CX50 foam or rubber

[Pindsen]

Hi,
Replacing surrounds on CX50 (or CX100) you can many places choose between foam or rubber.
Was the CX50 from factory produced with foam surrounds? and would the characteristics of the speaker change notably by repair with rubber surrounds?

Some claim that using rubber surrounds last longer but what about the sound quality?
What you you choose?

/Pindsen

 

[sonavor]

Hi,

The originals were foam type surrounds.
How noticeable the difference is will be purely dependent on the listener.

If you are trying to keep things to the original design then stick with foam surrounds.

It would be interesting if you were to do one with foam surrounds and the other with rubber, then see if you can tell a difference.
Those are pretty easy drivers to replace surrounds on so it wouldn’t be difficult to try.
Plus, those being small drivers, the surrounds don’t cost much.

If you do the test be your and post about it here.

-sonavor

[AdamS]

The originals were foam, therefore I’d replace them with foam.

Changing to rubber will alter the parameters of the drivers and make them sound different. Whether this is an improvement or not is purely subjective.

[Mark-sf]

Specifically changing from foam to rubber will alter the low frequency resonance changing the bass response.

[Pindsen]

I will try to compare and return with my perspective as I have both.

/Pindsen

[Dillen]

Foam, where foam was used originally.
Repalcing with rubber changes the T/S parameters drastically.
If you only had the T/S to compare, you would never suspect it to be the same driver.

Martin

[Pindsen]

What does T/S mean?

/Pindsen

[Glitch]

Thiele/Small parameters

BTW, one thing that has not been mentioned is that the lifespan of modern foam is likely much longer than the original foam. Progress in material science has advanced in the decades since the original surrounds were produced. Of course, one could still end of with bad surrounds, either foam or rubber, if purchased from a poor source.

Glitch

[Blokkenpiloot]

I also liked glueing foam more, as the glue goes into the foam and paper/carton, which made glueing the surrounds more easilly.

With rubber i often had spots i had to glue twice, with foam, always first time!

[xschop]

1. Thank you. You did a fine job yourself, takes Alot of patience. Yes, I painted the frames satin black to match the cones. I rebuilt crossovers with film caps and wire-wound resistors. I also machined and phase-plugged the midranges, as well as foamed the inner baskets frames for ultimate clarity. I’m running them in conjunction with a rebuilt Polk RM-1000 subwoofer and custom tpa3255 amp to match aesthetically. Pure audio bliss.

 

 

 

[xschop]

[xschop]

Oh indeed, typing on a smart phone renders one inattentive at times…

The CX30’s have a 4.7 ohm cast resistor in their crossover. I added the wire-wound resistor and new film capacitors as well…

<!–more–>

After all said and done the CX30s trump the modified Polks even with their exquisite sound signature and especially their tweeter’s sound reproduction

accuracy…

 

[xschop]

“I just touched up the metal of the drivers with a black marker as they will be playing with (freshly washed) frets.”

 

I have to ask what is a “fret”? I am currently looking for a set of C75’s to rebuild as well. I see they don’t have the mid-drivers angled like the CX100’s.

[Tignum]

Hello xschop, with frets I meant the cloth covered plastic speaker fronts. Nothing much to mod there I guess :-). Best of luck, regards, Johan

[Author]

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