Is it ok to run a speaker with a deteriorated foam?

Is it ok to run a speaker with a foam that has separated in several spots (or is totally gone?).

I got some goodwill NHT 1.8 towers but the upper drivers on each tower have almost all missing foam surrounds.

If I plug them in just to hear them (lower volume, of course), will I potentially do damage, or does the spider do enough to keep them centered?

What damage could I do if I do it, but keep the volume down.

Tim

I asked a similar question awhile ago. The consensus was that it's not a good idea, but if you do, put the speaker in its back and don't play loud.

If your just trying to see if the drivers are working, so with very low volume, you should be OK. You turn it up to see how loud you can go, that is a problem

Not a good idea. Ok to test at (very) low volume but generally best avoided.
The damage that could be done would be most likely deformation of the voice coil. A dragging voice coil would pretty much require replacement (i.e., no amount of shimming will typically "fix" a distorted VC).

If you need to test a speaker/driver, use a DMM to see if it is "open". You could power them up at low levels, but with missing foam, you are risking VC damage that might not easily be resolved. So the basic answer is NO--don't do it.

savatage1973 said:

If you need to test a speaker/driver, use a DMM to see if it is "open". You could power them up at low levels, but with missing foam, you are risking VC damage that might not easily be resolved. So the basic answer is NO--don't do it.

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There you go... Done.

IBTL.

Seriously though, would you test-drive a car with disintegrated shocks and springs?

Seriously though, would you test-drive a car with disintegrated shocks and springs?

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How else would i know the shocks and springs were deteriorated?

bowtie427ss said:

How else would i know the shocks and springs were deteriorated?

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Push down on a corner of the vehicle and release. Or look for leaking around the strut/shock. Same way your state safety inspection does it!

Akin to would you want to drive down Pike's Peak on 30 year old tires, clearly weather-cracked and extremely poor shape, to see if it's driveable?

Now if they are White Van Speakers......

captouch said:

put the speaker in its back and don't play loud.

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This. Just loud enough to check that each driver is working. Then stop messing with it until you get new foams.

My take is as long as there is enough foam to keep the voice coil centered and you don't turn it up loud enough to cause overexursion of the cone then its fine, but it won't be for long, I would always keep my eye on it while waiting for new foams to arrive.

If there is no foam at all then I'd only play at very low volume for a few seconds with the cabinet laying on its back,

no play

use a dvm and yes I understand the previous owner/abuser may have trashed the voice coils already and how would you know ? a.) Usually if done with enthusiasm and ignorance - the VC will be open or occasionally shorted - this you can find out with a meter. b.) foam kits aren't all that expensive and while a PITA to install - still -worst case you install new surround and das iz kaput. c.) When foam surrounds get in this state it's fair to assume that the rest of the surround is just waiting to disintegrate in front of your eyes. You can ge away with the low volume test -but you'll hate yer self in the morning the very first time you permanently trash a repairable driver .
one of the great mysteries of audio life is what's going on with all the folks who continue to run speakers with rotted/holed surrounds - these sure do sound awful ?