Loudspeaker information sought

[Barry]

Hello Phil,

I've tried to do some research concerning your EMI speaker. As you say there were many different versions made, all of which have a driver identity starting with 14A/770 (such as, say 14A/770N/NX, or 14A/770C etc.). The various versions differ from one another largely in the laminated make up of the elliptical cone, and this will no doubt affect the design of a suitable enclosure.

Regarding the latter, there is scant, almost non-existent information on the web. If you type "EMI 14 x 9 inch elliptical speaker", you will be directed to a strange site which inter alia has many photos showing commercial loudspeakers using EMI elliptical drive units: some are ported, and some are infinite baffle stuffed with loft-lagging fibreglass wool. The audio quality of these examples is not discussed. https://sfmkm.blogspot.com/p/blog-page.html
(Frankly I would take most of what is written on this site with 'a pinch of salt', as it is opinionated and some of it is factually incorrect!)

Lencoheaven.net discussed the use of these drive units in a ported enclosure back in May 2018, and one of the members there actually built a three way speaker using the EMI elliptical drivers for the bass. His forum name is the same as one of our one-time members here, who is now retired. I occasionally speak with him, and will do so again, but it is quite likely he has forgotten the details of his design. Unfortunately all the photos in the Lenco Heaven thread are now no longer viewable in the UK (most likely they are hosted by Imagur, who for reasons best known to themselves have imposed this restriction). The speakers are discussed here: https://lencoheaven.net/forum/index.php?topic=29536.0

Another interesting post can be found on the diyAudio forum: https://www.diyaudio.com/community/t...y-rare.402300/

If you want to design a transmission line enclosure, you will need to know the Thiele - Small parameters for the exact version of your EMI driver. Goodness knows where you will find them, even if they have been measured.

In the first instance, I would simply cut an elliptical hole of appropriate size into a piece of 1/2" thick plywood or chipboard, of say 2' x 3' in area. It will be better than no baffle at all.

Cheers
Barry