hi!
it has been about 1 1/2 year that my studio is up
http://www.johnlsayers.com/phpBB2/viewtopic.php?f=1&t=11575
i admit i never spent so much in optimizing everything, but now i recognize that i have some problem in the bass-range.
for now, i will just describe the situation.
if i run a long bass sweep and i stand in my usual-listening-position, for some frequencies i have a sudden decrease in volume. but if i just move my head 30-40 cm away toward the back, the problem disappear.
is there a way to minimize this problem by moving the monitors?
in which direction? should i maintain the equilateral triangle configuration?
i cannot move my desk and listening position!
i post some photos here:
thanks!
This is typical room mode behaviour which theme you might want to check out. Realtraps.com has some very good articles regarding this phenomenon.
Yes moving the speakers could help with the problem, also adjusting and changing the treatments at your critical reflection points.
Seems to me you have simple acoustic foam on the side walls. You might consider adding a couple inches of rigid glasswool panels to the rear of these, and then mounting them so they stand off the walls a bit i.e. that there is an airspace behind them.
If you haven't already done so, download a copy of the free software REW and set up a room test. This will help you see what effect your changes are having.
thanks for the advice.
my bass traps are home made and behind them there is some gap between the foam and the walls.
but they lack the rigid glasswool panels. i will consider these. but what is their function? i.e. why i should mount this rigid glasswool panel?
Please reduce the size of your photos, so that the comply with the forum rules.
Also, do you have a SketchUp model of your room, or at least an accurate diagram that shows all the dimensions and the existing treatment? That would be helpful in trying to figure out how to solve your problem.
One other thing that you can do that would help a lot, is to use Room EQ Wizard (REW) to do an analysis of your room response, so we can see exactly what frequencies are causing you problems, and work out how to deal with them.
- Stuart -
The rigid glasswool or fiberglass panels are the prime ingredient for an acoustic absorber. It could also be mineralwool but this breaks apart too easily. Acoustic foam will have a noticeable effect on the upper and mid frequencies but falls short on the lower ones.
What you refer to as bass traps is actually a misnomer, absorber would be more correct. The thicker you make these panels the better.
From what I can see in your photos, you have something wrapped in fabric in the corners, you refer to this as foam. They also look very thin. How are they constructed?
Many people today use a chunk type absorber. These are triangular wedges of rigid fiberglass (as thick as possible but typically 4") stacked from floor to ceiling in the corners, the facing is then usually covered in a fabric.
You also have a window in front of your desk, this would require a good absorber to be placed on the wall behind you or as a standing panel behind you.
Do you have a cloud above the LP as per your original design (from the drawings in your original post I would say that the cloud shown should be angled in the other direction!). Such a cloud will bring amazing results, and it is built basically the same as the wall absorbers (although it could have a plywood or mdf backing).
"is there a way to minimize this problem by moving the monitors?"
What you have is a room with some stuff in it, a lot of glass reflection in the early region and minimal support for a controlled sonic experience.
You are not having issues with room modes as much as you are having with the, well, room.
Lot of stuff in a lot places, poor absorption for a mixing environment, glass creating early reflections and shimmering all over your mix.
I see what could be a corner broadband absorber in one corner...maybe half of one in the other corner (behind the monitors).
Foam on the walls, sort of works, but it isn't really taking anything away from the power of the glass...the hard walls///the hard floor/carpet and can we assume a hard ceiling?