acoustically i have done something wrong and need help

[nonamesleft]

ok, so i got a desk (Buy Studio RTA Producer Station | Desks, Tables & Workstations | Musician's Friend) a cheap plastic folding desk. As well, i moved my setup from a corner to the middle of the shorter wall (rectangle room) and put myself into the 38% spot.
I then got 12 bass traps (six 4" and six 2" mineral wool) and put them where i thought (probably incorrectly) they were supposed to go. (see pic)
i am planning on getting 6 more as soon as i have the funds.

i had to place my monitors on the lower tier of my desk because they are way too high when on the top...the tweeters are ear height currently, and i am in the proper triangle. I have a 12" sub behind the desk in the middle of the wall.


i assumed doing all this would make for a better freq response...not fixing all my problems, but what happened is something i did not expect. my room sounds awesome when i walk in...like i'd love to record anything in there...but my monitors sound downright terrible. in the corner with no treatment it sounded fairly decent, but now it is absolutely impossible to mix at all. My bass freqs (up to about 100hz) have been somewhat tamed, but my mid lows (150-400ish) are simply gone. My high mids are insanely loud (2k-5k) and my highs are actually alright.
seriously it sounds like i just bought a pair of cheap crate speakers when in fact i have some decent jbl's.

Surely i am doing something very wrong and was hoping to have some suggestions as to what that might be. Unfortunately i do not have any testing gear cause i have been spending all my cash on treatment of late. I tried the JBL auto eq thing but that is a waste of time cause it just puts a filter on 80hz and thats it...just like it always does no matter what room i am in. it even did it outside once...i wanted to see if i could get the freq to change...lol

i have attached a pic for reference...

[Glenn Kuras]

As well, i moved my setup from a corner to the middle of the shorter wall (rectangle room) and put myself into the 38% spot.

This is only a starting point. You may find that moving forward or back will give you a better response.
I would recommend that you down load the following program (it is free) to test the room. At that point you can post some graphs for us to see.
Room EQ Wizard Home Page

I have a 12" sub behind the desk in the middle of the wall.

Are you sure you need a sub?

[nonamesleft]

Hey Glenn, thanks for the reply.

This is only a starting point. You may find that moving forward or back will give you a better response.

i'll move my gear around a bit and see what i can do...

I would recommend that you down load the following program (it is free) to test the room. At that point you can post some graphs for us to see.
Room EQ Wizard Home Page

when using this program...what mic and preamp do i use? i currently have 2 omni mics (jbl lsr series testing mic that may or may not be flat and a telefunken ak47 which definitely is not flat) and i have an assortment of pres, all of which are colored in some way or another (api's, neve's, art mpa, solo 610, and solo 110...the 110 is probably the flattest response). I am just wondering if i'll use a mic and pre, see the results, and be fooled into thinking it represents an accurate picture of what i am dealing with when in fact it might be the coloring of the preamp and mic.

Are you sure you need a sub?

absolutely...i got the jbl's with the 6" drivers not the 8". the moment i hooked up my sub everything in my low end instantly started translating better since i could finally hear what was down there...it wasn't perfect, but it was certainly better.

[Weasel9992]

Originally Posted by nonamesleft

I then got 12 bass traps (six 4" and six 2" mineral wool) and put them where i thought (probably incorrectly) they were supposed to go. (see pic)
i am planning on getting 6 more as soon as i have the funds.

There are a couple of issues as I see it. First you have two repeating dimensions in the room, and second, the room is small. So from the start you have to realize that it's going to take a bunch of treatment to get the room under control. Personally I wouldn't put a trap under 4" thick in that room just because of the size and repeating dimensions; a good broadband trap will handle the highs just like a 2" panel plus add bass trapping down into the 60's where you're definitely going to need it.

Originally Posted by nonamesleft

The 2" panels at the reflection points and on the front wall can probably stay, but I'd replace the 2" panel on the back wall with at least one 6" bass trap, and preferably with two 6" bass traps. After that you'll need to add four more 4" traps for the corners, then I'd do 4" bass traps in a cloud above your head. Don't put any more 2" panels into the room.

i had to place my monitors on the lower tier of my desk because they are way too high when on the top...the tweeters are ear height currently, and i am in the proper triangle. I have a 12" sub behind the desk in the middle of the wall.

Like Glenn, I suspect that the sub is causing many more problems than it's solving. I use the LSR4328's, and I have used the 4326's...they'll produce all the way down to 50Hz pretty reliably. That 12" sub along a 10'H/10'D is putting a bunch of energy into the 50Hz primary mode.

Originally Posted by nonamesleft

i assumed doing all this would make for a better freq response...not fixing all my problems, but what happened is something i did not expect. my room sounds awesome when i walk in...like i'd love to record anything in there...but my monitors sound downright terrible. in the corner with no treatment it sounded fairly decent, but now it is absolutely impossible to mix at all. My bass freqs (up to about 100hz) have been somewhat tamed, but my mid lows (150-400ish) are simply gone. My high mids are insanely loud (2k-5k) and my highs are actually alright.
seriously it sounds like i just bought a pair of cheap crate speakers when in fact i have some decent jbl's.

From your diagram it doesn't look like you've got anything on the ceiling, and that could be part of the problem. Low mid problems are often caused by a floor bounce. I also think that your low mids were probably scooped out to begin with, but the problem was masked by the bigger low end issues you had until you put treatment into the room. Now that you've tamed those peaks you can hear the other problems clear as a bell. That's very, very typical for a room that size.

Originally Posted by nonamesleft

Surely i am doing something very wrong and was hoping to have some suggestions as to what that might be.

I don't think you're doing anything wrong at all...you're just not done yet, that's all. My room is a bit larger than yours and I have 14 244's, five Monsters and five 242's in mine...and I don't have any repeating dimensions. It's very common to expose problems in your room when you start treating it.

Frank

[nonamesleft]

hey Weasel9992, thanks also for the detailed response.

it is good to know that i am seemingly falling into a typical pattern of doing some treatment and finding problems that were previously masked. i was seriously considering putting everything back in the corner because the sound quality has gone from decent (i could get a mix done that would somewhat translate) to horrid (can't get a mix to translate in the slightest...like the 3-6k hurts my freekin ears to even listen to reference material).

so am i right that the suggestion for me currently stands at:
1. do some testing without the sub
2. put more 4" panels in the room (ceiling and corners)
3. move the desk back and forth to see if it helps
4. get some readings and post them for analysis...see my question about that in my previous post

any other suggestions?

[Weasel9992]

Originally Posted by nonamesleft

hey Weasel9992, thanks also for the detailed response.

it is good to know that i am seemingly falling into a typical pattern of doing some treatment and finding problems that were previously masked. i was seriously considering putting everything back in the corner because the sound quality has gone from decent (i could get a mix done that would somewhat translate) to horrid (can't get a mix to translate in the slightest...like the 3-6k hurts my freekin ears to even listen to reference material).

so am i right that the suggestion for me currently stands at:
1. do some testing without the sub
2. put more 4" panels in the room (ceiling and corners)
3. move the desk back and forth to see if it helps
4. get some readings and post them for analysis...see my question about that in my previous post

any other suggestions?

Nope, that's exactly right...I'd be very interested to see what you get with the sub turned off.

Frank

[Mulmany]

When you use a sub with any system make sure your phase response at the crossover is correct. That means - 80hz is at 40 degrees phase at the LR speakers but because of the sub displacement (distance) 80hz from the sub is at 70 degrees phase. This kind of combination will cause a comb filter on up though the frequency range. The numbers I picked are random, your system will be different.

Most subs come with a phase switch or knob that you can adjust. You want to send a sinewave though your system at the crossover frequency. (Your crossover frequency is the frequency that is -6dB at the natural low roll off of the speaker) For fun take a walk around the room and listen to the changes. Now invert the phase on the sub 180 degrees and move it around until the level drops at the listening position, this will take two people to make short work of it. Once you have found the position that creates the greatest reduction in level, switch the phase back to zero. If your sub has a phase knob - invert the LR speaker phase, and adjust the knob until you have a level drop at the listening position - correct the polarity on your LR speakers and take a listen. You should have a fuller, richer bass responce, since your Sub is now truly reinforcing the LR speakers. You also want to adjust the level of the sub to create as smooth and flat transition as you can into its range.

Advanced dual channel FFT programs will allow you to do this much quicker and more accurately like SIA's Smarrt.

This is not to say that you don't need more bass trapping. Put as much as you can! It will also help to aline the sub with the LR speakers as you will reduce the ringing in the room, and let you hear when you have cancelation.

Hope this helps

PS make sure that the sub and speakers are level matched before testing the phase.

[Weasel9992]

Originally Posted by Mulmany

When you use a sub with any system make sure your phase response at the crossover is correct. That means - 80hz is at 40 degrees phase at the LR speakers but because of the sub displacement (distance) 80hz from the sub is at 70 degrees phase. This kind of combination will cause a comb filter on up though the frequency range. The numbers I picked are random, your system will be different.

Most subs come with a phase switch or knob that you can adjust. You want to send a sinewave though your system at the crossover frequency. (Your crossover frequency is the frequency that is -6dB at the natural low roll off of the speaker) For fun take a walk around the room and listen to the changes. Now invert the phase on the sub 180 degrees and move it around until the level drops at the listening position, this will take two people to make short work of it. Once you have found the position that creates the greatest reduction in level, switch the phase back to zero. If your sub has a phase knob - invert the LR speaker phase, and adjust the knob until you have a level drop at the listening position - correct the polarity on your LR speakers and take a listen. You should have a fuller, richer bass responce, since your Sub is now truly reinforcing the LR speakers. You also want to adjust the level of the sub to create as smooth and flat transition as you can into its range.

Advanced dual channel FFT programs will allow you to do this much quicker and more accurately like SIA's Smarrt.

This is not to say that you don't need more bass trapping. Put as much as you can! It will also help to aline the sub with the LR speakers as you will reduce the ringing in the room, and let you hear when you have cancelation.

Hope this helps

PS make sure that the sub and speakers are level matched before testing the phase.

Fabulous post. As good an explanation of crossover tuning as I've ever seen.

Frank

[Mulmany]

Thanks! Smarrt certification helps, and alot of trial by fire live sound gigs.