ROGERS LS3/5A speakers for sale on the BHF ebay site

[Andrew]

If any audiophiles are interested

[williamwright]

I always think it's odd that a device designed to reproduce sound naturally and without colouration is made in a wooden box.

Bill

[Owain Lastname]

Slightly worrying if they PAT tested it

Owain

[charles]

I bought a second hand radio mic. The tested label was on the mic itself. Some people test anything that moves.

[John Walliker]

They did go to a lot of trouble to avoid that. Birch ply I think, to get the right damping in the wood. Lined with stick-on bitumen sheet. Filled with polyethylene foam. Back panel braced firmly against the back of one of the drive unit magnets. Felt around the inside edge of the front recess to damp resonances between the side panels. Perforated metal plate in front of tweeter for phase correction. Crossover used mu-metal cored tapped inductor and polycarbonate capacitors. The commercial ones that came later may have skimped on some of the finer details. I have a pair of the early ones that were available to BBC staff in kit form and still use them. John

[Clive Arthur]

As it happens, only this afternoon I packed my LS3/5A speakers in a box in advance of moving house. I bought them - with a staff discount - when working in Broadcasting House in about 1977. They still work.

[charles]

Mine are simialr vintage, I think. I bought them from an ad in Arial from someone in Designs Dept

[jkn]

somewhat to my surprise there was a pair in a local Cash Converters type shop a few months ago. Strange what you sometimes find in those places, can't imagine why...

[John Walliker]

I was a "Pre University Trainee" in Research Dept (Kingswood Warren) in 1974. It was fascinating. My department (Storage & Recording) was working on digital TV. John

John

[Paul]

"The primary role of the enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open speaker driver interacting with sound waves generated at the front of the speaker driver.

Because the forward- and rearward-generated sounds are out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced."

It makes it sound hollow and tinny.

Paul

[Clive Arthur]

An evacuated enclosure would be best. Brings other problems of course, but wouldn't need any significant volume.

I wonder if it's been tried?

[John Walliker]

It would need a pretty powerful spring to hold back the diaphragm of the bass driver. That spring would need to be linear and free of resonances. The diaphragm would need to be quite strong too. There would also need to be compensation for changes in barometric pressure. Of course, one way of making that spring would be to use an enclosed volume of air which is nearly linear and which has the nice property that it automatically compensates for barometric pressure changes through small leaks in the enclosure. Another nice property of an air spring is that it can be made to act uniformly over the whole area of the diaphragm, reducing the need for very high strength and allowing it to be lighter and therefore work over a wider frequency range. John

[Dave Plowman (News]

So have I. Came from Chartwell. Used in the bedroom. Still sound superb at the sort of levels you'd use there.

Also a pair of ex-broadcast Rogers with fairly beaten up cabinets which I swapped for something I can't remember. Managed to make them presentable enough and are in the kitchen, on wall mounting brackets.

Never heard anything better at their size for general domestic use - for those who appreciate decent sound at all times. But not sure they are worth the vast sums they can fetch these days.

[Dave Plowman (News]

Why? What material would you use? Even concrete has resonances. Steel too.

[Chris Green]

It would require a very stiff cone (or whatever sent the sound out) as one side would be vacuum and the other the air into which you are transmitting the sound.

[Dave Plowman (News]

If you attach a vibrating device to anything it is going to transmit that vibration to it regardless of air or not. Remove the air behind it and you've still got that in front. Removing that would certainly stop you hearing any colouration, though.

[Owain Lastname]

Stolen, or someone was clearing out the house of a deceased.

Owain

[Custos Custodum]

I have a vague recollection of adverts in Practical Wireless for enclosures fashioned out of concrete pipes. Back in student days, we use an old WC as a horn for a smallish speaker which we taped to the waste pipe. As you might expect, the sound was pretty awful but it was a great talking point at parties. I imagine the "horn" was witness to a fair number of musical tones and resonances in its previous life.

[Dave Plowman (News]

No matter what the enclosure is constructed of, there will be sounds reflected all round it. So a rigid material with sound damping inside is the norm.

Another BBC speaker design, the LS3/6, or Spendor BC1 in commercial form, accepted you couldn't completely eliminate cabinet resonances etc, so incorporated them into the design.

[tony sayer]

Someone has prolly passed on and the executors or possible the now widow will have asked someone to clearout his "junk" and they won't know quite what that they have there, and how much they are worth!...