Bose 501 - Diagnose and Repair

[501noob]

I'm a beginner here so any advice or help would be much appreciated. I saved some 501s from going to the dump that were my father in laws. They are functioning, but the sound leaves a bit to be desired. To start one speaker is worse than the other. It has more cracks and seems to be cutting in and out or volume is fluctuating as if its a power issue. The other seems ok but definitely needs a clean up. Both are visually in great shape and have been sitting in the original boxes for decades. I'd like to get them sounding better and fully functional but not sure what I should be looking for. I removed the grills (used a screw driver and pried gently) and was able to snap some pics. If anyone has experience or recommendations on what I should be looking for or what to fix I'd be much appreciated. They will definitely need refoamed as you'll see in the pictures.

 

[Eppie]

I'm reluctant to recommend restoring speakers that were not very good but I understand the nostalgia aspect. This would simply be a labour of love. Do not expect to make money on these.

You first need to determine if the one speaker is bad. Cutting out and volume fluctuation is a bad sign. Simple test is to swap the two speakers. If the same speaker cuts out, it is the speaker. If the other speaker cuts out, it is the receiver that needs servicing. Do not play them loud for any length of time as a bad voice coil could damage the receiver.

If the speaker is defective, then your restoration is likely no longer possible. Cutting out would indicate either a bad voice coil or bad crossover. The crossover can be repaired with modern parts; replace the capacitors with equal value parts. I'm curious what the glass tube is. It would be uncommon to have a fuse in-line in the crossover that is not user replaceable. If crossover is ok and the voice coil has gone bad then the speaker is no longer repairable.

If the individual speaker voice coils are ok, you can order new surrounds and glue from Simply Speakers. Once everything is sounding ok then you can consider refinishing the cabinets. That would be my approach.

 

[isolar8001]

Ask here also...AudioKarma is geared towards older/classic speakers and repairs.
The cabinets look real nice. If you decide not to repair there will surely be someone who wants those cabinets.

As Bose speakers go, the 501's were sorta OK...but nowhere near their selling price for what you got.

Speakers

The most vital link in the chain.....

audiokarma.org

 

[TLS Guy]

I'm a beginner here so any advice or help would be much appreciated. I saved some 501s from going to the dump that were my father in laws. They are functioning, but the sound leaves a bit to be desired. To start one speaker is worse than the other. It has more cracks and seems to be cutting in and out or volume is fluctuating as if its a power issue. The other seems ok but definitely needs a clean up. Both are visually in great shape and have been sitting in the original boxes for decades. I'd like to get them sounding better and fully functional but not sure what I should be looking for. I removed the grills (used a screw driver and pried gently) and was able to snap some pics. If anyone has experience or recommendations on what I should be looking for or what to fix I'd be much appreciated. They will definitely need refoamed as you'll see in the pictures.

Take them to the dump. Those speakers were junk when new and will be junk if you fix them which I doubt is possible. as I doubt there is a reconing kit for that driver. Those speakers are not worth a minute of your time.

 

[501noob]

I'm reluctant to recommend restoring speakers that were not very good but I understand the nostalgia aspect. This would simply be a labour of love. Do not expect to make money on these.

You first need to determine if the one speaker is bad. Cutting out and volume fluctuation is a bad sign. Simple test is to swap the two speakers. If the same speaker cuts out, it is the speaker. If the other speaker cuts out, it is the receiver that needs servicing. Do not play them loud for any length of time as a bad voice coil could damage the receiver.

If the speaker is defective, then your restoration is likely no longer possible. Cutting out would indicate either a bad voice coil or bad crossover. The crossover can be repaired with modern parts; replace the capacitors with equal value parts. I'm curious what the glass tube is. It would be uncommon to have a fuse in-line in the crossover that is not user replaceable. If crossover is ok and the voice coil has gone bad then the speaker is no longer repairable.

If the individual speaker voice coils are ok, you can order new surrounds and glue from Simply Speakers. Once everything is sounding ok then you can consider refinishing the cabinets. That would be my approach.

Very helpful! Thank you for the reply, and the ideas on isolating the issue. My guess is I'll end up needing something beyond the surround repaired on at least one. I like these primarily for the look as I've heard they aren't the highest quality, so I won't be too upset if the original speakers end up unrepairable and I need to install some new ones.

 

[501noob]

Ask here also...AudioKarma is geared towards older/classic speakers and repairs.
The cabinets look real nice. If you decide not to repair there will surely be someone who wants those cabinets.

As Bose speakers go, the 501's were sorta OK...but nowhere near their selling price for what you got.

Speakers

The most vital link in the chain.....

audiokarma.org

Thanks! I'll add the post there to see what help I can get. Ya I really wanted to save them because they are still in great condition externally. Hopefully I can get them back to functional.

 

[501noob]

Take them to the dump. Those speakers were junk when new and will be junk if you fix them which I doubt is possible. as I doubt there is a reconing kit for that driver. Those speakers are not worth a minute of your time.

I'd rather not just dump them because the box is in great shape and I like the look of them. Not dying for the perfect speaker, but from what I've read the sound quality wasn't junk. I found the surrounds online but I'll probably have to replace the sub if that doesn't help.

 

[isolar8001]

I'd rather not just dump them because the box is in great shape and I like the look of them. Not dying for the perfect speaker, but from what I've read the sound quality wasn't junk. I found the surrounds online but I'll probably have to replace the sub if that doesn't help.

501 pages.

Search results for query: Bose 501

What TLSGuy is referring to is the drivers that Bose used...and charged dearly for. (and the design in general)
They were as cheap as you could get.
I worked for one audio/video company and we kept a pair of 501's on a cart disassembled to show customers what were in them when they asked if our selection was as good as Bose.

 

[TLS Guy]

I'd rather not just dump them because the box is in great shape and I like the look of them. Not dying for the perfect speaker, but from what I've read the sound quality wasn't junk. I found the surrounds online but I'll probably have to replace the sub if that doesn't help.

Honestly you are wasting your time. If you change drivers the box will be the wrong volume and the crossover will not be correct. Reverse engineering a speaker which is what you are proposing is next to impossible. Those crossovers look like a birds nest, actually not as neat. I built far neater crossovers than those when I was seven years old.

What the drivers actually need is reconing with original parts. If you just replace the foam surround then the driver will most likely have gap rub, where the voice coil rubs on the pole piece of the magnet and makes a terrible buzz. To do the job properly with a driver that decayed, requires a new cone, surround and voice coil cap. It takes factory shims to align the VC properly so you don't get gap rub, and special loudspeaker glue to glue the surround and the dust cap. I have reconed speakers and there is significant skill to doing it properly. If there is no reconing kit of original manufacture you are going to be out of luck.

 

[Mikado463]

@501noob, first off, welcome to the fold ! Second, you're getting some good advice here on not wasting your time with a truly sub-standard speaker. Save your $$, focus your attention forward, read some of the speaker reviews here on Gene's (Audioholic's) review list and go from there.

plenty of knowledge on this forum to help you out

 

[Alex2507]

Honestly you are wasting your time.

As are you.

The guy wants to repair the speaker because he likes the way it looks.

I like the look of them. Not dying for the perfect speaker

Maybe a little voice coil rub after the expense and effort of that endeavor isn't as big a turn off as you think!

 

[Eppie]

@501noob TLS Guy is correct in that you can not just drop in different drivers that are the same size. Each driver has unique properties that determine the size of cabinet needed and the crossover design. You would likely end up with something worse than the original.

So you either need donor speakers from another 501, a cone and voice coil replacement kit (which would be ideal but likely not available), or a surround kit. Plenty of people have replaced surrounds without the use of shims, but there is risk of the coil rubbing if you are slightly off center. The solution would be to completely remove the new surround and glue and try it all over again. Whether it's worth the effort is up to you, but as mentioned, those were not very good speakers to begin with. This would be more or a learning exercise but the surrounds should not be that expensive.