Polk Monitor 7B Disaster - Did I Ruin My Speakers?

Freak When C

Man do I feel like a clutz. I accidentally knocked one of my Monitor 7B's off the stand. :eek:
I can't believe I did this. :(

Well, so I picked it up and placed it back on its stand and inspected for damage. There's no physical damage to the cabinet that i can see. But when I picked it up I heard some strange popping kind of sound. Almost sounded electrical but it can't be, nothing was powered on when the mishap took place (luckily). But now I figured out what made this popping noise.

When I lifted the speaker to place it back on the stand, I must have gently touched the edge of the foam round ring of the passive radiator. Normally y'all would say I was a clutz two times; once in knocking it off the stand and again with placing the speaker back on the stand because fingers should not come in contact with the tweeter, driver or radiator. I know this but in this case it's actually good that I did and heard the popping sound, because I would have thought everything was fine, otherwise. But I don't think that's the case.

I can re-create the popping sound (which sounds like pops when spinning vinyl that's dirty or scratched) by softly pressing the foam round outer ring of the radiator. I think the popping sound must be air and its coming from the driver when I press the foam around the radiator. I checked my other speaker and it doesn't make any sound if I gently press on the foam surrounding the radiator.

So what should I do? I'm afraid to turn on my amp because its a tube amp and if there's something wrong with that speaker (which it sounds like there is) it could cause even more problems. Any idea what happened or why I hear this popping sound out of the driver? I can dig out an old SS amp and I'll probably do this but I don't want to cause more damage. Perhaps the speaker can be repaired. Not sure what I should do next. I'd really appreciate some expert help as nothing like this has ever happened before.

woodsman10b

The passive is not a powered speaker, so testing with the power on low will not harm anything else. Another thing, there should be no foam surrounds on these speakers, only rubber surrounds.

Toolfan66

On your passive if you pull it out and look in back of it in the hole in the center, there is a little round piece of cardboard like ring in it about 3" round. it may have come free and is rattling with vibration. I had to drill 2 little small holes and put a little glue in the holes to hold it back in place.

Easy fix, good luck as I bet this is what it is. let us know how it goes..

AudioGenics

I think I may have a passive radiator
if you need one...or as a spare
(one) 8 inch passive radiator - like new condition
date of assy. 11/22/91 #BD0803-B SW83

Freak When C

woodsman10b wrote: »

there should be no foam surrounds on these speakers, only rubber surrounds.

Yes, that is correct. It is indeed rubber, not foam. Rubber surrounds on the driver as well.

TOOLFORLIFEFAN wrote: »

On your passive if you pull it out and look in back of it in the hole in the center, there is a little round piece of cardboard like ring in it about 3" round. it may have come free and is rattling with vibration. I had to drill 2 little small holes and put a little glue in the holes to hold it back in place.

Easy fix, good luck as I bet this is what it is. let us know how it goes..

OK, I just got home from work and first off, I want to be clear that its not a rattling sound at all. its a pop that comes from the driver when I very gently press the rubber surround on the radiator. Its like I can make it go pop, pop, pop if I gently press three times. And if I put my ear up to the driver I can hear a suction sound when I press the rubber surround of the radiator. It almost sounds like a piston in a cylinder. Very strange. Not a rattling sound at all. Any other ideas?

I still think I should check the radiator. So I removed the four screws holding the radiator in place. I tried to lift it out so I can check the back to see if the cardboard like ring you speak of had come loose. But with the screws removed I can't seem to get the radiator to break loose from the cabinet. Do I need to pry it loose with a flat-head screwdriver or something?

Toolfan66

Freak When C wrote: »

Yes, that is correct. It is indeed rubber, not foam. Rubber surrounds on the driver as well.



OK, I just got home from work and first off, I want to be clear that its not a rattling sound at all. its a pop that comes from the driver when I very gently press the rubber surround on the radiator. Its like I can make it go pop, pop, pop if I gently press three times. And if I put my ear up to the driver I can hear a suction sound when I press the rubber surround of the radiator. It almost sounds like a piston in a cylinder. Very strange. Not a rattling sound at all. Any other ideas?

I still think I should check the radiator. So I removed the four screws holding the radiator in place. I tried to lift it out so I can check the back to see if the cardboard like ring you speak of had come loose. But with the screws removed I can't seem to get the radiator to break loose from the cabinet. Do I need to pry it loose with a flat-head screwdriver or something?

Yes to prying to get it off but it sounds like a driver the way you discribe it..

Agent

Forgive me if this question is stupid, but why is it terrible to touch a speaker? I can understand jabbing or poking a tweeter or the center of a speaker in but just simply touching it? Am I missing something here or is it specific to his type of speakers?

Freak When C

Agent wrote: »

Forgive me if this question is stupid, but why is it terrible to touch a speaker? I can understand jabbing or poking a tweeter or the center of a speaker in but just simply touching it? Am I missing something here or is it specific to his type of speakers?

Well I meant in general you should probably not make it a habit of touching the actual speaker (driver, radiator, tweeter) when lifting/moving a speaker. I didn't mean to imply you should never touch it.

If a damaged driver is suspected, what should I do to confirm? And if it is damaged, should I replace both drivers in each speaker?

ben62670

Put a multi-meter on the speaker terminals and measure the resistance.

Freak When C

Hey Ben, thanks for weighing in. I never thought of that. I don't have a multi-meter but I can see now that I should. I will certainly be picking one up here as soon as possible. Any suggestions on a decent one ? And from what I described so far, does it sound like the fall damaged the driver?

gp4jesus

quick shout to agent: did you find your A7s soften as time went on? Just got pair love the imaging, just wondering about the slight brightness

Toolfan66

You won't have to replace both drivers just one if that is the case. Can you pull the driver and see what Number is on the back "MW6500?" If you do need a driver I might have one here, if so let me know as I will give you a killer deal on it if I have a matching one.

+1 on what Ben said..

Freak When C

To pull the driver I just remove the four screws, correct? And if it needs some persuasion to break it loose from the hole in the cabinet that its mounted in, then prying it loose with a flat-head screwdriver is the proper method, correct? (never done this before)

Toolfan66

Freak When C wrote: »

To pull the driver I just remove the four screws, correct? And if it needs some persuasion to break it loose from the hole in the cabinet that its mounted in, then prying it loose with a flat-head screwdriver is the proper method, correct? (never done this before)

Yep;) and if it is being stubborn pry around in about 3 or 4 places around the driver with little preasure, she will come free.

Freak When C

OK, she broke free. MW6500 she is. I noticed a couple things about the driver:

1.) the magnet on the back is not centered over the the silver metal (aluminum?) round disc mounted to the back of the driver. its definitely off center. Possibly this happened when it fell. Looks like I could maybe move it over and center it. Should it be centered and should I try and move it?

2.) the gasket that goes around where the mounting screws is kind of not laying flat in one area which doesn't look right and perhaps is cause there to be a leak, i.e, not an air tight seal. This seems like it could be what's causing the pops I heard, no?

Toolfan66

First: DO NOT TRY AND MOVE THE MAGNET. not all magnets were glued dead center.

Second: Take your fingers and gently push the driver in and out. if you feel any rubbing at all then the magnet has shifted and the driver is gone. it should move in and out smoothly.

Third: if this is the case I have a replacement Driver MW6500

Freak When C

Gently pushing the driver in and out re-creates the popping sound and it does not move freely. The magnet is also very much off center. Sounds like she's a goner.

What kind of deal can you offer me for a replacement driver?

Toolfan66

Freak When C wrote: »

Gently pushing the driver in and out re-creates the popping sound and it does not move freely. The magnet is also very much off center. Sounds like she's a goner.

What kind of deal can you offer me for a replacement driver?

I had a bad feeling thats what it was..


Hows $25 shipped sound..;)

Freak When C

Done deal, thanks. PM me.

Tony M

What a club....helping out at 11:30 at night. Priceless!;):cool:

Let's give an applaus. 19 posts from problem to solution. Gotta love this kind of empathy... I know I do!

Freak When C

Yeah, I couldn't have asked for better assistance and service. As Austin Powers would say, this is most excellent.

Thank you everyone. And a special thanks to TOOLFORLIFEFAN. Club Polk Rocks!