LS90 MW7100 driver replacement

vc69

I had a mid driver take a crap last night. I believe the rubber surround glue was old enough that it dried out and allowed the voice coil to short.:eek:

I called Polk CS this morning and was informed that they only have MW7010 as a replacement driver so I ordered two to maintain balance with the pair.

My questions are:
Does anyone have any input as to the difference between the 7100 and the 7010?
Are there any tips or tricks in the vast knowledge base here for things I can do to check the remaining 7100 driver without having to re-glue all the other poly-surrounds?
Is that even plausible?
Lastly, in your opinion, should I be looking for used 7100's?

I am also quite interested in any feedback on crossover modifications that have been made to this model of speakers. Has anyone done anything of that sort and if so what were the results?

I love my LS90's and would be willing to sink some cash into them if the results would be noticeable.


Thanks for any input you guys can provide.

adam2434

I can't answer your questions, but am interested in this topic, being a fellow LS90 owner.

Did Polk provide any additional info about the 7010? Like, are its electrical and mechanical characteristics very similar to the 7100? I guess I would start with trying to get more info from Polk. They likely won't give you actual woofer data, but might be willing to give you an idea of how close they are to each other.

The other question I would have is whether there is an ideal position for the replacements. I believe the top 2 woofers play a different range than the bottom 2, although I do not believe it's a classical 3-way design. It could be that putting the replacements in one of the bottom 2 positions would have less overall impact to the sound. Again, maybe a question for Polk.

The only thing I would do at this point to check the other woofers would be to inspect the surrounds and gently push on the cones to detect voice coil rubbing.

vc69

I have thoroughly checked the other drivers. No voice coil rub or surround loose thank goodness. I think you may have a good suggestion regarding replacing a bottom driver. Current research seems to indicate that the 7010 replacement is sub-par.

wallstreet

I've replaced one. The appearance is slightly different but I have noticed no audio differences. It would be hard to tell anyways. You have seven 7100's and one 7010 pumping prodigious amounts of decibels.

vc69

Well the 7010's arrived today. I'm going to install them tonite so we'll see. I am going to install them in the lowermost position and in a mirrored configuration so hopefully, they won't affect the overall character too much.

adam2434

Yes, please report back.

As a side note - was the 7010 a stock driver in a different speaker of the same era - perhaps from the original RT series? Or, was it created specifically to be a replacement for the 7100. Just curious if anyone knows.

stone of tone

Thanks vc69 for the point to this thread. How did it go? I love my LS90's and would go this same route to keep them.

vc69

adam2434 wrote: »

Yes, please report back.

As a side note - was the 7010 a stock driver in a different speaker of the same era - perhaps from the original RT series? Or, was it created specifically to be a replacement for the 7100. Just curious if anyone knows.

I really have no idea. The 7010's look a little different and do not have the "star" looking thing on the voice-coil domes.

I am actually quite pleased. I honestly have heard no difference.

shaironbob

I also have one that has failed. It appears to be glued in. I'm unable to get it out. Any suggestions would be greatly appreciated.

ken brydson

shaironbob wrote: »

I also have one that has failed. It appears to be glued in. I'm unable to get it out. Any suggestions would be greatly appreciated.

Shouldn't be glued in. If original, they've been in there a long time. Might need a little coaxing with a putty knife.

Good luck and welcome to CP.