John Sayers' Recording Studio Design Forum Archive

Hey John,

The Mackie 824's have a rear mounted passive radiator... what, if any, problem will I have mounting this into a soffit? I mean this is the same as mounting a bass reflex speaker with a rear mounted port into a closed space. When I used to build speakers you were supposed to watch out for the size of the enclosure when doing a sealed speaker enclosure vs a bass reflex or a passive radiator system

Just my Q's

Bryan Giles

Bryan,

Ports and passive radiators need to be unobstructed and free to radiate into the room. Soffit mounting a rear ported or passive radiator speaker is still possible, but very tricky. The only real purpose of soffit mounting is to enlarge the size of the front speaker baffle. Therefore, a rigid "floating" panel with an open back could work just as well as mounting the speaker into the wall. If the panel height and width are large compared to the panel's distance from the wall, then the sound waves will simply see the panel as an extension of the wall. The difficulty with a rear ported speaker, however, is that the panel dimensions must not be so large such that the path length from the rear of the speaker to the front causes phase cancellations in the frequency range where the port and the woofer are working together (i.e. the octave above the tuning frequency).

Basically, there's a pretty high risk that you won't get it right. So, I wouldn't recommend trying to soffit mount your 824's.

Thomas

That was pretty much my Opinion as well. All the years of building speaker, sealed, bass reflex and passive radiator has taught me that you dont do something like that (technically). I will try it for fun. If I like it.. HEY!!!! Cool

If it sounds funny to me, no big deal, pull em and place them on stands

I really want the K&H O300D's anyway... I can get them for about 3200.00 Locally.

Bryan

Well Here is the verdict.

Throw em in a soffit. Imaging is better. Bottom is tighter.

God, I have to remix this album I just finished.

Platinum album here we come!!!!

Bryan Giles

Bryan,

Can you post a picture, so we can see what you did?

Thomas

Sure can. It will be up as soon as I finish the upper part of the soffit above the speaker.

Bryan

I can't rave enough. These sound great. My Bottom is so well defined. Of course I modified the plan for the soffit a we bit. I used drywall for the enclosure instead of Plywood. With 1/2" Open cell rubber to somewhat isolate the box from the frame.

Why Drywall???

Glad you asked... I am an engineer not a carpenter, so which do you think is easier to work with and shape????

I used 1/2" drywall. It worked great. I set my mackies at B, not A. A gave me the impression of muted bottom. Almost as if there was a HPF inserted.

Bryan Giles

Mix On and Mix Well

So you have any pictures for us yet?

I have 824s as well, and I'm curious as to how you keep yours from overheating...

Kase
www.minemusic.net

http://www.johnlsayers.com/Studio/Pages/Giles.htm

Here are some old pics.

New pics coming soon.

Bryan Giles

Be honest with you, they've never overheated and I have done some very long mix and track sessions (10 hours). I Never turn them off and they are not in the auto mode either.

Giles,

How much space did you leave around the speakers inside?

And what kind of material for absorption if any?

Look at the plan on that page and you find the depth info.

I put a bunch of old auralex foam in there and set the switch to A

Bryan Giles

which basically means you could stuff it with mineral wool like dav blauvet (I know I mispelled it) did, etc.. It all absorbs bass.

Heh Giles,

can you give me some tips and hints what you especially did to soffit mount your mackies? I have Dynaudio BM6a and want also to soffit mount them but I don´t know how to do it right...

Dynaudioacoustic support told me that they can not recommend that cause they have no expierences whith that and say that the BM6a ist best sounding free standing..cause of the bass reflex rear port...

Michael