Room Tuning. Noise Generator + RTA.

[Dick ReesParticipant]

why not use the graphic?

When you “ring out” a room you are addressing room modes/standing waves which by their nature have very specific, fixed frequencies which are best dealt with using notch filters rather than GEQ filters which, although they are on 1/3 octave centers, pull down frequencies in a cut as wide as an octave thus removing or affecting program frequencies far in excess of those needed to address room/system interaction.

GEQ is then used for general tonal adjustments after the specific sonic surgery dealing with room modes has been properly addressed using the variable width PEQ filters. The narrowest filters available on the Qu desks are 1/9 octave. With my GraphiQ the filters are as narrow as 1/60 octave.

Side note: the greatest area of concern for room modes/standing waves will be found below 300hz…as a general rule. Above that there will be the possibility of anomalies between the measurement mic and the speaker system which will tend to disappear by simply moving the microphone. Room modes won’t disappear…

[[XAP]BobParticipant]

Hence the 8 parameter eq on the Roland outputs…

Narrowness is key…

[kngaParticipant]

Are there any frequencies that more often tend to cause feedback than others? Which frequencies would that be? I noticed that maybe those: 1kHz, 6,3kHz, 1,25kHz, 250 Hz… ? Your experiences?

[Dick ReesParticipant]

System interaction (mic/speakers) is situational and any feedback loops will depend primarily on physical distances (wavelengths/phase).

If you are working in rooms of the same dimensions you may find similar room modes. If your system setup always has the same physical relationship between the mics and speakers the same might be true…discounting reflections.

Thus any seeming consistent phenomenon would not be one of frequency itself but one of the physical similarities in setup and location manifesting in “hot spots”. I suspect that gross similarities in setup leads us to look to certain frequencies as “trouble spots”, but it is not solely the frequencies themselves that are the problem. Rather, they are a manifestation of problematic positioning and mic/speaker interaction.

There may be certain adjustments you’d need to make in your system DSP to address any consistent problems such as cross-over points/slopes and such. Speaker manufacturers often give “tunings” for their boxes which can either be implemented with digital system processing or by use of a proprietary “black box” processor.

Lastly, certain frequencies tend to stick in your mind from experience. I notice you mention 6.3K in your list. This is what I call the “ice pick” due to the pain produced when it goes off, so yes, I generally am careful about that particular one…not because it appears more often than others but because if it does appear IT HURTS!

[drumlyellParticipant]

Are there any frequencies that more often tend to cause feedback than others? Which frequencies would that be? I noticed that maybe those: 1kHz, 6,3kHz, 1,25kHz, 250 Hz… ? Your experiences?

There is some math with 250Hz and 1KHz: If 250 is a problem, check 500, then 1K. In this case 250 is the Fundamental Frequency and its upper harmonics may be causing problems too. 250 X 2 = 500 x 2 = 1K (Times 2). Also good to check 250 x 3 = 750 to see if theres any problem there.

DO NOT blindly follow this suggestion!! Using math is just a place to start, but it can help you get things rung out quickly with less trial and errors.

[kngaParticipant]

Thanks! I also have one small question, it is not related to this topic.
I’ve read that cold can affect mixer’s working, tomorow I’m mixing outside, temperatures will be around 5 degrees Celsius. Is this no problem, or should I be afraid?

[Dick ReesParticipant]

Wear long underwear…

[[XAP]BobParticipant]

Recently mixed in a football stand, mixer was out from 10 until 7, temperatures were low single digits for much of the day…

[AndreasModerator]

I’d rather be worried bringing the unit back indoors regarding moisture. Its probably wise to keep it in case or at least a sealed bag for some hours until the unit got warm again.

By the way: Merry Xmas to all of you!

[GCumbeeParticipant]

I would not bag it. Moisture could build up within the bag. I think the natural heat of most mixers will help with condensation. I would try to leave it plugged up as long as possible till temps compensate. Only real concern are motor faders. Moving parts.

I have operated equipment in extreme conditions. Audio gear, television cameras as well as airplane avioincs. Just have to consider a few things. Good to let them warm up before moving things.

[Dick ReesParticipant]

I’d rather be worried bringing the unit back indoors regarding moisture. Its probably wise to keep it in case or at least a sealed bag for some hours until the unit got warm again.

Definitely NOT in a sealed bag! GC is correct.

If you have it in a case, crack it open a tad in the new environment and let it acclimate as gradually as time permits. Ventilation is good, sealed bags are not.

If you’re in extreme humidity, throw bags of silica gel in the case when packing up.

[AndreasModerator]

hmm, surely depends on the humidity level outside when packing stuff together, I see.
Anyway, for me getting the unit back into warmth would be the critical part…
…and don’t forget your condensors, these are much more sensible to humidity…

[John-SParticipant]

Bob,

Answer: Fixed Q vs variable Q. Plus being able to put the equalizer directly on the offending freq. Speaker errors are broad response errors. Room resonances are narrower errors and speaker to microphone feedback is narrowest of all. The trick is to get a feel for which is the problem. Not the easiest thing to do. I do not claim to be an expert but I realize they are there.

J

[drumlyellParticipant]

Critical part is NOT getting it back in warmth quickly. Critical part is letting things (any gear) acclimatize properly before turning it on.

Make sure it can breathe and try not to handle too much because lots of moisture will come from hot little hands.

[Anonymous]

We all understand that in a super global, we would work in a professionally tuned room.

It could be one that become designed with acoustics in mind. One with slanted partitions and ceilings to avoid standing waves. One with diffusers and absorption panels. But in case you’re like me, you have get admission to to professional studios with incredible acoustics, but due to consumer budgetary issues, you often come to be running in your home setup. And if you’re like me, your own home setup isn’t a perfectly tuned room. Now, what are you able to do to enhance your listening environment with out starting an high priced creation challenge to improve your acoustics?

This room tuning technique (good enough, it is technically speaker tuning) involves measuring the frequencies you hear out of your listening position, after which growing an EQ preset on your grasp fader.

The EQ preset will try and catch up on the frequency imbalances heard out of your listening role. It’s a common trick used by live sound engineers to atone for the often less than ideal acoustics in a venue. I picked it up even as doing live sound, and figured it’s adaptable to recording. It’s also better than not anything when working in your private home studio. So right here we go:

1. Position your self and your monitors in their final spots in the room. Make certain you’re sitting in which you may be at the same time as listening and combining.

2. Open up Pro Tools and create one audio song and one master fader.

3. Use the sign generator plugin on the audio song to generate a few crimson noise. Make positive that’s routed to exit your video display units thru your master fader.

Four. Insert a plugin at the audio track that does RTA frequency analysis. This can be your manage evaluation. You’ll compare the evaluation of the frequencies to your room to this evaluation of the output of your device.

Five Use a great RTA frequency analyzer to measure the frequency stability in the room (from listening function). In a pinch, you could use a telephone app just like the RTA frequency analyzers I stated in my 4 Types of Apps Every Audio Engineer Needs article. However, in case you do, you’ll must understand and compensate for the truth that your cellphone’s hardware will restrict and modify your readout. So, I could incredibly suggest borrowing or investing in a decent standalone analyzer, or a flat frequency measurement microphone like this one, or this one. No rely what you operate, be privy to your tool, and what sort of you might ought to compensate for its limitations.

6. Compare the readout from your in room RTA frequency analysis to that of your purple noise output. Use the frequency evaluation plugin in Pro Tools as a crutch, or if you aren’t sure what pink noise need to look like.

7. Place your preferred EQ plugin at the grasp fader in Pro Tools. Adjust the EQ parameters till your in room frequency evaluation matches your completely digital pink noise analysis. Be positive to use and accept as true with your ears at some stage in this method! Once you’re satisfied with the EQ settings, keep it as a preset. I would advise AB trying out some of your favorite reference tracks with and with out the EQ before finalizing the preset.

Eight. Now you simply have to use that EQ preset for your grasp fader even as blending like DURAFLEX DISTRIBUTION AU. Just make sure you get rid of the EQ before bouncing out a combination for a customer – you don’t need something which you constructed to compensate for a less than best room stability getting into your mixes.

So there you go! I’d love to pay attention what you guys consider this trick. I know it’s no longer a great restore, mainly when you get into the info of ways acoustics surely work. But I suppose it’s higher than nothing. At any fee, I’d like to pay attention your opinions on the problem, and what different recommendations you men might have!

[Author]

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