Consistency of enclosure types?

[Kev06]

Hi,

I'm going to build a set of 3-way 'Hi-Fi' speakers. So far, my initial favourites for woofer and mid drivers ideally require sealed and vented enclosures, respectively. I probably do need a 'proper' enclosure for the mid to get the low-mid range that I want with the small size of driver that I'd like.

There's lots of info on sealed vs vented enclosures in the forum, but what I'm actually interested in is: how important it is to be consistent between mid and bass enclosure types?

I'm no expert in this field and so I may not fully understand affects such as phasing and delay in such a combination of enclosures.

Can anyone help?

cheers
kevin

[Shaun]

Hi, Kevin


Venting a midrange driver is going to give you more problems than it's worth. Pipe resonances and enclosure resonances are difficult to dampen, and when it's done, you'll probably end up with aperiodic loading (actually not bad in itself) which defeats the purpose of the vent. Also, although a vented enclosure will theoretically extend the low end, right there where it starts to drop off is where you'll have poor group delay. It will be difficult to integrate into the system.

Rather choose a driver that has natural low extension, or add a mid-bass driver, or use a woofer that extends up high enough to integrate easily with the mid.

Actually, if the mid needs extra boost on the low end to meet the fall-off of the woofer, then your size jump is probably too big.

See here

http://www.troelsgravesen.dk/Design_criteria.htm

[Kev06]

Great, thanks very much for the advice Shaun.

I was already a little concerned about a vented mid, as it was a fairly small enclosure and the tollerences would have to be tight to get it right, so what you say reinforces my misgivings.

I think you've hit it with the driver size too: I normally like small mid drivers for their high frequency performance (particularly off axis), but as my main intention this time is to have a nice wide mid-range band between the crossover points a larger mid-range driver would probably be a better/safer way of getting the lower end of the range than fiddling around with challenging boxes.

Thanks - you've helped clarify things,

cheers
Kevin