my studio spl readings.. help/advice plz

[Disjointed]

i have finally finished a nice lil studio, and i decided to take some SPL readings last night to calculate the science of sound...
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- disclaimers = testing was done with a cheapo radioshack SPL meter
= i like the sound of the room, but i have been having trouble with bass translation
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ok so,
my readings are freaking me out a little bit... they seem real 'wavy', but this is the first space i have tested, or seen results to...

do i have a problem? are my monitors that bad (wharfendale 8.2a), do i need more absorption in the room.... tuned specifically, broadband? (probably)

the room is approx 24'x18'x10', there is a 6'x4' cloud over my desk..

graphs and room layout attached, (graphs are C weighted, first is octaves, second is from 1-18k))
thanks for any help

[jwl]

Those curves actually look to be quite smooth for room response. Usually comb filtering makes things much worse than that, HUGE peaks and valleys very close together -- we're talking differences of 25-30dB or more over a fraction of an octave, say from 51Hz to 54 Hz -- are common.

I'm not sure what resolution you are using for your room tests. One problem is, as I mention above, there are often large peaks and valleys spaced close together, so if you are using a 1/3 octave RTA these peaks and valleys will be averaged out over each 1/3 octave. Therefore you won't really see what's happening in enough detail.

You may be interested in checking out some more sophisticated testing programs such as R+D or Room EQ Wizard...

As far as flattening the bass response of the room, in general I recommend starting with broadband absorption in the room corners. Treat as many corners as you can, and go from there. From your drawing it looks like you've done the wall/wall corners, consider treating the wall/ceiling and even wall/floor corners where appropriate.

[Disjointed]

jwl, thanks for the help!

i ran room Eq wizard in the studio... the results are attached..(full measurement/LF decay)

i saw the massive comb-filtering you are talking about, ... is that normal/average acceptable?

these are smoothed out to 1/24 octave?

thanks

[jwl]

I would say that those curves are both normal and average, but only you can decide if they are acceptable.

The solution is: more bass traps. I recommend broadband traps using membrane designs, this will maximize bass absorption without killing the highs too much. Get as many of them into as many corners as you can. The more you have, the flatter the room gets (ie, the peaks and nulls are reduced).

Once you've got as many traps in as many corners as you can, if there are still problem areas you can treat those specifically with tuned absorbers (ie, slot resonators).

[Glenn Kuras]

do i need more absorption in the room.... tuned specifically, broadband? (probably)

the room is approx 24'x18'x10', there is a 6'x4' cloud over my desk..

Not sure if you need tuned at this point in time but you could also start to straddle ceiling to wall corners along the side walls. Also on the back 1/3 of the room I can see put diffusion.

Glenn

[nosebleedaudio]

Looks like the low end rolls off pretty bad.
One way to see if its mode problem is inject a 60hz for example and only the left speaker on and check for SPL at the sweet spot, then add the other speaker and see if the level goes up by 6db. If it goes down, then you have mode problems that bass trapping in the right place should make a big difference. This test should be done going up and down the scale. And will add that a continuous tone is the acid test, real music will sound better...Not sure why that is, but it is. I have some examples I could share if your interested...
One thing for sure in my pea brain is I don't believe you can have too much bass absorption. The bass will keep getting better and more defined.

[Disjointed]

thanks for the responses!

i have tried single note readings (the very first post/graph).. and i dont have a null in the mix position, phase seems to be ok.. i have noticed 2 nulls (in almost all frequencies marked with X's in the attachment), but these are out of the way and dont seem to cause too much trouble

i must attach that these readings were not done with a calibrated mic.. they are the sound run through my monitors, into a (relatively flat) omni sdc at mix position

i do have plans to add diffusion on the rear wall (there is a sliding glass door in the center), i was planning on draping (wavy) a heavy fabric as a curtain over the door, and a 4 x 6' diffuser above it (skyline style most likely) ...

i have 2 pcs of 2'x4' 4" mineral wool, and 8-9 pcs of 2" left for absorption purposes.. suggestions appreciated .. i was planning on putting some 2" on the ceiling(indicated in green).. since this is also a tacking/mix room..

how about 2 lower-bass traps (membrane 1/4 ply, airspace. 4"mineral wool,airspace = in a 7.5" deep sealed front box) on the side walls ??

any of these ideas sound good? bad?

ps: i did move my speakers farther out from the wall last night and got a nice increase in bass clarity..

thanks again for your help!

[jwl]

I don't recommend tuned absorbers at this stage. I think you are better off with broadband treatments, then if there are still a few issues you can target them with a tuned absorber or two.

You will likely want to get some absorption on the rear wall, since the (very nice) shape of your room will be aiming reflections back there. I'd probably put much of your remaining rockwool on either side of the glass door, in the rear corners of the room.

You could still go with some broadband bass trapping in the front of the room, though.

[Glenn Kuras]

Originally Posted by jwl

I don't recommend tuned absorbers at this stage. I think you are better off with broadband treatments, then if there are still a few issues you can target them with a tuned absorber or two.

You will likely want to get some absorption on the rear wall, since the (very nice) shape of your room will be aiming reflections back there. I'd probably put much of your remaining rockwool on either side of the glass door, in the rear corners of the room.

You could still go with some broadband bass trapping in the front of the room, though.

I think for that back wall you are right but would start with it behind the skylines.

Glenn

[Disjointed]

how would i install the broadband behind the skyline?

side bass traps good idea or no?

ceiling bass traps? (wont help the mix position, but will help the room)


thx again!

[Disjointed]

sorry to rebirth this thread, but i feel incomplete...

would i put absorption on the wall directly behind the skylines, make a resonant box with the skylines as the front, float the skylines in front of the absorption, maybe put them both at a 45* angle (downward)..???



thx for all your help!