Vintage radio loudspeaker dust bag - UK Vintage Radio Repair and Restoration Discussion Forum

Alf Fisher · 21st Feb 2020, 4:37 pm

Hi folks,

Not sure if I have described this properly but speakers used to be enclosed in a cloth bag to keep the dust out. The bag enclosed the whole of the speaker and was tied around the magnet with thin cord or string.

I'm have an 8 inch extension speaker where the bag has decayed into a very fragile state and has been torn on the front where fingers have been poked through the fret so can anyone recommend a source of these please.

Alf

paulsherwin · 21st Feb 2020, 4:43 pm

Philips were very keen on these.

You don't really need them in a modern domestic environment, though you could easily make one with some acoustically transparent fabric. Time to get out the sewing machine!

A fabric peg bag (for clothes pegs) might be suitable.

Graham G3ZVT · 21st Feb 2020, 5:12 pm

Quote:

Originally Posted by paulsherwin

Philips were very keen on these.

You don't really need them in a modern domestic environment, though you could easily make one with some acoustically transparent fabric. Time to get out the sewing machine!

A fabric peg bag (for clothes pegs) might be suitable.

Military boat-anchors too. I'm sure my R107 had a bag with a draw-string.

paulsherwin · 21st Feb 2020, 5:17 pm

It does make sense to do it if the speaker is to be used in a hostile environment, as you don't want large particles lodging in the voice coil. A typical modern house won't have an open coal fire or smoking occupants though - most dust will be tiny dead skin particles which aren't abrasive.

Stylo N M · 21st Feb 2020, 5:43 pm

Hi Alf,

I remember making one of these many years ago out of some thin cloth, worked great i drew round a cercular dinner plate with a pen, and had a bit of help from a family member to sew it up on the sewing machine.

As paul said an old peg bag would be ideal, i used a long black boot lace to tie the finished bag arround the magnet. If you have a short off cut of a piece of net curtain wire, you can use that with the boot lace or string, attached to the end of it to help thread the lace or tie through the hem for tieing.

The curtain wire can then be disgarded once the lace or tie is threaded through the hem, and then the lace will act as a draw string to tighten the finished cover arround the speaker magnet.

Paul

PJL · 21st Feb 2020, 6:03 pm

Later speakers have dust caps that prevent dust entering the gap around the voice coil. Early speakers were often open and there are plenty of threads here discussing how to remove the accumulated dirt and dust,

crackle · 21st Feb 2020, 7:44 pm

A modern home with pets will have an enormous amount of dust and hair floating around. We have to empty out the "hoover" at least once a week, it is always full of hair and dust. Curtains, clothing, skin, furnishings, hair, I would imagine there is more around now than in the old days when rooms were more spartan.
As the speaker moves, dust can be drawn in and out of the speech coil gap. So I consider a dust bag is always a good idea if the voice coil is open to the atmosphere.
Even more so if you put the speaker down on a bench where their may be a speck of rust or iron filing.

Mike

G6Tanuki · 21st Feb 2020, 8:00 pm

Having lived for decades in seriously-dusty/furry environments [a couple of 110-pound dogs throw off lots of fur and dander] I've never found the need for 'dust-bags' on any of my speakers.

Turn it up! [I can't hear the guitar] . . . .

Refugee · 22nd Feb 2020, 12:29 am

A Numatic motor filter for a Henry cleaner would be a good thing if you are prepared to put up with it being white.
They are round and are also about the right size (the same diameter as the cleaner body) and are still made and sold as a spare part. They are made of very fine plastic mesh and can be hemmed with a hot metal clad resistor or hot melt glue in very small spots.

Silicon · 22nd Feb 2020, 11:48 am

I tried to identify the type of fabric used for the dust bag in an old radio.

I think it was a Philips or an Ultra. The type of fabric does vary. Some are surprisingly brittle.

If you use the search term 'japanese double gauze fabric black' on a well known internet auction site, you may find a black lightweight open weave cotton fabric that looks similar to the vintage cloth.

I have not bought any fabric yet. I want to check at a fabric shop first to see what options are available.

Radio_Dave · 22nd Feb 2020, 12:02 pm

On the two occasions I had to remake these bags I found the originals to just be simple square bags with a drawstring at one end. I used a cheap black bed sheet to make the replacements

.

David

paulsherwin · 22nd Feb 2020, 12:03 pm

An old polyester cotton bed sheet will probably be OK. Even if you have to buy one from Primark it will be cheaper than buying a metre of fabric from a haberdasher (if you can even find one). Many of the original bags were unbleached cotton so a sort of cream colour, while others were dyed black.

Robert Gribnau · 22nd Feb 2020, 12:22 pm

According to Philips the purpose of the bag is suppression (about 6dB) of the lower resonance frequency. Source: p. 157 "Van microfoon tot oor", G. Slot, second edition, 1960, Philips Technische Bibliotheek.

Tractionist · 22nd Feb 2020, 1:25 pm

I've made a few of these - usually for Phillips sets [V5A's etc.]. I've always used fine white muslin [dyed where appropriate]. As others have stated - this entails cutting-out a circular shape; hemming the perimeter; and threading a tie cord through the perimeters' hemmed section i.e. prior to 'shrouding' the speaker itself.

Alf Fisher · 24th Feb 2020, 8:55 am

Guys,
Thank you for all your suggestions. Paul mentioned using a sheet but I have found pillow cases are a lot cheaper than a whole bed sheet and would certainly provide enough material to make one - assuming that the material is suitable. Its not a Hi-Fi speaker by any means but a vintage Tannoy model as installed in buildings on military bases.

Alf

paulsherwin · 24th Feb 2020, 11:59 am

Yes, a pillowcase would be fine if you are buying new. I only mentioned a bedsheet because lots of people have old worn ones sitting in a cupboard.

rockinmark · 24th Feb 2020, 5:50 pm

I used the wifes washing bra bag it was perfect size and has draw strings to close it as I said it was perfect well until the wife asked if I had seen and of course I said no lol

Glowing Bits! · 24th Feb 2020, 7:48 pm

If the OP has not yet found a workaround, I have one taken from an old 40's speaker if it's any use, it has not crumbled away as of yet.

vintage_8bit · 25th Feb 2020, 2:03 pm

Last year I Re-bagged a speaker on a 1946 Ekco. After a few fails, I purchased Muslin (Cheesecloth / Midex M34) from an auction site £5.50 a metre. I purchased it in black, other colour are available including white. It was indistinguishable from the original, I was really happy with it, it looked totally original. This speaker had an open Speech coil, so I felt happier with it having an extra layer of protection.

21st Feb 2020, 4:37 pm	#1
Alf Fisher Hexode Join Date: Sep 2005 Location: Potton, Bedfordshire, UK. Posts: 293	Vintage radio loudspeaker dust bag Hi folks, Not sure if I have described this properly but speakers used to be enclosed in a cloth bag to keep the dust out. The bag enclosed the whole of the speaker and was tied around the magnet with thin cord or string. I'm have an 8 inch extension speaker where the bag has decayed into a very fragile state and has been torn on the front where fingers have been poked through the fret so can anyone recommend a source of these please. Alf

21st Feb 2020, 4:43 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,927	Re: Vintage radio loudspeaker dust bag Philips were very keen on these. You don't really need them in a modern domestic environment, though you could easily make one with some acoustically transparent fabric. Time to get out the sewing machine! A fabric peg bag (for clothes pegs) might be suitable.

21st Feb 2020, 5:17 pm	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,927	Re: Vintage radio loudspeaker dust bag It does make sense to do it if the speaker is to be used in a hostile environment, as you don't want large particles lodging in the voice coil. A typical modern house won't have an open coal fire or smoking occupants though - most dust will be tiny dead skin particles which aren't abrasive.

21st Feb 2020, 5:43 pm	#5
Stylo N M Heptode Join Date: Jul 2012 Location: Derby DE1, Derbyshire, UK. Posts: 626	Re: Vintage radio loudspeaker dust bag Hi Alf, I remember making one of these many years ago out of some thin cloth, worked great i drew round a cercular dinner plate with a pen, and had a bit of help from a family member to sew it up on the sewing machine. As paul said an old peg bag would be ideal, i used a long black boot lace to tie the finished bag arround the magnet. If you have a short off cut of a piece of net curtain wire, you can use that with the boot lace or string, attached to the end of it to help thread the lace or tie through the hem for tieing. The curtain wire can then be disgarded once the lace or tie is threaded through the hem, and then the lace will act as a draw string to tighten the finished cover arround the speaker magnet. Paul

21st Feb 2020, 6:03 pm	#6
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Vintage radio loudspeaker dust bag Later speakers have dust caps that prevent dust entering the gap around the voice coil. Early speakers were often open and there are plenty of threads here discussing how to remove the accumulated dirt and dust,

21st Feb 2020, 7:44 pm	#7
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Vintage radio loudspeaker dust bag A modern home with pets will have an enormous amount of dust and hair floating around. We have to empty out the "hoover" at least once a week, it is always full of hair and dust. Curtains, clothing, skin, furnishings, hair, I would imagine there is more around now than in the old days when rooms were more spartan. As the speaker moves, dust can be drawn in and out of the speech coil gap. So I consider a dust bag is always a good idea if the voice coil is open to the atmosphere. Even more so if you put the speaker down on a bench where their may be a speck of rust or iron filing. Mike

21st Feb 2020, 8:00 pm	#8
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,995	Re: Vintage radio loudspeaker dust bag Having lived for decades in seriously-dusty/furry environments [a couple of 110-pound dogs throw off lots of fur and dander] I've never found the need for 'dust-bags' on any of my speakers. Turn it up! [I can't hear the guitar] . . . .

22nd Feb 2020, 12:29 am	#9
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Vintage radio loudspeaker dust bag A Numatic motor filter for a Henry cleaner would be a good thing if you are prepared to put up with it being white. They are round and are also about the right size (the same diameter as the cleaner body) and are still made and sold as a spare part. They are made of very fine plastic mesh and can be hemmed with a hot metal clad resistor or hot melt glue in very small spots.

22nd Feb 2020, 11:48 am	#10
Silicon Nonode Join Date: Jun 2007 Location: Coulsdon, London, UK. Posts: 2,161	Re: Vintage radio loudspeaker dust bag I tried to identify the type of fabric used for the dust bag in an old radio. I think it was a Philips or an Ultra. The type of fabric does vary. Some are surprisingly brittle. If you use the search term 'japanese double gauze fabric black' on a well known internet auction site, you may find a black lightweight open weave cotton fabric that looks similar to the vintage cloth. I have not bought any fabric yet. I want to check at a fabric shop first to see what options are available.

22nd Feb 2020, 12:02 pm	#11
Radio_Dave Nonode Join Date: Jun 2004 Location: Norwich, Norfolk, UK. Posts: 2,543	Re: Vintage radio loudspeaker dust bag On the two occasions I had to remake these bags I found the originals to just be simple square bags with a drawstring at one end. I used a cheap black bed sheet to make the replacements. David __________________ http://www.youtube.com/ My Nixie Clocks

22nd Feb 2020, 12:03 pm	#12
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,927	Re: Vintage radio loudspeaker dust bag An old polyester cotton bed sheet will probably be OK. Even if you have to buy one from Primark it will be cheaper than buying a metre of fabric from a haberdasher (if you can even find one). Many of the original bags were unbleached cotton so a sort of cream colour, while others were dyed black.

22nd Feb 2020, 12:22 pm	#13
Robert Gribnau Heptode Join Date: May 2017 Location: Konongo, Ghana Posts: 513	Re: Vintage radio loudspeaker dust bag According to Philips the purpose of the bag is suppression (about 6dB) of the lower resonance frequency. Source: p. 157 "Van microfoon tot oor", G. Slot, second edition, 1960, Philips Technische Bibliotheek.

22nd Feb 2020, 1:25 pm	#14
Tractionist Heptode Join Date: Apr 2016 Location: Cheltenham, Gloucestershire, UK. Posts: 874	Re: Vintage radio loudspeaker dust bag I've made a few of these - usually for Phillips sets [V5A's etc.]. I've always used fine white muslin [dyed where appropriate]. As others have stated - this entails cutting-out a circular shape; hemming the perimeter; and threading a tie cord through the perimeters' hemmed section i.e. prior to 'shrouding' the speaker itself. __________________ Red to red, black to black. Throw the switch and stand well back!

24th Feb 2020, 8:55 am	#15
Alf Fisher Hexode Join Date: Sep 2005 Location: Potton, Bedfordshire, UK. Posts: 293	Re: Vintage radio loudspeaker dust bag Guys, Thank you for all your suggestions. Paul mentioned using a sheet but I have found pillow cases are a lot cheaper than a whole bed sheet and would certainly provide enough material to make one - assuming that the material is suitable. Its not a Hi-Fi speaker by any means but a vintage Tannoy model as installed in buildings on military bases. Alf

24th Feb 2020, 11:59 am	#16
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,927	Re: Vintage radio loudspeaker dust bag Yes, a pillowcase would be fine if you are buying new. I only mentioned a bedsheet because lots of people have old worn ones sitting in a cupboard.

24th Feb 2020, 5:50 pm	#17
rockinmark Heptode Join Date: Sep 2014 Location: St Albans, Hertfordshire, UK. Posts: 594	Re: Vintage radio loudspeaker dust bag I used the wifes washing bra bag it was perfect size and has draw strings to close it as I said it was perfect well until the wife asked if I had seen and of course I said no lol

24th Feb 2020, 7:48 pm	#18
Glowing Bits! Octode Join Date: Oct 2011 Location: Wrexham, North Wales, UK. Posts: 1,457	Re: Vintage radio loudspeaker dust bag If the OP has not yet found a workaround, I have one taken from an old 40's speaker if it's any use, it has not crumbled away as of yet. __________________ Rick, the annoying object roaming the forum.

25th Feb 2020, 2:03 pm	#19
vintage_8bit Heptode Join Date: Feb 2013 Location: Rainham, Kent, UK. Posts: 525	Re: Vintage radio loudspeaker dust bag Last year I Re-bagged a speaker on a 1946 Ekco. After a few fails, I purchased Muslin (Cheesecloth / Midex M34) from an auction site £5.50 a metre. I purchased it in black, other colour are available including white. It was indistinguishable from the original, I was really happy with it, it looked totally original. This speaker had an open Speech coil, so I felt happier with it having an extra layer of protection.