iso
09-16-2012, 03:56 AM
I bought 2 pcs 123A-1 woofers some time ago. Woofer serial numbers are close to ea. other around 82000 and both have cone numbers 21005P. When I tested woofers I found that one unit had fs at 24HZ and other one has fs at 34HZ. The Q of resonance is clearly higher on 24HZ unit. Coil inductanses were measured with ordinary LCR meter and were 0,79 mH for 24HZ unit and 0,65mH for 34HZ unit.
It seems that 34HZ unit has been reconed , as aquaplas coating has clearly smoother texture and less brownish ring close to surround on this unit. However it seems a bit odd that this unit seems to have firmer suspension, even surround dope should be newer.
As it was discussed earlier that old 70īs to 80īs dope can be rejuvenated with acetone, but with newer dope this is not possible. Is there any way to check if this acetone rejuvenation is possible without damaging this reconed unit?
Surround dope on front side of 24HZ unit seems to be missing on some places. Therefore I am also wondering if I can lift old dope to these places with acetone and brush.
Best Regards
Kimmo
It seems that 34HZ unit has been reconed , as aquaplas coating has clearly smoother texture and less brownish ring close to surround on this unit. However it seems a bit odd that this unit seems to have firmer suspension, even surround dope should be newer.
As it was discussed earlier that old 70īs to 80īs dope can be rejuvenated with acetone, but with newer dope this is not possible. Is there any way to check if this acetone rejuvenation is possible without damaging this reconed unit?
Surround dope on front side of 24HZ unit seems to be missing on some places. Therefore I am also wondering if I can lift old dope to these places with acetone and brush.
Best Regards
Kimmo