Golanr
Active Member
Hello everyone.
I had the opportunity to buy a pair of 105.2, SP1118 S/N 1921A and 1921B.
The seller mentioned that the voice quality is not good and I figured the issue was with the old caps, so I ordered a new set from Falcon Acoustics and replaced them even prior to connecting them to my receiver (Sansui G-9000DB)
Surprise surprise, they still sound bad, which ended up being rubbing voice coils. I tried turning them 120 degrees and even 240. Waited a day after every turn with no luck.
So, I have taken them to a local shop (PM me if you want more info) I have learned that both voice coils are in bad shape due to the rubbing and needed to be replaced, together with the spider. since he had no similar voice coils, he had shipped them to California to someone who can create new ones based on the size measured. the Bextrene membranes were not replaced.
Talking with speakerguru from http://www.hifiloudspeakers.info it appears that he designed the B300 and wound all the prototype coils himself. The coil is 0.5" longer than the magnet top plate thickness. The pole piece is 2.0" diameter and the coil former i.d. is 0.020" smaller than that radially. i.e you use a 20 thou shim to center the v.c. in the magnet gap. The coil was wet wound using a high temperature epoxy and a high temperature polyamide/polyester coated wire. The coil former was split anodized aluminium with a nomex top tube to stop the heat getting to the bextrene cone. He did not remember the wire gauge.
It took about a month and both B300s came back home and boy was it worth waiting.
The Spiders, Voice Coils and Dust Cups were all replaced.
The tech had to manually wind them, but now has all data in his computer, in case someone else will need the same service. He also stated that it will take the new spiders about 100 play hours to break in.
I am attaching photos of the old voice coils and speakers.
Note the date Sep 24th 1979
You can clearly see the rubbing here
Original and Updated Crossover
I had the opportunity to buy a pair of 105.2, SP1118 S/N 1921A and 1921B.
The seller mentioned that the voice quality is not good and I figured the issue was with the old caps, so I ordered a new set from Falcon Acoustics and replaced them even prior to connecting them to my receiver (Sansui G-9000DB)
Surprise surprise, they still sound bad, which ended up being rubbing voice coils. I tried turning them 120 degrees and even 240. Waited a day after every turn with no luck.
So, I have taken them to a local shop (PM me if you want more info) I have learned that both voice coils are in bad shape due to the rubbing and needed to be replaced, together with the spider. since he had no similar voice coils, he had shipped them to California to someone who can create new ones based on the size measured. the Bextrene membranes were not replaced.
Talking with speakerguru from http://www.hifiloudspeakers.info it appears that he designed the B300 and wound all the prototype coils himself. The coil is 0.5" longer than the magnet top plate thickness. The pole piece is 2.0" diameter and the coil former i.d. is 0.020" smaller than that radially. i.e you use a 20 thou shim to center the v.c. in the magnet gap. The coil was wet wound using a high temperature epoxy and a high temperature polyamide/polyester coated wire. The coil former was split anodized aluminium with a nomex top tube to stop the heat getting to the bextrene cone. He did not remember the wire gauge.
It took about a month and both B300s came back home and boy was it worth waiting.
The Spiders, Voice Coils and Dust Cups were all replaced.
The tech had to manually wind them, but now has all data in his computer, in case someone else will need the same service. He also stated that it will take the new spiders about 100 play hours to break in.
I am attaching photos of the old voice coils and speakers.
Note the date Sep 24th 1979
You can clearly see the rubbing here
Original and Updated Crossover
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