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Is It Possible to "Over-Treat" a room?

Discussion in 'Room Acoustics / Isolation / Treatment' started by DonnyThompson, Jun 14, 2015.

  1. DonnyThompson

    DonnyThompson Distinguished Member

    @Brien Holcombe @kmetal
    Is it possible to add too much treatment to a room?

    Okay... this might appear to be a dumb question, ( and Brien, I apologize because this query isn't what you would call to be a "precise" scenario) but because I'm a nice guy and you both like me - LOL - could you guys humor me on this? I would like to know. ;)

    Example... let's say I have a room in which I mix and record, and this space has been treated to the point where the acoustics/RT60 are fairly well-balanced overall.

    What would happen if a heavily padded cloth couch was brought into this room? Or a couple of chairs of similar construction - thick and dense? (LOL I'm sure that you guys are now thinking that I am of the same construction as well... thick and dense, :p )

    Maybe those weren't the right examples to use, but I'm curious... is it possible to have too much BB absorption? Or, too much bass trapping...

    I'm not saying that the room would be treated to the point of being anechoic - or, maybe I am... ?

    What would the results be - for both recording and mixing - if the environment was anechoic, or at minimum, being very dead across the entire measurable frequency spectrum? Recording Scenario wise, let's say... for acoustic guitars and vocals, and mixing scenario-wise, any music that has an audibly full bandwidth?

    Thoughts?
     
  2. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    The answer is Yes ! If you over damped a room but with a flat frequency response, you'd be ok to record in it but to mix would be hard because of the spacial interpretation of the music and amount of reverb applied.
    But in reality many adds too much of the same material and end up with a hole in the frequency spectrum which makes the other frequencies appear to peak... at that point it may sound worst than before any treatment.
     
  3. pan60

    pan60 Active Member

    I would say yes and no?
    You could always ad more diffusion if needed.
     
  4. DonnyThompson

    DonnyThompson Distinguished Member

    I hadn't thought of this. So, what you're saying is, that if "over-treated" in a certain way, that one could actually end up hearing more of a certain frequency range ? I find this to be intriguing.

    Not that I'm going to actually do any of the above scenarios I mentioned as examples... I'm just curious as to what might happen if someone did. And, I understand that unless I am specific about the materials being added, that it would be very difficult to nail down a potential result, past that of an educated guess...

    Here's one in particular that has often had me wondering about - I've read articles that have mentioned that "there's no such thing as having too much bass trapping in a mixing environment"... and of which, I don't know is actual fact, or internet-generated myth, because I've also read articles that take objection to that premise.

    Based on my own research ( which is certainly not on the expert level ) my knee-jerk reaction to this, is that this is far too generalized of a statement, and which must be based solely on the environment in question - size, dimensions, shape, construction materials, current in-place treatment methods, distance from listener to monitors, monitor sizes, the physical location of the mixing control center in the room, etc.

    I'd like to have this one cleared up - and not just for me, but for anyone else who might also have the same question.

    I'll state the question for any potential future internet searches on the subject:

    Is it possible to have too much low-frequency treatment/absorption devices in a space used for accurately monitoring and mixing/mastering audio recordings?

    This would include commercially-made bass traps, and/or BB absorbers designed and constructed to intentionally and effectively reach down into and treat lower frequencies ( 150hz and down).

    Further - this would include "typical" home "studio" sizes - taking an "average" of 10' x 12' x 8' (height) with standard drywall walls and ceilings, one doorway, one window, and both carpeted and un-carpeted flooring ( considering that a standard 1/2" padding and 1/2" carpet aren't going to do much for effective bass frequency treatment anyway, right?)

    I understand that these factors are anything but scientific... I'm just trying to grasp the whole "never too much" statement, in relation to the "common" home "studio".

    LOL... I'm just waiting to be blasted by Brien - or one of the other acoustic guys - on this whole topic, because I'm being far too vague in my "what ifs".

    It's okay... I don't mind... blast away. ;)

    d.
     
  5. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    Picture your 10x12 room with just 1'' thick foam that absorb only around 1k and up. It will kill the flutter echo but will also unbalance the frequency curve of the room.

    This graph show the absorbtion of a 2'' foam :
    1220fb_adb502926e714704bfc9258b87b32a5d.png
     
  6. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    These are some fairly common questions.

    Just like a good mix, balance is crucial in the frequency response of the room. Broadband covers the low-mids/highs. The general rule of thumb for absorbsion is 20-30% of the surface area in a listening room should be absorbent. This is very general, and by the time you cover the 'mirror' points on the front,rear, side walls, and ceiling, your about there math mathmatically. Roughly.

    A sofa, or couple of chairs should neither make nor break a home studios acoustics. My thoughts on this are simple, as long as the stuff is not in the immediate sweet spot, there won't likely be any problems with adding a couple soft chairs. A couch behind you isn't gonna hurt. It won't 'help' mich either as some people would hope.

    This type of treatment, absorbsion (rigifiberglass, rock wool, acoustic foam, ect), can be over done in listening rooms. Rt time is largely a guesstimate of the trends in small rooms, as they are not large enough (cubic footage) to develop true reverberation time. This holds true for diffusion, an is the main reason why it is omitted in a lot of small listening room discussions.

    Bass trapping is necessary. The reason behind the "...can never have too much bass trapping in small rooms" is based on some basic ideas. The room your describing in the hypothetical, is gonna have some real modal issues in the 80-100hz range, just based in its dimensions.

    For the trapping to be effective in general you need thickness of at least 1/4 wavelength, so sometching like 3-4feet thick should do just fine. Unfortunately that makes your room tiny. So, that's in a nutshell the reason (as far as I know) behind never have too much trapping, In small rooms. It's obviously not quite that cut and dry, and devices like helmoltz resonators, and velocity based trap designs, can be effective, and take up less space than some other things. To give you an idea, the bass trap in the home theater project I'm working on is about 5ft deep, 8ft wide and 7 ft tall. According to the math the resonant frequency of that is in the mid 30hzs. And that's the fundamental (or 1st harmomic?) mode of the room. 18hz was the lowest, but slightly below the threshold of common hearing. Now that chamber + copious fiberglass, should be pretty effective. Note that it's not too far off from a common size home studios vocal booth.

    Just to clarify, a flat dead room, would be pretty awful to track in as well. Tracking rooms hold a different set of design parameters, as they just have to sound subjectively "good" not "flat". Recording rooms aren't designed to be flat, they are designed to be complimentary.

    The thing with sound is it needs cubic footage to develop. Devices like trapping, take the sound energy, that would otherwise continue far beyond the walls, and (transduce) change them into heat. doors and windows are poor mans bass traps, and I have used them.

    Sizing the speakers, and acoustic power, appropriately is one of the best things home studios can do for their acoustics. Smaller speakers will excited less low frequency problems in the room in general.

    As an aside, I think the only problem with general questions on acoustics, is when people get mad with a general reply. Questions like " how do I soundproof my bedroom" are perfect. That is usually the question in its entirety, but the persona is really looking for approval of their egg crate idea, or to just simply be told what to do precisely, while never grasping the concepts for their own use.
     
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  7. DonnyThompson

    DonnyThompson Distinguished Member

    Thanks, kyle... I was hoping you would weigh in. ;)

    I think that what you mentioned about small rooms being so problematic is one of the main reasons that home "studios" require so much work to get right. When working with such limited space, there's only so much one can do, especially taking into account the other point you brought up - and what others in similar situations have faced, in that the more treatment you have in place, the less room you might end up having to actually work in.

    example, from right here on RO:

    http://recording.org/threads/dynamic-mic-for-an-acoustic.58721/

    gitlvr said:

    "..Donny, thanks. I went the treatment route. There was so little room in that small space after treatment that some of my instruments were damaged just trying to move around enough to record. I am very limited in funds. I spent $150 I did not have on treatment with 4" Rockwool, 1x2 framing and fabric to cover, just to pull it all out and trash everything except one panel I keep to park a mic in front of for vocals(2-2'x4', 4" thick panels on each wall, 1-6'x2' by 4" bass trap in two of the 4 corners, placed across the corners). Not feasible for me in the room I have or the budget I have.
    I will be buying a set of Sony MDR 7506's as soon as I can scrounge the cash up, and mix on them. My research tells me they are pretty much the flattest out there, and a studio standard for decades. Reference tracks and checking my mixes in a ton of different places/devices is going to have to suffice. I will have to use my ears and my brain to learn what I have so that I can put out a decent mix. I have no illusions that I'm going to be banging out pro mixes in this space.
    I know this won't be easy, and I know it is not anywhere near optimum, but it IS the situation I must deal with..."
     
  8. Brien Holcombe

    Brien Holcombe Well-Known Member

    OPEN doors and OPEN windows...

    For the same reasons that small rooms, less than 1500 cubic feet of volume, require so much bass trapping. Usually the folks that either are pushing product or the followers of such people are the ones that promote bass trapping in every corner that you can get one into. Does it help? Sure it does, in the low frequency area, but you can spend quality time with standard treatments and get a good response from the room. Diffusion is such an exacting science that starts with "is the room big enough to even handle it" Much in the same way that low frequency needs length/volume to expand accurately, diffusion needs the proper distance to be able to scatter and be effective at all. Usually small rooms with short distances are just not enough and , while it might look cool, it really isn't as effective as many suggest. Broadband will usually settle the argument.

    Direct to your question, that others have handled already, yes you can over treat. Over treating would be the direct result of a poor or misinformed person I would have to think. But in your example of a couch or a heavy padded cloth in a well treated room...that is where you would have to install the item and listen for the difference. The couch would help with low/mid frequency and might promote scattering of upper mids and highs so it might be effective in that respect. If it turns out the couch is taking away some of your highs as well, maybe you need a leather couch to get those back.

    Like the bass trap that Kmetal is building, the couch can have this same kind of effect, not to as low a frequency as what K is getting, but still, small rooms have low frequency energy that needs to be converted so in this respect the couch would help.

    The good thing about the over treating is this. Even IF it were done, you can add high frequency response back into the room with several hardboard, wood slats, or convex type panels.

    Overall, this is why it takes a lot of time to establish what the room is, what it is doing, what the owner wants it to do versus what reality says you will get. In this example you suggest, we spent far to much money and expired way to many man hours simply because someone did not do the home work. But at least the owner learned a few things even if it was only how to make multiple types of panels.
     
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  9. DonnyThompson

    DonnyThompson Distinguished Member

    Thanks for weighing in, Brien. I'm now more informed than I was before I started this thread. Some of my suspicions were confirmed, but, I also learned some things that I didn't know.

    like:

    So, basically, what I'm understanding is that you can over treat; theoretically/mathematically it is possible - but, this can also be corrected without a great deal of trouble, too - either by reducing some of the low frequency trapping, or by adding reflective surfaces ( and depending on the size of the room, perhaps some pre-planned/custom diffusion as well) and it really just requires sonic measurement, along with room dimension measurements and calculations, to get a space as close as possible to being "balanced", or at least to the point just before diminishing returns start to occur, which are based on what the physical limitations of your particular space allows.

    Is that correct?

    Again, this isn't something that I'm thinking about doing myself, it was really all just a "hypothetical", but all the same, I feel it's good information to know, especially when it's so obvious that so many people with home "studios" seem to make so many mistakes with their room treatment.

    Thanks also to Marco, Pan and Kyle for taking the time to reply and provide info.

    -d.
     
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  10. avare

    avare Active Member

    I do not know how to addres where this thread has gone, so here are some points. Boggy's Myroom design uses thick (eg 2') absorbers with high frequency reflectors on all surfaces except for the floor. Non-Environment rooms are thick absorbent (up to 4') on all surfaces except for floor and front wall. Professionally designed control rooms have up 60% of their volume devoted to sound treatment. That works out to deep absorbers!

    Andre
     
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  11. DonnyThompson

    DonnyThompson Distinguished Member

    Thanks, Andre. :)

    I didn't know this... the "up to 60% of volume being devoted to sound treatment" - although I'm not really surprised by it.

    I would think that it would be "easier" to treat a bigger room - I'm not referring to the calculations or the process of treatment, here - I'm thinking more in terms of logistics related to size; in that the smaller the room is, the more the potential for the treatment devices to physically "be in the way". If I were to take that same percentage you mentioned above that applies to the bigger mixing rooms/spaces, and apply it to my own room, I wouldn't be able to move my arms. LOL ;)

    In one of the many pages of texts you sent me last winter, I read a paragraph, (and I'm paraphrasing here) the summation of which was that "sound is sound"... 100hz will always be just that: 100Hz. It will have the same foundational physical properties to it, regardless of where it exists ... it's the space in which we hear it - within the confines, limitations, and inaccuracies of a particular environment - that is the variable, ( along with our own individual physical variables and limitations) and it's this environment which needs adjusted, so that we can hear that sound in a way that allows us to further alter it, for our own particular sonic requirements - ie, monitoring audio as accurately as possible for mixing music/audio into a cohesive form.

    At this point in time, given the space that I am currently working in, I believe it would be pointless for me to do any further treatment. Having read through the notes you've sent me, along with reading parts of Everest's book, and reading Brien's posts; while further treatment might improve the space, it just isn't realistic. It's true that I could add further bass trapping, or more BB absorption ( although based on my research, I don't believe that diffusion would be worth the effort in a space this small, and any benefits would be minimal), but it wouldn't allow me any room to work, and, I'm already feeling claustrophobic as it is now, so while further treatment might help the room, it won't help me to do my job any better.

    In short, I need a bigger space, and I need to start from square one with it, in terms of acoustic correction ( sound proofing is not a current concern). I do have a bigger space available... but I'm not going to get into that here.

    Thanks Andre, and to everyone who weighed in on this thread. I've learned much. ;)

    d.
     
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  12. Rod Gervais

    Rod Gervais Active Member


    When the space can support it I design control rooms using 60% (or more) of the room volume devoted to low frequency treatments.......

    This is often accomplished by utilizing spaces adjacent to the room in question as part of the equation...... for example a room behind a control room can be used for low frequency control along with being used as a tech room/computer room/etc.

    Now - I also then add some hard surfaces to these spaces to bring some (very controlled) life back into the rooms.

    Having said that - I do not agree that a live space that is totally dead is necessarily a problem in and of itself.

    It doesn't matter what instrument you want to look at - they all have their own signature sound...... if there are no reflections - and if the room adds nothing whatsoever to any of the various frequencies coming from them - then what you are left with is the pure sound from the instrument alone.

    That doesn't magically disappear because they are in a dead space........

    This is not meant to suggest that a room can not add something (something significant in fact) to the sound of an instrument being recorded - simply that the sound of the instrument being recorded is not necessarily dependent on the room adding something to the equation.

    Rod
     
  13. audiokid

    audiokid Staff

    choice post Rod. (y)
     

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