Motion Feedback Subwoofer

[spot]

Hi,

I've been reading the article in 'Electronics World' 1997 called 'Roaring subwoofer'.
Looking at the feedback loop it seems as though it might work, with about 26dB feedback - not huge but very beneficial. This has got me wanting to make one (but with 12" woofers).

I would be really interested to hear from people who have actually tried this sort of thing how it went, expecially how good the feedback sensing was. This design uses a second voice coil - that may have practical issues with coupling from the other coil & what happens outside of xmax. It seems microphones might have a problem with sensing too much of other sounds. Haven't hear any serious complaints about accelerometers yet (except price).

(It seems a good idea at the outset might be to build some protection circuitry so if it goes crazy it will cutout quickly)

[revboden]

I can't really help with this but I found the article and you should know that Russel Breden is an alias of Jeff Macaulay (jeff macaulay's audio amp designs) .

article: http://www.macaulayaudio.co.uk/roaring%20sub.pdf

[spot]

Originally Posted by revboden

I can't really help with this but I found the article and you should know that Russel Breden is an alias of Jeff Macaulay (jeff macaulay's audio amp designs) .

article: http://www.macaulayaudio.co.uk/roaring%20sub.pdf

That was the article that got me interested all over again!
I hadn't seen Jeffs web pages though, will be interesting to see his updated design when it comes out.

[spot]

Originally Posted by spot

Hi,
... about 26dB feedback ...

Oops, its less than this

[Nelson Pass]

That's a good article. I licensed a similar design to Linear Power in the 80's,
so it was nice of Jeff to wait until after I got paid to publish it.