Any distortion measurements on the IB drivers?

[chrisbee]

REW: Tools: Generator: SPL meter: Sine wave: Frequency follows cursor. Leave all boxes open while you play selected tones.

SPL Meter has the harmonic distortion figures in the box.

Generator has the Frequency in large digits. (so you can easily read it off the monitor screen during long sweeps if you leave it open)

Thanks to JohnM for REW and the useful details above.

Use a wireless mouse and you can sit beside the spl meter at the listening position scribbling down the SPL figures and probably still see the monitor screen.

(Not applicable if you are using a microphone of course)

[diycable]

To do good driver - driver comparisons you really need a chamber. The noise floor in a room, not to mention all the sympathetic vibration of walls, floors ceilings etc. make it pretty much impossible to do an in-room distortion measurement for anything but gross distortion levels.

Doing an A/B comparison with 10% levels may be meaningful but trying to compare drivers at 1-2% just isn't because of the noise component.

[carvernut]

diycable said:

The noise floor in a room, not to mention all the sympathetic vibration of walls, floors ceilings etc. make it pretty much impossible to do an in-room distortion measurement for anything but gross distortion levels.

dang chris, if your IB only was measuring 2% in such a imperfect environment thing of how it would do in a chamber

imo: chamber tests are rather impractical because they are lab numbers... you'll never see those numbers in real life situations short of a true sound treated room specially designed and built for total isolation and soundwave control... IE more money then i'll ever have to spend on a room

[diycable]

carvernut said:

imo: chamber tests are rather impractical because they are lab numbers... you'll never see those numbers in real life situations short of a true sound treated room specially designed and built for total isolation and soundwave control... IE more money then i'll ever have to spend on a room

That isn't the point though. They are used to do real driver to driver comparisons so you can get good data. The chamber is just a measurement tool.

Its sort of like a machinist trying to compare different cylinder bores using a tape measure. Obviously, he couldn't tell you much with the limitations of the measurement device. With the proper measurement tool though, he could give you a valid opinion of the merits of different cylinders.

Same here.... the in-room measurement is comparable to the tape measure. It can only show you high level differences. It is pretty much useless for looking at small subtle differences.

[chrisbee]

I wasn't comparing drivers with drivers.

I was reading numbers from REW at around 100dB in my real world situation.

Had I chosen to test at 10% distortion I probably wouldn't have a house left!

At the likely SPLs to produce 10% in my room it would be much like an earthquake.

I could hardly tolerate a steady 100dB(C) sinewave at some frequencies just to do these tests.

[diycable]

Man.... I'm not getting my point across am I?

You would test ONE speaker. The original post was about testing various IB speakers for distortion. My only point is that to do it in a meaningful way you need the proper measurement setup and you would need to test them at the same output levels to do a direct A/B comparison.

[chrisbee]

diycable said:

Man.... I'm not getting my point across am I?

You would test ONE speaker. The original post was about testing various IB speakers for distortion. My only point is that to do it in a meaningful way you need the proper measurement setup and you would need to test them at the same output levels to do a direct A/B comparison.

That would assume that one had access to however many different drivers one thought worth testing. Most of us only have access to multiples of one particular driver... but if you want to volunteer I wont stand in your way.