Optimal Enclosure Shape For The Mid Section?

[Ben Reginato]

Hello All,

I just inherited a RAW RA8 speaker kit that is WWWMTMWWW ported.
The MTM part of the speaker is sealed with an inner dimension of 15.5"X7.5" rectangle.
What is the optimal inner shape for the Mid Bass unit? Should I fill the corners with epoxy?
Should I keep it sealed or cut out a hole in the middle and put a PVC pipe in it to make a T-Line out of it? How good does a Mid sound as a T-Line? And one last question about baffle round over’s what is the point of diminishing returns and how thick would the baffle and sides have to be to get it there?

Thanks Ben

 

[Zarathu]

Use a 23.5 inch closed pvc pipe. Stuff it with 4lb/cu.ft fiberglass wrapped in sheet fiberfill. You can use an elbow on the pipe if you need to make the outside enclosure have less depth. At 23.5 you will get a resonance around 155 hz which will help the upper bass if you cross that low. You will find that the clarity increases compared to mids put in square boxes, both because of the physics of sound in tubes, and because the back wave of sound will have to travel through almost 4 feet of dense fiberglas to make it out through the front again.

 

[TerryO]

Hello All,

I just inherited a RAW RA8 speaker kit that is WWWMTMWWW ported.
The MTM part of the speaker is sealed with an inner dimension of 15.5"X7.5" rectangle.
What is the optimal inner shape for the Mid Bass unit? Should I fill the corners with epoxy?
Should I keep it sealed or cut out a hole in the middle and put a PVC pipe in it to make a T-Line out of it? How good does a Mid sound as a T-Line? And one last question about baffle round over’s what is the point of diminishing returns and how thick would the baffle and sides have to be to get it there?

Thanks Ben

Ben,

This is a question that probably be directed to Al Wooley, the owner of RAW. There is most likely a reason that the MTM part is sealed. It may be that Al wanted a sharper roll off for the mids than any TL or BR could give him. He's on this forum as well as Audio Circles. It's not generally a good idea to second guess why a design is the way it is, especially when it's really easy to contact the designer and simply ask.

As for roundovers, anything with less than a 3 inch radius doesn't really do much in the way of significantly reducing diffraction, although a 3/4 or 1 inch roundover does make it "much" easier to apply wood veneer to the cabinet.

Best Regards,
TerryO

 

[RAW]

Re: Re: Optimal Enclosure Shape For The Mid Section?

Ben,

This is a question that probably be directed to Al Wooley, the owner of RAW. There is most likely a reason that the MTM part is sealed. It may be that Al wanted a sharper roll off for the mids than any TL or BR could give him. He's on this forum as well as Audio Circles. It's not generally a good idea to second guess why a design is the way it is, especially when it's really easy to contact the designer and simply ask.

As for roundovers, anything with less than a 3 inch radius doesn't really do much in the way of significantly reducing diffraction, although a 3/4 or 1 inch roundover does make it "much" easier to apply wood veneer to the cabinet.

Best Regards,
TerryO

Ben
As Terry noted the design was done for a reason and the mid chamber can be altered yes as a fact if you want to a big change in the mid range vocal.Make the MTM a angled cabinet.Slanting the rear wall of the MTM.But this will be only a small amount due the volume needed behind the MTM for the 3 woofers above and3 woofers below.This space is calculated in the total volume for those 6 woofers.

By all means drop me a email and we can get them going for you.
Not sure why you would have purchased a kit from someone who kept all the documentation?And why did they keep the documentation?

I just placed your area .
Did Bill sell you his set?