Is there a grinding/rubbing sound/sensation when you push the cone, or does it move freely?
Based on this, both are pretty far off, though until suitably loosened up, no way to know for sure: Coral Beta 8 Fullrange Loudspeaker Measurements Data and Information Full Range
GM
GM
so ive had the speakers running since yesterday and 1.8 q(ts) seems to be the lowest figure i can get from the driver,i also gave the surround a lite wipe of 50/50 ahcohol and water which did bring the figure down to about 1.3 but as it dried it the higher figure came back.
so with that in mind what should i do? give up? what effect is this going to have on the sound? what would be your next step?
so with that in mind what should i do? give up? what effect is this going to have on the sound? what would be your next step?
Run it in at progressively higher safe/max excursion since ferrite magnets tend to only lose their 'edge' if heated to extreme temps [propane torch high], so the lower in frequency [I use 1 Hz] the better as the other chemicals I might use depending on type/condition could/would eat it up.
Re alcohol, might work if [re]applying as required while being flexed, especially if using industrial strength, but it's a drying agent, so long term maybe the wrong choice and why if they were mine I'd carefully test with Wintergreen and/or Vit. E skin oil, which will clean and lubricate some types of foam/sponge, lossy rubbers and dissolve others or at least use as a protective coating/lubricant after the alcohol 'rub' if proven safe.
GM
Re alcohol, might work if [re]applying as required while being flexed, especially if using industrial strength, but it's a drying agent, so long term maybe the wrong choice and why if they were mine I'd carefully test with Wintergreen and/or Vit. E skin oil, which will clean and lubricate some types of foam/sponge, lossy rubbers and dissolve others or at least use as a protective coating/lubricant after the alcohol 'rub' if proven safe.
GM
They're not like the B8s? Specs imply the same except bigger frame size: Coral Beta 8 Fullrange Loudspeaker Measurements Data and Information Full Range
If doped cloth like Altec, et al, then use fingernail polish remover [acetone with a little baby oil] and a cheap brush such as these or similar: 36 Pc 1/2 in. Horsehair Bristle Acid Shop Brushes
Need to be careful and only work the flex ribs as it will soften the surrounds mounting. Don't want to have to reinstall them, though sometimes better to just replace.
GM
If doped cloth like Altec, et al, then use fingernail polish remover [acetone with a little baby oil] and a cheap brush such as these or similar: 36 Pc 1/2 in. Horsehair Bristle Acid Shop Brushes
Need to be careful and only work the flex ribs as it will soften the surrounds mounting. Don't want to have to reinstall them, though sometimes better to just replace.
GM
Humm, that's for doped accordion cloth surrounds, [touched up my 'weeping' Altecs today/been super hot here] so is that half roll made with doped cloth? Looks like some sort of sponge rubber to me, which the acetone will likely dissolve if not immediately, then over time with no way AFAIK to neutralize it.
GM
GM
I tried a lot of things/solvents (including full strenght acetone) on the surrounds of the ones i had with no luck.
dave
30 years ago I had a pair of Beta 10 in a back loaded horn and I liked the bass.
Here you can find a drawing of the cabinet:
Coral Speakers
Here you can find a drawing of the cabinet:
Coral Speakers
thanks for the link 
so today i quickly knock up a pair of frames to mount them in for measuring.
but the metal screwed around with the measurements
so im now letting them run through some test tones to see if that loosens them up,fingers crossed.
i think the surrounds are made of cloth as you can see the weave and also they are not opaque .
the saga continues!
so today i quickly knock up a pair of frames to mount them in for measuring.
An externally hosted image should be here but it was not working when we last tested it.
but the metal screwed around with the measurements
so im now letting them run through some test tones to see if that loosens them up,fingers crossed.
i think the surrounds are made of cloth as you can see the weave and also they are not opaque .
the saga continues!
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