what is stuffing good for?

[slackerbob]

What's the difference between stuffing your boxes and leaving them empty? It changes the "Q" yes, but what does Q measure?

[SkinnyBoy]

what is stuffing good for?

Chickens and Turkies...

[7V]

Originally posted by slackerbob
What's the difference between stuffing your boxes and leaving them empty? It changes the "Q" yes, but what does Q measure?

In the sense that you are using it, Q describes the bass resonance charateristics of a speaker in an enclosure. Actually, you're talking about Qtc which is the total Q of the speaker in its enclosure at its resonant frequency.

A speaker system with a Qtc of 0.5 is described as "critically damped" but is sometimes considered to be overdamped, while a Qtc of around 0.707 is often felt by designers to be the optimum. Small speakers with a Qtc of between 0.707 and 1.0 have a bass hump and this has been used to give the impression that the speaker has more bass. Reducing enclosure size increases its Q.

Really, you have to look at some curves and, preferably, listen to some examples to get a real idea of what this all means. I would recommend "The Loudspeaker Design Cookbook" by Vance Dickason as a good introduction to the subject. You could also download some free software which allows you to model loudspeaker characteristics and see the effect of changing Q on the frequency response curve.

With regard to stuffing, it's true that stuffing can give an effective enclosure size a little larger than the actual size, thus reducing the Q. However, stuffing is usually used as a way of killing the standing waves, resonances and reflections that arise inside an enclosure. It's usually used, therefore, to compensate for poor enclosure design. The downside is that too much stuffing can 'deaden' the sound of a speaker.

Good speaker enclosure design will reduce the need for stuffing and will therefore give a sound that's more 'live' but without the resonances that are caused by internal standing waves. Such designs often avoid the more common rectangular-shaped enclosures.

I hope that you find this helpful and not too confusing.

Steve