Bass transfer through glass

J.J.McLeod · Post by **J.J.McLeod** » Fri Mar 28, 2003 4:31 am

As we discussed, I'm thinking about building a wall opposite of the slanted wall between my control room and the booth. I'm trying to improve symmetry, especially in the bass frequencies. I realized, however, the the bass must be passing through the window (2'x3') into the booth, which is about 1000 cubic feet.

Does this create a kind of bass trap then? If so, would I be better off just putting a bass trap with hangers in the other corner instead of a solid wall (like your original plan, I know)? It would be in a corner and would be about 6 square feet (a triangle 3'x4'x5'). Seems like a solid wall would reflect more bass than the wall with the glass, creating more cancellation on the solid wall side. I plan to hang a 703 panel over the glass for critical mixing, but the bass would still pass through into the booth, I think.

Thanks,

J.J.

J.J. McLeod
Different Drummer Studios
www.differentdrummerstudios.com

Post by **John Sayers** » Fri Mar 28, 2003 8:38 am

How much bass passes through the glass is dependent on hwo thick the glass is and the window construction. What do you intend doing to the rear of the room? are you putting a door system in or what??

cheers
john

J.J.McLeod · Post by **J.J.McLeod** » Fri Mar 28, 2003 9:24 am

Well to be honest, I still haven't figured it out. The realization that the distance to my hard ceiling, which happens to be almost exactly half of the room length, is what determines the ceiling node frequency has made me consider closing off the alcove with a wall. That would change the room length from 20' to 15'. If I did that, I'm still trying to decide if I should stay where I am or adopt the first plan you drew for me (thanks!). Either way I'd end up with a wall behind the monitors that's only 7', which is kind of tight. The difference is the angle of the angled walls, which would be wider in my current position, which I think would be good for side reflections - but of course the back wall is closer than in your first plan.

It also depends somewhat on how much construction is involved, and whether I need to add a diagonal wall or a corner bass trap for best symmetry. If I stay where I am I'd probably put the door in the wall that closes off the alcove (close to the booth door). If I followed your plan I 'd put it where you did, depending on surround speaker placement.

Thanks again,

J.J.

J.J.McLeod
Different Drummer Studios
www.differentdrummerstudios.com

Post by **John Sayers** » Fri Mar 28, 2003 10:15 am

Well - if you were to go with my first plan

You could always add a soffit mount later that is built above the line of the top of the window and angled down.

cheers
john

J.J.McLeod · Post by **J.J.McLeod** » Sat Mar 29, 2003 5:14 am

Unfortunately the bottom of the window is 4' high and the top is 80", so it's probably too tall to soffit above. However I'm liking your plan for a couple of reasons. One is that I wouldn't have to do anything to the machine room wall, (I would if I face the direction I'm facing now). The other is the symmetry between the control room door and the machine room door.

BTW, the glass in the window is only one pane of 3/8 inch, although inside the booth I hear a lot more bass when I open the door compared to having it closed, so maybe the bass isn't escaping in there as much as I orginally thought.

So is the new angled wall made of drywall in your plan? Or could I put hangers with a false wall? And do you agree that I should shorten the room from 20' to 15' for node reasons? If so, I assume the wall would have to go past the drop ceiling to the hard ceiling, or else the bass would just pass over the wall.

Thanks,

J.J.

J.J. McLeod
Different Drummer Studios
www.differentdrummerstudios.com

Post by **John Sayers** » Sat Mar 29, 2003 7:51 am

Well to drop the height of the glass pane isn't too much of a pain (pun intended

)

I'd make the wall out of drywall to match the opposite wall and shorten the room and you will need to go up to the original ceiling.

The space taken out (i.e. top section of the room) could be modified to be another small vocal booth??

cheers
john

J.J.McLeod · Post by **J.J.McLeod** » Tue Apr 01, 2003 3:11 am

The space taken out (i.e. top section of the room) could be modified to be another small vocal booth??

Great idea! Of course, if I wasn't careful it would be 10'x10'x5'

Well to drop the height of the glass pane isn't too much of a pain (pun intended )

Ouch

What height were you thinking? I'm considering soffit mounting at the outset if I build a wall. Isn't it possible to soffit in the 7' wall, especially since the _maximum_ (not shouting, see

) distance Genelec recommends for 1032A's is 7'10"? Or has your experience shown otherwise even in smaller rooms like this? I'd love to avoid angling the monitors.

BTW, Genelec really recommends soffit mounting, so if you ever need backup (like in Brad Blackwood's forum) you might send people to Genelec's site. Now if only Dunlavy agreed...

Thanks,

J.J.

J.J. McLeod
Different Drummer Studios
www.differentdrummerstudios.com

J.J.McLeod · Post by **J.J.McLeod** » Thu Apr 03, 2003 2:39 am

So is there a minimum length you recommend for a soffit wall? Is it possible my proposed 7' wall would be long enough for Genelecs with a _maximum_ recommended range of 7'10"? The booth wall and the matching one would splay out from the 7' wall at approx 127degrees (37 degrees wider than perpendicular) until they reached the room's 13' width.

Thanks,

J.J.

J.J. McLeod
Different Drummer Studios
www.differentdrummerstudios.com

Post by **John Sayers** » Thu Apr 03, 2003 9:52 am

well you need the front end to look like this attched pic. To be honest - if it were me I'd take down the window wall and start again and build a new front with a full soffit mount. I try to get 9 feet between the speakers if I can cos then you get the full spread.

You camn then build a window in UNDER the soffit mounted speaker and maybe have a glass door between them going into a small booth and then accesss to the studio.

cheers
john

J.J.McLeod · Post by **J.J.McLeod** » Fri Apr 04, 2003 3:02 am

Many thanks John! I've also considered getting rid of the angled wall and starting over, so thanks for the confirmation of the benefits of that idea, as well as the specifics about the width of soffited monitors. You even took the time to draw another version for me. I really appreciate your effort.

Again, thanks for your acoustic expertise and endless patience during my quest to solve this rubic's cube of a control room!

J.J.

J.J. McLeod
Different Drummer Studios
www.differentdrummerstudios.com

Post by **John Sayers** » Fri Apr 04, 2003 7:40 am

my pleasure JJ - let me know how you go with it

cheers
john