Just doing some light restoration to a newly acquired pair of Yamaha JA6681b compression drivers:
The back chamber has 1/4" thick "felt type" pad and foam that is disintegrated, and no gasket between the chamber cover and the driver.
1. Do I need to add a gasket?
2. Do I need to replace the old foam with open cell foam? Or with another felt pad?
thanks!
The back chamber has 1/4" thick "felt type" pad and foam that is disintegrated, and no gasket between the chamber cover and the driver.
1. Do I need to add a gasket?
2. Do I need to replace the old foam with open cell foam? Or with another felt pad?
thanks!
Hi, mine don't have a gasket and I don't believe you need one. For the foam, it gets old and starts disintegrating. Because you still have it, I'd try to get the most similar one.
Best regards,
S.
Best regards,
S.
No gasket, even better! I filled mine with a wool pad (as foam replacement). I don't have a point of reference but works alright.
This tip may be long after the fact but Pierre, who long had these drivers before selling them to a friend at the Beyond the Ariel thread said:
"Personally, I am worried that a new open cell foam replacement might deteriorate over time and eventually become brittle. We saw this happening on the original foam that Yamaha put in these drivers, many woofer suspensions, and the padding in LP and CD box sets. The chemical that gives the foam its flexibility outgases over time, making the foam brittle. This is precisely the reason why I use (more expensive) wool felt, which will maintain its properties for 100 years at least. Perhaps Troy knows something about a particular open foam material that I don't?
In any case, the replacement for the deteriorated foam that I put in the back of Gary's drivers is: 3/8-Inch-thick Pressed Wool Felt. This can be purchased online. "
Assuming this is exactly what Pierre has, here's the best I could do for prices.
https://www.mcmaster.com/products/~/hard-felt/thickness~3-8/?s=3/8"+pressed+wool+felt
https://www.mscdirect.com/product/details/48544811
Hope this helps some day. Ho
Meanwhile, how are those Yamaha diaphragms holding up? Still using them in your systems?
I'm about to build a system with a pair in mint condition, but aware that there's always the risk of blowing a driver even at the moderate SPLs I listen at. As there are no OEM brands making replacements for these diaphragms, are there any precautions or sonically transparent protection circuitry that have been devised to guard against this?