Where can I find subwoofer harmonic distortion and CSD plots?

[owdi]

Where can I find subwoofer harmonic distortion and CSD plots? I'm not looking for information on any specific driver, just some charts that cover 20-200hz. Frequency response charts are easy enough to find, but harmonic distortion and CSD seem impossible.

Bonus points for plots that show distortion at high power levels.

Dan

[simon5]

I know Aurasound show THD, but CSD never seen a subwoofer manufacturer publishing that data.

http://www.aurasound.com/

Someone else?

[mike.e]

You request too much
JBL tends to measure distortion at 1w and 10% Pe I think..

http://www.mfk-projects.com

DATA:

Blueprint Series I 12"

DPL-12

Peerless XLS 12"

Shiva

Titanic (Original)

Titanic MKII

Titanic MK III 15" vs Bully 15" plus more data on the XLS 12"

TC2+ vs XLS

Dayton RS 12" Hi-Fi High Excursion Woofer

[owdi]

mike.e - you are THE man. That is exactly what I have been looking for. The price/performance ratio of the Dayton RS sub is intimidating. I'm surprised just how much distortion all subwoofers generate, especially down in the 20 - 40hz region. This makes me question whether I've truly heard a 30hz tone, or just the harmonics.

Dan

[mike.e]

Bear in mind that with music present,you can not notice that distortion. For example I had a 96kbps mp3,that was a recording off a cassette,which was in turn off the radio. When I down 'rated' it to 8bit audio,I couldnt hear any difference

You probably havent heard a proper 30hz tone - You have to hear a decent reproduction of it ,and then youl know that you mainly feel it ;-)

Brings up an interesting issue - because everyone(well 90%) of people havent heard it,they dont know what they are missing.

The few that do,have only made a small investment too,and try to encourage the rest

Driving a sub free air gives an indication of cleanliness,my 2226JBL was silent to my ears(absence of gross distortion).

Mike.e

[owdi]

Originally posted by mike.e
You probably havent heard a proper 30hz tone - You have to hear a decent reproduction of it ,and then youl know that you mainly feel it ;-)

Whenever I find the time, I'm going to try a 4th order bandpass that goes from 20 to 60hz. Harmonic distortion should be much lower than sealed, since there is an acoustic filter blocking high order harmonics.

Dan

[mike.e]

Youd think so. But I dont know how effective it will be at 'blocking' since the chambers are normally not THAT large. I think of it in terms of gradually reducing output,so the distortion will decrease too,but its no magic bullet. Its just like putting an electrical filter there with say a bass reflex sub,except it is there physically.

Sure,there is definately a filtering effect,when combined with a decent active filter could result in a 4th order LR type of response.

Ive seen in an acoustics textbook some kind of FEA predicting higher port modes on a BP4due to physical dimensions and driver placements,but have never seen anything solid on the matter.

Check out beyma and JBL drivers for their distortion plots.