Hello ,
i have a the export version of Cambridge Audio R40 vintage Transmission line loudspeakers which i got from my father in the 90's.
I decided to upgrade and retouch these and change the crossover with a better on instead of recaping the original and got one from Wilmslow Audio (Great Guys by the way very helpful).
When i removed the front baffle i found that the foam curtain behind the buffle was cut behind the speakers and torn in some spots.
Perhaps the person who changed me a couple of caps in the 90's did this to reach the crossover which is behind the woofer (b139) and on the speaker wall ,unlike the R50 which has this on the baffle back.
Obviously this needs replacement and were can you find such a foam from 1976 ?
So i ordered a transparent speaker foam from adam hall (5mm thick) ,original is 5,5 mm after reading that the foam behind the baffle with the speakers and in front of the speaker cabinets full of wool, should be open type.
Today the foam from adam hall arived yet the material seems more open to me the then original.
Adam Hall Speaker front foam 200 x 100 cm, 5 mm
- DV247
So i would like to ask what is the proper acoustic foam curtain to use ,is this one ok or i need something ealse ?
I been searching weeks on the net with no info and saw some of you that had repaired r40-r50's so your help is appreciated.
Also were can you source such wool dumping?Is the original sufficient ?
Cheers to all
Pictures of the open speaker :
i have a the export version of Cambridge Audio R40 vintage Transmission line loudspeakers which i got from my father in the 90's.
I decided to upgrade and retouch these and change the crossover with a better on instead of recaping the original and got one from Wilmslow Audio (Great Guys by the way very helpful).
When i removed the front baffle i found that the foam curtain behind the buffle was cut behind the speakers and torn in some spots.
Perhaps the person who changed me a couple of caps in the 90's did this to reach the crossover which is behind the woofer (b139) and on the speaker wall ,unlike the R50 which has this on the baffle back.
Obviously this needs replacement and were can you find such a foam from 1976 ?
So i ordered a transparent speaker foam from adam hall (5mm thick) ,original is 5,5 mm after reading that the foam behind the baffle with the speakers and in front of the speaker cabinets full of wool, should be open type.
Today the foam from adam hall arived yet the material seems more open to me the then original.
Adam Hall Speaker front foam 200 x 100 cm, 5 mm
- DV247
So i would like to ask what is the proper acoustic foam curtain to use ,is this one ok or i need something ealse ?
I been searching weeks on the net with no info and saw some of you that had repaired r40-r50's so your help is appreciated.
Also were can you source such wool dumping?Is the original sufficient ?
Cheers to all
Pictures of the open speaker :
Attachments
Could the foam sheet simply be intended to prevent the loose long-haired wool damping material from coming into contact with the vibrating cone of the woofer?
If so, the Adam Hall foam will be perfect for this purpose.
Long-fibre wool damping is available from this supplier although the original should be sufficient:
Long-Fibre Lambs Wool, Carded buy at hifisound.de
If so, the Adam Hall foam will be perfect for this purpose.
Long-fibre wool damping is available from this supplier although the original should be sufficient:
Long-Fibre Lambs Wool, Carded buy at hifisound.de
To be clear, the foam sheet is not there to provide damping, but only to contain the long-fibre wool damping material. So the foam should be acoustically transparent.
Thanks for your reply,after reading allot of the info and the original TL speaker specs that are posted from the 70's ,they even mentioned a thin bird type net from plastic.Later they introduced the foam ,the only mention was open cell type.Thats why i got that speaker transparent foam.
I have seen the site you mentioned just didnt know if tit was they same type.
I think the original is the one that was suposed to be there according to the volume of the cabin,just a thought that after 40 years maybe it needed replacement or just to some.
Than i read that you have to somehow re-fluff the wool it has settled in order to gain volume once more.That seems little hard since the fibers are tangled together.
I have seen the site you mentioned just didnt know if tit was they same type.
I think the original is the one that was suposed to be there according to the volume of the cabin,just a thought that after 40 years maybe it needed replacement or just to some.
Than i read that you have to somehow re-fluff the wool it has settled in order to gain volume once more.That seems little hard since the fibers are tangled together.
You may be interested in the link below, particularly the section "Loudspeaker sheep's wool: Internal support with netting".
This explains how to stop the wool ultimately settling within the cabinet, with a subsequent reduction in performance:
How to Use Sound-Damping Materials in DIY Loudspeakers
Purchasing options for sheep's wool are shown in the sister page:
Loudspeaker damping materials for DIY speaker kits.
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