JKent Posted August 27, 2008 Report Share Posted August 27, 2008 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!Kent Link to comment Share on other sites More sharing options...
Pete B Posted August 31, 2008 Report Share Posted August 31, 2008 Hi Kent,There's a picture of a Genesis tweeter here in this thread:http://www.classicspeakerpages.net/IP.Boar...&hl=genesisSome good pictures of the EPI, it may be difficult to see but the dome doesgo in rather than out:http://www.humanspeakers.com/e/epicure-1205.htmhttp://www.humanspeakers.com/tweeters-rebuilt.htmI have commented about how I always liked this tweeter based on seeing thedesign concepts behind it and hearing it. It has a relatively small concave, fullyexposed dome, and large Xmax to allow it to reach fairly low for a tweeter. It isand was hyped as an air spring (acoustic suspension) tweeter. It also has a small3/4" voice coil but with ferro fluid to help keep it cool. It had tinsel lead in wiresto allow for long excursions without breakage. However, there is a problem withthe 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 thesetweeters: http://www.classicspeakerpages.net/IP.Boar...&hl=genesisHere are links to early reports of ferrofluid issues by Linkwitz:http://www.linkwitzlab.com/images/graphics/sb186-48.gifhttp://www.linkwitzlab.com/images/graphics/sb186-50.gifIt 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 employedhard paper domes, the Genesis version has what looks like a phenolic dome, and Humanspeakers is currently making an aluminium dome version:http://www.humanspeakers.com/diy/parts/002.htmThis version is rather expensive and was found to have a step in the response inone measurment report:http://www.audioheuristics.org/measurement...002_tweeter.htmI also cover some tweeters in this thread:http://www.classicspeakerpages.net/IP.Boar...amp;#entry75390 Link to comment Share on other sites More sharing options...
redpackman Posted July 14, 2013 Report Share Posted July 14, 2013 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. Link to comment Share on other sites More sharing options...
ra.ra Posted July 15, 2013 Report Share Posted July 15, 2013 Cannot seem to find any reference to that particular part number on humanspeakers site, but here is a pic of the original inverted dome tweeter on an early model EPI-100. Concave dome? Yes. Link to comment Share on other sites More sharing options...
JKent Posted July 15, 2013 Author Report Share Posted July 15, 2013 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 allKent Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.