ML Sub Pics-almost Done

[nsgarch]

Servo?

What I noticed most about both the ported and sealed sub I built, was that there was a significant resonance at 65hz and 75 hz. I thought this was pretty wierd. Especially since they are completely different designs.And why are there 2 distinct resonances? My only conclusion is that it was the resonant frequency of the speaker...but can a speaker have 2 resonances???Dominick

All of ML's subs (including the Grotto) employ servo controlled feedback circuity which cancels any cone movement that doesn't match the incoming audio signal. Since the drivers you used came from an existing unit, I'd expect to see some kind of accelerometer connection somewhere on the driver unit(s)?

 

[Peter Hogan]

Peter,
I suppose this would be the most logical explanation since I tested them on the same wall.

But just for arguments sake...all speakers are said to have a given resonance at some frequency. Can a speaker have two true resonant frequencies? I would think that one speaker could not since the resonant frequency has more to do with the mechanical factors of the speaker?????

Do all speakers have multiple resonances-is this common or uncommon?

Thanks,
Dominick

Hi,
It is not uncommon to have harmonic resonances, though these usually occur at multiples of the fundamental one. It is also possible to have more than one resonance point. This can be due to different causes, for instance, one may be due to the speakers natural resonance point, and the second due to the box it is in.

If you change the box, you'll change the second resonance, but not the first. Put a different speaker in the fist box, and you can change the first, but not the second point. Once you start adding in room resonances, things can get really complex. That is why speaker makers do measurements in anechoic rooms, so they are looking at just the speaker response, and not the rooms.

Peter

 

[Dominick22]

nsgarch,

There is a connection on the speaker that looks just like the + and - terminals which is for the servo portion of its ability.

Dominick