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Inverted dome: DUMB question


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Please excuse my ignorance, but here's a question from one new to EPI:

Can you tell an inverted dome by looking at it? In other words, does the dome in the center of the tweeter go "in" (concave) on an inverted dome design?

Reason I ask: I bought a pair of EPI tweeters, pulled from a pair of EPI Epicure T/E 100s and they were described as inverted dome tweeters. When I got them, the center dome is convex. Part 0940 with date stamps from 1985. Can anyone help here? I bought these to experiment with, as replacements for AR speakers and I had read that there was something special about the EPI inverted dome tweeters. Did I get had? (to be honest, I did not pay a lot for these, but I'd like to know if I got what I thought I was buying)

Thanks for any help!


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Hi Kent,

There's a picture of a Genesis tweeter here in this thread:


Some good pictures of the EPI, it may be difficult to see but the dome does

go in rather than out:



I have commented about how I always liked this tweeter based on seeing the

design concepts behind it and hearing it. It has a relatively small concave, fully

exposed dome, and large Xmax to allow it to reach fairly low for a tweeter. It is

and was hyped as an air spring (acoustic suspension) tweeter. It also has a small

3/4" voice coil but with ferro fluid to help keep it cool. It had tinsel lead in wires

to allow for long excursions without breakage. However, there is a problem with

the early ferro-fluids; they are highly non-linear with temperature and you can

read about the issues that I found here with high Fs, and shifts in Fs for these



Here are links to early reports of ferrofluid issues by Linkwitz:



It does not sound like the tweeters you bought are real inverted dome units.

The EPI inverted dome tweeter was made in many variations. The early units employed

hard paper domes, the Genesis version has what looks like a phenolic dome, and Human

speakers is currently making an aluminium dome version:


This version is rather expensive and was found to have a step in the response in

one measurment report:


I also cover some tweeters in this thread:


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  • 4 years later...

Here is a series of four photos I took of an EPI inverted (concave) dome tweeter from a pair of EPI A120's I've had since they were new, so I know they've not been messed with.

I don't know if this was the model tweets your system had.

This one is from the late 70's I'd guess.

Even the photographs don't clearly show (optical illusions) that the dome is indeed not convex, but is rather concave. It dents in. Great speakers. Tweeters are over 35 years old now and still going strong.





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Wow. A 5 year old post resurrected! Pete's original response gave a lot of good information and it was clear I had not bought what I was looking for. The tweets that I bough 5 years ago were subsequently sold. They had the regular domes.

Pretty sure the ones shown in ra.ra's photos are the ones some people said are good replacements for the AR-3a. Apparently based on faceplate size and the quality of the inverted dome design but I have no idea whether these will actually work well in the ARs.

Thanks all


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