Improving my studio

At first I would like to say that I'm very happy with my new (1 year old) studio. Also, thank you very much all of you guys helping me especially John and Steve. Well, here's the reason why I think that improve of my studio is possible and needed. I work a lot with pop and dance kind of music and this area is very critical for good bass and kick thump. Also, I like to play loud and I have the feeling that loud listening extends all standing waves, so, will be nice to fix this 110hz issue :wink: Also, I have some problems with blurred sound picture ( some kind of comb filtering) and i suspect that is caused by side area of my studio. (BTW the small part of the glass door and above "depends" to RFZ and I didn't covered that with any type of absorption. BTW at this moment my rear wall is 10cm of 50kg/m3 + 5cm 80kg/m3 rock-wool and the cloud is 10cm 50kg/m3. So, here is my idea how to solve problems, pictured and described. Please, let me know what you think about? Cheers, Moby

a couple of thoughts come to mind: if the drawing is accurate, you appear to be sitting right in the middle of the room (wall-to-wall). what happens if you move your seating (and console) toward the front wall ~0.75 meter? also the ceiling elevation over the console does not look to be symmetrical. not sure if that combined with the glass on each side is causing the combing but it would seem that putting up some treatment to even out or reduce any reflections would be helpful. maybe something you can slide in place when you don't need to see through the doors.

gullfo wrote:

a couple of thoughts come to mind: if the drawing is accurate, you appear to be sitting right in the middle of the room (wall-to-wall). what happens if you move your seating (and console) toward the front wall ~0.75 meter?

Yes, drawing is accurate, and the mix position is in the middle. I tried to move, something changes, but that something is some other frequency problem. BTW if I move i loose hot spot (and 60 degrees) :wink:

also the ceiling elevation over the console does not look to be symmetrical. not sure if that combined with the glass on each side is causing the combing but it would seem that putting up some treatment to even out or reduce any reflections would be helpful. maybe something you can slide in place when you don't need to see through the doors.

Yes, ceiling is asymmetrical and cloud helps a lot to compensate that, but I'm afraid that you are right about glass doors.... But, I was thinking about putting some kind of hanging absorber only on one part of the door surface, which provides me the Reflection free zone. You can see that yellow "thing" hanging in the corner of the door and soffit. BTW, thanks for the piece of advice. :D

Is the distance from your front wall to the back one by any chance very close to 4.7 meters? Also, are your front soffits really built like that? IF not, what is covering the frames exactly? Steve

also - are your speakers in phase??

knightfly wrote:

Is the distance from your front wall to the back one by any chance very close to 4.7 meters? Also, are your front soffits really built like that? IF not, what is covering the frames exactly? Steve

Sketch shows just the frame, sorry I was too lazy to draw surfaces, but here's the pic of the "naked" soffit. This black fabric covers the soffit. Front panels are 2 and 2.8mm MDF. Also here's the measure you asked. BTW, is this relation between left soffit and rear brick wall critical. It's not parallel , but it's close to be... :roll:

John Sayers wrote:

also - are your speakers in phase??

Yes, they are :D I hope you are asking about electronics phase. Because in some frequencies they really sound like out of phase, but that's the acoustical phase. Am I right?

I'm still a bit confused - is that wide brown line at the rear of the CR (one side has rockwool attached) an actual WALL, or is the room open all the way to the rear brick? IF the brown line is a wall, this would be the endpoint of the distance I'm looking for; that would probably account for the null you're (not) hearing at the half-way point... Steve

knightfly wrote:

I'm still a bit confused - is that wide brown line at the rear of the CR (one side has rockwool attached) an actual WALL, or is the room open all the way to the rear brick? IF the brown line is a wall, this would be the endpoint of the distance I'm looking for; that would probably account for the null you're (not) hearing at the half-way point... Steve

Sorry if I'm confusing you with my laziness to finish sketch :oops: Brown-yellow-green or whatever line is the brick wall, outer wall of the house. The false rear wall of the control room (brown) is completely same from left and right. Want to say it's symmetrical, and wooden frame is filled with insulation of 10cm 50kg/m3 + 5cm layer of 80kg/m3. Of course it's covered with fabric, because I don't like to eat rock wool. :wink: Also, there are the hangers hanging' between false and brick wall, but if I draw them you will not able to see "situation". BTW, I tried to remove them (hangers) and measure without and fount that situation around 110 hz is the same. They are doing some nice job below 70 hz :wink:

Try moving the mix/measure position forward by 200-300mm and see if the null gets better... Steve

knightfly wrote:

Try moving the mix/measure position forward by 200-300mm and see if the null gets better... Steve

I think I tried that few months before, but don't have the graph :? Will try again and post the result. Are you think that changing the mix position can solve the problem or just want to figure source of standing wave?

Hopefully BOTH - a quick way to see more of what's going on (for low freq ONLY) is to set up some sort of stand for your speaker that puts the woofer exactly where your head would normally be - then generate the offending tone into the speaker, and move your mic around the room noting peaks and dips (some strips of masking tape can help flag these) LF sound is omnidirectional enough that this will be a much quicker/easier way to find room anomalies than trying to move a speaker around (especially when they're soffited) nearly any speaker that can reproduce 60 hZ or so can be used, so you don't need to remove one of your soffited ones. This same test can be run using ETF software or similar, set to continuous repeat - you can hold the mic in any location for 3-4 repeats to see what that spot looks like, then move on. An entire room can be checked out pretty quickly this way... Steve

Thanks Steve. I tried this method few years ago when I was trying to find position for the sub-woofers. If I remember, best (most linear) position was the right place. But for finding position for bass trap I'm not sure am I looking for the mirror position of the problematic freq.? To be more precise, if I have dip at 100 Hz at mix position around 15 db , I have to find +15 db somewhere. :?: Sorry, if I ask dumb question, just want to be sure about :wink:

the modal reinforcement point could be "outside" of the listening area since you have false walls and the brick wall... so you may have a -15db null but not a readily accessible "mirror" point. same for modal reinforcement - you might have a peak without a readily accessible null point. thats part of the problem with low frequency and odd shaped rooms and multiple leafs. for all of its other issues, a single leaf rectagular room is somewhat predictable... maybe mapping out the modes in the room based on the brick walls as well as the audio measurements may help spotting the problem areas...

Hello, Try running sweeps of your room first with Left only and then Right only. Overlay the curves and note the differences. If you are having phase problems they will be represented by Left peaks lining up with Right nulls and visa versa. These anomalies slur the center image making tracking and mixing difficult. Room modes show up in both Left and Right. Our new rooms here at PCC are experiencing the same problem with phase. Diffusion has helped much. Room layout including gear, people and furniture must also be symetrical.

Guys, thanks for helping. I'm still running through my head John's question about speakers in phase. Yes, from electronics side of view they are in phase, but there is some acoustical phase anomalies in my room.... About measuring left and right speakers, I already did that ,and you can check the graphs here http://www.johnlsayers.com/phpBB2/viewt ... sc&start=0 BTW, right now in the middle of mixing one project and will do all the tests again next week. I must run around with Mic stands speakers and rock-wool, so clients can easily think that I'm crazy :wink: But, I have some ideas about possible positions of the peaks in that 100hz area.... I didn't measure but listened the problematic tones and found that.

I did some measuring... Wasn't in the situation to try with speaker at mix position , but here's the response from 4 positions Please, tell me do you figure something :?:

Hello, Just at a glance I would think the 110 notch is probably a phase anomaly due to the asymetrical shape of the rear wall. The rear absorber structure is symetrical but the low fz are being reflected off of the solid wall behind. It shows up in the LT vs RT sweeps from the earlier post. To bad you dont have enough space to 1/4 wave trap the back wall at the fundamental. I think low fz traps would improve your situation though.

Thanks, I was thinking about , yes there is just around 30cm space behind false wall, and of course if I sacrifice some hangers :? But, maybe this side "box" can be used for some trap.... I filled that space with hangers too, but what to do :wink: Also, I'm not sure about 1/4 wavelength traps... Are they have to be 1/4 of wavelength deep? In this situation around 80cm?

Hello, I was thinking about your mid phase problem too. You might be able to remedy that with 1/8" (3cm) luan plywood applied to the back of your absorber wall (with air space or not depending on result). It would give the low mids enough mass to reflect symetrically. It might improve the low fz but some energy would still be asymetrical. I'm trying to come up with some clever innovative solution but really feel the need to stand in the room and listen. The fact that the rear wall is asymetrical is really challenging.

Maybe, on the side of the room where the solid wall is further from the mix position, you could temporarily place a sheet of MDF or plywood a couple of feet off the floor (say, on chairs or packing crates) to simulate a solid panel in the main part of that wall, letting the top and bottom bleed through into the absorbed cavity - this may give you a more symmetrical back end while allowing the absorbed cavity to act somewhat as a "folded horn" approach to bass trapping? Just a thought... Steve

Guys, thanks a lot! Must say that I'm thinking about this problem all day long, not to mention that its "ringing" in my head during mixing because of phase problems... :? I played today with signal sinus gen. and listened the problematic freq's and when I listen just one side (right at around 110hz) I have the feeling that sound is coming from left speaker! So, I think that this panels solution can be easy to try, why not? BTW, I finally found info about rock-wool I'm using, (that's the one of two available in my area, mine is the better one). I think that this can be problem too, because not so great in low frequencies. I think it's much worse compared to OC products. Please check this and tell me what you think about. http://www.termo.si/en/tervol.asp?f=/en ... L_DP-5.htm My false rear wall is 10cm of dp5 and 5cm dp8. I remember that before adding the 5cm of dp8 situation with low end was worse. Should I add some more of dp8? Maybe to make some hanging traps too in the inside area? In front of the existing wall?

Just a little about soffit mount theory before I do the upgrade of my rear wall.... :roll: I understand that soffit is baffle extension and stops 360 deg. radiation of the speaker. Also, I understand that it is the closest to infinite baffle theory. That's great, all waves are radiating in same phase, no delay from back and side walls ( if side walls are angled properly). But, I remember that John was stressing ( year and half ago , when my studio was in progress) that rear false wall have to be heavy filled with insulation! Now I understand why :idea: Simply, all waves reflected from back are "mixing on the baffle" with my speaker 0 time signal and causing really serious phase problem. :cry: Please, correct me if I misunderstood something! If I'm right, I think that maybe I can try to add some more insulation , maybe to do that with the few layers of rock-wool with higher density just to compensate my brick wall non-symmetry. Let's say that if I add layer of mdf behind insulation, reflections will be symmetrical, but they will still "mix" with my speakers, but if I try with insulation, maybe I can do something more... Just a tought, because density of the MDF is approximetly 700kg/m3, maybe 5cm layer of 120kg/m3 r.wool + 3 cm 250/m3 can do the job... At last, I still have some space to add the layer of MDF too at the back of the insulation. Please tell me what you think about. :D

this may be a case where you want to construct some panel traps on the back wall specific to the problem frequencies rather than (what sounds like) creating a third leaf situation with the MDF. the low bass frequencies (pressure more than velocity) are more problematic because of the brick exterior walls are doing a really good job of keep them in the room... the velocity attentuation happens due to the false wall, insulation, and the air gap spacing. now you need to deal with the pressure levels by building panel (or tube) traps to absorb/cancel the problem peaks @ 40, 90, 330. nulls are probably do to positioning of speakers and/or listener. lows at 70, 110, 150, 180, 350 could all be a matter of a few-500 cm forward or back, up or down.

Thanks, what about adding some more rock wool with higher density too?