Rumble in our video, yikes!

farss wrote on 8/7/2006, 6:27 AM

Until I'd hooked a very el cheapo set of speakers that came with a 'sub woofer' I'd never thought to pay much attention to what was happening down at the very bottom end of the audio.
Now I'm noticing that typical outdoor footage has a lot more wind noise below around 80Hz than I'd like, not that getting rid of it with some serious Eq is that hard. Just that OK, most TV speakers aren't going to reproduce this stuff anway but for any viewer with a sub it could sound pretty bad.

Bob.

Comments

John_Cline wrote on 8/7/2006, 7:27 AM

Back in the "old days", we could pretty much count on the fact that people would be listening to our video productions on a single 3" TV speaker. These days, I certain we can assume that a large (and ever increasing) number of people will be listening on home theater systems that include a subwoofer. The introduction of the audio CD in the early 80s dramatically increased the audio quality awareness of the average consumer. The same arguments that apply to using a calibrated video monitor also apply to the audio system we use to create our video "masterpieces." Any producer/editor that utters the words, "oh, they'll never see that" or "they'll never hear that" should be shot. Audio is at least as important, if not more important, than the video. As I've said here before, try watching the six-o'clock news with the sound off and see how much you get out of it.

John

farss wrote on 8/7/2006, 1:43 PM

I think I've been as fanatical as anyone about the importance of audio to our video productions. Anything that involves me mixing or in anyway altering audio gets checked on mutliple systems as I've found (duh) there can be dramatic differences in how things sound on different setups.

So this kind of caught me by surprise. This is just straight from the camera audio using the on camera mic at the side of sports ground on a not overly windy day. There's no great amounts of energy down at the bottom end, yet it took two stacked LP filters to really put a dint in this sound. It's almost like the sub is looking for any LF sound and when it finds it it's trying to make certain you get to hear it. That might be good for things like explosions that add a certain drama to a movie but this 'rumble' is most annoying.
I am talking about a very cheap setup, it certainly isn't there listening to the audio on a typical HiFi systems or in cans. Should I even worry about how this sounds on such crud, well a lot of the public do buy crud. Probably the problem is some huge resonance in the subs response, hit it with the right frequency and the thing just vibrates like an earthquake.

Bob.

winrockpost wrote on 8/7/2006, 2:16 PM

Farss, if you you have good monitors , which I am sure you do, I wouldn't give it a second thought . OK, if I was to give it a second thought I would check it out on at least a middle of the road sub , not a cheap one.

Serena wrote on 8/7/2006, 10:56 PM

In general I think it's better to get rid of unwanted frequencies where possible. Low end reproduction used to be almost non-existent and even "HiFi" speakers fell off quickly below 80 Hz. In the old days of 9 cubic foot reflex enclosures with 15" drivers we aimed to get down to 20 Hz. Many people now have 5.1 systems and many of these aren't expensive, costing in total much less than a good sub. People seem to want those rumbles for effects and want them loud. Very likely many subs employ/suffer resonance and there seems little concern for smoothness and width of response. Bob, I think you did the right thing cutting below 80 Hz.

farss wrote on 8/7/2006, 11:59 PM

Ah yes, now I'm getting all nostalgic, remember those Klipschhorns, I recall a demo where they drove them with a 10 watt per channel amp and could lift the ceiling tiles out of the grid.

And those Cerwin Vega speakers they had in cinemas for Sensaround I think it was called.

Oh dear, think I'm showing my age again....

But there's hope yet, Klipsch still make those 15" horn loaded monsters, part of their Heritage range. And I remember the design was in the Radiotron Designers Handbook from AWA, sadly my copy got lost in a move.

Bob.

Stuart Robinson wrote on 8/8/2006, 9:27 AM

I'm an audio/video journalist part of the day (!) so can offer two pieces of really important subwoofer advice...

1) Calibrate it - with a test disc and SPL meter
2) Disable the internal crossover and use bass management elsewhere in the chain

The second is critical and often overlooked especially if you're working with multi-channel; even major studios make the mistake of relying on a sub's crossover when monitoring.

3) Position the sub correctly in your room, plonking it under the desk isn't good enough!

OK, that was three, I didn't say I could count. ;-)