2 way speaker - airspace?

[x2percentmilk]

Hey everyone, just as some quick background I'm new to the diy audio forums, and although I have no hands on experience with home theater (mostly do to $$), I have been obssesively reading and studying alot of the theory and math for a few years.

Im planning my first speaker system, which will be comprised of 5 two-way vented speakers (5.25 midbass/fullrange woofer and a 1" tweeter), and a seperate sub.

Ok, now my question is: When constructing the cabinet, is it common practice for the tweeter and the woofer to share the same airspace? Or is the tweeter placed inside its own floating "mini box"? I've done a fairshare of searching and could not find anything on the topic, and the only pictures of internals are either of incomplete boxes, or complete boxes stuffed with polyfill (ie: cant see crap).

As a more general question, what are the effects of either option?

Thanks
- Matt

[infinia]

Originally posted by x2percentmilk
Ok, now my question is: When constructing the cabinet, is it common practice for the tweeter and the woofer to share the same airspace? Or is the tweeter placed inside its own floating "mini box"? I've done a fairshare of searching and could not find anything on the topic, and the only pictures of internals are either of incomplete boxes, or complete boxes stuffed with polyfill (ie: cant see crap).

No mini box needed.
Almost all modern tweeters (non-cone or dome types ) are closed from the backside, they have their own built-in sealed enclosure with acoustic absorbers, at least on properly designed units. As you surmised , it would be bad for the tweeter to be affected by the larger airpressure from a midbass.

[x2percentmilk]

Brilliant. Just what I needed.
Thanks

[Moondog55]

This can be true, but there are some tweeters on sale with very thin and flimsy plastic plates ( I know I bought a half dozen or so ) these could benefit from having a small airspace of their own.

I use a small scrap of whatever I have lying around.

Some plastic is too thin to be tightened enough to give a good air seal unless using silicon, which is very difficult to remove.

[Cal Weldon]

Originally posted by Moondog55
using silicon, which is very difficult to remove.

Unless you oil either the basket or the cabinet rebate, set the driver in place but do not fully tighten until the silicone has set thus making a gasket. It is still difficult to remove from the side without the oil though. Rope caulk can be used the same way without having to worry about the set up time.

[Moondog55]

That is why we have this forum, so I can learn stuff, I never thought of that, thanx Cal

Regards
Ted