Modern Alternative,s EMI 14A 770N and Kef T27

[madtecchy]

Hi All.

I have been listening to a pair of custom built vintage loudspeakers. They look very much like they where built using a Drive unit baffle kit which where very popular at the time . The drive units are . Bass Mid EMI 14a/770n cast aluminium chassis in hammered silver finish and Tweeter KEF T27 dated 1974. My interest is more towards the Bass/ Mid driver. As the T27 is very nice and very well documented.

 

[SCALEXCENTRIC]

Modern Alternatives.

The EMI elliptical speakers were developed by Dr Dutton at Marconi EMI to recreate the sound of the 1950’s Tannoy Monitor Silvers. Elliptical woofers can have better distributed resonances than conical woofers, and they can either have better dispersion in the narrow plane, than the equivalent surface area cone, or larger surface area, hence deeper bass, than a cone with the same radius as the smaller dimension of the ellipse. They were more expensive to make, especially if they had a multilayer construction as with the 14A/770NX which was a corrugated roll edge pepper pot elliptical bass mid- woofer - triple laminated paper cone, aluminium centre with PVC surround. These were used by Mordaunt Short in the MS400 by B&W in modified form for the DM3 with the addition of fibreglass and dampening of the cone as well as by Monitor Audio and EMI.
The best examples of this elliptical design are also highly regarded in Japan.
As cast aluminium speaker chassis batch production evolved into pressed steel mass manufacture quality began to suffer and later pressed steel versions of these speakers were sold as budget speakers.
It is a testament to the quality of the build of these speakers that some still survive today producing a rich, warm sound which is at its best with classical and jazz.

 

[sreten]

Hi,

There is no modern alternative to elliptical bass/mids,
(except in cars). The last company to try them was
AFAIK Spendor in an AV range and they didn't do well.

rgds, sreten.

 

[Inductor]

For members experimenting with vintage drivers or modern alternatives of classic full ranges and various designs by Weber Rhede (Rehdeko), EMI and Audax/VEGA or PHILIPS/GRUNDIG/JENSEN (and others) there's various alternatives to look for, here some links:

1. Audax AM21LB25ALBC
2. Supravox 215 RTF 64
3. EMS (by Catherine Fertin) - Electro Magnetic Speaker

Here in the Madotec form l'enceinte bleue |l'enceinte bleue | | Site officiel de l'enceinte bleue Site officiel de l'enceinte bleue
Audax AM21LB25ALBC - RumoH - Caps, coils and speakers
http://www.audax.com/archives/AM21LB25ALBC.pdf
215 RTF64 SUPRAVOX
ems_welcome
AnsaHT.com :: Leggi argomento - Reference Monitor Speakers - Rehdeko RK115, Danley TH-MINI
Philips AD3701M

link#1/ebay: Rare EMI speaker chassis, oval elliptical, tweeter, B&W
Rare EMI speaker chassis, oval elliptical, tweeter, B&W | eBay
link#2/ebay: EMI, B&W, Monitor Audio, Hacker oval speaker enclosures
EMI, B&W, Monitor Audio, Hacker oval speaker enclosures | eBay

Austin Hifi | Weber Rhede
http://www.muenster.de/~w.beinha/SE/PDF/rehdeko.pdf
http://jipihorn.free.fr/Documents/Divers Blog/Rehdeko_Banc_d_essai.pdf
https://sites.google.com/site/rehdeko/Home/game/autres-rk175 found this link here

 

[madtecchy]

thanks Sreten , Inductor and Scalecentric. I have been listening to theses speakers for a few months now. It is a shame there is no modern equivalent. They sound very nice indeed. have posted some piccys .As you can see the cabinets break some basic design rules. The baffle is recessed also the cabinet is wide all bad in respect to causing diffraction. I would like to build some new cabinets using the same internal volume of the originals but slimmer and slightly taller. what problems should I look out for ?. baffle step seems to come to mind..

 

[Phenoholic Anonymus]

Thanks Inductor for the Rehdeko links, very amusing and interesting. Never heard of these. They look like a joke / boombox from leftover carhifi stuff.

 

[madtecchy]

@ Phenoholic.. And there is your Problem.. Lets have a look and see what they sound like.... Or maybe it is you are just dam good with your micro phonic eyes

 

[Inductor]

Use some simulation tool usually available in most type softwares. If you are not using one you can use a simple tool by Tolvan named The Edge here.
Home of the Edge

 

[sreten]

Hi,

New cabinets wont improve matters much. A chamfered
grille will fix the the recessed issue. A narrow baffle will
increase BSC issues not reduce them, if anything.

Measurements and / or careful listening tests * and
looking at the x/o will yield the best improvements,
if there are any real improvements to be had.

rgds, sreten.

* Test tones , not music.