Small Room Acoustics and appropriate treatment:
It has been said that ‘You’ll never get a home studio room to the point where you can do professional mixes like they do in the big studios’.
This is false.
Today a great many commercial productions are done in small studios & home studios. You see production after production recorded and mixed ‘at the private home studio of the producer’.
The job of any Studio Designer is to create an acoustically accurate environment so that YOU, the artist, can work; faster & easier – Get the job done & enjoy it – Knock it out and do the next one – Make more money – Have an edge on your competition. This simple result is what my job in room acoustics and room treatment boils down to.
Amazing productions have been done in the past in horrible rooms because of the talent of the musicians, engineers, & producers – and they continue to this day. This may seem an odd thing to say coming from a design professional. But I follow the wise motto (modified for the music business): “If it’s not Baroque, Don’t FIX it!”
That said, I’ll move on to my recommendations for Treating your Space.
Room size and Ratios:
If you cannot build or move a wall, room mode calculators will only tell you what you’ve got. Don’t try to see if you have a good ratio. It is irrelevant.
It is, however, important that you have good modal distribution, especially if you don’t use enough bass trapping. (When I say enough, I mean A LOT!)
Cubes are bad, as are room dimensions with common denominators. (When designing a studio from ground up I will use prime numbers for the room dimensions where possible.) For example; if you have a room that is 5 by 10 by 8, you have common denominators of 2 and 5, so 10 would need to change to 11. This works in feet or meters. It is simple mathematics. Of course, you should run it through a room mode calculator like the one on my resources page to be sure. Again, this is only IF you can do anything about the dimensions. Most people can’t, and if that’s you, it’s not the end of the world.
The point of checking your room ratio or dimensions with a mode calculator is; it can tell you where you might have problem areas – plus information like: the lowest axial mode (if your room is concrete), the Schroeder frequency of the room, the ideal RT-60 (target), listening position, etc.
Treatment & Trapping:
I will always design for ‘optimal’ although, you can always do less. It is important that one knows and accepts the limitations that the real world imposes.
For best results, I recommend a bare minimum treatment of 20% of 5 surfaces. The floor is excluded and since I am mentioning floors; All studio rooms should have hard floors, EXCEPT for Foley rooms which use thick padded carpet.
Ok, so this means that 20% of four walls and the ceiling will be covered with treatment. Of primary importance are first reflection points (side walls and ceiling) and the back wall. The treatment of the back wall, or lack thereof, will greatly affect the perceived peaks and dips in the frequency response at the mix position, as will:
Speaker position:
The speakers that you use, be they M-Audio or ATCs, will always be the ‘Elephant’ in the room. In other words, compared to the technological advances of electronics and data storage these ‘things’ are ancient relics that color, distort, and literally screw-up the recorded sounds as they try to ‘reproduce’ them in your room. The physics of this energy transfer is complex, so I’m not going to bore you. We are stuck with these ‘things’ for the time being but I wanted you all to know that there are no perfect speakers. More expensive units are usually much better, but get what you can afford and work with it. With the exception of my speakers which I have designed for flush mounting in our studios and they are perfect!! – Just kidding! But they are very, very good and on par or better than the competition. (of COURSE, I’m gonna say that!)
SBIR or Speaker Boundary Interference Response is usually the cause of most monitoring anomalies. – I continue to see folks quoting online references that tell them to keep the speakers at least ‘so far’ away from the walls. Audiophiles are told to put speakers about 8 feet away from the front wall, etc. This is simply FALSE. I will explain:
First, let me say that if you get the Low Frequency response in your room ‘right’, you have won 95% of the battle. Low frequency begins folding around objects at the top of the transition region and truly becomes omni-directional at the Schroeder frequency of the room. (Study the information just below the Bonello Distribution graph on the AllModes tab of my room mode calculator)
So, the low frequencies produced by the speakers will fold around the cabinet and expand in a sphere in all directions until they hit an obstruction and reflect back. It is this REFLECTION that causes the problems.
When the speaker is further from the room boundary the reflection will be delayed for a longer period of time. Sound travels at 343.54 m/sec @ 20° C or 1129.42 ft/sec. @ 70° F. If your speaker baffle (face) is 1.22 meters or 4 feet from a boundary the delay will be 7.1 milliseconds. This is half the length of a sound wave at 70 Hz, therefore full trapping is required at this frequency to eliminate the destructive reflection. NOW, push the speaker closer to the boundary so that it is half that distance or 61 cm / 2 feet. The resulting reflection will cause a delay (compared to the source) of 3.5 mS, corresponding to the half-wavelength of 141 Hz.
Now that is quite a bit easier to trap. I’ll explain with an example; At zero degrees incidence, a 1/4 wavelength trap is required to be as deep as the speaker is far from the boundary. 61 cm distance = 61 cm deep trap. 122 cm distance (4 feet) = the SAME distance filled with an absorptive trap. — This is simply TOO MUCH to put in most home studios!
Solution: Put the speakers/monitors as close to the front wall (boundary) as physically possible. This will result in a much higher interference frequency and therefore a much easier treatment solution.
Treatment options & fabrics:
When you build treatment panels, the density or GFR (Gas Flow Resistivity) should follow the thickness of the panels. For example, use higher density/GFR product for thin panels. As the panels go thicker, use lighter/lower GFR product. Rockwool & Fiberglass are made with the same process but with slightly different materials. Rockwool is made from Basalt and Fiberglass from Silica Sand. Rockwool tends to be crumbly while Fiberglass can be made more rigid and still have a low GFR. BOTH are equally suitable but not perfectly interchangeable. However, it is my opinion that there is too much ‘splitting of hairs’ over these minute differences. Bottom line: Get what is available to you in your area of the world and make it work. I have never recommended higher density than 60kg/m3 or 4lbs/ft3. (m3 = cubic meters and ft3 = cubic feet)
Any trap deeper than 4” should be composed of mostly lightweight regular building insulation. The cheap stuff!
The fabric that you choose should be breathable. In other words, you should be able to put it across your face and still be able to breathe comfortably. If not, the gas flow resistivity is too high and it will be acoustically reflective especially at glancing angles.
If you are concerned with fibers escaping, you can use a 1/2″ (12 mm) layer of Dacron. Dacron is used in dress making and furniture, pillows, etc.
Foam acoustic treatment:
Everything has a place. I have often used foam wedges on top of regular treatment panels that are placed at reflection points in critical listening environments since the fabric used can be (will be) somewhat reflective. If the treatment is very close to the operator, this could be a serious problem. Therefore highly absorbent foam can be used on top of the treatment panels to take care of the upper midrange frequencies that would otherwise be reflected into the sweet spot. Or simply use a very low GFR fabric like burlap or similar.
Take care in using ONLY foam treatment in your room. It IS helpful, very useful, and has a place – especially in HOME studios, but it is NOT the Full solution to your room treatment needs. You will need much more trapping than can be obtained with a foam treatment plan. Now, I am not saying that you can’t do it with foam. I am saying that proper treatment done with foam can cost at least 5 times the price of treatment that you can build with a little plywood, rock wool, glasswool, and fabric. These days, every penny counts and it will certainly add up when you build your home studio. For more information subscribe to my youtube channel.
Vocal booths and recording:
It is important to eliminate destructive reflections into the microphone when recording, however panels placed behind a cardioid pattern microphone will do little for room reflections. If the recording is important, the room should be treated so that the frequency response at the mic is uniform and uncolored as it is very difficult to remove the room coloration without affecting the original sound of the voice or instrument. Although today’s software IS very good and filters can do the job, that’s not the way a good record is made.
Panels around the vocalist will improve the recording in a treated room. They can help in an otherwise untreated room, but small panels that are mounted on the mic stand are, in my opinion, far too small to have much of an effect – especially in an untreated room.
For absorption panels to work properly in an otherwise untreated room, you will need to place them AROUND the vocalist & microphone so that they;
1. Absorb the initial sound waves from the vocalist and reduce the sound available to reflect off of surfaces in the room.
2. Absorb any reflections that ‘get through’ and keep them from entering the microphone at interference levels (higher than -30 dB relative to the source sound).
Panels will do next to nothing for frequencies below 250 Hz. The frequency range of 80 – 300 Hz is the most problematic for voice / vocal recording… That’s why trapping is so very important for a vocal booth.
Mixing position:
#1 . IF your mix room, control room, or critical listening room is very large, {over 30 square meters or 323 square feet}, you have the option of facing either the short or long wall. HOWEVER, the option of facing the long wall usually corresponds to having a DOOR in the long wall leading into the tracking area or other ‘Limitations’. It is not desirable from a design perspective, nor is it optimal!
#2 . If your room is small, i.e.; less than very large (see above), you must ALWAYS face the short wall.
NOT facing the short wall usually will place the listener in the CENTER of the room, which is a very bad place to try to get accuracy in the low frequencies. Also, facing the long wall situates the ears too close to any diffusing surfaces in the back wall, assuming that you are trying to make an LEDE or RFZ style room.
Therefore; Small rooms shall always be oriented so that the listener faces the short wall.
Listening position: Start by seating yourself so that your ears are lined up with a line, parallel to the front wall, that is exactly 3/8 the length of the room. This dimension is obtained by multiplying the length of the room (in inches or millimeters) times 0.375. Take the result of the equation and measure back from the front wall. – Not the treatment.
All the best!
Cheers,
John
https://www.producelikeapro.com/video/john-brandt-interview/
There is a video on Sweetwater.com where a guy named Mitch Gallagher (sp?) shows his basement studio set up. He needed to adjust his room dimensions and given he had space he built a wall on one side that also created an equipment closet. But he did something I’d never seen before. The wall, instead of being a solid surface what made of a peg board like material (thousands of little holes) and he said the closet then also worked as a trap. Any thoughts on this?
Hi @l_scott_knight:disqus That’s cool information! Thanks for letting us know! Best of luck with your own studio design! http://www.bbc.com/news/entertainment-arts-35787187
Well, I think I’ve come up with a way to reorganize with a stub wall. I’ll have to contact John someday to get help determining where to put the wall exactly (or if it will work like I think even). But that will have to wait until I get the room back. Could be up to another year. Sigh. Which is why I just got new headphones. Gonna learn a new DAW too. S1 v3.2.
I guess the peg boards are an attempt to build some sort of Helmholtz resonators.
So much great information and affirmations, too! You answered a plaguing curiosity I had about my mixing room, because I have it set up where I am facing my monitors in the ‘short’ dimension of the room and they do not aim toward my tracking room. This was an accident (not intentionally planned), but I have been itching to turn my setup 90 deg. for the long dimension. You saved me so much work, haha! _ One thing about the speakers – I have a pristine pair of 4311 JBLs, but because my room has limited treatments, I literally have them set up as near-field monitors, because they seem to be very focused. If I move a foot to either side, I lose the sweet spot. I think I am ok in that regard, but it makes it tricky when collaborating on a mix so both of us hear the same thing. – I really want to extend a healthy Thank You for sharing your experience and wisdom, John, you rock!!
Hi @frederickthorne:disqus Yes indeed! John Rocks!! Thanks John for all of your insight! Have a marvellous time recording and mixing, many thanks Warren
Thank you so much John, these informations are gold !
I was researching a lot in gearslutz in the last months (acoustic), I found a lof of useful information but also many confusing things until I found some video with you, where you get to the heart of things.
I am always afraid of the rockwool fibres, so the tip with dacron is very welcome. I Considered already to work with polyester foam panels, but they are soooo expensive for 4+ inches.
Thank you also Warren for sharing with us John’s work !
Cheers from Switzerland,
Lars
http://www.thesessionguitarist.com/
Hi @disqus_MNUH4Zm90W:disqus My pleasure! I enjoyed talking with John and knew he would be able to give us even more detailed information in the forum! Have a marvellous time recording and mixing, many thanks Warren
Thanks Warren and John! I found this v interesting, I’ve been interested in acoustics for many years 🙂 I came up with an analogy to explain sound absorption materials… however I’m not sure if it’s much use, anyway…
If you imagine a white light bulb (AU says “light globe”) suspended in a glass cube (UK says “greenhouse”)
If I measure the light escaping from all around the cube I can see that…
– if the glass is clear, all energy escapes (this equates to 0kg/m2 soundproofing or complete air gap)
– if the glass is black, no energy escapes (this corresponds 30kg/m2, e.g. concrete wall = expensive!)
– any air gaps completely quickly defeat the use of expensive black glass. I may as well use blue glass if I can’t seal up the cracks.
– A black cube is of little use if the window and door glow orange
– I can experiment using cheaper materials, in two layers, so their absorption is complementary, but using two layers of orange glass gets me a dark orange leak – the common frequency of light just passes straight through!
– using red and blue gets me a dark purple result, as their absorption is complementary
Next step for audio guys is to change the light bulb colour to pink, so their gear will measure it! 😛
Hi @kennymac:disqus thanks very much for all of your great insight!! I really appreciate it! Have a marvellous time recording and mixing, many thanks Warren
I watched and listened to the video interview of John Brandt. Very useful and helpful. He seemed like a genuinely straight forward, stand up guy. Downloaded his incredible spreadsheet. It’s now on file in my folders for all things IMPORTANT to mixing. Although there’s not a lot I can do about treatment of this apartment (management would pitch a bitch.) The “Library” of Information is now starting to get extensive and one day will be applied to it’s full potential. (We are seeking to find a way to retire and get our own home, then we can do what we wish with walls and bridges (get it?)
Sent the link to the interview to an engineer friend of mine who said to say hi to John for him. They apparently know each other. So if you talk with John again soon Warren tell him Evens Colas said “hey!” See proof positive that the universe is in fact shrinking.
While some of the suggestions are for us simply not doable at this time I take comfort in finding out I’m doing a few things right. (facing the short wall, and proper distance from it.
Please thank John for the article if you talk to him again as it’s being copy/pasted to my word processor to add to the “Library.” And thank you for continuing to publish great and useful information that helps all of us make better music. You are a Prince Warren…and we all love you for this. Peace!!
…oh yeah…”have a bodacious day!!” 😀
Hi @martin_weeks:disqus Truly blessed to have John here to help us!! Have a marvellous time recording and mixing, many thanks Warren
So much information and actual tips what to do before you buy that $2k powercord. Not that I have thought of ever getting one of those:)
Hi @plap-disqus-37a749d808e46495a8da1e5352d03cae:disqus Haha yes indeed! Have a marvellous tie recording and mixing, many thanks Warren
Hi Warren,
yeah doing or considered most of this. I have my small room acoustically treated. I use Vicoustic tiles. They offer a service on their website whereby you submit your room dimensions and they will tell you what and where to place the acoustic product you purchase from them. I mean they design the layout for you. It is inexpensive, a small cost. I think it woks. I have massive bass traps and it’s a small room! My bass recording still come out boomy though… However, the bass tone is fantastic in my room! So, something wrong there I think but that’s another story. Great info here.
Cheers Wozza!
Hi @plap-disqus-f2217062e9a397a1dca429e7d70bc6ca:disqus Wonderful! Great stuff! Interesting that the Bass doesn’t translate outside of the room, did you ask John and any info on it? Have a marvellous time recording and mixing, many thanks Warren
well… it’s probably just my ears/monitors. It been a problem for awhile now. I think I’m staring to get over it. I tried different techniques over the years, yours being the most recent and has given me better results but still a bit boomy. If I remove the RBass it’s gone but then I loose the overtones!
Could it be the strings! they’re over a year old? I use a Radial DI track. I duplicate it two times. I keep one as the DI and process it as you do (from your video) the second DI is them fed to an Ampeg Bass Amp Model plugin and processed as a mic-ed cab (again as your video) the third is sent to softtube for distortion and blended back. Since I duplicated them from one source I don’t have an issue with the phase. I’m getting better but not fast enough! lol ☺♫♪♫
Thanks Warren / John. Great stuff! I’ve always been a hands on, the more I can learn the better kind of guy! The photo I’ve attached is my room (it was still in the building phase) however, in the bottom left of the photo, you can see I had bought a book a couple years ago called “Master Handbook of Acoustics” by Ken Pohlmann. Some of it is quite complex, but there is a lot of useful information in there as well. The panels I’ve installed are from “Primacoustic”. Each panel is 6lb high density glass wool that is covered in a rugged acoustically transparent fabric. So far the room sounds great, but I’m just starting to track in there… Hard to tell from the photo, but my outer speakers are about 6 feet from the walls, and there’s enough room to get behind the desk for wiring etc… so the mix position is at least 8 feet from any wall, with the panels placed to grab early reflections. If, John sees this and anything jumps out at him as being wrong or problematic… please tell him to let me know! Thanks again!
Hi @dannymacnevin:disqus Great photo! That looks like a fantastic studio!! Did you post in the Forum with John? Have a marvellous time recording and mixing, many thanks Warren
Yes I did post on the forum with John. You’re having a hard time keeping up with all the posts Warren…lol but that’s a good thing… because you’re busy which is good, and obviously you’re getting more subscribers, which is also good. Produce like a Pro is the best informative site, hands down! Keep up the great work Warren! Danny.
Hi @dannymacnevin:disqus Haha yes thank you I am very busy, but my focus is on the Academy. As time goes on you’ll start to see all of my ventures focusing towards this. It is REALLY important to me to build this community! I value it so much!! Have a marvellous time recording and mixing, many thanks Warren