Share:
Notifications
Clear all

Old radio speakers...

 
Alastair
(@alastair)
Reputable V-Ratter Registered

Why is it that old radio speakers are often fitted inside a black cloth bag....? :aab

ReplyQuote
Topic starter Posted : 26/12/2013 1:34 pm
malcscott
(@malcscott)
Noble V-Ratter Registered

Keep them clean??

ReplyQuote
Posted : 26/12/2013 1:37 pm
Alastair
(@alastair)
Reputable V-Ratter Registered

Could be......!

ReplyQuote
Topic starter Posted : 26/12/2013 1:41 pm
Lloyd
(@lloyd)
Noble V-Ratter Registered

Hi,
I think it's something to do with keeping bits of muck out of the gap between the voice coil and magnet, as a lot of them were not sealed in any way. Later speakers with little dust covers glued in the center, didn't need to be in dust bags.

Cheers,
Lloyd.

ReplyQuote
Posted : 26/12/2013 1:57 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

Hi,
I think it's something to do with keeping bits of muck out of the gap between the voice coil and magnet, as a lot of them were not sealed in any way. Later speakers with little dust covers glued in the center, didn't need to be in dust bags.

Cheers,
Lloyd.

This.

It was quite easy to view the pole piece and voice coil on many a loudspeaker (especially the energised types) - however later devices, with the centring device sealing the coil away from sight and a felt pad over the centre of the cone covering the pole piece rendered the need for a dust bag unnecessary.

ReplyQuote
Posted : 26/12/2013 2:39 pm
mark pirate
(@mark-pirate)
Reputable V-Ratter Deactivated Account

I have a Philips set with the cloth bag, but the speaker does have a dust cap as well.
They do keep the speaker clean though!
They were widely used in the 30's and 40's, but not fitted to any 50's set that I can recall.

ReplyQuote
Posted : 27/12/2013 11:17 am
Anonymous
(@anonymous)
Illustrious V-Ratter Deactivated Account

Modern dress lining Muslin is a good replacement.

ReplyQuote
Posted : 27/12/2013 11:29 am
Terry
(@terrykc)
Famed V-Ratter Rest in Peace

The reason for the cloth bag - or lack of one - is because of a difference in the way that loudspeakers are made.

Early moving coils speakers relied on a flexible 'Spider', usually punched from a sheet of thin fibre, for suspension.

The spider was secured to a post on the magnet centre pole by means of a nut which was tightened after the speech coil had been centred in the gap using feelers. However, the gaps either side of the speech coil were left open by this style of construction so a cloth bag was often fitted to keep foreign bodies out of the way.

(Even if the central gap was sealed with a dust cap there was no way of sealing the outer gap.)

Modern construction methods dispense with the central spider and use an outer corrugated surround which is glued to the frame. This automatically seals the outer gap:

A dust cap seals the central gap and no bag is required.

When all else fails, read the instructions

ReplyQuote
Posted : 27/12/2013 4:31 pm