I have a pair of Bose 901 series 2's. I am the second owner. I bought the pair w/EQ from a high school friend about 78 or 79. He bought them in the mid seventies to play music at parties. The rub is that although the cabinets are the same the drivers are not...one has the early cloth surrounds and the other has the later foam surrounds. Serial #'s are about 4000 apart. 281415(foam surrounds) and 285230(cloth surrounds). I have not checked the wiring yet, but would suspect that one is a series arrangement, and the other a series/parallel. I never really noticed any sound difference before, but maybe I wasn't looking for it. I would suspect that the cloth surrounds would provide more bass as it appears that the coils could move more with a bigger lip to the cloth surround.
Anyway all the drivers work best I can tell, but as you might expect the foam surround speaker has no more foams. I have seen the replacement drivers from parts express, as well as some of the original cloth surround drivers on ebay....what would be the best way to go here...just buy foam drivers for the one and forget it....or replace the foam drivers with the original cloth drivers and re-wire the cabinet?
Thanks for your time, Chip
Anyway all the drivers work best I can tell, but as you might expect the foam surround speaker has no more foams. I have seen the replacement drivers from parts express, as well as some of the original cloth surround drivers on ebay....what would be the best way to go here...just buy foam drivers for the one and forget it....or replace the foam drivers with the original cloth drivers and re-wire the cabinet?
Thanks for your time, Chip
If you really really want to keep them going (NB - a lot of people here wouldn't), I'd pick up a complete set of replacement drivers, and do the lot. Wire the same way for both. If the replacement drivers are 1ohm, put them all in series. If they're 8ohm, series-parallel.
That'll get you consistency between left and right speakers, and up-to-date drivers that can be replaced if necessary.
Sell the old drivers online to recoup some of your expenditure, and you'll have a set of 901s that'll run for years.
You could even pick up a couple of spare drivers to be on the same side, but I'll leave that up to you.
Chris
That'll get you consistency between left and right speakers, and up-to-date drivers that can be replaced if necessary.
Sell the old drivers online to recoup some of your expenditure, and you'll have a set of 901s that'll run for years.
You could even pick up a couple of spare drivers to be on the same side, but I'll leave that up to you.
Chris
Thanks for the reply's
New info: I pulled out drivers in each cabinet today.
Cab1: serial #281415 had the 3 screw drivers with round magnets and dated July 76
Cab2: serial #285230 had the 4 screw drivers with round magnets and marked Lot 6906
Neither cabinet shows any signs of speakers ever having been replaced. Does this information correspond to build years and series ?
New info: I pulled out drivers in each cabinet today.
Cab1: serial #281415 had the 3 screw drivers with round magnets and dated July 76
Cab2: serial #285230 had the 4 screw drivers with round magnets and marked Lot 6906
Neither cabinet shows any signs of speakers ever having been replaced. Does this information correspond to build years and series ?
Thanks for the reply's
new info: pulled drivers out of each cabinet
Cab1: serial#281415 3 screw drivers with round magnets, marked July 1976
Cab2: serial#285230 4 screw drivers with round magnets, marked Lot 6906
Neither show any signs of ever being apart or drivers being replaced....seems to be inconsistent with the information that's out there on Series II's. Cabinets are 4000 apart and the earlier cabinet has the later drivers...strange
new info: pulled drivers out of each cabinet
Cab1: serial#281415 3 screw drivers with round magnets, marked July 1976
Cab2: serial#285230 4 screw drivers with round magnets, marked Lot 6906
Neither show any signs of ever being apart or drivers being replaced....seems to be inconsistent with the information that's out there on Series II's. Cabinets are 4000 apart and the earlier cabinet has the later drivers...strange
Very odd! Are you sure that the 3-screw drivers are from a cabinet that said "Series II"? I have owned (used) of original 901 (series I, II) and later (series III up). I was under the impression that the 3-screw driver was only used in Series III onward. The Series I and II used 8-ohm CTS drivers wired series parallel. The "box" is sealed. In contrast, Bose with Series III went to a different (custom?) driver, 1 ohm, series wired, and ported enclosure. Really, Bose ended up with two quite different speaker technologies between I-II and III-VI. I can't imagine what a "new" driver would be doing in a Series II box. Weird!
You are a brave man (or newbie?) to admit owning Bose here.
Bose had (has?) a reputation for not being properly "hi-fi" pedigree. I think the animus against them was overdone, but agree that their stuff was overpriced. However, I am the owner of three pairs of Bose 901 (series I or II) that were bought at cheap prices and now collect dust (unused for a couple years). Do you need a pair cheap?
You are a brave man (or newbie?) to admit owning Bose here.
Bose had (has?) a reputation for not being properly "hi-fi" pedigree. I think the animus against them was overdone, but agree that their stuff was overpriced. However, I am the owner of three pairs of Bose 901 (series I or II) that were bought at cheap prices and now collect dust (unused for a couple years). Do you need a pair cheap?
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Yes, after taking off the covers I was surprised too. That is why I put it out to the forum. My original suspicion was that either Bose or an authorized Bose repair shop had replaced the drivers in one cabinet and changed the wiring to accomidate the impedance. However that's just not the case as the earlier serial # cabinet has no sign of having (4) screw holes and was definitely built the way it is from the factory.
Yes, I may be interested in your old 901's. PM sent shortly, thanks
Yes, I may be interested in your old 901's. PM sent shortly, thanks
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