrounds (flat edge), dust caps and shims for the Watkins. Even though I get no readings from the 4-ohm side on one of them, I'm going to remove the caps and center the VC's with those shims in hopes that I'll magically fix the 4-ohm output. I know, wishful thinking, but it's a whole lot less expensive than sending it off to Mr. Watkins to do. And if doesn't work, I'm sure I'll be fine!
- I picked up a very nice, clean working pair of EMIT's from an RS5 Kappa (#902-3082, diaphragm #751-3722) to replace the non-working pair of stock #902-5086 (well, I assume that the stock chrome/silver faced EMITs that came off of mine were #902-5086's as they sure as hell are NOT the elongated #902-2252's as indicated on the QLS4 Technical Manual sheet). Anyway, I think I'll be fine here as the replacement diaphragms are identical and they fit in the machined hole perfectly.
- Now as to the POS, non-working Dome Midranges #902-0206 - I haven't seen any for sale over the last several weeks. So I think I'm going to replace them with the Dayton Audio DC50FA-8 Classic Series 2" Dome Midrange from PartsExpress. I found one comment on the PartsExpress site that indicated that the DC50FA-8 was a good replacement for the Infinity #902-0206's. Has anyone here given the Dayton speaker a shot and, if so, were any mods required and, more importantly, how did they sound?

I would appreciate any and all comments regarding these recent moves in my attempt to resuscitate the Quantum 4's.
 
As for the faulty woofer,, you may be lucky enough to find the teeny tiny single strand from the heaver terminal wire to cone junction is broken at some point before the actual voice coil winding.
With good eyes, decent solder skills, and a little patience (and maybe some sort of magnifying glass) you might be able to repair it.
The tinsel leads on the dome mids on have a similar type failure and similar repair procedure.
I do see dome midranges fairly often on ebay, however when you really want some they may not appear of course.
Many EMIT diaphragms are the same, there is a tutorial (on AK Infinity homepage, might be in one of the stickies at the top...ok here it is... http://www.audiokarma.org/forums/index.php?threads/emit-emim-tweeter-diaphragm-repair-how-to.65571/ ) on how to make a fixture to keep the magnets from causing damage to diaphragms while replacing diaphragms. Some have reported using extra length proper thread size bolts rather than a fixture. Should be in the link above.
If in doubt, Millersound is highly recommended. Honest, quick, reasonable pricing, and just plain great service.
 
I don't think that refoaming will automagically fix the impedance problem with the woofer. In fact, new foam might make it more difficult to access and fix the actual problem, which is often a broken wire coming out of the voice coil. I'd strongly recommend taking a good look at the wiring coming out of the voice coil, through the cone, and to the terminal. Try to measure impedance as close to the voice coil as you can. Theres a good chance the wire is broken somewhere along the way, and that will be a lot easier to access if there are no foams in place.

bs
 
I missed that part, I seriously doubt new surround will fix a broken speaker as bshorey mentioned.
I believe in miracles, but not that one.
 
OK, here's what I've done since my last post and reading your suggestions (thanks, BTW):

- I've ordered new surrounds (flat edge), dust caps and shims for the Watkins. Even though I get no readings from the 4-ohm side on one of them, I'm going to remove the caps and center the VC's with those shims in hopes that I'll magically fix the 4-ohm output. I know, wishful thinking, but it's a whole lot less expensive than sending it off to Mr. Watkins to do. And if doesn't work, I'm sure I'll be fine!
- I picked up a very nice, clean working pair of EMIT's from an RS5 Kappa (#902-3082, diaphragm #751-3722) to replace the non-working pair of stock #902-5086 (well, I assume that the stock chrome/silver faced EMITs that came off of mine were #902-5086's as they sure as hell are NOT the elongated #902-2252's as indicated on the QLS4 Technical Manual sheet). Anyway, I think I'll be fine here as the replacement diaphragms are identical and they fit in the machined hole perfectly.
- Now as to the POS, non-working Dome Midranges #902-0206 - I haven't seen any for sale over the last several weeks. So I think I'm going to replace them with the Dayton Audio DC50FA-8 Classic Series 2" Dome Midrange from PartsExpress. I found one comment on the PartsExpress site that indicated that the DC50FA-8 was a good replacement for the Infinity #902-0206's. Has anyone here given the Dayton speaker a shot and, if so, were any mods required and, more importantly, how did they sound?

I would appreciate any and all comments regarding these recent moves in my attempt to resuscitate the Quantum 4's.

Hey Jeff, any long term updates on your QLS-4s? Did all of your planned fixes work? I finally got to mine like a decade later due to covid, and was happy for it. Refoamed woofers, repacked cabs, NOS mids, and AVA membrane repaired EMITs. I lucked out with the NOS mids to be sure, and also for a reasonably-priced local speaker repair shop that could refoam DVC Watkins woofers well, and for the AVA replacement membranes that were not quite a perfect fit, but worked with some small mods.
 
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