Need a bit of advice - standing wave issue

[IntelDoc]

All,
I built my home studio to the point where I can safely move without really having to do any surgery on the walls. The slot wall is one thing, but no big deal. I had a fellow studio owner come by this weekend and he told me that I had a standing wave issue behind my desk. I made a diagram of the room as best that I could today with the time I had. Any ideas would be great. To me the room sounds great, but I am certain it can sound better.

The demensions are pretty plain for a basement studio.

Sound room is 12.5 wide x 22 deep. There are almost 3 foot firewalls all the way up to the attic on wither side so the neighbors are cool (yes it is a townhouse) Then standard interior walls, drywall, insulation, etc. The glass door I have is a thick $1500.00 dollar job, double pane, injected and really stops the outside noise from coming in for the most part. Ceilings are unfortunately low at 8'4" give or take. The floor is wood flooring on top of rubber and then concrete. Oriental rugs in the middle and back. The bass traps I made from Ethans design and work great from before and after tests. They are 2" 703 rigid fiberglass in a 2 x 4 frame. 1" gap from the wall to the 703 too.

Here is the diagram. Any ideas to further trap bass at the front or placement would be most appreciated. You all have been a tremendous help in the past.

http://www.tbrstudio.com/StudioPics/tbrsoundroom.jpg

Real room pics are located here...

http://www.tbrstudio.com/newstudio/finishedroom4.jpg
http://www.tbrstudio.com/newstudio/finishedroom1.jpg
http://www.tbrstudio.com/newstudio/finishedroom2.jpg
http://www.tbrstudio.com/newstudio/finishedroom3.jpg
http://www.tbrstudio.com/newstudio/finishedroom5.jpg

Thanks,

- Chris

[knightfly]

"he told me that I had a standing wave issue behind my desk" - That sounds like a pretty generic comment - does your friend have any more details, or could this just be a way to SOUND knowledgable?

I ran a modal analysis on those dimensions, and distribution isn't too bad; there's a slight "hole" in modal density around 63 hZ, and another down around 40, but other than that the room dimensions shouldn't cause serious problems.

ANY room has peaks and dips, and you don't have enough corner absorption to fill those in noticeably (it would take a complete fill across all corners with the front face at least 3' wide to get close) - but even then, moving front to back near the mix position in nearly ANY room will give you hot and cold spots at different frequencies.

Have you measured exactly the distances from your speakers and ears to each boundary in the room? If so, what are they? Gotta start somewhere... Steve

[IntelDoc]

nightfly,
First off, thanks for the reply. Teh guy who was over is a respectable high end studio owner in the Washington D.C. area. I trust him greatly, so yes it was an educated assumption.

My measurements are as follows:

spacing between speakers now laying on sides is 41 inches
2 x 20.1 inch widescreens between sitting flush

Right speaker:

18 inches from center back edge to the wall
21.5 inches to the wall to the right

Left speaker:

18 inches from center back edge to wall
27 inches to the left wall

Not sure what other boundaries you need?

Also, I was thinking about maybe getting the corner trap foam and putting it along the wall/ceiling edge???? good idea? or build maybe a floor to wall trap across the back as well.

Another thing is that I do not have any absorbtion above my mix position? Should I? Their is room for at least 2 traps at 2x4'

Thanks,
Chris

[rod gervais]

The bass traps I made from Ethans design and work great from before and after tests.

Chris,

Exactly what tests did you preform?

By the way - having a standing wave isn't an issue if you are not sitting in a node or anti-node.

You can have a peak - a null - or normal amplitude at a number of given points through a standing wave - as long as your ears are at a point where there is normal amplitude, then the remainder of the room isn't an issue - because you can't hear it............ you can only hear what happens exactly at your ears.............

Sincerely,

Rod

[IntelDoc]

Rod,
We shot the room with a omni mic and a wave form to get the peaks but I really need to do it again now that everything is set. The PING is definitely gone asfter the traps went up. Had that "I am a rectangular room" ping going on. Once the traps went up, it was all sucked out, and was cool to hear stuff on the monitors finally. Honestly I think that the room sounds good. Better than the smaller room I used to use. The node is to the left and right only when you are standing about 4 feet back from the mix position. The center is actually pretty balance. I reference a few Sting Cd's as they tend to translate well and have a nice overall mix on everything I put them through. As for the room, it is somewhat typical for the room demensions I think?

I need to get the other trap up in the Right corner and I may put 2 above my mix position as well. There is enough in there to add a nice diffusion in my mind, but I could be wrong. Can only do so much with the space.

Thanks,
Chris

[rod gervais]

Rod, The node is to the left and right only when you are standing about 4 feet back from the mix position. The center is actually pretty balance. I reference a few Sting Cd's as they tend to translate well and have a nice overall mix on everything I put them through. As for the room, it is somewhat typical for the room demensions I think?

Chris,

If the mix position is right - I wouldn't mess with it.

One of the problems with adding treatments when you don't need them is the more you make the room dead the less natural reverb you get from it........ and room response is important - because it helps to determine how much reverb you add into the mix.

As I said above - especially in a room that size - if the mix position is right - screw anywhere elese in the room.

This is a case of "if it ain't broke - don't fix it".

Sincerely,

Rod

[pantalaimon]

I ran a sound field for your room. all frequencies were okay, the few that caused problems were the ones between the following:















and i ended up with this for optimal positioning:

[knightfly]

Judging from your comments and the pix, about the only change I'd make is putting your speakers back vertical (wider sweet spot, see Philip Newell's Recording Studio Design for more or ask me if you want clarification) and, I'd build a gobo (essentially at least two of your wall panels made portable) for in front of that sliding glass door during mix. I'm not seeing any absorption on the ceiling over the mix position; if that's the case, a couple more similar panels hung there will clean up early reflections off the ceiling.

Play a bunch of well-mixed commercial CD's, some of your own mixes, check your mixes in a few other places (cars, living rooms, etc) to test for translation, and you should be good... Steve

[IntelDoc]

Panta and nightfly,
One thanks for the diagrams... jesus dude that is crazy! What program is that? Very cool.

Also, night, I plan on building 2 more pnels for above. That was the original plan anyways. The room does sound good to me, and the mackies on the side was a test. I will stand them up though as I am trying to get a pair of Blue Sky System 1's for a sub setup. Eventually at least. The glass door has a curtain in front of it, but another gobo may be a good thing.

Thanks again, and I will post back once I build the other pieces.

Thanks for all the input.

Also, for the most part all my mixes have translated very well on systems.

- Doc

[knightfly]

"for the most part all my mixes have translated very well"

Cool, if it ain't broke don't fix it...

[IntelDoc]

I still think that the overhead traps will be of use though.

Thanks,
Doc

[knightfly]

Absolutely; never meant otherwise...

[pantalaimon]

no probs. i guess you just have to watch out for multiples of 20Hz.

hope it works out, but i think the best thing to do is "what sounds right".

pan