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Bose 901 IV w/ Spacial Control Receiver for FREE!!!

Broken.Ears

Broken.Ears

Active Member
Found someone who was storing a pair of 901 IVs and a matching Spatial Surround Receiver. They had got it the set from the original owner about a year ago. The person I got it from had run them for a little while, but put them away because they didn’t sound good -- week sound with too much distortion.

Got them home and think I found out why -- the surrounds are completley rotted. The person I got it from had the receiver shut down on them periodically. I imagine it was probably running too hard with the rotted drivers and shut down as a safety precaution. The fuse looks okay.

Despite the the opinions regarding Bose, I think this set would be worth fixing up. Before shelling out for a set of new surrounds, I would like to figure out if any of the drivers are blown. They were probably run for awhile with the surrounds completely rotted which can’t be good for the drivers.

Questions:

How can I test the drivers to make sure they are operational?

Is the 901 surround replacement complicated or a fairly straight-forward operation?

Foam or cloth surrounds, is there a preference?
 

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Broken.Ears said:
How can I test the drivers to make sure they are operational?

Is the 901 surround replacement complicated or a fairly straight-forward operation?

Foam or cloth surrounds, is there a preference?
Click to expand...

1. Pull drivers and check for continuity with a MM and check that the coil moves freely over the pole piece.

2. Tedious, with tight VC gaps x 18. The battery method of alignment would probably work best.

3. The drivers were designed with foam. I'd stick with that.

Good luck!

Ken
 
Hi,

The Bose Spatial Control Receiver is very excellent and quite powerful. 100 Watts/Channel. It's easily the best Bose product out there. Truly quality. The 901 and 901 Series II are the best of that line. Your main challenge is the fact that small drivers are tricky to resurround. Nice score! :tresbon:
 
Urizen said:
1. Pull drivers and check for continuity with a MM and check that the coil moves freely over the pole piece.

2. Tedious, with tight coils x 18. The battery method of alignment would probably work best.

3. The drivers were designed with foam. I'd stick with that.

Good luck!

Ken
Click to expand...

How do I test for continuity with the multimeter?


KentTeffeteller said:
Hi,

The Bose Spatial Control Receiver is very excellent and quite powerful. 100 Watts/Channel. It's easily the best Bose product out there. Truly quality. The 901 and 901 Series II are the best of that line. Your main challenge is the fact that small drivers are tricky to resurround. Nice score! :tresbon:
Click to expand...

Thanks! I figure even if the speakers don't work out, the receiver still has potential. Hoping it all goes well though.
 
Holy Crap! For free? I'd take that all day long! As being someone who's refoamed all 18 drivers on a pair of Series IV's, I will say it is something a person can do themselves with a little patience. I was quite surprised at how they sounded with some power behind them. Not my favorite speakers in the world, but not the worst I've ever heard.

It will be easy sell them if you are so inclined and recoup your expense. Wait...you HAVE NO EXPENSE unless you count the cost of new surrounds. :D

Congrats!
 
avguytx said:
Holy Crap! For free? I'd take that all day long! As being someone who's refoamed all 18 drivers on a pair of Series IV's, I will say it is something a person can do themselves with a little patience. I was quite surprised at how they sounded with some power behind them. Not my favorite speakers in the world, but not the worst I've ever heard.

It will be easy sell them if you are so inclined and recoup your expense. Wait...you HAVE NO EXPENSE unless you count the cost of new surrounds. :D

Congrats!
Click to expand...

This is by far my best gear score. I figure if the drivers test good, I could refoam and decide if I like the speakers enough.

I looked up your thread about replacing the surrounds last night. Would you recommend keeping the drivers mounted or pulling them out during the refoam? I found the kit you got from the guy on eBay. Were the directions good? Any tips you have would be appreciated.
 
Broken.Ears said:
This is by far my best gear score. I figure if the drivers test good, I could refoam and decide if I like the speakers enough.

I looked up your thread about replacing the surrounds last night. Would you recommend keeping the drivers mounted or pulling them out during the refoam? I found the kit you got from the guy on eBay. Were the directions good? Any tips you have would be appreciated.
Click to expand...

Well, for me it was easier to have them all out of the cabinet as I also had to refinish the cabinets. Plus it made them lighter weight for moving them around during sanding, etc. I just liked having them all right there where it was easy to maneuver them around while doing the refoam. Others have done them in the cabinet but one slip of a tool or something and you could potentially puncture a cone. Just make sure you have a diagram of what wires go where. Although, there are diagrams on the net so even if you didn't, you can find reference. I might have it saved where I could email it to you, too.

That kit was very nice and the instructions very informative. I've refoamed many woofers but up until that point, not the Bose 901 drivers. The one thing about doing them singly and out of the cabinet as a whole, you have to be careful hooking one driver up to an amp or receiver as each driver is around .9-ohms like Urizen mentioned. You can shut an amp off fast (or "chooch it") if you're not careful with that low of an impedance. Just be careful....
 
The "Spacial Control" is designed for series II & III (I think) 901's specificity. The speakers have 3 terminals, and when hooked up correctly, the receiver allows you to control how much power is applied to each "face" of 4 rear facing drivers. It allows you to control the width of the sound stage.

I had that setup one time, and came VERY close to re-foaming the drivers and setting it up. I would have liked to be able to form my own opinion on these. But, the fact that I was NOT looking forward to re-foaming 18 drivers and rearranging my house to accommodate enough wall space, I decided to sell as is.

PS: Have you figured out how to turn the receiver on yet?
 
That is an unbeleivable deal, congrats. I like to re-foam speakers. However, the thought of re-foaming so many drivers for one pair of speakers is a tad intimidating from a price and time standpoint for me. Don't get me wrong, it is well worth the effort.
 
It's not the worst way ever to spend the better part of 3 days (spread out of course). :D Plus, you chalk it up to some major experience of refoaming woofers. I think it took me about 2 hours total to clean all 18 driver and have them ready for the new foam. Hell, I spent more time on refinishing the cabinets than anything.
 
avguytx said:
It's not the worst way ever to spend the better part of 3 days (spread out of course). :D Plus, you chalk it up to some major experience of refoaming woofers. I think it took me about 2 hours total to clean all 18 driver and have them ready for the new foam. Hell, I spent more time on refinishing the cabinets than anything.
Click to expand...

It's like speaker refoam boot camp. :zoom:
 
himm37 said:
The "Spacial Control" is designed for series II & III (I think) 901's specificity. The speakers have 3 terminals, and when hooked up correctly, the receiver allows you to control how much power is applied to each "face" of 4 rear facing drivers. It allows you to control the width of the sound stage.

I had that setup one time, and came VERY close to re-foaming the drivers and setting it up. I would have liked to be able to form my own opinion on these. But, the fact that I was NOT looking forward to re-foaming 18 drivers and rearranging my house to accommodate enough wall space, I decided to sell as is.

PS: Have you figured out how to turn the receiver on yet?
Click to expand...

Yes, turning it on was a weird one. Kind of similar to touch lamps. First time I tried I forgot to turn the back power switch on, which made for a moment of worry, but now I'm good.

My Series IV have the additional Spatial Control lead to the speaker and seem to work with the very limited testing I did.


NYListens said:
That is an unbeleivable deal, congrats. I like to re-foam speakers. However, the thought of re-foaming so many drivers for one pair of speakers is a tad intimidating from a price and time standpoint for me. Don't get me wrong, it is well worth the effort.
Click to expand...

Yeah, I'm a bit intimidated by the prospect of all those drivers, especially considering I've never done a refoam before. Further, my listening space for these is small (10 x 10 feet), so I'm not sure how they will sound in it. My wife voted them out of the living room with a crinkled nose and a comment of "why does all your stereo stuff have to look old". At worst, I'm getting them ready for a profitable flip.
 
avguytx said:
Well, for me it was easier to have them all out of the cabinet as I also had to refinish the cabinets. Plus it made them lighter weight for moving them around during sanding, etc. I just liked having them all right there where it was easy to maneuver them around while doing the refoam. Others have done them in the cabinet but one slip of a tool or something and you could potentially puncture a cone. Just make sure you have a diagram of what wires go where. Although, there are diagrams on the net so even if you didn't, you can find reference. I might have it saved where I could email it to you, too.

That kit was very nice and the instructions very informative. I've refoamed many woofers but up until that point, not the Bose 901 drivers. The one thing about doing them singly and out of the cabinet as a whole, you have to be careful hooking one driver up to an amp or receiver as each driver is around .9-ohms like Urizen mentioned. You can shut an amp off fast (or "chooch it") if you're not careful with that low of an impedance. Just be careful....
Click to expand...

Careful and incredibly, meticulously slow is what I'll end up being, I'm sure. I don't want to permanently damage these.

I will be doing what you did and lightly sanding and oiling the cabinets. They need it. So it looks like I'll be installing them out of the cabinet.

Does the kit come with a chemical to remove the old foam? If not, what did you use? What do I need to watch out for when removing the old foam?

The diagram, if you have it would be great.
 
I got a pair of 901 IVs, they had been refoamed-except for the 2 in the fronts.
I refoamed them, and they sounded good.
Then I noticed some of the other drivers had the surrounds installed upside down.
A few had voice coil rub, so I refoamed them.
Should I refoam the rest, or leave them alone?
They all feel the same when I push the cones in to check for VC rub.
 
Doing a pair of 901 IVs was my first (and so far only) attempt at refoaming. They turned out really well. Because of their small size, I didn't have to remove the dust covers or use shims. I just followed the instructions from the folks that sold me the foam. The first one I did, I left the drivers in the cabinet. This became a pain in the rear because I had to maneuver the whole speaker instead of just the driver while I was working on it. On the second, I was intimidated by the tangle of wires and was worried I would rewire one wrong. So I would remove one driver, refoam it, and then replace it before I pulled the next one. Doing this, you could also test it with the MM.

Do you have the equalizer? It is a must have for 901s although I don't know if it's required if you use the Bose receiver. Besides rotted foam, no EQ may be a reason it sounded bad.
 
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