cosaw
Established Member
*****The detail (for those interested) - skip this first but come back if you want to learn more.******
I have some approximately 20 year old Technics stereo equipment of my dad's which is good stuff but has never really had much use. The equipment is and has been located in an atmosphere which is subject to temperature and humidity change. Anyway after recently moving the equipment to the front room I have been giving it some more use.
The speakers (Technics SB-3050) are three way and the woofer diameter is 10". The woofers are of paper/card type with foam mounting. While trying to figure methods of insulating them from the floorboards I was keeping an eye on them and driving them quite hard but not overly. I had faded out the left speaker with the balance control (Presumably balance fades out one speaker as opposed to increasing the volume/wattage to the other? Anyway as there was no increase in volume in the right speaker or increased peaking on the power meter I continued.) Noticed a slight buzz/rattle which shouldn't have been there, I thought just a bit of distortion and maybe a flaw in the original speaker design. After listening for moments longer this increased and I quickly turned the volume right down. On closer examination the cone had dislocated itself from it's sponge type mounting. The cone itself is intact but it is dislocated from the foam mount, plus some of the mount is torn. On closer inspection of this spongy material it seems that it has been subject to some perishing over the years. Though its natural colour is a dark grey there is some brown discolouration in places. If you rub the foam gently with a finger it gradually wants to disintegrate, I compared this to a newer cone of similar design where the foam was firm and resilient.
*****END********************************************
**In brief**
While driving some old Technics speakers the 10" paper/card woofer started becoming detached from its foam mounting, the cone itself has not been damaged. There is some perishing of this foam mounting and I believe this to be the cause of the problem rather than me overdriving the speaker.
*********
I'm pretty sure the voice coils aren't damaged. The speakers are my late fathers and hold sentimental value. To this end I would prefer to try a fix before buying a new (different ) woofer, even if I make a botch it's worth a try and would be interesting to see what results could be achieved.
First I will attempt: extracting the woofer and gluing the cone back to the mounting from the rear. First question: What sort of glue would anyone recommend? Presumably it would need to be strong yet flexible. Preferably this glue would be easy to remove in case I have to try my second method. I was thinking something like Copydex. Also to reinforce the ageing foam I may think about somehow flexibly securing some gauze type material to the rear of the foam, but this would need some more research.
Second method (if first unsuccessful or until foam mounting fails again): Remove the whole foam mounting ring and replace. Second question: Does such a ring of foam material or equivalent remedy exist for purchase?
When I have time to attempt a repair I will post my results.
Any ideas/experiences welcome.
Simon
I have some approximately 20 year old Technics stereo equipment of my dad's which is good stuff but has never really had much use. The equipment is and has been located in an atmosphere which is subject to temperature and humidity change. Anyway after recently moving the equipment to the front room I have been giving it some more use.
The speakers (Technics SB-3050) are three way and the woofer diameter is 10". The woofers are of paper/card type with foam mounting. While trying to figure methods of insulating them from the floorboards I was keeping an eye on them and driving them quite hard but not overly. I had faded out the left speaker with the balance control (Presumably balance fades out one speaker as opposed to increasing the volume/wattage to the other? Anyway as there was no increase in volume in the right speaker or increased peaking on the power meter I continued.) Noticed a slight buzz/rattle which shouldn't have been there, I thought just a bit of distortion and maybe a flaw in the original speaker design. After listening for moments longer this increased and I quickly turned the volume right down. On closer examination the cone had dislocated itself from it's sponge type mounting. The cone itself is intact but it is dislocated from the foam mount, plus some of the mount is torn. On closer inspection of this spongy material it seems that it has been subject to some perishing over the years. Though its natural colour is a dark grey there is some brown discolouration in places. If you rub the foam gently with a finger it gradually wants to disintegrate, I compared this to a newer cone of similar design where the foam was firm and resilient.
*****END********************************************
**In brief**
While driving some old Technics speakers the 10" paper/card woofer started becoming detached from its foam mounting, the cone itself has not been damaged. There is some perishing of this foam mounting and I believe this to be the cause of the problem rather than me overdriving the speaker.
*********
I'm pretty sure the voice coils aren't damaged. The speakers are my late fathers and hold sentimental value. To this end I would prefer to try a fix before buying a new (different ) woofer, even if I make a botch it's worth a try and would be interesting to see what results could be achieved.
First I will attempt: extracting the woofer and gluing the cone back to the mounting from the rear. First question: What sort of glue would anyone recommend? Presumably it would need to be strong yet flexible. Preferably this glue would be easy to remove in case I have to try my second method. I was thinking something like Copydex. Also to reinforce the ageing foam I may think about somehow flexibly securing some gauze type material to the rear of the foam, but this would need some more research.
Second method (if first unsuccessful or until foam mounting fails again): Remove the whole foam mounting ring and replace. Second question: Does such a ring of foam material or equivalent remedy exist for purchase?
When I have time to attempt a repair I will post my results.
Any ideas/experiences welcome.
Simon
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