Musings about diaphragm materials

"It does not address my original question: Why aren't we seeing more recent developments of plastic and compounds in speaker designs"

Because all the testing has shown that great cone behavior is more to do with the overall execution, not the specific material. Going the "pistonic" rout was, in theory anyway, a way around the trouble of learning how to cook well.
 
And where can we buy those woofers with 5 Hz resonance?

BTW, easy to portray how perfect a vc driver can be in theory until you remember it is made of rubber, fabric, paper, and all kinds of little gremlins that shake and behave badly.

B.

My woofers in open baffles have 30 Hz Fs, they could have a lower resonance, for sure. But the combination of a large speaker diameter and such a Fs is not too bad, for now I stay with these drivers...
 
Last edited:
"It does not address my original question: Why aren't we seeing more recent developments of plastic and compounds in speaker designs"

In the Planars, Exotics and new stuff forum you'll find threads like graphene. Started by ahem, ahem. That's the forum to post innovative ideas rather than here.

And you'll find plasma speaker threads.

B.
 
Last edited:
It does not address my original question: Why aren't we seeing more recent developments of plastic and compounds in speaker designs, even when they could be drop-in replacements?:confused:


Because the facilities to make paper cones are already installed and payed off and the process of making paper cones is known without much need to experiment.


Who has the money to invest in various plastics and associated molds when basically no one cares (enough to not buy a driver because it doesn't made using a propriety plastic cone) and paper cones are still selling
 
It does not address my original question: Why aren't we seeing more recent developments of plastic and compounds in speaker designs, even when they could be drop-in replacements?:confused:

I like my current 12" prosound paper cone widebanders a lot. I have tamed them with DSP, but even without much EQ they don't sound as harsh as measurements would suggest.

AlBeMet and TF-25, afaik, are great substitutes for aluminum and titanium.
I asked Materion about the availability of the promisingTF-25 diaphragm's for a compression driver. They had none availability.

If someone can point out these diaphragma's availability..

If not I'm afraid they aren't that good for replacement or they don't want to kill their current High End prices of Berylllium..
 
I made a two way once ( large free hanging ribbon down to 150 hz cross to a cone ). The cone was weighted (filled with duct seal) until Fs was around 8 hz. System sensitivity was like 70 db . Max volume was maybe 85-87 db

BUT the sense of depth was by far the best Ive ever heard.
 
I made a two way once ( large free hanging ribbon down to 150 hz cross to a cone ). The cone was weighted (filled with duct seal) until Fs was around 8 hz. System sensitivity was like 70 db . Max volume was maybe 85-87 db

BUT the sense of depth was by far the best Ive ever heard.

Klippel has measurements of the impact the spider and surround have on the bass driver. In short and all things being equal: the distortion is mostly because of non linearity of the suspension, espescially around and below Fs. In other words: if you want low distortion (don't want distortion products mixing with your bandwidth of interest), you must have a low Fs.

Afaik ESL' s have very low Fs
 
interesting
In another experament I cut the spyder out of a cone and replaced with two crossed and tensioned threds. Probably 1000 times less mass than original spyder BUT perhaps more important was the fact that now had a linear spring suspension ?? Anyway the soound , in the dipole it was used as anyway, was immediately obviously different.
Fs was still around 30 hz or so BUT the bass had a lively dynamic quality to it AND low volume listening was Wayyy better than before.
Did not have a measurement system back then so....
 
Right now we're in the process of evaluating our After Market JBL woofers (K151, K140, K130, 2235, 2245's). We al had them reconed to mimic the renowned 2235 or 2245, because of low Fs etc. Read: studio or home use.
They don't compare at all.
Fs is being way too high (around 32-34 Hz).

Now there are a few things you can do.
Less stiffening of spider, the suspension and add mass.
Adding mass should be done because the After Market cones lack the Aquaplas coating(less weight). We added between 30 to 60 grams, depending on woofer size.
Second thing we also tried was, after excessive heating of the spider which didn't help much loosening it up, to cut the spider and sand of a part of the surround.
This brought down the Fs around 24-26 Hz.
We compared the 18" drivers (After Market recones a la 2245 on the 2245 and the K151)) to a original 2245 from the 1980's.
The difference in SQ was huge.

The original 2245's gave more articulation and way more presence, contrast of bass notes of music. This was the case with any amplifier and source we tried(tubes, ss, feedback, non-feedback amps).

Now I know this is a slippery slope.
None were blind done neither level matched, but the issue wasn't that the sound was lean or missed weight per se. It just had the sound of a musician with a bad instrument: it was hard to hear what was being played, how it was being played and missed depth and weight all around.
Still, these after market recones should have performed comparable to the original ones yet none of them came close. We have many years of experience with this brand and these drivers, we trust our ears to do this.
The difference is so big that, in comparison, the enjoyment of music is almost gone.

We're currently gathering spare parts that can replace the after market stiff spiders and surrounds, but they're hard to source in a world where stif and stiffer seems to be the new hype and most of the parts are hardy described technically: size and description of "medium" stiffness is hard to compare to a B or C spider etc. It should be measured and quantified.

In short: besides cone material, I'm currently way more worried about the surrounding material and parameters. Paper cones, fwiw, come in al sorts of sizes and shaps and suffice for the time being, for bass that is.
 
Last edited:
I wonder about the stiffness thing and suspect theres more to "tuneful" bass than just a low Fs.

In another experament I had a cheap 15" radio shack woofer from the 80s'. Fs was 20 hz. It was a light PP cone with a foam surround and a small motor. Just about worthless driver really. Couldnt handle any power. So I painted the surround with silicone calk. Layed it on thick. This raised Fs to around 40 hz. The transformation was almost unbelievable. Used below 200 hz the bass was dynamic and alive. Totally different characture than before. And again just like the tensioned thred spider experiment on woofer mentioned a few post ago , the difference was obvious even at quite low volumes where we cannot make the argument that the stiff suspension just handled power better.
The common thred in these experiments is a low hysteresis character to the cones suspension. This lead me to think that a suspension with very low hysteresis can play a significant part in how bass sounds. As well its interesting to me that this kind of mechanical property is exactly what u get with tensioned film planer loudspeakers
 
Last edited:
I guess there is more. It`s not about low Fs per se, but about having an unrestricted cone movement, being able to follow what the voice coil is telling it where to go.
To me, all restrictions should be about prohibiting mechanical failure (mechanical limitation) and centering, nothing else.

I`m not sure if you can relate your SQ to hysteresis (you mean non-linear suspension,in what way exactly, some memory effect?) or something else. Upping Fs also means you`re not hearing frequencies you did before, so the spectrum gets smaller and that e.g. might just combine better with the rest of your stereo. How did you correlate this to hysteresis?
 
The Art of Speaker Design, Part II..."...the driver is actually flexing thruout the entire frequency range, but the lossy damping material hides this from instrumentation, but not the ear.

Wow, sounds like someone has the infamous "golden ears".


........................................................................................Rick.............
 
The Art of Speaker Design, Part II..."...the driver is actually flexing thruout the entire frequency range, but the lossy damping material hides this from instrumentation, but not the ear.

Wow, sounds like someone has the infamous "golden ears".


........................................................................................Rick.............

I`m still looking at the measurements and how they correlate Rick... ;-)