After a long wait I was informed that unfortunately the guys from speakerrepairshop.nl was not able to get hold of the original spec surrounds.
Full set of measurements before and after would be the only way to justify such drastic change.
Xmax was around +/-4mm with the half round, what do you think the excursion limit is with the flat surround?
My bet is it makes "pup-pup' noise at no more than 2mm peak to peak, but I'm curious how much stretch before noise..
I was only going to use them above 200 hz or so. Hence the limited surround travel being an acceptable compromise.
They would be working perfectly fine with original surround above 200Hz. But you had an itch, so you scratched it.
Since the original surrounds are only reasonably within specs when applying methyl salicylate (wintergreen oil) once a week, I decided that something had to be done, so I have ordered these from tlhp in France. Dimensions are fairly close to the originals. Hopefully they will not introduce any bad resonance or otherwise alter the performance to much.
For those who want to try to keep the original surrounds alive, here are a few notes from my trials.
Jacob
For those who want to try to keep the original surrounds alive, here are a few notes from my trials.
- Add a few percent silicon oil to the methyl salicylate. This seems to trap the methyl salicylate a bit better. It will however evaporate fairly quickly.
- Apply two or three times with a q-tip once a week.
- It might dissolve the glue on the polypropylene membrane, but it can successfully be reglued without too much trouble.
- On a warm day resonance frequency can be restored to original specs. After a day it starts to increase.
- There is a very clear improvement in perceived sound quality right after methyl salicylate is applied. Without, they sound unpleasant and harsh.
Jacob
No. They weren't matching in specs and in overall sound to each other. The flat foam would work fine, but its not worth the hassle.
With hardened surrounds they have different midrange response. I checked myself. I'm a little more picky than most people. I did notice the surrounds were very close to the ones on the SB13PFCR25, which I have a few of. They'd be a reasonable sacrifice to transplant onto the P13s.
I thought I'd better give an update on the replaced surrounds (#87) I ordered from TLHP in France. I used glue from Good HIFI which I found easier to work with than what I got from TLHP. I shimmed up the cone (using pencils) and glued the surround onto it first, then removed the pencil shims and glued it to the frame while making sure the voice coil did not rub.
They have now been playing for about 3 months and I'm very happy.
I really should do at least an impedance measurement, but right now I really can't be bothered since the dimensions of the new surround is so close to the original. The ME2's are playing effortlessly again.
Jacob
They have now been playing for about 3 months and I'm very happy.
I really should do at least an impedance measurement, but right now I really can't be bothered since the dimensions of the new surround is so close to the original. The ME2's are playing effortlessly again.
Jacob
I don’t know if the following has been suggested but for > 20 years, BMW has recommended a product called gummi pflege for application to rubber door seals on their cars. I wonder if this will help with hardened surrounds.
How did you noticed the hardened surrounds? My ME2 still play fine, but they aren't in my main system and I was wondering what to look for?
Thanks.
Depending on the severity it is quite easy to feel with your fingers. If you gently poke the surround there will be a delay in the time it takes to return to original form. Also, everything what markbakk says.
As for the sound, the effect I could hear was distorted voices that sounded strained and stressed. Not pleasent at all. I suspect this is the result of introduced resonances (?).
If you can measure impedance it is quite easy to see if the resonance peak has wandered up significantly. Mine was above 120Hz if I remember correctly.
Cheers
Jacob
It's all the same as with my examples before the upper suspension was replaced. Complete change of all TS parameters compared to the datashhet.
Post #31
Post #31
P13WH before and after surround replaced.
Ebay rubber surround (thnaks @NIXIE62 ) , fixed with PVA craft shop adhesive.
fs was 281Hz - now 61Hz (data sheet 60Hz)
Qms doubled to 2.6 though. Does the adhesive affect this parameter?
1. : Old hardened rubber surround
2. with replacement surround
Ebay rubber surround (thnaks @NIXIE62 ) , fixed with PVA craft shop adhesive.
fs was 281Hz - now 61Hz (data sheet 60Hz)
Qms doubled to 2.6 though. Does the adhesive affect this parameter?
1. : Old hardened rubber surround
2. with replacement surround
I never managed to get factory parameters by replacing the suspension. And I don't even know if the drivers had factory parameters at the start.
The new rubber surround is the reason for the changed Qms. I think that is preferable to have a higher value.
The new rubber surround is the reason for the changed Qms. I think that is preferable to have a higher value.
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I emded up getting the surrounds from Speakerrepairshop.nl
They had a surround model # R5C11 which fits correctly.
They had a surround model # R5C11 which fits correctly.
Or should I say, we'll see if it fits correctly. According to the measurements, their R5C11 is supposedly the correct surround for the P13WH-00-08. The dims on these are 126mm, 113mm, 98mm, 91mm.
The original surrounds made by Kurt Müller, Germany has slightly different measurements, but the ones you found will likely be fine. Here is a screenshot from the catalogue:
I got confirmation by Scan-Speak that these were the original production surrounds.
Cheers
Jacob
I got confirmation by Scan-Speak that these were the original production surrounds.
Cheers
Jacob