Bose 901 (I) drivers repairable? - diyAudio
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Old 25th December 2013, 03:19 AM   #1
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Default Bose 901 (I) drivers repairable?

Well, I've done it again. In this case, tonight I was being a "Renegade of Funk" and I guess I had just a little bit too much "Rage Against The Machine" and fed my 901 II (x 4) up to redline of the NU6000 -- presumably 3000 w/ch into 4 Ohms. Each 901 II is rated at peak 400 W/8 Ohm, so 800 peak into 4 Ohms. Oops. Now I get the tell-tale crackle indicating an unhappy driver or two. Fortunately I am skilled in the art of scavenging 901 drivers, and even was going to assemble a "new" one from scratch. But now I have an unexpected repair.

Ok, enough already with the gasbag introduction. the point? Ah yes, the point! This is applicable to any dynamic driver of course, but what are the options, if any, for repairing working but buzzy or noisy speaker drivers? Also, how about treatments for the ancient (around 40 years!) paper cones? They often crumble at a finger poke...probably they were a bit sturdier than that when new. Any magic oils, varnishes, etc?


From sorting out dubious ones (when I buy a specimen), I usually give up on the obvious duds (cone or coil seized, won't move at all, etc.) But I am going to see if I can make the magnetic cat toy from one of them


Yours truly,
Soldermizer...slowly turning his several pair of old 901's into less and less as the months go by

Inventor of the "Hosed 900 1/2" !!!
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Old 25th December 2013, 04:04 AM   #2
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Old 25th December 2013, 04:19 AM   #3
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Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
Parts-express.com direct replacement, part no. 290-922 , one ohm, for series III, IV, V, or VI and others???
Sometimes a re-cone job doesn't work out well, for twenty bucks for each new driver it is still a bargain....even for the eight drivers per enclosure.
They probably will sound closer to original sound when they were new.


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Old 25th December 2013, 09:10 AM   #4
ODougbo is offline ODougbo  United States
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Old 25th December 2013, 10:45 AM   #5
sreten is offline sreten  United Kingdom
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Hi,

Buzziing or noisy from decayed surrounds
can be fixed by replacing all the surrounds.

Buzzing or noisy from fried voicecoils
cannot be fixed without full reconing.

PVA watered down a little can stabilise
cones but TBH the PE drivers look a
no-brainer to me, instant upgrade.

rgds, sreten.
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Old 25th December 2013, 03:18 PM   #6
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Um, some good news. I was ready to replace the buzzy driver and after removing the rear grille (and breaking its cardboard backing), I ran a sine sweep of the 901 and viola, problem has disappeared. I assume it is due to the rear grille contact with the cones, a problem I had read about (no doubt on this fine forum) but had not experienced before. So now that speaker is back in my main system (less a grille) and I have a pile of parts in my living room, awaiting me to assemble it into a working (probably) 901, albeit one that will not cosmetically match its mate. My Christmas

has been a screwed up one (girlfriend blues)

Stated in mathematical terms:

+ + (- Brain) =


and now I am putting stuff into a box...I thought 12/26 is boxing day??? Am I allowed to go punch my "ex" in the nose? That type of boxing? Probably not, the USA doesn't celebrate Boxing Day...

and besides we enjoy our Second Ammendment here and solve our problems with modern technology, like this all too often (although I plan to avoid such activity at least today -- and besides, I'd have to clean my gun afterwards

As for repairing the drivers, thanks for the tips. This is my second asking for such information and as one guy said, probably better to just buy new drivers (but not the ones for series III-onward, they won't work in the paleo-901s. Different driver.) I guess I am condemned to continue to bottom-fish on Ebay for 901s for parts

I did a little research here about stiffening drivers and, in fact, have tried the urethane idea before, although I can't claim a change in sound or (what I'm looking for) resistance to tearing of the cone. I did an experiment last night and can vouch that WATCO Teak Oil does not seem to make cone more durable. It works better on the veneer and smells nice I have two more Hosed 901 drivers (buzzy) that I can use for further Mengele-like experimentation

Nothing to lose (except some time, an asset I am skilled at squandering...) in my experience, and I've seen a lot of 901 drivers in the years, is that I have NEVER seen a surround failure on the "original" (CTS) drivers. In order of failures observed, common to rare: "buzzy" at a certain frequency, torn cone, seized voice coil.

I hope everybody (except me!!) had a nice holiday and may you enjoy the upcoming New Year in your own fashion, typically that means
Dec. 31
Jan 1

For some of us there is AA and I don't mean Audio Asylum

"Was it a woman or a bottle/That's brought him down so low?" -- Robert Cray, "Night Patrol"
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Old 26th December 2013, 04:01 AM   #7
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Mission accomplished. Who needs family and friends and all that holiday malarkey when you can isolate and repair old speakers! I was able to assemble a working 901 and it works (I am being redundant again all over). Only silly period was when I had to decide what to stuff it with. Dryer lint? It would take too long to accumulate enough. Fiberglass? I was going to pillage my attic insulation, even put the ladder up into the garage attic, plan was to put it into old socks, but too messy. In the end I just stuffed as many old rags as I could fit into the maw of the particleboard abomination and was done with it.
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