Switching subwoofer from "discrete mode" to "stereo mode"?

[Slerker]

Hi all!

Asking perhaps a novice question here, but I'm pretty new to audio post so bear with me. I've been mixing in surround at a facility for the last few weeks, and all has gone well. The outputs of the interface go via a Multimax EX controller to a Genelec 5.1 monitor system.

Now, I am asked to do a stereo project on the same system, and I am uncertain on how to deal with the bass management. I understand that in a stereo project I have no discrete subwoofer, but I would like the subwoofer to take care of all frequencies below a set cutoff, in order to mimic what people watching with a home cinema system would experience, right? (or wrong, I'm on thin ice here)

Since the subwoofer of the Genelec system is linked to an output on the interface (output 4 in my case, as it is wired in a LRCLfeLrRs configuration), running stereo material on the system bypasses the subwoofer entirely. How do I go about changing so that the subwoofer stops acting as a discrete speaker, and kicks in as a bass enhancer for my stereo material? Do I change a setting on the Genelecs? Or in the Multimax setup? Or do I even want to change anything at all?

Your help and patience is much appreciated,
/Eric

[AudioPostChris]

Your subwoofer on your Genelecs may have bass management built into it with a crossoever filter , my Adams sub12 does. If not you'll need bass management controller (something like blue sky mkII ).


So many people have small speakers with subs, that I think it's a good idea to reference your mixes with this type of system "bass managed" but you must make sure you properly calibrate the sub and the satellites at the same volume.

[Eric Seaberg]

If you're running the outputs of your controller THROUGH the Genelec sub, then it will handle all bass management of 5.1 and Stereo material.

Which system/sub are you using?

[Slerker]

Thanks guys.

I'm running 8040A Genelecs with a 7070A sub, all going through the sub. And actually, upon closer inspection, I do have output from the sub in stereo operation. It's just significantly lower.

Which of course leads me to question if this is normal. If I play content that is to be reproduced only via the subwoofer (i.e. a sound containing no information over 85Hz), it will sound substantially louder if I output it directly to the subwoofer compared to just playing it "in stereo" and letting the bass management redirect the signal. In my world, they ought to sound equally loud, but this is clearly not the case. So, am I still doing something wrong, or is it the setup?

Thanks again,
Eric

[Eric Seaberg]

Genelec has great setup docs for the 7070. Have you taken a good look at them? If you're only running STEREO through the 7070 you won't have the option to send specific LFE information, only with 5.1 do you get that. If you've setup the system correctly, bass management should be correct, i.e. an extra octave of bass compared to without.

We're running the 8240s (with DSP) in several rooms and love the way they automatically setup with the GLM software. A real time saver.

[Slerker]

Thanks Eric.

I do recognize that running in stereo will not let me output to the subwoofer directly. However, if I play a sound that has no content above the crossover frequency for the bass management, it should be taken care of solely by the sub, right? And in that specific case, playing the file should sound identically whether I'm playing through my stereo output or outputting it directly to the subwoofer, shouldn't it? That is clearly not the case here, there's at least a 9dB difference from what I can tell. The room has been calibrated by a representative from Genelec, so I'm hesitant to believe that there is anything wrong with the setup, but something is strange for sure.

/Eric