Are paper cones good at high level ? What about MCA15CRY ?

[gtb]

Quote from Troels Gravesen website (PMS-) :
"Paper, when done right, can provide a speedy, transient sound and usually the break-up of the paper cones is of an ear-friendly kind. The sound simply gets muddled when the speakers are driven too loud."

Can someone comment on this ?

I am using a Seas MCA15RCY as a midrange in a 3 way speaker. I have a pleasant sound when played at low level. But a sligthly harsh sound when played a bit loud (for exemple during action scenes in films).

With very steep filters, I found by ear that the problem is coming from the 1250Hz region. The 2nd graphic on this page (Midrange test data) show a ripple at this frequency. I don't read complaints anywhere on the web about this driver. So it disturbs me. Is the ripple cone breakup ?

Any thougth about this ?

Guillaume.

[Inductor]

Maybe the problem is with the tweeter (or xover). It can also be the woofer. Disconnect the tweeter and try again. I would listen to the mid (only) carefully in it's box.

[gtb]

I already disconnected the tweeter and the woofer. I'm sure the harshness comes from the mid.

[McCormack]

I don't know if this applies to your situation, but I've found with my own DIY designs that if internal standing waves aren't damped they can come back through the cone and cause harshness. I've also found that narrow baffles that place the driver too close to the enclosure's side walls can increase harshness.

[trd1587]

Good Point

[asbjbo]

The impedance ripple is probably a cone breakup. In a distortion sweep, like the ones at Zaph audio, you would probably also see a step change in distortion around that frequency. Look at the Seas CA15RLY (also that a coated paper cone) at Zaph|Audio

[gtb]

Originally Posted by McCormack

I don't know if this applies to your situation, but I've found with my own DIY designs that if internal standing waves aren't damped they can come back through the cone and cause harshness. I've also found that narrow baffles that place the driver too close to the enclosure's side walls can increase harshness.

The box is a narrow rectangular closed box loosely filled with MDM3. I didn't know narrow boxes can increase harshness. The speaker hole is not chamfered but the baffle thickness is just 19mm and the hole diameter is 11.5cm implying a resonant frequency of 1500Hz (not the 1250Hz that I expect).

[gtb]

Originally Posted by asbjbo

The impedance ripple is probably a cone breakup. In a distortion sweep, like the ones at Zaph audio, you would probably also see a step change in distortion around that frequency. Look at the Seas CA15RLY (also that a coated paper cone) at Zaph|Audio

Yes, I should do a distortion measurement.

[David Gatti]

The voice-coil former may be the culprit, flexing under high stress.
Many of the newest drivers are now using titanium formers.

[McCormack]

Originally Posted by gtb

The box is a narrow rectangular closed box loosely filled with MDM3. I didn't know narrow boxes can increase harshness. The speaker hole is not chamfered but the baffle thickness is just 19mm and the hole diameter is 11.5cm implying a resonant frequency of 1500Hz (not the 1250Hz that I expect).

It's been my experience that if a driver is real close to a sidewall and the reflections aren't damped, then it can contribute to glare/harshness. I'm not saying that that's what's going on in your situation - I was just throwing out there as something to be aware of.