Dave Rat - Mic Polarity Setup Part 3 of 3 for Live Sound Engineers

[mattfender]

hey dave, learning loads thanks so much for these videos. am I right in flipping the polarity of just the resonant head of the bass drum and leaving the 57 i have at the beater untouched? ive tested out a load of theories youve demonstrated in your videos on the tour im on and have made a big difference. and the band love your theory of just jamming at soundcheck and not hitting each drum 5000 times :) cheers man, owe ye a beer! matt

[www73171]

@mattfender Yep, usually flipping back side and leaving beater side in is the way with most setups. Glad some of these things are working for ya and thanks for commenting!

[6imzadi]

Something you did not touch on is if you are running main and monitors from FOH. Does reversing the kick, for example affect the system as a whole? Will it cause a reduction in overall low end output? What if the drummer has in ears?

Thanks for your time to shoot these videos, I am learning alot.

[www73171]

@6imzadi If the mon and main rigs are wired correctly and the same way, then both mons and mains should have the same polarity reversals. Polarity reversals alone will not effect low end output, combining in polarity and out of polarity sounds or signals will reduce low end output. In ears have a polarity as well and ideally the polarity of the in-ear system would be set to correct with the monitors.

[chickenfizz]

Hi Dave, thanks very much for these videos, this is one of the very few videos on live sound that has actually made me think! I'd always thought of sound behind the speakers as being out of phase, which it of course is not!

[YannickDP]

Hey Dave! Thx for all vids! Just a (possibly stupid) question. But how can you do all the things in the vids in a live situation we're you almost allways have maximum 20 or 30 minutes to soundcheck. I'm already glad if my main graphic EQ is set right and all compressors and gates are running right, groups and VCA's are made..

[www73171]

@YannickDP Well, it only takes a very short time to turn the kick up in the drum fill and determine the correct polarity of the mon system, then its super fast to hit polarity reversals to make everything correct. That will get you really close.

[rdnymllnele]

Can you talk a little bit about polarity with acoustic guitars?

[www73171]

@rdnymllnele Thats easy, polarity does not matter for acoustic guitars except if you have more than one mic, more than one pickup or a mic and pickup. If you have multiples, all of them should be in polarity.

[danielsittler]

these are so awsome. please keep it up

[akshayesinghkhanna]

Very informative! I look forward to seeing more videos. Cheers

[GeorgeSonatic]

Hey Dave, quick remark: if your kick drum channel is revered polarity and your bass channel is not wouldn't that create problems at FOH (like sound cancellation or chorus-ing at low freq)?

I understand the monitor logic but it seams to me that for FOH you will have problems between instruments if you revers polarity.

Thanks, George.

[www73171]

@GeorgeSonatic Polarity is only an issue when you have the same signal recombining with itself as in acoustic kick sound combining with kick sound coming from drum fill. Or bass rig sound combining with bass from monitors. With unrelated signals like bass combining with kick or guit with vox or one vocal with another vocal, polarity reversal makes no difference because the musician playing the same note a fraction of a second early or later will completely alter the way the signals combine.

[MikeLombardoMusic]

Dave, I love these. Can you talk about amp/speaker impedance - i.e. running 2 -8ohm speakers in parallel yields 4 ohms, etc. Is it bad to run unmatched impedance loads on stereo channels of an amplifier? (4ohms on one channel, 8 ohms on the other).

[www73171]

@MikeLombardoMusic Hmmm, I will ponder that. Maybe something on impedance and bridged amps versus stereo operation which seems to be quite misunderstood as well as there are some interesting aspects that few seem to realize with bridged amps.

[MikeLombardoMusic]

@www73171 Awesome, that would be great. I think I might shoot you an email to say hey.