I have a RS 18" sub that has a Foam surround that is at least 20 years old and it is still in good shape.
Sunlight UV and Ozone are the biggest factors that cause foam rotting.
I used to have a very large smoke eater made for bars and it produce quite a bit of ozone.
I had it in the same room as my Infinity SM-150's and I had got in 1985.
They were fine for the First 10 years without any sign of rot until I got the smoke eater in about 1995.
After that they were completely shot by 2000!!!
Those where the only speakers I have ever owned that suffered from foam rot.
We had lots of foam on the walls in the studio I had and some of it started to break down as well.
When we tore it all out it, a lot of it was smoke filled and stinky but I was going to use the good pieces again in my news house.
I never had a chance to because I had them stacked up outside in the hot Florida sun and they didn't last even a year with that even though I had them covered up with some blue tarp.
They just disintegrated.
I still have some RS 8" woofers and various other drivers that are older than my RS 18" sub that still have the original foam surrounds intact too.
I look at it this way, if the foam lasts 10 or 15 years then I'm sure there will be a better product to replace them with by then.
Most all of the drivers I have seen from the 70's have suffered from this but not so many from the late 80's and 90's.
Although, It can and does still happen.
Rubber can go bad as well.
Maybe not so much with the Neoprene types though.
The rubber wheels on my Tape decks just recently started to break down and one is nearly 25 and the other is 20 years old and they both use the very same capstan tire.
Two years ago they were both just fine and didn't show any signs of failure at all.
They have gotten soft and the tape sticks to them and strips the oxide clean off of the tape!
I have also some much older machines with rubber parts that have gotten hard as a rock!!!
So you never know!!
It was claimed that Tascam had got a bad batch of rubber in that era when my machine was made but it last 18 years before it showed up and now I can't even hardly find one.
Tascam repair did have only 3 of them left for $60 a piece and I should have snagged them a few years ago.
Now they are $100 to $200 when I can find them on the web!!
I need 3 of them, 2 capstan rollers and a counter wheel and with my luck it had to happen when I just got a serious recording gig!!!
Anyhow sorry to go OT, But you never actually know how long they will last.
But, I would think that in this day and age of new formulations that it is not anything to worry over.
FWIW
jer
Sunlight UV and Ozone are the biggest factors that cause foam rotting.
I used to have a very large smoke eater made for bars and it produce quite a bit of ozone.
I had it in the same room as my Infinity SM-150's and I had got in 1985.
They were fine for the First 10 years without any sign of rot until I got the smoke eater in about 1995.
After that they were completely shot by 2000!!!
Those where the only speakers I have ever owned that suffered from foam rot.
We had lots of foam on the walls in the studio I had and some of it started to break down as well.
When we tore it all out it, a lot of it was smoke filled and stinky but I was going to use the good pieces again in my news house.
I never had a chance to because I had them stacked up outside in the hot Florida sun and they didn't last even a year with that even though I had them covered up with some blue tarp.
They just disintegrated.
I still have some RS 8" woofers and various other drivers that are older than my RS 18" sub that still have the original foam surrounds intact too.
I look at it this way, if the foam lasts 10 or 15 years then I'm sure there will be a better product to replace them with by then.
Most all of the drivers I have seen from the 70's have suffered from this but not so many from the late 80's and 90's.
Although, It can and does still happen.
Rubber can go bad as well.
Maybe not so much with the Neoprene types though.
The rubber wheels on my Tape decks just recently started to break down and one is nearly 25 and the other is 20 years old and they both use the very same capstan tire.
Two years ago they were both just fine and didn't show any signs of failure at all.
They have gotten soft and the tape sticks to them and strips the oxide clean off of the tape!
I have also some much older machines with rubber parts that have gotten hard as a rock!!!
So you never know!!
It was claimed that Tascam had got a bad batch of rubber in that era when my machine was made but it last 18 years before it showed up and now I can't even hardly find one.
Tascam repair did have only 3 of them left for $60 a piece and I should have snagged them a few years ago.
Now they are $100 to $200 when I can find them on the web!!
I need 3 of them, 2 capstan rollers and a counter wheel and with my luck it had to happen when I just got a serious recording gig!!!
Anyhow sorry to go OT, But you never actually know how long they will last.
But, I would think that in this day and age of new formulations that it is not anything to worry over.
FWIW
jer
The use of foam surrounds actually isn't determined by cost savings, as the cost differences is very few pennies (if even that much). The modern foam surrounds don't rot, have better cone edge damping and allow a longer, more linear cone excursion. On large drivers like Subwoofers, they also eliminate "Suck-Back" which occured often with the older non-foam surrounds that would, during high-Excursion, actually invert due to a partial (momentary) vacuum within the cabinet.
As I have friends that design and market their own line of drivers, I will tell you a little secret of the industry. The last thing they want to see, is their driver being returned due to a flaw, fault or failure. The postage involved all by itself, will literally "eat" the savings involved in using a cheaper surround in a production run. Notice that we haven't even counted the additional cost of the replacement driver!
Best Regards,
TerryO
As I have friends that design and market their own line of drivers, I will tell you a little secret of the industry. The last thing they want to see, is their driver being returned due to a flaw, fault or failure. The postage involved all by itself, will literally "eat" the savings involved in using a cheaper surround in a production run. Notice that we haven't even counted the additional cost of the replacement driver!
Best Regards,
TerryO
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Define modern Terry, was that last week ...
Modern? Last week certainly works....
Actually, when we were designing the "Shiva", which was originally "The Official Bass List Subwoofer" back in 1997-98 the Modern Foam had already appeared. As you might imagine, there was a lot of talk over the merits of each type of surround, although Dan Wiggins was very articulate in his thinking about foam. The first "Shiva" Subwoofer, as it was later named, was delivered to me 45 minutes after the initial shipment arrived at Avatar (later Adire) Audio. That Subwoofer was installed in a Cabinet that was already to receive it and went in a buddy's system (BTW: He's still using it).
Best Regards,
TerryO
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An externally hosted image should be here but it was not working when we last tested it.
MCM 8" High Excursion 55-2421
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Here are
An externally hosted image should be here but it was not working when we last tested it.
the Tang Band spec.
From what I understand the new w8740p is the same as the c series so here's there spec. seeing how the others don't want to load...
http://www.parts-express.com/pedocs/specs/264-854-tang-band-w8-740p-specifications-45675.pdf
I have some documents I found buried deep in the web of a Horn project that used them that happened about 10 years ago or so.
It showed actual A&B comparative measurements and tests that suggest that they are nearly the same driver with similar specs between the two.
Sorry, I am not sure if I still have the links to the pages but I did save all of the pages for safe keeping and my personal info.
It is the only detailed document of the driver that I have ever found on it.
I will look them up and see if I can find out who the author was and maybe post the pages that compare the two.
I had seen the write up some time before about 10 years ago when the driver first came to everyones attention.
But since MCM has such poor support as too their speaker spec's many have not tried them but just a few handful.
Since they were used in a horn they performed very well according to the document.
But, After a while it was stated the the spider eventually showed sign of weakening.
I once read this same report form someone on a forum back in that same time and it may very well have been the same author.
It was the only bad report I have ever read by any one that has ever used them.
I had the same ting happen to one or two of my RS 8" sub's were the spider came loose and I just simply glued it with some epoxy and never had an issue since.
This was not a very big deal though as it was in a horn type structure and they ran it for several days at full power and high excursions.
A very heavy and gruesome test for any driver but it did hold up well and the performance was very impressive as stated in the article.
I will look for those later tonight was I have to sift through 2TB drive that is full in order to find them.
jer
It showed actual A&B comparative measurements and tests that suggest that they are nearly the same driver with similar specs between the two.
Sorry, I am not sure if I still have the links to the pages but I did save all of the pages for safe keeping and my personal info.
It is the only detailed document of the driver that I have ever found on it.
I will look them up and see if I can find out who the author was and maybe post the pages that compare the two.
I had seen the write up some time before about 10 years ago when the driver first came to everyones attention.
But since MCM has such poor support as too their speaker spec's many have not tried them but just a few handful.
Since they were used in a horn they performed very well according to the document.
But, After a while it was stated the the spider eventually showed sign of weakening.
I once read this same report form someone on a forum back in that same time and it may very well have been the same author.
It was the only bad report I have ever read by any one that has ever used them.
I had the same ting happen to one or two of my RS 8" sub's were the spider came loose and I just simply glued it with some epoxy and never had an issue since.
This was not a very big deal though as it was in a horn type structure and they ran it for several days at full power and high excursions.
A very heavy and gruesome test for any driver but it did hold up well and the performance was very impressive as stated in the article.
I will look for those later tonight was I have to sift through 2TB drive that is full in order to find them.
jer
Hi,
If you search there is loads of info on the MCM driver,
its being going a long time. FWIW in this case you
just simply need about 10L per driver sealed, it
doesn't need to be well stuffed but some helps,
to get a low Q 0.4 to 0.5 sealed box alignment.
rgds, sreten.
There are some Zaph measurements in the fora.
If you search there is loads of info on the MCM driver,
its being going a long time. FWIW in this case you
just simply need about 10L per driver sealed, it
doesn't need to be well stuffed but some helps,
to get a low Q 0.4 to 0.5 sealed box alignment.
rgds, sreten.
There are some Zaph measurements in the fora.
Have you actually measured one (MCM) to confirm specs , Great deal or does specs flatter to decieve ..?
84db sensitivity , use 3 per side ..
I don't believe there is any deception in there spec I think they are actually better ,but I haven't ran any test on then except this utube bass test I was playing around with, just to see how low they would go and be audible . keep in mind these are in a sealed cabinet and I only had 25 watts running to each sub cabinet and at 10 hz you could not hear it that load but it rumbled my chest and at 25hz she;s coming alive ,you could definitely feel it. But Gerald will dig out his test results and post them soon. Ultimate Bass Test (Various Frequency Ranges) - YouTube
I have mine mounted in 2 sq ft. cabinet and they groulllllllllllllll, and give you a true clean drum reproduction and some the best organ tones as I use these for my Keyboard , I literally have tried to fault them but cant.
This is a correction of the upper statement about using a 2 sq.ft. cabinet , I have built so many lately I get them mixed up....
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