lambda poly cone vs paper

[Austin]

The price on the Lambda drivers is too good to pass up, but I need some help determining which driver to get. I'm considering the SB15-LE and the SBP15-LE. The important differences between the two are as follows:

SB15-LE
poly cone
14mm Xmax
88dB efficiency
.50 qts

SBP15-LE
paper cone
10mm Xmax
90.7dB efficiency
.43 qts

I know nobody has heard these drivers yet, but I thought you could comment on the tradeoff between the efficiency and Xmax, and also the cone materials.

These will be going into sealed stereo subs, most likely powered by a Leach amp. I want the speed of a sealed sub, but also don't want to give up the bottom octave. Which is my best bet?

[Circlotron]

I imagine the polycone one would be more consistent over a long period of time because the cone would not absorb and release any moisture from the air with changes in humidity and temperature. If paper cones were the be-all and end-all, why would they have gone on to develop poly cones? They must have something going for them?

[roddyama]

Originally posted by Circlotron
If paper cones were the be-all and end-all, why would they have gone on to develop poly cones? They must have something going for them?

Hi Graham,

I know this would be the first thought as well. It is what I thought for a while myself. But, if you look at your logic the other way around, you might say, Why are paper cone speakers still around after, I don’t know, 80 years? They must have something going for them.

My TAD’s have paper cones and they are the best woofers I’ve ever owned. I’ve heard it said that the speaker brake-up modes are easier to control with paper cones. Also that paper cones are faster and tend to sound “tighter” then poly cone speakers and tend to be more efficient (as they are in this case).

If I were to pick between the two woofers mentioned, all else being equal, I’d go with the more efficient paper cone speakers. Although, I suspect that all else is not quite equal. The Q of the paper cone, and the higher efficiency tends to point toward a ported enclosure where it doesn’t need as much xmax as the poly cone speaker. Where the poly cone speakers with a Q of .5, and lower efficiency (higher mass, lower f3) will probably have as much bass extension in a closed box as the paper cone speaker does in a ported box, but will require about 50% more power for the same output. In the end, I wouldn’t be surprised if both their response curves as subs turned out to be very close.

Austin,

Do you have more of the T/S parameters for these drivers?

Rodd Yamashita

[JohnR]

G'day Rod, specs for the SB drivers are here:

http://www.lambdacoustics.com/drivers/SBdrivers.html

There's a whole 'nother series of drivers for ported boxes

HTH

JohnR

[thylantyr]

I think if you are running subwoofer frequencies, ie
crossed over very low 80hz - 100hz, sonically, it
would be harder to distinguish (paper or poly).. But if you
ran the woofers at low pass 500hz or even higher (LOL),
then the woofers personality starts to manifest
with the various materials.

ie, I never like the sonics of poly cones when playing
back midrange.

[roddyama]

Originally posted by thylantyr
ie, I never like the sonics of poly cones when playing
back midrange.

I agree.

Thanks John,

Some of those drivers look kind of tempting. Too bad their going out of business. I particularly like the 10” TD’s. That's the highest efficiency I’ve seen in a 10” woofer. I recall someone on the forum looking for exactly that a while back.

Rodd Yamashita

[thylantyr]

I talked to Nick, he really recommends the TD15 for
sonics, especially midrange clarity. He also said
the TD12 is pretty close to the 15". When I ask
about the 10" TD, he said it sounds bad compared
to the 12 or 15, the 15 being the best one.
It's the cone design he said.. At least Nick was honest
about his products and didn't BS me. People whom
used TAD woofers say to me that the TD15 is better.
.. subjective debate... hehe