51-54Hz = 6db Hump?

Nate74

Nate74

HR4FREBR
Is this frequency a common problem spot?

I downloaded a series of mp3 files that were supposed to be 10Hz to 300Hz, all at the same dB level. I put them into my Daw, plugged in a mic with a Figure 8 pattern and positioned it roughly where my head is during mixing, with the 8's pointing out like my ears. I played the file and recorded it back through the DAW.

Not surprisingly, nothing was very well represented until approaching about 40Hz (I'm running VXT6 Monitors), but there was about a 6dB hump centered at about 52Hz.

I have about as much 703 trapping in my new room as possible so am not sure what else to try, but was wondering if this is a common problem spot?
 
Just flip the low cut switch on your mic and the hump will go away in future tests :D

I kid, I kid.

Low frequency nodes and peaks are just part and parcel for small rooms. I don't think that any of us can realistically expect a ruler-flat response under 600 Hz. From what I understand, small rooms would require so much trapping that there would be no room left for a person and recording equipment!

If this is your only trouble frequency, then you're probably better off than the vast majority of the rest of us who are recording in bedrooms and garages. I don't think that there is anything magical about your 52 Hz hump. I'd be willing to bet that if you plugged your room dimensions into a room mode calculator, it'd corroborate your real-world findings. But to only have a 6dB hump, and only one...that's not too bad relatively speaking.

As far as solutions, I can't think of much to do other than experiment...try moving your monitors closer or farther away from the wall and see if that hump moves accordingly. If your monitors have low-frequency adjustments, try that. If you have corner traps in, say, 2 corners...try them in the other 2 corners. Try straddling different boundary junctions with bass traps (try wall/ceiling, try floor/wall, try wall/wall).

Or just accept the fact that you've done the research, you've done the measurements, and now you have the knowledge that bass frequencies are exaggerated by 6dB at 52 Hz at your mix position, and keep that in mind as you're mixing.
 
Nate74 said:
I have about as much 703 trapping in my new room as possible so am not sure what else to try...
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I know 703 is the first choice for many....but it's not really going to do anything much for shit down that low all by itself.
It's good broadband...but those real low frequencies need specific-built very low-end trapping.
Often those types of traps employ a membrane(s) and air spaces in addition to the actual "fill" (703 or whatever)...or you have tuned traps that target specific low-end frequencies.
 
Massive Master said:
I'm gonna guess that at least one wall in your room is around 11' long...
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What are you, some kind of a wizard? :)You nailed it dead on. This stinkin' room is almost a cube, 11'x11' with 9.5' ceilings. That's pretty funny, I'm guessing there's a software package out there that calculates that?

Thanks for the big grin!
 
Nate74 said:
What are you, some kind of a wizard? :)You nailed it dead on. This stinkin' room is almost a cube, 11'x11' with 9.5' ceilings. That's pretty funny, I'm guessing there's a software package out there that calculates that?

Thanks for the big grin!
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It's not that hard to convert frequency to wavelength in your head or with a basic calculator. You just need to know the formula. I believe 11' is half the wavelength of 52Hz so one might infer a 2:1 ratio between the resonant frequency and the dimension of the room.
 
And with a room like that, you might need tuned absorption to really kick that frequency's butt. Not that the broadband trapping isn't helping -- Undoubtedly, it's doing a helluva job I'm sure. But (A) that is a really low freq and (B) with multiple axes (axies? Sorry - Jaegermeister makes it hard to type), you're going to have multiple build-ups which might exceed what the broadband traps can effectively counter.
 
Some interesting thoughts, thanks all.

Are there programs out there (preferably freebies) that would let me put a .wav file into it and it can show me how much of this particular frequency is present? My thought is, since this is pretty low maybe paying $$$ to chase it down might not be worth it. It looks like it's down around the low G/G# range so I'm not sure...
 
Nate74 said:
Some interesting thoughts, thanks all.

Are there programs out there (preferably freebies) that would let me put a .wav file into it and it can show me how much of this particular frequency is present? My thought is, since this is pretty low maybe paying $$$ to chase it down might not be worth it. It looks like it's down around the low G/G# range so I'm not sure...
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Spectrum analyzers are common. If you want to get more deeply into it there is more sophisticated software. The industry standard is SMAART, another is TEF. A freeware program that does much of that is REW, Room EQ Wizard, oriented toward home theaters. You have to sign up at Home Theater Shack to get it.

But to do it properly you need a reference mic, which are omni. Your hearing is essentially omnidirectional so an omni mic, not figure-8, is what you need to use.

---------- Update ----------

Rick Finsta said:
So on a related note... how does one account for this in the mix?
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You don't account for it in the mix, you apply room treatment so you can trust what you hear.
 
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bouldersoundguy said:
Spectrum analyzers are common. If you want to get more deeply into it there is more sophisticated software. The industry standard is SMAART, another is TEF. A freeware program that does much of that is REW, Room EQ Wizard, oriented toward home theaters. You have to sign up at Home Theater Shack to get it.

But to do it properly you need a reference mic, which are omni. You hearing is essentially omnidirectional so an omni mic, not figure-8, is what you need to use.
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Thanks. I used a mic that has Cardiod, Figure 8 and Omni for my test so I'll try it again with it set to Omni. I'm also going to try it with the closet door open, and the two entry doors open. They're the reason I don't have traps in two corners of the room, but it occured to me that by leaving them open, the cube is less "cube-ish."
 
Rick Finsta said:
So on a related note... how does one account for this in the mix? Mix to taste and then throw a 6db narrow cut at 52Hz in the EQ when you're bouncing to your final stereo .wav?
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It's sorta out there, but it's important to note that the bump only exists in that space. This is why proper (PROPER) room treatment (along with a quality monitoring chain) is the most important part of ANY rig.

You will only ever hear as accurately and consistently as your monitoring chain allows you to hear. Your monitoring chain will only ever be as accurate and consistent as the space allows them to be.

You could have thousands - or tens of thousands - invested in just your monitoring chain. If the room isn't up to it, they aren't worth anything.

If he has a 50Hz-ish bump in one spot in the space, its' very likely (especially considering the square aspect) that there are null points somewhere also -- Might be 40dB down from where it should be. Probably scattered around the room in different frequencies for that matter. You can bet that bump that exists at the mix position is completely different just a foot away (probably in any direction including vertically).
 
Nate74 said:
That's pretty funny, I'm guessing there's a software package out there that calculates that?
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You can do it in your head.

Find out the length of the frequency: 344 (speed of sound in m/s) divided by 52 (the frequency in Hz)

So you get 6.6m, which is the wavelength of one cycle of a 52 Hz wave.
And I guess that 6.6m is 11 feet or something.

That wave is "standing" between the two parallel surfaces and superimposing onto itself, making it loud.
 
Schwarzenyaeger said:
You can do it in your head.

Find out the length of the frequency: 344 (speed of sound in m/s) divided by 52 (the frequency in Hz)

So you get 6.6m, which is the wavelength of one cycle of a 52 Hz wave.
And I guess that 6.6m is 11 feet or something.

That wave is "standing" between the two parallel surfaces and superimposing onto itself, making it loud.
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6.6 meters - 21.5 ft, actually, so 11 feet is about half the wavelength.
 
Yup, clearly my 11'x11' room is an issue here. No room for any more traps or other treatments though.

But an earlier question has me wondering:

Since I know that 51-54Hz is a 'trouble' spot for my room, this means that my mixing room will exaggerate those frequencies by about 6 dB. I would then presumably cut those frequencies in my mixes by about 6dB to compensate, leaving my mixes fairly week on the bottom end in other playback environments. So would it be possible to set up an EQ on my playback mix that cut those frequencies by 6dB so that I wouldn't be inclined to mix them out in my mixes? Sort of counter-acting the issues with the room?

Did that make sense?
 
You don't want to adjust anything in your mix based off of a false impression that your room is giving you. If you're listening to your mix and you feel like it's too exaggerated at 54 Hz, I would be really reluctant to cut there because you know that it's your room that's exaggerating it, not your mix.

And the trouble about EQing your monitors is that if you move your head a little in any direction, the exaggerated/null frequencies will change. You can EQ it so it sounds fine at one spot, but it won't sound fine a few inches or a foot away from there. You'd have to be really consistent with where you put your ears!
 
Tadpui said:
You don't want to adjust anything in your mix based off of a false impression that your room is giving you. If you're listening to your mix and you feel like it's too exaggerated at 54 Hz, I would be really reluctant to cut there because you know that it's your room that's exaggerating it, not your mix.

And the trouble about EQing your monitors is that if you move your head a little in any direction, the exaggerated/null frequencies will change. You can EQ it so it sounds fine at one spot, but it won't sound fine a few inches or a foot away from there. You'd have to be really consistent with where you put your ears!
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I wouldn't leave the EQ on the mix for final mixdown, just for the time I was working on it. Or like the phrase you said, "EQ the monitors." I hadn't thought about the effect moving my head around might have. Seems like a few inches in one direction or another wouldn't be that big a deal, but this whole thing is full of surprises ;)

Thanks for the input!
 
So what about using headphones to check the 52Hz balance?

I understand this isn't the ideal way to do things, but if you are unable to fix this issue the correct way, what is the best band-aid approach?
 
Rick Finsta said:
So what about using headphones to check the 52Hz balance?

I understand this isn't the ideal way to do things, but if you are unable to fix this issue the correct way, what is the best band-aid approach?
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Better yet ..or in addition :) just get up and move around a bit, you get 'average response.
 
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