Acoustic Treatment Can Cause Acoustic Problems? Help! I'm Scared Of 'Wasting' Money

[PeteJames]

Formerly: "Acoustic Treatment Can Cause Acoustic Problems? Help! I'm Scared Of 'Wasting' Money"

I've done a bit of reading up and looking at designs and room setups - this is not a show me how to build traps because I couldn't be bothered reading other posts thread. I'm just a bit anxious about forking out a lot of money (to me) on something that could hinder my response - and can't really be easily quantified by me. If I buy a synth or new monitors at least I know I have them and they work - see what I mean? I'm not a pro and don't know what to expect and can't really test the results properly without getting all technical. Ethan Winers DIY treatment says it doesn't have much affect down past 80hz ish - when monitors and subs can go down to 30hz and flat bass seems the most crucial.

The threads regarding acoustic treatment making problems worse makes me wary of spending a bunch on acoustic treatment when I only have the slightest of ideas about the detailed science of acoustics. If I buy a bunch and can't tell the difference or make things worse what do I do then - buy my £1000? I don't want to deal with measuring SPLs and graphs and all that boring stuff. I'm only thinking about treatment since everyone on here goes on about it ever time you mention buying new monitors (which is what I want to do). GIK say on their site there's 100% money back guarantee which is good if it is so, but even then how will I know if it's worked effectively without all the headache of researching? The truth is I don't know what a flat room with flat monitors sounds like (I mean this relatively) so how am I supposed to know what I'm doing and if I've got a big improvement? I really wish I could call up an acoustician, have them see my room and assess the materials, and have them tell me if my room is good and what needs doing, and then do all the testing. I'm no expert and I don't want to be - I want a good room without the headache and worry of wasting money This is what I've been looking at - half of my budget for monitors :-/
Room Kit 3 521 20 Exc VAT 599 38 Inc VAT

I'm not a mixing engineer, I'm not a mastering engineer, just a home producer who wants to turn out decent good tracks on a budget (which kind of makes me need to mix and master a bit)

[SAC]

Hmmm. You will pardon me as I have not seen many posts where valid acoustical treatments made things "worse".

By "worse", you could be referring to cases where remediating one issue made other issues that were previously masked by the larger issue become more relatively pronounced, but I am not aware of any widespread potential for such treatments resulting in the creation of new issues.

What may help you is to do a bit more research into the various acoustical room models - meaning the sonic characteristic of the final result you wish to achieve. As the goal dictates the appropriate path to accomplishing this, knowing what you want is the best way to avoid inadvertently creating a response that you do not want.

For example, if you do not want an overly damped 'dead' room, then you will want to mitigate the potential for such by using bass traps that are more selective in their energy absorption, and utilize methods that control and tailor the specular reflections such that you create an initial signal delay gap followed by a well behaved semi-diffuse field - if that is what you want.

But as always, knowing where you want to go is the most important determining factor in deciding the route to get there. And the lack of such a goal will most likely lead to a response that you are not happy with, unless you simply want a very dead room - as some most definitely do - and is one's right by preference. But I single out 'dead' rooms here as almost any room goal can instead be turned into a very damped dead room with the 'over' application of more and more absorption.

So, know where you want to go and what you want to achieve. THAT is the best way, along with some basic measurements enabling you to know where you are starting, and to evaluate the real problems that you want to mitigate, and to evaluate your results at each step in order to insure that you stay on your path to achieving results consistent with the goal you desire.


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Oh, and to go on a pertinent tangent for just a second, you mention much of your budget allocated to monitors!

A few considerations which are far too often not considerations until after they are purchased and they have become the SOURCE of many of the problems many want to solve in the room!

Several factors to consider for which many manufacturers do not provide meaningful specs...

First, the almost universally available ruler flat free field anechoic frequency measurements mean almost nothing - unless you are going to suspend them in the center of a large anechoic chamber! And if these are the specs provided, be very wary, as these have not been designed for a practical application within a given environment.

In fact, I take that back, the provision of only such measurements indicate that they are trying to sell you something that, while it looks good on paper, most likely will not look or sound that way in your environment! Treat such specs as lipstick on a pig.

Real meaningful measurements are made with a specific environment referenced - such as mounted on one boundary, ( a free mounted shelf), or against 2 boundaries (a shelf and a wall), or in a corner, or soffit mounted. All such environments contribute various amounts of SBIR, real world factors that are critical to their real world use!

Controlled dispersion across the power spectrum. How many buy speakers and then immediately must begin to remediate the boundary reflections that cause destructive interference.

Also, SBIR - boundary reinforcement that will augment the speaker's natural balance based upon the designed emphasis combined with the emphasis added by the proximity to a boundary. You want to select a speaker that will match your intended use and placement! In other words, a speaker designed to be placed against a wall will not have as strong a bass response in the free field, as the boundary gain will sum to reinforce it and achieve the proper balance.

And also VERY important - signal alignment - often referred to as 'time alignment'. You want the various driver sources to have their acoustic origins aligned in the time domain, such that the signals that emanate begin at the same time and thus arrive at the same time. This is evaluated via an impulse response or an ETC response. This is normally most effectively done via an active crossover with delay.

The same effects created by the early reflections in a room combining with the direct signal that we seek to correct are also created by unaligned signals emanating from individual drivers and from cabinet edge diffraction.

A simple ETC on axis of the speaker will provide this information. Also, such a measurement can be made relatively easily by a user if they are aware of the interfering environmental reflections that can negatively interfere with the measurement. For a near field monitor, I would INSIST on such certified data as a condition of purchase.

Oh, and also consider mounting the speakers on stands mechanically isolated from the floor (unless it is slab) mounted 1 or 2 feet BEHIND the work surface, such that early reflections off the work surface can be avoided entirely, or at the very least, more easily mitigated - as opposed to sitting them directly on or above the surface on the 'oh so convenient' desk supports or bridge! Again, a little planning goes a LONG way in avoiding issues that can otherwise be very difficult to adequately resolve afterward!

Select a speaker that addresses these issues to begin with, and you have already avoided quite a few problems that many will spend much time, money and effort to later try to address!

------------------------------

Also, don't expect a manufacturer or sales organization to do your due diligence for you!!!

If you do not want to do all the busy work of assuring that the speakers, and room treatment do not perform appropriately, why should others?????

And if you do not, you had better include an objective proof of performance clause utilizing a reputable acoustical analyst who employs industry standard best practices relative to a CLEARLY stated OBJECTIVE performance metric stated in writing! (Good luck with that!)

And while I do not assume that all are disreputable, neither are they responsible for your application and your preferences!

So, after all is said and done, if you are worried about the final result, YOU, and ONLY YOU are ultimately responsible for ascertaining the applicability of each of the components and their function within your environment! And this may start with something as simple as return privileges if they are not as you like in your environment.

But, bottomline, a demand or expectation for results coupled with an "I don't want to be bothered" attitude is a prescription for the proverbial victim's whine deservedly accompanied by the world's smallest violin. And if you expect others to do this for you, expect to PAY for it!

If you want something better, its up to YOU to do your due diligence - not someone else. But this is no reason to panic! Just proceed slowly and do the research necessary and ask questions. You can do it!

[steveschizoid]

Originally Posted by PeteJames

I'm only thinking about treatment since everyone on here goes on about it ever time you mention buying new monitors

What problem(s) are you trying to solve with new monitors? The reason experienced engineers bring up room treatment whenever you mention buying new monitors is because there is a likelihood that your untreated room's acoustical properties will cause even the best monitors to lie to you. Imagine spending $7000 on a pair of Barefoot Micromains and still not being able to hear where your kick drum and bass guitar coexist....until you take your mix to the car where your ears are bludgeoned with it!

Originally Posted by PeteJames

I don't want to deal with measuring SPLs and graphs and all that boring stuff.

This is a problem if you can't hire an acoustician. I can say that the people at GIK (as well as Ethan Winer I suspect) will bend over backwards to help you solve your acoustic issues. If you have a standard rectangular room and give them its dimensions, they will be able to tell you what you need to do.



Also, taking measurements and observing what your room is doing is actually kind of fascinating, and not as difficult as you might think.

A sine sweep test one can be found here: http://www.gearslutz.com/board/tips-techniques/187046-acoustics-hearing-your-room.html I'd be surprised if a quick listen didn't expose your some of your room's idiosyncrasies in a fairly obvious light.

[PeteJames]

Thanks for the responses. I understand most of what your saying SAC.

I would kind of like to pay someone reputable to check everything is all good with my setup. I didn't expect anyone to do it for free - it's just that i've never had anyone round to my home studio and a professional opinion on my environment would be most helpful. Maybe it's unnecessary, I just don't like trial and error when it comes to £500 - £1000

The thread that worried me was this one my freq response changes everywhere!!

I'm getting new monitors because I am currently using a £100 Denon amp and some speakers that were never sold in large numbers - they were made by vestax (maker of turntables) but they obviously made a few and decided it wasn't viable to go into the monitor industry. I bought them 10 years ago for my dj setup. I don't know if they are good or not; they sound pretty clear but In all probability they are not accurate. Listening to KRK VXT 6s in a shop (untreated) the sounded way more controlled and much flatter - almost boring sounding (less hyped).

What I want from my treatment is to turn a room with gear in it into professional (as far as possible) environment. A flat response for mixing, recording, producing.

[steveschizoid]

Originally Posted by PeteJames

The thread that worried me was this one....
What I want from my treatment is to turn a room with gear in it into professional (as far as possible) environment. A flat response for mixing, recording, producing.

Worrying is a waste of time. Your choice is to pay an acoustician or take some steps proactively to optimize your monitoring situation.

Did you read Peeder's contribution to the tips and techniques forum that I recommended? Play the sine sweep contained therein?

I have a truly unorthodox setup/room dimensions that was creating huge monitoring issues. Check out this post of mine (or read the whole thread - it's not long and kind of fun) that includes a diagram and before/after treatment graphs: http://www.gearslutz.com/board/3704411-post61.html

I am no acoustician, but I have a particularly problematic couple of rooms, and I have manged to make them useable.

You are in a bit of a tough situation since your monitors are such an unknown quantity.

[PeteJames]

Originally Posted by steveschizoid

Worrying is a waste of time. Your choice is to pay an acoustician or take some steps proactively to optimize your monitoring situation.

Did you read Peeder's contribution to the tips and techniques forum that I recommended? Play the sine sweep contained therein?

I have a truly unorthodox setup/room dimensions that was creating huge monitoring issues. Check out this post of mine (or read the whole thread - it's not long and kind of fun) that includes a diagram and before/after treatment graphs: http://www.gearslutz.com/board/3704411-post61.html

I am no acoustician, but I have a particularly problematic couple of rooms, and I have manged to make them useable.

You are in a bit of a tough situation since your monitors are such an unknown quantity.

Yeah, that's why I was thinking of getting something more reputable or 'standard' and active like Adam A7s, Mackie, Dynaudio, Focal or KRK. I've read those posts and they were pretty interesting. I'll have a go with the test tones when I get back home, could be enlightening.

My monitors are actually bottom ported and will be different distances from the back wall as one is by a deep set window. I think I may be sitting around 38 %

My Listening position is 5 - 5.5 ft back which is pretty much spot on!

Length 14ft 4 inches (4.34m)
Width 9ft 10.5 inches (3.0m)
Height 8ft (2.44m)

One thing I don't get is why your supposed to put your monitors and equal distance from the side walls yet some stuff i've read says it's bad to sit equally between side walls?

[PaulP]

What are the dimensions of your room PeteJames ? What is the construction
of the walls, floor and ceiling ? These will ultimately affect how good you'll be
able to get your room to sound. Most people see some improvement with not
too much treatment but you'll never attain the quality of professional studio in
a tiny bedroom.

EDIT: I see you just posted your dimensions. So you're in a pretty small room.
Is the room a rectangle or does it have a weird shape ? What about doors
and windows ? A floor plan would great.

It'll probably be a challenge to get it to sound really good but you should
be able to attain something you can work with. Unless you invest a lot of
time and money into things like resonators and diffusers the room may end
up on the dead side which may or may not be to your liking.

Paul P

[PaulP]

Originally Posted by PeteJames

One thing I don't get is why your supposed to put your monitors and equal distance from the side walls yet some stuff i've read says it's bad to sit equally between side walls?

You need symmetry for proper imaging but the center does not have the
greatest frequency response (but then it won't be great anywhere in your
room). It's worse if your head ends up in the middle between the floor and
ceiling as well. Everyone just seems to live with it.

Paul P

[DanDan]

Pete, the articles on Room Setup and Treatment at RealTraps and GIK are worth reading. In such small typical rooms there are treatment 'bankers' which will work in every situation ( within reason).
Do play some bass sine tones. Tune to the room modes and listen to how loud they are and where they build up. That simple procedure will very likely convince you that you need to act. Even without that test, four corner bass traps will always help. For other reasons an RFZ created by side and ceiling reflection killing panels always works. The improvement is actually a pleasure.
I strongly recommend that you just go for it.
DD

[gremmy]

Proper application of acoustic treatments does not make acoustical problems worse. As was previously stated, it can sometimes do one of two things:

1) Unmask a previously hidden problem (gives you something else to fix, eh?)

2) Could over deaden the room, which is why most recommend the use of FRK to reflect high frequencies on traps that are outside of your RFZ (reflection free zone), assuming an RFZ is part of your design.

If you go slow and take measurements, none of this will be a problem.

The process I recommend is this:

1) Before you put any acoustic treatments in the room, download REW (it's free) from hometheatershack.com and measure your inroom frequency response. Then, adjust the position of your monitors and seating position until you can get the smoothest response possible without treatments.

2) If you still have uneven frequency response below 300hz (and you will), start adding bass traps to room corners. Do all four corners floor to ceiling and you will notice improvement, but other configurations are possible as well (plenty of reading material exists on proper placement of traps).

3) Control early reflections with absorption and/or diffusion (depends on what you're trying to do -- most recommend absorption). Assuming you are running REW with a calibrated mic that extends to 20,000hz, you should notice an improvement in comb filtering, plus an overall reduction in decay times.

Again, it's not hard. But if you make your own treatments, it is a lot of work. Measurements can take time as well. Mostly, what you'll lose is time, not money.

[Ethan Winer]

Originally Posted by PeteJames

If I buy a bunch and can't tell the difference or make things worse what do I do then

I absolutely guarantee you will clearly hear a very positive difference after treating your room. Assuming you don't expect just one bass trap to solve all your problems, of course. As gremmy said, sometimes adding a bass trap can make a single peak or null measure worse. This is a rare occurrence, and the affect is local and never far reaching. Untold thousands of people have added treatment and been thrilled with the result. I can count on one hand the number of people I've heard of over my entire career that were not satisfied after adding bass traps and other treatment. And every single one of them was an audiophile type, versus a home recordist or musician.

When people are skeptical I suggest doing some simple trials. Get a pair of large bath towels, fold them over two or three times to be thicker, then hang them on the side walls at the reflection points. Likewise, get a few pillows and/or folded up blankets or clothes from the hamper etc, and stuff them into some corners. I'm sure you'll hear a small but real improvement. Then you'll know that when you get proper treatment the improvement will be much larger.

--Ethan

[PeteJames]

Thanks for the responses so far guys

Here are some pics to give you an idea of the features of the room Paul.

The wall on the right hand side - the one where you can see the stone chimney breast is about 18 inches thick and made out of stone - the side wall on left (where the beam is) is about 5 inches thick and made out of partition board. I never thought of it as a particularly small room - do you guys like in palaces?

Cheers for the trial ideas and reassurance Ethan

There are a few things I'm unsure of in some posts:

How to: "play some bass sine tones. Tune to the room modes and listen to how loud they are and where they build up."
What's FRK and a RFZ (reflection free zone)?
Treatment 'bankers'?

I downloaded REW but it doesn't work on OSX (it won't even open) but I could borrow my bro's PC - don't in need some kind of SPL meter to use this software?

[gremmy]

PeteJames, when people use the term "small room," it is usually a term to separate the two different types of rooms that exist acoustically (ie, the small room -- which is what most everyone here is dealing with -- and the large room -- for example, a concert hall or commercial movie theater).

[PeteJames]

Originally Posted by gremmy

PeteJames, when people use the term "small room," it is usually a term to separate the two different types of rooms that exist acoustically (ie, the small room -- which is what most everyone here is dealing with -- and the large room -- for example, a concert hall or commercial movie theater).

Oh right, I thought my house was being insulted

Perhaps I'm expecting too much but that graph on Ethans page doesn't look very flat to me :-/ I mean it's a lot better in the corner but at the listening position it's pretty much the same give or take a few db

[DanDan]

Pete, this stuff has all been written about tightly. It won't take long to read the articles. RealTraps - Acoustics Articles
It would save a lot of time if you would do that. Then if you have questions....

The sine thing is me, so I will explain. Rooms are tuned to low musical notes, just like organ pipes. If you play a pure tone at the actual tuned frequency, the room will resonate, loudly. This resonance will result in areas of loud peaks and almost silent nulls in the room. These are modes. They make bass lines very erratic, some notes wildly loud, others almost absent. If you weaken the modes, the bass gets more even, and sounds more solid. Strangely this is achieved by 'trapping' the bass at the hot spots, absorbing it, usually at the boundaries. Corners are where boundaries meet so absorbers there do double or triple work. So, fire up a signal generator in your computer. Sweep the frequency slowly from say 30Hz up. The room will resonate loudly when you hit a mode. Hold it there. Move yourself around the room, checking in corners, up near the ceiling. The hot spots will be really loud. That's where to place your bass traps.

FRK is Foil Reinforced Kraft paper. This is often found on the semi rigid batts of building insulation. It is a damp proofing membrane. Such panels and this membrane have great acoustic effects. Placed across a corner, they can seriously weaken the modes, greatly enhancing the bass in a room.

RFZ, see the link above.

DD

[Bubbagump]

Looking at your pics, that room will be an absolute peach to treat. Seriously, that is an easy room to deal with as you don't have all sorts of weird features all over and it is a pretty reasonable size. Follow the typical small room cook book recipes and go from there. Fill all vertical corners with 4" or 6" panel traps or SuperChunks. Treat your wall/ceiling corners with 4" traps. Create an RFZ. As Ethan said, you absolutely will hear a dramatic improvement.The difference will not be subtle like comparing pre-amps.

[PeteJames]

Originally Posted by Bubbagump

Looking at your pics, that room will be an absolute peach to treat. Seriously, that is an easy room to deal with as you don't have all sorts of weird features all over and it is a pretty reasonable size. Follow the typical small room cook book recipes and go from there. Fill all vertical corners with 4" or 6" panel traps or SuperChunks. Treat your wall/ceiling corners with 4" traps. Create an RFZ. As Ethan said, you absolutely will hear a dramatic improvement.The difference will not be subtle like comparing pre-amps.

Sweet, the only problems i'm not sure how to solve are with the beam that goes across both corners on the left hand side. Would it be ok just to beam the bottom half of the wall

Should trapping be symmetrical or not - ie. should I put 2 full corner traps from floor to ceiling on the right hand side and two that go half way up on the left hand side as the beam obstructs getting into the top corners? Do I need to do anything about the deep set window? Also, does skirting board preventing the bass traps from getting close into the corners matter? Glad to hear the difference should be quite profound. I don't like spending money on loft insulation lol.

Any traps I get must really be movable, not built into the room.

Cheers,
Pete

[Glenn Kuras]

Should trapping be symmetrical or not - ie. should I put 2 full corner traps from floor to ceiling on the right hand side and two that go half way up on the left hand side as the beam obstructs getting into the top corners?

In the front of the room it is important to make things as symmetrical as possible.

[PeteJames]

So really I should just put 1 tri trap in each corner. Any thoughts about one of the speakers having a window behind it and the other being closer to the wall?

[Glenn Kuras]

Originally Posted by PeteJames

So really I should just put 1 tri trap in each corner. Any thoughts about one of the speakers having a window behind it and the other being closer to the wall?

Well that could cause problems with the SBIR which panels behind the speakers will help cure that.
As far as 1 trap trap, that would be a good start, but note that is only a start.

[DanDan]

Petejames, with respect, I urge you to read those articles. Otherwise this will just be a string of questions and answers.

One trap will do little. Four corners, eight traps would be a good start IMHO.
DD

[PeteJames]

Originally Posted by DanDan

Petejames, with respect, I urge you to read those articles. Otherwise this will just be a string of questions and answers.

One trap will do little. Four corners, eight traps would be a good start IMHO.
DD

I read them I meant 4 traps (1 in each corner as opposed to 2) since the beam gets in the way and would lead to uneven symmetry if i put 2 in the left corners and 4 in the right corners.

[DanDan]

Good, I am sure you will have noticed the mantras, 'never enough Bass Traps', 'More is better', etc. etc. They are true and trump symmetry. Symmetry as Glenn said is very important in the RFZ. Try the Sine thing. It is very convincing. It makes all this talk very real and tactile.
DD

[PeteJames]

Maybe I'll have to try and build my own corner traps so I can build them right up to the height of the beams or get GIK custom ones. According to my understanding of the RFZ diagram the corner traps don't fall into this 'category' so more would be ok anyway.

Here is a response graph I got sweeping a sine wave - only using my macbook pro's internal mic at the listening position. What do you think?

[Bubbagump]

Originally Posted by PeteJames

Here is a response graph I got sweeping a sine wave - only using my macbook pro's internal mic at the listening position. What do you think?

Pretty terrible and I'll tell you why. That mic is not meant for such things. Either you have the worst room in the known universe or that mic is made for basic web chat use and has a built in HPF at about 120hz and LPF at 12khz. Get a real measurement mic.... no an SM58/AT4040/U47 won't work.

[PeteJames]

Originally Posted by Bubbagump

Pretty terrible and I'll tell you why. That mic is not meant for such things. Either you have the worst room in the known universe or that mic is made for basic web chat use and has a built in HPF at about 120hz and LPF at 12khz. Get a real measurement mic.... no an SM58/AT4040/U47 won't work.

I read it's an SPL meter I need: Will one of these do the trick?

Digital Sound Level Meter by RadioShack
Silverline 633937 Sound Level Meter

or this kind of thing

Behringer ECM8000 Omnidirectional Measurement Condenser Microphone? I don't have phantom power though and they are expensive - this is the cheapest one. I don't want to spend £100 just to find out my room sucks ;-)

[DanDan]

I beg to differ on several counts. With the exception of the bottom end, the response appears to be within a 10dB window and quite flat. In an untreated room I would consider that pretty good so far. The speakers look quite small so that LF roll off may be a combination of speaker, mic, room, and location.
Time will tell whether that roll off is primarily the mic or all of the above.
Like many tiny electret elements though, the rest of the spectrum is probably quite flat. Note the widespread use of the 1 dollar Panasonic electret in many DIY and custom mics with remarkable response. See Old Colony etc. etc.
I will suggest that the AT condensers mentioned are quite capable of reasonable full range COMPARATIVE measurement. I am bound to get flamed on this, so I may as well continue.... The use of omni mics seems almost universally recommended. Our ears on the other hand are quite forward directional. Which type of measurement will be more useful?
Lastly, Room Analysis Primer V2 Pete. You are not the first to take this journey. It's all written down, and it's all close at hand here at GS.
DD

[Ethan Winer]

Originally Posted by DanDan

With the exception of the bottom end, the response appears to be within a 10dB window and quite flat. In an untreated room I would consider that pretty good so far.

Just to keep this in perspective, the graph above is smoothed to 1/12th octave.

--Ethan

[PeteJames]

During the test I didn't actually hear my speakers produce the low bass tones for some reason - the test sweep was really quick though. Strange.

[Bubbagump]

Not to mention a very limited vertical scale. I would revisit your test methods in any case. To have roll offs like that tell me something is up.

I can't get with using a cardioid mic for measurement. Ignoring the back of the mic and the change of response due to distance makes them very suspect IMO. The Radio Shack Meter can work... see here:

RealTraps - SPL Meters