Beginner seeking advice on DSP+Room treatment for Living Room + Studio

[adam_dan]

Hey all, have been lurking for a couple years, was going to build the LX521.4 but my room at my new place is too small (Roughly 25x12ft, combined living and dining area) - just moved into a new place and getting my system setup. At my prior apartment, I had a larger room with the back wall treated, and was able to move the speakers further from the walls. I was able to get relatively good measurements with Dirac. I've moved into a new place and am unsatisfied with the sound, but having trouble determining where to start.


Here is my living room setup:

• Mains: Titan615Lx
• Subwoofer: Speedwoofer 12S
• Amplifiers: 2x Schiit Vidar as Monoblocks
• Preamplifier/DSP: Minidsp SHD

The other room is a music production studio, and my previous room was smaller, squarer, and untreated, so I'm hoping I can get this room measuring quite well.

• Mains: Yamaha HS8
• Interface: Motu M4
• Planning on upgrading to a pair of KH310+2xKH750 once I get the room treated and measuring well, and maybe an RME interface.

I am still unpacking boxes, but will post some photos once I get the rooms cleaned up, along with REW measurements. I've also picked up a copy of Toole's book, which should come tomorrow.

These are both living spaces as well as listening spaces, so I can't go too crazy with the acoustic treatment (moreso in the living room). Fortunately, my partner is also an audiophile and is willing to compromise aesthetics for sound quality. I listen to and produce what I would describe as experimental electronic music, so bass reproduction is critical, but many other genres too, so soundstage and timbre are equally important.


Here are my initial questions as I dive further down the acoustics rabbit hole:

1. In addition to Toole's book, are there any "must-read" papers?
2. What is the best/easiest software tool to draw a layout of my room if I don't want to use a full CAD package Solidworks/Fusion360?
3. Should I Dirac before I treat my room?
4. I haven't been able to find anybody running Dirac Bass Mgmt. on the SHD, is this a limitation of the hardware, and does that mean I will need to learn MSO?
5. What are the most useful measurements for me to post? I was planning on taking spectra of the left and right mains and a stereo RT60. Are there any other graphs y'all would like to see?
6. Would any of the roughly $2000 I plan to spend on room treatment be better spent on upgrading equipment? I've had my Titan speakers for ~7 years now, built them for my 16th birthday and while I'd be sad to see them go, if it's the best thing I can do for my sound, I'll do it.

Thanks so much in advance for the help

 

[dfiler]

Your equipment is already good enough that the room is the limiting factor. This is true quite frequently. It’s more tempting to buy a new piece of gear with better specs. But really, it’s the typical echo chamber living room that dictates sound quality beyond what you have. The most expensive speaker in the world will still sound the like the inside of a steel can when listening in an untreated room.

The best way to improve your sound is to add as many square feet of absorption as you’re willing to accept in that room. White panels on the ceiling and printed art acoustic panels can help make them disappear if that’s a concern. Theoretically you can over damp a room but that pretty much never happens in a mixed living space.

 

[Flaesh]

I was planning on taking spectra of the left and right mains and a stereo

Just post .mdat file with these three measurements. And room dimensions\layout.

are there any "must-read" papers?

This is the most important AES paper regarding subwooferolgy© Michael Lowe . The article at the link and there are the posts below

Essential AES reading for high fidelity home reproduction

Eventually we made a large sonic boom simulator for NASA research Oh yeah I remember that thing, that was crazy! You should make those segments again and sell them to South American soundoff competitors :D

www.audiosciencereview.com

 

[kemmler3D]

Fortunately, my partner is also an audiophile and is willing to compromise aesthetics for sound quality.

You are already way ahead of the game, in that case.

What is the best/easiest software tool to draw a layout of my room if I don't want to use a full CAD package Solidworks/Fusion360?

Depends on what you want to draw it for, if it's just for illustrative purposes you can use Inkscape (free) to do a scale drawing, there's also sketchup and Blender for 3D drawings.

Would any of the roughly $2000 I plan to spend on room treatment be better spent on upgrading equipment? I've had my Titan speakers for ~7 years now, built them for my 16th birthday and while I'd be sad to see them go, if it's the best thing I can do for my sound, I'll do it.

Probably not, but depending on your propensity to DIY stuff you may not even need the whole $2000.

Theoretically you can over damp a room but that pretty much never happens in a mixed living space.

Disagree, if you're using thin absorptive panels only, depending on rugs / furniture, you can get overdamped by covering 20-25% of the surface. Granted, not many people get that far, but it's not that hard to do.

A $2K budget spent on inappropriate types of DIY panels could end up overdamping the room for sure. That will buy you >800 square feet of 2" Corning 703.

Should I Dirac before I treat my room?

I would start with REW measurements, see what needs to be done, and go from there. Probably there is no harm in correcting the low end before you do treatments, unless it takes you a really long time.

 

[Flaesh]

if you're using thin absorptive panels only, you can get overdamped by covering 20-25% of the surface. Granted, not many people get that far, but it's not that hard to do.

Yeah. Especially at high frequencies; the lows are still as bad as they were. This is probably the dumbest anecdote in room treatment.

I glued a few thin foam panels, the sound got better. I glued some more - it got a little better. I glued even more foam panels, the sound got crap. I was happy when I peeled them all off and took them to the trash.

The initial state of the room matters too. So

start with REW measurements, see what needs to be done, and go from there.

Overdamping at LF (tens of hertz) is impossible in room.

 

[Keith_W]

1. In addition to Toole's book, are there any "must-read" papers?

It will take you some time to understand everything that Toole says in his book and even longer to come up with questions that he does not cover. About my only criticism is that Toole's book has very weak coverage of DSP, which is one of the major tools to combat acoustic issues.

1. What is the best/easiest software tool to draw a layout of my room if I don't want to use a full CAD package Solidworks/Fusion360?

Sketchup. It is hidden in the website, but you can use it for free. It is easy to use and you can make images like the one I made above Go to Youtube and do a search for tutorial videos.

1. Should I Dirac before I treat my room?

You should MEASURE before you spend any money on anything! Microphone and REW first. Everything else second!

1. What are the most useful measurements for me to post? I was planning on taking spectra of the left and right mains and a stereo RT60. Are there any other graphs y'all would like to see?

The easiest way for us to comment is to upload your .MDAT to ASR. You will have to zip it first. Make sure you label your graphs so that we can understand what we are looking at.

1. Would any of the roughly $2000 I plan to spend on room treatment be better spent on upgrading equipment? I've had my Titan speakers for ~7 years now, built them for my 16th birthday and while I'd be sad to see them go, if it's the best thing I can do for my sound, I'll do it.

Nobody knows the answer. Don't spend any money yet. I assume you have a proper omnidirectional condenser microphone for your Motu M4 interface and a mic boom stand?

 

[Flaesh]

I assume you have a proper omnidirectional condenser microphone

The microphone is not listed in the equipment lists, but TS announced measurements with REW))

 

[adam_dan]

Alright, here's measurements, floor plans, and some photos. It sounds noticeably better with Dirac. I am planning on putting in cellular shades in my studio hoping that they do a little bit better than the wood shades I have now. Hoping to get the rooms treated by Thanksgiving, please advise. I am not allowed to hang any more art until I get this room treated

Thanks in advance.

Some notes:

• In my living room, the subwoofer is crossed over at 80Hz.
• In the living room, the windows rattle in their frames. I'd like to prevent this, but also would like to be able to open the windows.
• Treating 1st reflections in the studio seems like a no-brainer. Treating 1st reflections in the living room seems harder. I was thinking acoustic curtains behind me and some sort of diffusion behind the speakers?
• I am planning on building sit-stand desks in the studio - the monitors will be on "outriggers" with isolation to decouple from the desk, but will be moving up and down so I'd like to treat accordingly. Placement in both rooms is flexible, SQ is my first priority, followed by aesthetics.

I've attached measurements, floor plans, and photos. Pardon the green light, was getting bulbs setup. Also, apologies about the ugly couch, I know...

 

[dfiler]

Appologies for the green light and ugly couch? I didn't even notice. I was too busy hyperventilating over the dented dust cap.

You're on the right track! With those subs, the windows are going to be moving in and out no matter what. The easiest option is a small wood shim that is removable when needing to open.

With the back wall / window immediately behind the couch, that is another excellent spot for acoustic treatment. Extra thick curtains (insulated) would help with the highest frequencies at least. Another option is put a 2" thick panel behind the couch and move it up to the window sill when in use. It's about as much work as opening and closing a curtain. This would really help the imaging and soundstage in your room. Reflections that close to our ears are more troublesome to our brains. It's the same problem as an early reflection. Two versions of the sound, at roughly the same volume, reach your ears at only a very slightly different time.

 

[Keith_W]

Apologies for not using REW to view the graphs. I am such a REW n00b that I do not know how to overlay phase plots from multiple measurements on the same screen. I exported your measurements to Acourate so that I can show this to you.

Here we are looking at your post DRC filters.

Red = left speaker full range with DRC.
Green = right speaker full range with DRC.
Brown = L + R speakers playing together with DRC.

First look at the upper graph. We see that individually, left and right speakers look fine. But when both speakers play together, there is a huge broad dip between 70Hz - 90Hz. The reason why can be found in the lower graph (see the shaded area). We see that left and right speakers are almost 180deg out-of-phase. Although I have not shown it, your "before DRC" L+R summation also shows a similar broad cancellation in this area, although it is not as severe.

Unfortunately, I can only supply the diagnosis. I can not supply the remedy. I don't use Dirac, and I don't use minimum phase IIR's (which is what the MiniDSP uses). I will have to defer to the ASR community on this one. I strongly suspect that there is nothing you can do, and if you want to get rid of it you may have to move to linear phase FIR's so that you can manipulate phase independently of amplitude.

 

[adam_dan]

Apologies for not using REW to view the graphs. I am such a REW n00b that I do not know how to overlay phase plots from multiple measurements on the same screen. I exported your measurements to Acourate so that I can show this to you.

View attachment 406447

Here we are looking at your post DRC filters.

Red = left speaker full range with DRC.
Green = right speaker full range with DRC.
Brown = L + R speakers playing together with DRC.

First look at the upper graph. We see that individually, left and right speakers look fine. But when both speakers play together, there is a huge broad dip between 70Hz - 90Hz. The reason why can be found in the lower graph (see the shaded area). We see that left and right speakers are almost 180deg out-of-phase. Although I have not shown it, your "before DRC" L+R summation also shows a similar broad cancellation in this area, although it is not as severe.

Unfortunately, I can only supply the diagnosis. I can not supply the remedy. I don't use Dirac, and I don't use minimum phase IIR's (which is what the MiniDSP uses). I will have to defer to the ASR community on this one. I strongly suspect that there is nothing you can do, and if you want to get rid of it you may have to move to linear phase FIR's so that you can manipulate phase independently of amplitude.

I do see that. I have some flexibility in speaker placement, so might be able to shift the frequency of the cancellation. I suspect the subwoofer may be involved (just now realizing I forgot to turn it off, so the "full range" measurements are full-range as in frequency, not as in "measuring just the full-range speakers" - I will post for just the speakers when I get home. Putting the sub between the speakers might be making it act as a phased array type of lobed pattern.

70-90Hz is where the kick drum "punch" is, right? I'm gonna need to solve that, or at least move it to somewhere else in frequency space.

 

[adam_dan]

Appologies for the green light and ugly couch? I didn't even notice. I was too busy hyperventilating over the dented dust cap.

You're on the right track! With those subs, the windows are going to be moving in and out no matter what. The easiest option is a small wood shim that is removable when needing to open.

With the back wall / window immediately behind the couch, that is another excellent spot for acoustic treatment. Extra thick curtains (insulated) would help with the highest frequencies at least. Another option is put a 2" thick panel behind the couch and move it up to the window sill when in use. It's about as much work as opening and closing a curtain. This would really help the imaging and soundstage in your room. Reflections that close to our ears are more troublesome to our brains. It's the same problem as an early reflection. Two versions of the sound, at roughly the same volume, reach your ears at only a very slightly different time.

I let some friends borrow them for a party in college. Never again... When I have more time/funds I will source a replacement driver, it really is an eyesore and no amount of vacuuming did anything.

Where does the shim go? Between the sash and the frame in the plane of the wall? That may work.

Time to look into how I can raise/lower a panel from the ceiling. There's a table behind the couch, mainly to push it out from the wall, but I could easily get rid of that and add a rockwool panel. Also could do permanent panels by the walls, and have panels that slide behind those on sliding door rails or similar that would cover the windows.

Thanks

 

[Keith_W]

70-90Hz is where the kick drum "punch" is, right? I'm gonna need to solve that, or at least move it to somewhere else in frequency space.

Yup. You are right, it could be an issue with your measurement. Time for a redo, then Good luck and keep us posted.

 

[adam_dan]

Okay disabling the subwoofer moved the issue to ~58Hz - Here are my new measurements. I'm not entirely convinced it's not a room mode issue. I've ordered some OC 703 panels and fabric, going to build absorption panels for both rooms as a "starting point" for treatment (placed at 1st reflections & behind, maybe some ceiling cloud stuff too).

I'd like to get my speaker placement finalized before then treating and running MSO+Dirac. I doubt that moving the speakers is going to make that much of a difference, 60Hz is a pretty big WL. Would bass traps help? I've read they only generally go down to ~80Hz.

 

[Keith_W]

Firstly, DSP is better for bass, and room treatment is better for treating upper frequencies. Forget about absorbent bass traps, they need to be massive to work. If you want to trap bass, you are better off with a membrane absorber or Helmholtz resonator. The problem with both of them is that they are narrow band and need to be tuned. The former is tuned by adjusting the tension of the membrane, the latter by adjusting the size of the mouth and length of the throat. Attenuation is adjusted by adding more units or increasing the size. Even after that, you would still need DSP for time and phase alignment. DSP is by far the superior tool, it is more precise and it can do almost everything that room treatment can. Including fixing ringing, to a degree.

The only practical role room treatment plays for most people is fixing upper frequency problems. So we should ask ourselves whether you have an issue here.

This is your ETC for your left speaker. The goal is: all reflections arriving within the Haas fusion zone of 20ms after the direct signal (the first peak, normalised to 0dB) should be -15dB or more. Here we see two very early reflections, only one of them peeks slightly above the target. Your right speaker is better.

I calculated your RT60 target for the DIN 18041 standard using your room dimensions of 25ft x 12ft (and assumed a ceiling height of 9ft) and drew them in for you. Again, left speaker. Ignore anything below 200Hz, those are room modes and not reverberation. We can see that your upper frequencies are bang on target. It might be slightly too high if you wanted a studio.

Room treatment is specified with the NRC (Noise Reduction Coefficient, sometimes known as Absorption Coefficient) or sometimes in Sabins. NRC of 0 is 100% reflection, NRC of 1 is 100% absorption. I found a random curve for you with a Google image search. As you can see, sound absorption is not uniform and each panel will have its own NRC curve. Sadly, most manufacturers do not publish the NRC, probably because they haven't measured it in the first place. Measurement of the NRC is not straightforward. The standard required is ASTM C423 and requires a reverberation chamber and controlled conditions.

These things have a profound impact on the sound and it is very likely that room treatment will colour the sound by distorting the spectral curve. In short: I don't think you need any room treatment.

That leaves the question, how are you going to DSP your bass. The usual recommendation on ASR is multiple subwoofers + DSP. I personally don't trust Dirac, I would rather do a manual correction. But since you have a license, you can give it a go and see how you fare. Or you could use MSO as you mentioned.

 

[adam_dan]

Sounds like I still may see some benefit from treating the windows behind me and the walls behind the speakers, to damp those early reflections. Unfortunately, the MiniDSP doesn't support Dirac Bass MGMT, so it's going to be a combination of MSO + Dirac, MSO for the subs and Dirac for the full range. I prefer slightly deader rooms generally, so think that covering ~20% of the wall with paneling won't make it too dead. Leaves lots of room for art too

 

[adam_dan]

Going to run some MSO this week to get my sub integrated. All the guides I have found seem to assume multiple dedicated subs, rather than a sub + fullrange mains - could anybody point me in the direction of some resources that might help me do this?

 

[adam_dan]

Alright, still figuring out this whole MSO thing but I have a couple of specific questions about room treatment after playing around with AMROC and the Porous Absorber simulator.

• It looks like 4in panels with a 4in gap will reach down lower. I think this makes more sense for the living room than the studio, it seems like the general philosophy is treat down to the Schroeder frequency (~200Hz in the living room, ~300Hz in the studio), and then correct issues lower in the frequency spectrum with multisub+DSP. Does this mean that in my studio, I should go with 2 inch panels, and 4 inch panels in the living room?
• I assume the general workflow is something like treat, measure, repeat? Any tips on this process?
• I prefer a deader room, listen to a lot of synthesized rather than recorded sounds and the natural room reverb can muddy stuff up. Am I targeting a sub-.2s RT60? Is RT60 even a meaningful measurement in rooms this small?

Thanks again for all the helpful feedback, and sorry for the repeat posts, hopefully this one brings some more substance to the discussion.

 

[Keith_W]

Alright, still figuring out this whole MSO thing but I have a couple of specific questions about room treatment after playing around with AMROC and the Porous Absorber simulator.

• It looks like 4in panels with a 4in gap will reach down lower. I think this makes more sense for the living room than the studio, it seems like the general philosophy is treat down to the Schroeder frequency (~200Hz in the living room, ~300Hz in the studio), and then correct issues lower in the frequency spectrum with multisub+DSP. Does this mean that in my studio, I should go with 2 inch panels, and 4 inch panels in the living room?
• I assume the general workflow is something like treat, measure, repeat? Any tips on this process?

Yes. Treat, measure, and repeat.

• I prefer a deader room, listen to a lot of synthesized rather than recorded sounds and the natural room reverb can muddy stuff up. Am I targeting a sub-.2s RT60? Is RT60 even a meaningful measurement in rooms this small?

If you are treating a studio, then yes the RT60 target is much lower. I suggest you buy and read this book Everest and Pohlman and read the section on studio design. There are some very specific requirements which I admit I did not pay attention to because I have a listening room and not a studio.

A quick explanation on "reverberation". Reverberation is multiple room modes overlapping each other until the sound field is uniform. All wavelengths, no matter how short, form room modes. But short wavelengths form thousands of modes. It is only with longer wavelengths do the modes separate and are observable as individual peaks and dips. As you can imagine, this is not a sudden transition but a gradual one (hence the transition zone).

The RT60 makes less sense for those of us with small rooms ("small room" = any room which is not an acoustically large spaces like stadiums, concert halls, etc. where the room dimension is long in relation to bass wavelengths). It is defined as "time for a reverberant field to decay by 60dB after the early decay time". As we have seen, small rooms only have reverberant fields above a certain wavelength. As for the 60dB decay, the noise floor of most typical listening rooms is 40dB, so you would have to measure at least at 100dB.

Fortunately, volume decay is linear. So we measure the T20 and T30 instead - dropping the reverberant requirement, and only measuring 20dB or 30dB decay and extrapolating it to 60dB by simple multiplication of 3x or 2x respectively. This also means that interpretation of the T20 and T30 has to be done with caution because there is no bass reverberant field. A LF null will shorten the T20/T30, and a peak will produce a spike in T20/T30.

The T20/T30 can be used interchangeably with the RT60 in small rooms above a certain frequency, determined by the size of your room.

 

[Keith_W]

Using your room dimensions given in your PDF:

L 10' 4.5" (3.16m) and W 11' 3.25" (3.44m) and assumed a room height of 9ft (2.7m) I recalculated the RT60 target using the more stringent EBU 3276 studio standard and overlaid it on your RT60 measurement of your left speaker for you.

It looks like you have a lot of work to do.