New Recording Room for Acoustic Guitar and Vocals

[Noise Commander]

Hello!

I already have a professionally treated control room in the basement...(kinda small, 18' x 10,1')

Now I'd like to treat another basement room, I want it to be a recording room for Acoustic Guitars, Vocals, and maybe E-Guitar cabs...

The room is 201'' x 217'', (16,75' x 18') and is 89'' (7,4') high.
It has a wooden ceiling, a carpet on the floor, and 2 walls have a wood covering, one of them embedded mirrors.
The other two walls are smooth plastered/trimmed stone walls.

From recording there I know that the room sounds kinda weird right now.
Some early reflections, but not much. Kinda harsh, without sounding naturally alive, combined with the obvious bass room modes.

So I thought of getting good bass traps for the corners,
Nice diffusors for one or both of the stone walls, an acoustic curtain to cover the mirrors, And maybe a few absorbers at problematic spots.

Which modules do you recommend, how many, and where would you put them?

I attached a drawing...you could sketch it in there...

Thanks a lot in advance to Ethan, GIK, and co.!!

[Noise Commander]

Anyone?

[SAC]

So you want us to sit down and do the due diligence you can do?

First you can make frequency response/cumulative spectral decay(waterfall) measurements in order to determine the real world LF modal behavior.

And then you can make impulse response measurements from which you will derive an ETC response such that the specular reflections can be identified and from that information, their paths and points of reflective incident determined such that you can identify the sites requiring either absorption or diffusion based upon their arrival times and gain.

From this information you can begin to decide what treatments you might like to make or buy on a NEEDS driven basis.


Or you can of course simply buy a few blue, red and green 'panels'.

[Noise Commander]

No, I don't want you to make my work.

But I am no expert in these things.

What software (im on mac) do I need for a waterfall diagram?
What is an ETC?

Which mic do I need for measurement...those cheap Behringers are good for this purpose aren't they?

Still, I hope somebody here is nice enought to HELP me with general ideas. Where you guess I'd have to put panels. How much diffusion a room with the given measurments usually needs for recording acoustic intruments ...etc...

Thx again.

[SAC]

Fuzzmeasure or REW (perhaps running VMWare Fusion and a virtual Windows environment if necessary).

And the ETC is an Energy Time Curve, more appropriately (and now officially) referred to as an Envelope Time Curve that is convolved (generated) from the impulse response.

The Behringer mic can work, although I will admit that I am not a fan (but if this is simply for a project it will do fine - but to ramble a bit, you might consider a slightly better mic that can also be used in the future for actual recording with an exceptional response...as I might suggest that this would be a better investment than one where you will effectively let it live in a drawer with no further use after testing. If you desire a list that range in price from ~$200 up, let me know)

And if you measure, you can tell exactly where to treat the room. There will be no need to guess.
As far as guessing, read the generic how to treat your room here or on a site such as Ethan's Realtraps site.
But with measurements you will have answers specific to your room, and not to someone else's.

[Noise Commander]

Ok.

I have Fuzz Measure, and the ECM 8000 here now!
I hate that I have to use an edirol Firewire AD/DA because my G5 with the Lynx Aurora 16 doesn't have OS X Leopard...
Well...


So how do I have to set up FM?
ATM it's set to 10s sine sweep, no smoothing, 50 Point Resolution, Min Freq 30 Hz, Max Freq 400 Hz. Magnitude - 40, Offset 45 ms, Duration 500 ms.
Are the settings right?

What graphs and measurements do you need to judge my rooms?
Waterfall, reverbation and freq curve? Anything else?

I want to measure my control room first, at mixing position. The room is really small, and has been treated. Is one channel enough? I playback through K & H O300.

Then I want to measure the mentioned recording room, that is not treated yet.

[Noise Commander]

[liscio]

Originally Posted by Noise Commander

Ok.
What graphs and measurements do you need to judge my rooms?
Waterfall, reverbation and freq curve? Anything else?

Please see: Measuring and Treating a Home Studio Using FuzzMeasure Pro: Part 1 for some examples. In going through my own room measurements, I provide tips on creating the graphs you see in the article yourself.

That should get you started...

[Noise Commander]

Thanks.

Here is the data:

Control Room: (Mixing Position)
Waterfall:

Reverberation:


Ugly build up at 50 Hz. And a mode at 80 Hz.
Reverberation not very linear...is it ok? How to further treat the room? Are there bass traps that go down to 50 Hz? Problem is there is no space left in the room...


And now the untreated future recording room:
I measured at three room positions, 3 different speaker positions also.

M1


M2


M3


And Frequency curves:

F1


F2


F3


And Reverberation...





As there are a lot of cases, amps and stuff flying around in the room, there is a lot going on...The mentioned mirrors are not covered yet...etc...
So ...how to proceed now?
What panels and traps do I need? Remember I want the recording room to sound alive, but still controlled. For Acoustic guitar, e-guitar and vocals...(Pop, and Rock music)

[Weasel9992]

SAC? He did what you asked. How about some help interpreting?

Frank

[SAC]

Nope. Not at all. Go back and read what measurements were requested to help.

I have never claimed to be able to analyze the spectral reflections of a room from the frequencies response! Quite the opposite.

Thus far he has modal issues at ~ 50 and 80 Hz and comb filtering. Nothing new or unexpected here. The frequency and waterfall plots are quite sufficient to identify this.

The RT times in a room where reverberant fields at those frequencies do not exist are of no use as they have no meaning. You already have the information many are mistaking for reverberation in the resonant decay times in the waterfalls sufficient for modal analysis.

Actual reverberation simply acts as a noise floor potentially masking signals. It is NOT the delay many think of when they add "reverb" as an effect! Nor is it the ratio of direct to first reflection to which many mistakenly refer to as reverberation when they clap their hands in a room to determine its 'liveness' or 'deadness'.

In order to interpret reflections, as mentioned specifically earlier, we need an ETC or at least a log-squared response generated from the impulse response.

Some have done this in FM, but I do not know what function they selected, and the user manual I have perused did not have a complete list of selectable functions available; so as I don't have the program I do not know what function they selected.

From what I can tell of FM, it supports a loopback in one channel (which they describe in one of their user guides) which is highly recommended to correct for the non-linearity of the test unit itself. Also, as it does not support a weighted sweep (providing greater low freq information without over driving and blowing HF drivers) one is apparently limited to a log sweep. A sweep length of 1.4s with 4 averages repeats should be sufficient for the impulse.

Oh, and please be sure the impulse/ETC responses are made with 'one' speaker at a time driving the room - not both - in their 'actual' locations. And the mic is placed where the center of your head would be in the mix or listening position.

When/If we can obtain them I will be glad to try to help.

[Weasel9992]

Using Fuzzmeasure or REW how would the OP accomplish this? You'll probably need to be pretty specific in terms of the steps. If he can't use those programs perhaps you could point him (and others) in the direction of one that is suitable?

Frank

[SAC]

Several who have and use those programs have generated the impulse response and the ETC or, at least, the log-squared response (which only shows the real component without the imaginary), but that is close enough.

They have not supplied the information as to where those functions are located in the program, and as I am not psychic, I do not know to pass on such information. But such information would indeed be useful for us to be able to suggest it to others. And screen captures of the interface indicating this would be even nicer.

If one wants to use Easera or TEF I can tell them exactly how and where to generate the ETC, as it is a fundamental function easily sourced.

[Noise Commander]

I don't want to sound unreasonable...

But the already given data should help to decide what treatments to make.
thumbsup

Recording Room:

50 Hz mode, 80 Hz mode.

Comb filtering.

Average RT of 0,4 seconds...about 1 secoond under 80 Hz.

Mids and Highs seem to be kinda "nervous" and busy, from what I can tell.

----> Conclusion?

I have no bass traps, absorbers, diffusors or anything else in the room yet, plus 5 uncovered mirrors. 2 wood covered walls, 2 smooth brick walls.

Here is the drawing again:


What general treatment I should make in any case for the recording/live room??

PS: I'm new in this part of the board...But SAC, are you angry? I seem to sense a weird undertone in your posts. But I'm no native speaker, so I guess I'm wrong.

[SAC]

First you were frustrated with FM and seemed to expect others to configure it for you.
Some may be able to help, and they usually do. But not all of us use that particular program.

And when we didn't respond quickly enough you follow it with some emoticon ...

And now you tell us what measurements are adequate for analyzing a room after repeatedly being told we need time domanin measurements in addition to the frequency response.

Well. you already have all of the specific info we can provide from your measurements. You have a a mode at ~50 and 80 Hz.

You are welcome to use corner porous bass traps or tuned resonator style traps placed at the location of the modes.

As far as anything else, you have comb filtering - which simply tells us that you have the superposition of multiple signals causing the destructive behavior. And anyone here could have accurately predicted that this is a normal condition for almost ANY room prior to treatment with out any measurements.

So we have NO measurements from which we can identify or gather ANY information about the reflections. That is provided by the ETC or log-squared response.

But as you "don't want to sound unreasonable...But the already given data should help to decide what treatments to make", and have decided what information we need and don't need, I hope I don't sound too unreasonable in telling you that you we have told you all we can from the measurements you provided.

So, lacking additional information, I am not sure what more you want.

[Weasel9992]

What's all this "we" stuff?

Though SAC will undoubtedly lambaste me for saying it, I'd start with absorption and work from there. It probably won't be the *only* thing you do, and you should approach it conservatively at first, but broad band absorption will take you a long ways toward addressing the stuff below 250Hz. Start with bass trapping in the front corners, floor to ceiling, thicker bass traps on the back wall (6" or better) and something at the reflection points, on the ceiling and on the front wall. Either 4" or 2" would work there, but given the issues down low I'd be thinking in terms of 4".

There isn't much subtlety in this approach. We're looking to just flatten things out some and reduce ringing down low. After you get the room a bit more under control, then you can start looking at a more nuanced approach from there. There are other treatment options to consider, but my opinion is that you need to solve the big problems first.

The alternative is to hire somebody like SAC, Jeff Hedback or Bob Hodas to plan the acoustics of the space for you. If the budget is there, then that's a great way to go.

Frank

[SAC]

As was stated.

You follow the general process stated in the thread for generic room treatment with absorption, or with the additional measurements more specific information can be gleaned to treat the reflections that dominate the region above the modal response.

We are simply repeating the same suggestions over and over.

And for those not aware of, or unfamiliar with using the measurements above the critical frequency regarding specular reflections, well, life is very blissful.

And it would be nice if folks discovered the meaning and use of an "editorial" "we" or "you" referring to people in general.

[DanDan]

NC. If you hang around here for while you will see remarkably similar questions cropping up repeatedly. It is necessary to search before posting. SAC always trots out this ETC nonsense and never ever comes to any conclusion or gives any actual help. If you wish to further understand SAC aka foxfyr, try a search of his posts.

Most of the advice on the websites is about setting up and treating listening rooms. Recording rooms have a different purpose. I work in both acoustics and recording so I do have some answers for you.
Your room has plenty of very hard surfaces, they will not flex or vibrate even at very low frequencies. This means you will have very strong modes. Use a room mode calculator to predict the frequency of the modes and their high pressure areas. Then use sine waves to confirm the location of the hot spots. Corners are very likely but you will probably get a few surprises and certainly will learn a lot.
Place enormous bass traps in these hot areas. Next create a checkerboard pattern of absorbent panels on the walls. Have a treated area face an opposite untreated. This will kill all flutter echo but will keep the room somewhat live by treating only half.
Many instruments, such as drums, violins, sax, like such a live but flutter free space.
The floor ceiling is a problem. They are the two largest surfaces. The wooden ceiling may be functioning as a sort of Bass Trap. A loose fill of insulation above the wood should improve this. However, HF will bounce back down to the mics causing comb filtering. Try it as is, but be aware that most great recording spaces seem to end up with a hard floor and a high and/or absorptive ceiling.
You could try a cloud over a drum area and place a plywood panel on the floor to liven up drums and some instruments. Vocals will benefit from a cloud also.
I hope that helps.
DD