Does anyone here know how to access the diaphragm in an EV coax (12TRXB/15TRXB)?

mhardy6647

Señor Member
OK, I am getting a little desperate, so I am doing the "Johnny Appleseed" thing -- posting this plea at various & sundry fora, hoping some grizzled old (or young, for that matter!) EV guru will take pity on me ;-)

Besides that Altec Duplex thing... I have this other, somewhat nonlinear obsession related to Electrovoice components. I (literally) grew up with EV loudspeakers (My parents had EV Wolverine twincone "fullrange" drivers in home-made cabinets when I was a wee lad). Consequently, I've acquired... a few... EV drivers over the past couple of decades. So, indulge me, if you would, and let me know if anyone here can help with an EV coax question.

15TRXBfront by Mark Hardy, on Flickr

Does ANYone here know how to get access to the tweeter diaphragms on these old EV coaxes (either the older or the newer basket/tweeter design; there're a smattering of 'em both down in the basement, as I recall).

I "know" from the internet :-) that one can access the crossover components & the back side of the tweeter by removing the nameplate on the bell cover, and I further "know" that judicious use of a heat gun can enable such... but, beyond that, I can find no info.

A fellow on AK recently reported trying to get at the diaphragm on a 15TRXB, but it seemed that discretion was the better part of valor, and he backed off and decided to add a separate tweeter.

It appears that original EV diaphragms (which used to be sold as a unit with their housing and gaskets) are no longer available, but aftermarket diaphragms are.

Thanks for any and all insight!

I am getting tired of having large paperweights taking up so much space; I am really, really tempted to try replacing a tweeter diaphragm in one (or more!) as a winter project this year.

* Pretty sure the tweeter diaphragm in this one's bad; even gave it a CAT scan for noninvasive diagnosis ;-)

EV15TRXBflipside by Mark Hardy, on Flickr
 

Redboy

Knobophobe
CAT scan, har!!

Can't help you, but I have a Lafayette driver in need of similar help, so I'll be paying attention...
 

TubeHiFiNut

Administrator
That link is interesting. I can't read Russian (or whatever languages they are writing) but it does appear that the surgery was performed successfully.

Another route may be to search out pro audio techs who know ElectroVoice stuff?
 

Golden Gate ER

Senior Member
Depending on model, year & where it was made there is a few ways to open thoes up. 1, the horn unscrews from the front. 2, the horn is fassend down by 3 to 5 screws located at the bace of the horn. 3, remove the metal tag on the rear where you will find a bolt remove the bolt will allow the entire back to come off. Then the entire tweeter is removed then disabled. Your welcome to bring it over to my shop, where I could match it up to what parts are available or possibly get one made. Do you still have my number?

You must be careful not to dammage the surrounding componets while working on the speaker
 
Depending on model, year & where it was made there is a few ways to open thoes up. 1, the horn unscrews from the front. 2, the horn is fassend down by 3 to 5 screws located at the bace of the horn. 3, remove the metal tag on the rear where you will find a bolt remove the bolt will allow the entire back to come off. Then the entire tweeter is removed then disabled. Your welcome to bring it over to my shop, where I could match it up to what parts are available or possibly get one made. Do you still have my number?

You must be careful not to dammage the surrounding componets while working on the speaker
I hate to revive an old thread, but I saw your post here and I am dealing with the same issue, and afraid to damage anything further. I have attached pictures of my 15TRXBs showing which version I have. I see (and removed) the 2 screws at the base of my horn and I see the center bolt that goes through the back of the woofer magnet. I gently wiggled the horn partially away from the driver but it seems to be hung up on something, preventing it from coming all the way off. Any idea what to do next?

By the way, the tweeter in this 15trxb has an open coil, and I'm hoping to replace it. If I can remove the whole tweeter somehow I will likely send it to Bob Crites for repair
 

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I have successfully performed this procedure on a pair of 15trx (non B variant). IIRC, from where you’re at, the only thing left is to carefully trim the felt away from the woofer cone. The pair I had were the creamy white version so they may have different construction that yours. I used a hobby knife to perform the task. I called all around at the time (2013?) and Bob was the only person that had the parts and necessary tooling to do the installation. He said something about he had a tool made to center the diaphragms. Newer t35’s do not need the tool. At that time Bob only had a few diaphragms left. I know that Bob’s son Michael has had a role in the business for many years but do not know if he has taken over entirely after Bob’s death. It’s probably worth a phone call as Crites is very likely your only source to repair these.
 
Looking at your pictures, I am fairly certain that you will need to remove the magnet cover as well. You may need to gently tap it side to side with a rubber mallet. I dont think you need to remove the bolts that hold the horn lens on to remove the tweeter, it may be easier with the lens attached to the tweeter body.
 
I have successfully performed this procedure on a pair of 15trx (non B variant). IIRC, from where you’re at, the only thing left is to carefully trim the felt away from the woofer cone. The pair I had were the creamy white version so they may have different construction that yours. I used a hobby knife to perform the task. I called all around at the time (2013?) and Bob was the only person that had the parts and necessary tooling to do the installation. He said something about he had a tool made to center the diaphragms. Newer t35’s do not need the tool. At that time Bob only had a few diaphragms left. I know that Bob’s son Michael has had a role in the business for many years but do not know if he has taken over entirely after Bob’s death. It’s probably worth a phone call as Crites is very likely your only source to repair these.
That explains why Michael replied rather than Bob... I was not aware he passed away.. RIP!

I was wondering if I'd have to trim away the felt.. Assuming I get that far, any ideas on a source for adequate replacement? I have no idea what effect different felt will have on the whizzer. I do see, though, that it looks like someone has already removed and replaced the felt on my other 15trxb.

Regarding the magnet cover... On this model the magnet cover is part of the basket.. All one single piece. To remove it means to remove the cone. It's hard to see in the picture, but there is no seam. Does this mean I am out of luck
 

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mhardy6647

Señor Member
I would think that the best replacement (absent a source of NOS EV diaphragms) would be an "organ donor" T35.
I am more than tempted to try one of the cheapie aftermarket diaphragms on eBAY -- I mean, how bad could they be? ;)
 
I would think that the best replacement (absent a source of NOS EV diaphragms) would be an "organ donor" T35.
I am more than tempted to try one of the cheapie aftermarket diaphragms on eBAY -- I mean, how bad could they be? ;)
Sorry, I was referring to the felt, actually!

I think Michael crites has a diaphragm for it, assuming I can send the tweeter to him.

But yes, I agree, I'd probably try to scavenge a used original if it were that or a Chinese copy
 
With your magnet cover being fixed, the tweeter removal may be a different procedure than mine were. For the felt, I trimmed it as close to the cone as I could leaving nearly no felt still attached. I then sent the tweeters to Bob with the lens and felt ring attached. He returned them the same way and I reinstalled and carefully glued the felt back using super glue iirc. To remove the tweeter, I remember loosening the center bolt and sliding the tweeter out, once the felt was cut.
 
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