GEC metal cone speakers and kelly ribbon tweeters

[weegs]

Hi
I have just obtained 6 (8 inch ) GEC metal cone speakers made in about 1955 . Does anyone know much about them and are they any good . I also got kelly ribbon tweeters from the same place ,I have heard they have a following . Is there a market for these things

[planet10]

Originally posted by weegs
I also got kelly ribbon tweeters from the same place ,I have heard they have a following . Is there a market for these things

Are they the gold DK30 Kelly ribbons? They are excellent... and worth a fair amount of money -- a freind paid $650 for his pair.

pictures?

dave

[jordanblack]

I was intrigued to hear you had discovered some GEC metal cone loudspeakers down in Dunedin. I worked at GEC Wembley labs in the 1950s when they were being developed by Hugh Brittain, and was subsequently involved in audio demos of them. They were best installed in GEC’s own heavy, octagonal, walnut cabinets designed to provide correct reflex loading and great rigidity to enable flattish output down to 45hz and residual output down to 30hz. Visitors to the demos were amazed at the realism, unheard before in domestic loudspeakers.

The cabinet contained 2 metal cone speakers and a (GEC branded) Celestion HF1300 tweeter mounted in the centre of one of the mc speakers with a screw-in adaptor, in place of the screw-in bung itself intended to give better off-axis treble spread. A massive crossover was used with large inductors and capacitors, connected to a multi-tap transformer to enable balance adjustment. A later mod was the provision of a “power bracket” across the rear of the pressed steel speaker frame to strengthen it.
The mc speakers were very robust, occasionally suffering from overload coil burn-out, and deterioration of the roll surround if kept in a humid (tropical) climate.

I had a pair of the octagonal cabinet speakers at home. They had a warm, smooth, wide range sound with excellent stereo imaging, when used with valve amps as intended. I imagine there might be some internal resonance in the cones if driven from a hard-hitting transistor amp. Unfortunately, I had to abandon the speakers when I moved home in the late 70s (they ended up in Australia where they were still giving satisfactory service in 1997), and I subsequently threw away the drawings and specifications. I believe the GEC Marconi museum was closed in 2003 and its contents dispersed but perhaps some relevant references could be unearthed on the web.

As a point of interest, working with Brittain at the GEC labs was Ted Jordan who was particularly interested in internal cone resonances. The spaced indentations in the mc speaker cones were introduced to deal with the problem. Unfortunately, GEC did not build on their head start in domestic hi fi and dropped out of the market in the mid-60s. Jordan left the labs for another manufacturer and later formed his own company, Jordan-Watts Loudspeakers, to manufacture his own designs of metal cone speakers, which were very well respected at the time, but the development of new composite cone materials which were cheaper to produce and form accurately eventually made metal cones obsolete.

I realise that all this is of little practical use to you but at least you may enjoy knowing that you hold a piece of hi fi history in your hands!! Regards - JB

[Jonathan Bright]

Thanks for that up date. I appreciate the nostalgia. Can you tell me a little more about the HF1300's? Is it true that originally they were designed as a "pressure unit" for a horn tweeter rather than direct radiators? I recall reading that somewhere. Poss' in an article by Barlow in the JAES or Spencer Hughes. I have a pair (sold as Celestions, of course) but Gilbert Briggs book on Loudspeakers (5th Ed. circa 1960) has a photo' of one and at that stage clearly lists it as a GEC unit. Regards to the West Country. We left in '57. Dad was fed up with the "socialist gov't"!

[jordanblack]

Hi Jonathan - Many thanks for your mail. I have not heard of HF1300s being used with horn loading, but that doesn't mean they weren't - possibly under some other brand name. They were described by GEC as pressure units because they were sealed -not open backed, which lends itself to the possibility that they might have originally been conceived by Celestion as horn drivers. The familiar slotted front plate design was said to have been arrived at after much experimentation as a means of widening the polar distribution.
Gilbert Briggs was being generous in attributing HF1300s to GEC, although they were certainly an early user. There was one small difference in the GEC version - because they were coaxially mounted there was no flange.
Best regards - JB

[Colin]

Originally posted by jordanblack
new composite cone materials which were cheaper to produce and form accurately eventually made metal cones obsolete.

Interesting background but metal cones are still going strong and Ted Jordan is still producing them. I understand he takes a different approach to the stiffer is better school of composite materials.

[jordanblack]

Many thanks for updating me about Ted Jordan. Yes I see from the Jordan Watts website that his metal cones are indeed still going strong - my apologies to Ted for implying otherwise. They seem to have solved the cone ringing problem which was not completely overcome by GEC - perhaps by limiting the cone diameter??

[Colin]

From articles of Ted's, it seems he has used the cone profile and flexibility to remove any ringing.

Having used his drivers for the past ten years or so, I can confirm that they certainly don't ring. The latest JXR6 sounds as good as an electrostatic with a very sweet, clear HF.

[jordanblack]

Thanks - you tempt me to try one!

[Colin]

Go for two - the imaging is to die for!