Bullet Tweeter 4~16 Ohms

[Leo_Gnardo]

If it's any help, Parts Ex carry Eminence coaxial 12 inch speakers. Only $75, and they look very tough on their data sheet.

https://www.parts-express.com/eminen...river--290-504

Out of stock now, but due back in stock Cinco de Mayo... hey it's the day after tomorrow. Woo-hoo, where's the tequila?

[TomCarlos]

Thanks Leo...

The speaker's tweeter diaphragm is open (looks burned) and the terminal for attaching the speaker leads is broken. The photo I posted previously was from a similar speaker. So it a speaker and or bullet option becomes costly, I might opt for something like the Eminence Coax. Thanks.

[Leo_Gnardo]

Same advice holds for a coax tweeter. Looks like there's just a single 2.2 uF electrolytic cap used as a crossover, plus the Raychem "fuse". Deafinitely avoid 'lytics, go for a film cap in this application. Also, it's not certain but it looks to me like the red speaker wire is pointed towards the wrong terminal. If you go coax, no harm in building a steeper-slope crossover as Juan recommends, don't expect just that raychem to save your tweeter's bacon.

[TomCarlos]

Ah... so that is what those devices are.... fuses! Good to know.

The photo I posted in #15 was for a different (but similar speaker) that I have on hand. Here are the photos of the speaker in question and the diaphragm. Someone installed a 6.8uf cap that is open. There is continuity across the fuses.

I found the PRV Audio RPTW350Ti Replacement Diaphragm from Parts Express that might fit this application. For less than $10, I will give it a try.

If I can repair the tweeter in this speaker, I will open a new post and show how to do it. There are tons of these Peavey Coax Speakers out there and a bit challenging to find a generic diaphragm that will fit. I will contact Peavey to see if they still carry this diaphragm.

[J M Fahey]

Sorry Tom, use any diaphragm but that one ... whichis for a Bullet tweeter only.
Notice the ring shaped "V" shaped metllic diaphragm, mounted on an orange/brown Kapton or poluesterbase, whith a gaping hole in thne middle.

The (Blue Marvel?) Peavey speaker is as Asian as can be (telltale frame arms and even without seeing it, the hot forged single piece back plate/polepiece) and I was very surprised at the cheesy tweeter, instead of the little horn I expected it seems to be a *paper* dome tweeter, haven't seen them in since the 80's.

What you need is an ***exact same** diameter voice coil , driving a dome, I guess most today will be kapton/polyester/phenolic/aluminum/titanium/"silk" (some kind of impregnated nylon cloth) , anything but paper.

The important parameter is the voice coil, if it does not fit in the tiny gap anything else is irrelevant.
Dome material will change sound and efficiency , but worry about that *after* it fits the tweeter magnetic structure.

Please post a couple close up diaphragm pictures: front/back/sides and post exact voice coil diameter, we need millimeters here instead of those old measures based on then current King's parts.

*Maybe* some popular Fostex replacement diaphragm fits there, it would be a Godsend
Also search driver diaphragms, phenolic types are usually cheapest.

or:

Plan B

Try to dismount the existing burnt tweeter or check how it's mounted, most probably on a plastic or aluminum post glued/screwed to the main cone polepiece ... the idea is that you might mount another tweeter there, even a light Piezo.

We are talking a small combo with a coax speaker where you don't want to ruin the speaker cloth to mount a regular tweeter or plain have no useful space for it, otherwise it's the simpler preferred solution.

[The Dude]

Tom,

It's near impossible to judge size from the picture. I have a box of assorted diaphragms. If you want to measure the voice coil, I may have something that will work for you. Let me know if I can help.

[TomCarlos]

Thanks Monte and Juan....

We sorta got off track here. So I am going to open a new thread for repairing the Peavey Speaker.

The takeaway on this thread will be to use caution when it comes to specs or products that are vague. Juan also mentioned (#20) the difference in diaphragms for a Bullet Tweeter vs a compression horn or something else.

One other thing... (for anyone who strays here).... The Peavey Coax used in their keyboard amps is 8 ohms and the Speaker used in the Ecoustic is 4 ohms. So you need to watch that. I will address it in the new thread.

Much appreciated...

Tom

[olddawg]

Check out MCM Electronics for cheap speakers and tweeters:

MCM Electronics: Home and Pro Audio/Video, Security and Test Equipment

They are even having a 5% off Cinco de Mayo Sale...

[Enzo]

Don't recall if it was mentioned, but PArts Express also is a good place to shop for all things speaker.

[Leo_Gnardo]

Don't recall if it was mentioned, but PArts Express also is a good place to shop for all things speaker.

You bet, circle cutting jigs, tee nuts, clamps, spare dust covers, crossover components, steel circle grilles, PX has it all, and very affordable too.

[TomCarlos]

Sorry Tom, use any diaphragm but that one ... which is for a Bullet tweeter only.
Notice the ring shaped "V" shaped metllic diaphragm, mounted on an orange/brown Kapton or poluesterbase, whith a gaping hole in thne middle.

Juan.... I wanted to follow up on your note here. I'm still learning the differences in tweeter, drivers, bullets, etc. Is a bullet tweeter (and this item I noted) different than a typical diaphragm, say for the Fostex? I see one is metal and the other is not. But what else is the difference?

Thanks, Tom

[The Dude]

The diaphragm you linked earlier has a big hole in the middle for the center part of the waveguide/ring radiator of the bullet. Maybe easier seen in the picture(s) on this page. You can zoom the pics for a better look.

PRV Audio RPTW450-Ti Replacement Diaphragm for TW450-Ti

[J M Fahey]

In a ring radiator (a.k.a. "bullet" because of the plug shape which is part of the horn), you have a diaphragm whose suspension is clamped all around and also clamped in the middle.

The center disk does not move at all, only moving part is a V shaped ring around it.




this cheap one isn't even metal, but still is a V shaped ring, clamped outside and inside:




The dome radiator, a.k.a. dome tweeter , has a dome shaped diaphragm, with a flexible suspension all around, is clamped all around but is free to move as a whole, including the middle of the dome, a very important difference



As homework, look at these Selenium diaphragms and decide yourself which are rings and which are domes:
https://www.google.com.ar/search?biw...30.hhoD9LaGE0I

[TomCarlos]

Excellent !! Thanks Juan....

And yes, I will do my homework!!

Tom