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Sub Low Pass/Volume

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Sub Low Pass/Volume

Postby aremator » Tue Sep 11, 2018 3:21 am

How do you know where to set the low pass on your subwoofer? I am using HS8's and a KRK 10 sub. I have heard you take the lowest frequency your monitors can go and double the number, and then set your cross over at that point. Is that true? Also, how do you know how loud to set the volume on the sub? Is there some rule of thumb?


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Re: Sub Low Pass/Volume

Postby Wonks » Tue Sep 11, 2018 1:16 pm

If the choice of crossover frequency isn't fixed, I'd look at the frequency response charts of the monitors and sub and choose a point where both of them have a flat as possible response, but probably as low as possible. Stereo information is carried on to quite low frequencies, somewhere to below 100Hz, so around 80Hz should be a good point to look at to avoid blurring your stereo field in the the upper bass frequencies. You basically want the sub to extend the bass end rather than provide more overall volume like a PA, where the crossover point is normally higher but the sound is mainly mono..

You first need to select the best place to position the sub. More low frequency means more need for room treatment, especially bass traps, so it's almost pointless using one without proper acoustic treatment installed.

To set the volume up, you really need some basic test equipment. You can just try and use your ears and play notes back from a soft or hard keyboard and adjust until the notes around say 90Hz sound the same level as ones at 70Hz (if using an 80Hz crossover point). or you could play back pink noise and use a measurement microphone to record the sound in your normal listening point and adjust the sub volume until the recorded or displayed frequency response looks even. Beware real-time frequency curve displays for this as they are normally poor at low frequencies de to the short FFT sample times used for real time displays. Bar type frequency displays are much better for this. Otherwise record the noise and then use an off-line frequency analysis tool on the recording.

There's an old but good SoS sub locating and setting up article here https://www.soundonsound.com/techniques ... -subwoofer

There's a lot to be said for using a good pair of headphones with an extended bass response (e.g. AKG K712), especially if used with Sonarworks EQ correcting software, just to check you low-end on as it takes the room response out of the equation, otherwise then mix on the monitors as before.
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Re: Sub Low Pass/Volume

Postby w oxo cube » Tue Sep 11, 2018 2:08 pm

I work as a sound tech in a few clubs with large PA systems. Generally having the subs on a Aux group tends to work best and is the most flexible way of adding how much is required dependent on the program material. I generally ride the Aux group giving it a bump when needed and vise versa.
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Re: Sub Low Pass/Volume

Postby Wonks » Tue Sep 11, 2018 3:30 pm

w oxo cube wrote:I work as a sound tech in a few clubs with large PA systems. Generally having the subs on a Aux group tends to work best and is the most flexible way of adding how much is required dependent on the program material. I generally ride the Aux group giving it a bump when needed and vise versa.


This is a sub for a home studio installation. Aux channels and riding the fader simply don't apply here. :headbang:
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