SDA SRS 1.2TL MW6511 Issue or Not?

kitetripper

Hello, I’m new here today but I’ve had my 1.2s for a number of years, they have sounded and continue to sound great. The pair I own were upgraded into 1.2TLs with a kit just before I got them and I have upgraded the cross-overs per someone's post/worksheet that was posted and vetted here years ago - a bit of pop and crackle for a while then some nice sweet sound after the caps burned in. All of my 6.5" drivers (6511 & 6503) still look practically new and there are no signs of over excursion in the surrounds. I very rarely crank my 1.2s; I usually prefer to savor the huge sound and wide sound stage and occasionally let them get a little loud.

The reason I’m posting is that I was recently turned on to a band called Gus Gus, dance music with some songs going a little over on the 4/4 bass/kick
While listening to the first song on Gus Gus vs The World - Anthem, I could hear a vibration in the left channel (on the bass/kick) and sure enough I have troubleshot that to a rattling MW6511. I have replaced one MW6511 already, for the same rattle issue, which I scored off Walter in Toronto a couple of years ago.
Well, I switched those two drivers within the same cabinet and I found that the newer MW6511 has less excursion whereas the rest of the MW6511s have more excursion, the rattling MW6511 driver has the most excursion - nothing looks extraordinary though with regard to the amount of excursion and this is at dance party volume levels.

So I am asking anyone who might know, should I expect more of my older MW6511s to show more excursion and then begin to rattle at louder volumes as they age?
Should I just bite the bullet and replace them all or is that knee-jerk?
Should I replace in pairs as in, as I replace a left driver then replace the corresponding right driver?
Should I move any new drivers to the stop of the column or the bottom, does that even matter?
I have not contacted Walter yet, I thought this would be a good time to ask around before I do.
Please feel free to add your two cents and thanks in advance for any advice and help.

nooshinjohn

There was no 2.1TL, though we are quite familiar with the 1.2TL... If you are getting a popping or "****" sound from the mid-drivers, I would first turn the volume down and then look at what type of amplification you are using.

What are you using to drive the speakers?

kitetripper

Thanks nooshinjohn, i'll edit my post from 2.1 to 1.2 - first post, dumb mistake.
I do not have a pop issue, please read on.
Amp is noted in my signature, Carver TFM55x which I have had serviced and all tech notes added.

nooshinjohn

There is no need to replace the drivers... perhaps someone will jump in and confirm that the TFM-55 is common ground or not.

It does sound like you may be over-driving the speakers a bit. I am not familiar with the music you are listening to. Does it occur with other music at the same volumes?

F1nut

I found that the newer MW6511 has less excursion whereas the rest of the MW6511s have more excursion, the rattling MW6511 driver has the most excursion

Does the new driver look a bit different with a larger dust cap and no exposed leads? Regardless, the rattling driver has a weak spider and should be replaced. Check eBay for an original replacement.

kitetripper

Hi F1nut, thanks for your reply.

I have attached pics of the one newer driver and one of the original drivers, but to answer your question about the newer driver: same size dust cap, no leads on the front, cone is less glossy than the original drivers.

Do I need to wait for a MW6511 on eBay (or elsewhere) or are the replacements that Walter in Toronto orders from the states just as good/equivalent?

Thanks.

Newer driver


Older drivers

motorstereo

Did you check to make sure they're wired correctly (in phase)?

westmassguy

As F1 noted, there may be a weak spider, or the spider could be torn or partially detached from the basket frame. You'll have to pull it and insect it. The new replacement drivers need to break-in, just like a new pair of shoes. The suspension will become more relaxed over time. I noticed on the photo you posted of the new driver, you didn't trim the rubber surround by the mounting holes. Two look like you've separated the surround from the basket frame. This will cause air leakage, and a flapping or buzzing noise.

nooshinjohn

westmassguy wrote: »

I noticed on the photo you posted of the new driver, you didn't trim the rubber surround by the mounting holes. Two look like you've separated the surround from the basket frame. This will cause air leakage, and a flapping or buzzing noise.

Bingo!

kitetripper

@ motorstereo - thanks for your reply.
Polks in phase, I went through all that when I got them and when I upgraded my x-overs, years ago.

kitetripper

@ westmassguy thanks for your reply. The image of the new driver is misleading, there are no leaks on that driver and it sounds solid. I made cutouts for two of the screws, the other two didn't seem to need it, but it was nice to learn that you guys trim the excess near the screw from the new, replacement drivers - I was not sure what to do about that when I received that new one in 2012. I'll be sure to develop an elegant method for trimming the replacement I need for the MW2511 that is currently rattling at higher volumes.

westmassguy

kitetripper wrote: »

@ westmassguy thanks for your reply. The image of the new driver is misleading, there are no leaks on that driver and it sounds solid. I made cutouts for two of the screws, the other two didn't seem to need it, but it was nice to learn that you guys trim the excess near the screw from the new, replacement drivers - I was not sure what to do about that when I received that new one in 2012. I'll be sure to develop an elegant method for trimming the replacement I need for the MW2511 that is currently rattling at higher volumes.

- I mentioned it, because the roll on the surround is deformed.

F1nut

same size dust cap, no leads on the front, cone is less glossy than the original drivers.

Maybe it's just me, but the dust cap looked larger on the new drivers.

The new drivers available in Canada are exactly the same as the ones here. Although, they are spec'd the same some folks say they perform differently. I'd look for the originals.

Mr. Bubbles

westmassguy wrote: »

kitetripper wrote: »

@ westmassguy thanks for your reply. The image of the new driver is misleading, there are no leaks on that driver and it sounds solid. I made cutouts for two of the screws, the other two didn't seem to need it, but it was nice to learn that you guys trim the excess near the screw from the new, replacement drivers - I was not sure what to do about that when I received that new one in 2012. I'll be sure to develop an elegant method for trimming the replacement I need for the MW2511 that is currently rattling at higher volumes.

- I mentioned it, because the roll on the surround is deformed.

I'm a couple days late on this but this is exactly what i saw first. The roll is slightly deformed at 3 of the screw mounting locations. This definately shows a problem. How big that problem may be another story.

Either way older drivers will "have more excursion" for a given amount of power as they are more broken in than newer drivers. This doesn't mean they are bad. Noises on the other hand indicate problems. The source of the noise may indicate a bad driver or another simpler issue like a leaky cabinet/ gasket/ driver surround, oxidized connections, etc. One cant really tell until diagnosed properly.

Ageing drivers can also benefit from things like higher damping factor amplifiers (especially when played at high volumes), better quality/ lower impedance speaker cables that are as short as possible as well as being sure the speaker cabinet is properly sealed and all drivers are mounted and sealed properly as well.

F1nut

Mr. Bubbles, I respectfully disagree with your thoughts on the damping factor and speaker cable length.

motrctyman

When I picked mine up, they had a horrible rattle in them. One of the reasons I got them so cheap.

One of the cross braces had come loose in the back from the hotglue they used to fasten them. Quite the process to get screw and glue in there but fixed it.

Not saying that is your problem, but happened to me....

F1nut

For the record, Polk did not use hot glue inside your speaker cabinet.

kitetripper

Hi all,
As far as I am concerned, F1Nut had the answer, thanks - worn out spider, replace the driver.
I ordered and received the replacement driver and noticed the surround does not have a cut-out at the location of the hole for the mounting screw. The surround just lays on top of the hole.
I'm wondering how anyone has dealt with this?
Have you come up with a solution to trimming the surround with something other than an x-acto knife perhaps?
Many thanks in advance...
W

F1nut

I haven't purchased any of the new drivers, so no trimming experience with those, but I'm thinking a template could be made to copy the original cutout shape then overlaid on the new driver using the ever trusty X-acto knife to trim the rubber. Perhaps a piece of hard plastic ground to shape with a Dremel for the template.

westmassguy

A stove bolt with square nut would make a good template for a notch. I've also used a wood screw, and made a half-round cut in the rubber. Keep well away from the fold where the roll starts.