John Sayers' Recording Studio Design Forum Archive

Hello all,

Have been reading / visiting this forum for a few years now and have always found it to be a wealth of information (as well being somewhat entertaining at times!). I've always had an interest in acoustics and being an audio engineer, music technology. My main passion is mixing (as opposed to recording) and unfortunately, as I have never been able to build a dedicated mixing room I've had to "make do" with rented existing rooms which I have set up as my mix room. Up until now I've been pretty lucky with the various acoustic spaces I've "been dealt" and have had quite a bit of success with my mixes, however ...

Having just moved into a new house (rented) and set up all things domestic, the time came to set up my mix room in what the real estate agent calls "the home office" which is a small room at one end of the house. It's very nice, comfortable etc and far enough away from the rest of the house to not cause noise problems to either my wife or our neighbors.

So I set up my basic mix rig ... NS10's, 27" iMac, Interface, Pro Tools etc, nothing else in the room, no treatment at all.
Speakers set up along the only practical wall (being the 9'4" one) Listening position roughly 38% into the room.
... played some music and some mixes that I know very well ... the result was pretty astonishing and not in a good way! ... Absolutely no bottom end in anything. I estimated that the roll off started at about 100Hz.

About the room:

Dimensions: 10.3'(L) x 11.61'(W) x 8'(H) with a small indent where the door is (see pic)
Rear wall: Glass windows (floor to ceiling) covered with wooden Venetian blinds.
Floor: Wall to wall carpet
Walls: Drywall
Ceiling: wood panels (much like you would find in a sauna) with two exposed beams.

I did some measurements using Fuzzmeasure software and a Behringer ECM8000 calibration mic, pics attached.
As can be seen (assuming I'm measuring correctly) there really is nothing usable below about 100Hz.

My question is:
Can I treat this room with bass trapping to get some of the 100Hz and below back or is it virtually impossible given the dimensions / Frequency response measurements?

I have about $1000 to spend (I've been looking at this product: http://www.autex.com.au/acoustics/quietspace-panel/ .... although I'm quite willing and able to construct my own)


Please let me know if I have left out any pertinent information.

Many thanks,
Steve

Hi Steve, and Welcome to the forum!

I did some measurements using Fuzzmeasure software and a Behringer ECM8000 calibration mic, pics attached. As can be seen (assuming I'm measuring correctly) there really is nothing usable below about 100Hz.

That's not a room problem: that's a speaker problem. The NS10 has nothing down there either.

Here's the actual frequency response graph for the NS10, as measured in an acoustical lab:

Your graph shows pretty much the same. What you are seeing (and hearing) is the actual response of the NS10. It simply does not put out much useful energy below 100 Hz.

So if you want to mix well with good bass, you'll need new speakers that actually have some bass extension to them. There are a few good ones around these days that do a decent job down to 40 Hz or so at reasonable cost, and for a bit more you can get down to 30 Hz rather nicely. Getting good bass below 30 costs a lot more money, and isn't really necessary unless you are mixing earthquakes and battleship canon fights for movies.

However, on a budget of $1 k, there's not much you can do. Selling your NS10's plus the 1k would just about get you a decent pair of Adam's, Eve's, Genelecs, or suchlike, but then you'd have nothing left for treatment. You might need to increase your budget here.

Can I treat this room with bass trapping to get some of the 100Hz and below back

No, because it isn't a problem with the room: it's a problem with the speakers not putting out any bass.

That said, you WILL need bass trapping once you get speakers that do produce bass. Once you have speakers that go down low, they will certainly wake up the room, and make it show all it's ugly bass issues, which you will then need to treat.

or is it virtually impossible given the dimensions / Frequency response measurements?

It's a small room, and strangely shaped, but that doesn't mean it has to sound terrible. With good speakers and good treatment, it can sound quite decent. It won't be Galaxy or Studio Three, but it can be quite acceptable.

I did some measurements using Fuzzmeasure software and a Behringer ECM8000 calibration mic, pics attached

The mic is fine, Fuzzmeasure is somewhat acceptable (but REW would be much better), but your technique needs fixing!

First, smoothing the low end to 1/3 octave completely defeats the purpose! Room modes are very tight, narrow high-Q events that you just will not see at all on 1/3 octave. Even at 1/48 octave they can still be partly masked. For the low end, use only unsmoothed data, or smoothed to 1/48 max. For the high end you can smooth more, yes, but not for lows. You won't see any room response if you smooth lows.

Next, you need to get the scaling right. You ran the test from 10 Hz to about 15 kHz apparently. No common speakers put out anything usable at 10 Hz, and even if they did you wold not be able to measure it accurately. You don't need a start point so low. 19 Hz is plenty for the majority of studios and speakers, and maybe 17 or 16 if you have exceptional speakers in an exceptional room. At the top end, you need to go up to at least 20 kHz, and 22 would be better. You do need to see what the top end is doing.

Your scaling in the Z axis on the waterfall plot is also off: The scale is too long for that room, as the decay time seems to be around 500 ms or so. And your Y axis is also off: most of what you are seeing is just "mud". Ambient sound that is in the room all the time, but was not generated by your speakers. There's no point in looking at mud. Concentrate on the important part.

And finally, on the dB scale, you are looking at everything with reference to the peak level, so all of your graphs show negative values, relative to peak. That's not much use. You should switch to looking at the absolute SPL values (assuming you calibrated your system with a hand held meter). That tells you a lot more useful info about the room, and the response.

So, my advice would be to first swap your speakers out for something that really does have good bass response, then re-do your tests with REW, and use the correct scaling to look at the data.

With that information we can help you decide how to treat the room.

One final word, regarding this:

Rear wall: Glass windows (floor to ceiling) covered with wooden Venetian blinds.

That is going to be a problem! The rear wall is critical, and will need deep bass trapping, without any doubt. I hope you don't need access to those windows, since they will be covered up with many inches of treatment...


- Stuart -

Hi Stuart,

Thanks for taking the time to read my post, all very helpful information.
I will try and get a more accurate room response reading with your suggested parameters although I understood the process of testing a room with a calibration mic / software was actually measuring the response of the room as opposed to the response of the speakers?

Regarding the NS10's I am very familiar with their freq. response ... this exact pair have been "barking" at me for almost 20 years now! so I know exactly how they sound and what they are capable of, I know and love them like a child even if they are unpleasant to listen to at times!
In the past I've had them set up in many different rooms without bass issues ... obviously there is a bit of technique / guesswork with tones below 100Hz when mixing on NS10's which I'm pretty familiar with.

However this current room is the smallest I've ever had to deal with so I was thinking the problem would be with some kind of cancellation / null at a particular frequency in this particular room with the given dimensions? ... I was hoping to rule that out before everything else.

As I'm not an acoustic engineer I was hoping perhaps you (or someone else in this wonderful forum) would able to let me know - given the dimensions of the room, if I am in fact sitting in a null or if there is some kind of frequency cancellation below 100Hz and if it can be remedied with treatment as opposed to buying bigger speakers that will produce more bass.

Again many thanks,
Steve