Almost ready to start Modula MT build, couple questions...

[Cool Mr Steve]

I have a couple quick questions before I start the building process for these speakers, hopefully in the next couple of weeks. First of all, how closely do my measurements need to match the PE enclosure dimensions? I have no problem making the baffle with the proper dimensions, but I'm anticipating the internal volume being a bit off, i.e. the internal dimensions may be 11" deep instead of 10.75". Would this be noticeable at all? Secondly, is the tweeter supposed to have its own seperate chamber? If so, how is that supposed to be worked into the baffle? And lastly, what kind of wall lining is ideal for this design, and where should I put it, exactly? Does the wall lining take away from the internal volume measurements, or do I have to worry about that with the PE internal dimensions? Thanks a lot!

[JonW]

Steve-

I'm a newbie, so treat this advice as worth exatly what you're paying for it...

I'm anticipating the internal volume being a bit off, i.e. the internal dimensions may be 11" deep instead of 10.75". Would this be noticeable at all?

I'm not sure what 11" dimension you're talking about. But just keep the front baffle dimensions unchanged (10 x 17" I think) and you're fine. I added a lot of extra internal bracing to mine. I just extended the rear dimension to compensate. Try to keep the colume similar. But I'd think a 0.25" shinking of the rear dimension would hardly be noticable.

Secondly, is the tweeter supposed to have its own seperate chamber?

I did not do that.

And lastly, what kind of wall lining is ideal for this design, and where should I put it, exactly? Does the wall lining take away from the internal volume measurements, or do I have to worry about that with the PE internal dimensions?

People debate about what lining to use for sound absorption. Egg crate foam is popular. I used poly batting. Some use fiberglass insulation. Damping the walls for vibration absorption is a separate topic. People use different things- tar paper, bitumen, concrete, etc.

Do not change the volume based on any added wall lining.

Good luck with your build. Pics are required.

[Paul H]

Good advice JonW.

I'd add that most people would not create a separate chamber for the tweeter, as it is supposed to have its own integral 'chamber'.

Some, including our Jon M I believe, suggest a separate chamber is appropriate to ensure full and complete separation from the woofer(s) on high end designs, but probably not on bookshelves.