• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Live sound chit chat

#41

Here’s my tried-and-true method for eliminating feedback. I do this exercise before the show and have had good success with it.

First, nothing is better for feedback control than a parametric EQ. A parametric EQ can cut ringing frequencies with surgical precision. By contrast, a 1/3-octave EQ is a poor substitute. It just cuts too wide a path and sucks out much more than the offending frequency.

Of course, if you’re using different brands/models of mics, they first need to be gain-matched. What I typically do then is set up all the mics on stage as they’ll normally be used. Next set your parametric EQ for a narrow bandwidth, say 1/6 to 1/10-octave, and cut the filter gain -6 dB or so.

At the mixing console, push the master fader down low, and the individual mic-channel faders up really high. Then, slowly push up the master fader until feedback starts. Ride gain on the master fader to keep the feedback under control, then sweep the frequency knob on the EQ. When you hit the offending frequency, it will suck the feedback right out. At that point you can experiment and further tweak the bandwidth and gain controls, if desired. Specifically, if you need to cut more than 6 dB, then tighten up the filter to a narrower bandwidth setting.

Once you have the initial feedback frequency under control, push the master fader up some more until the next feedback frequency starts ringing. Engage another EQ filter and eliminate this problematic frequency too.

At this point you should be good to go and be able to enjoy a feedback-free show. However, if you expect really high system levels, and/or have mics in close proximity to the speakers, you might repeat the exercise for a third hot frequency. You should have significantly greater gain-before-feedback headroom, which you can verify by switching the EQ in and out.

Regards,
Wayne A. Pflughaupt



Administrator, Pedulla Club #45
Administrator, Tobias Club
Big Cabs Club #23
Pedulla Club #45

 
#42
Thanks, I'll try this approach instead of graphic!

I would just like to add that when finding a ring with a parametric, or just a nasty frequency (like a piercing guitar tone, for example), I find that it's good to boost when searching for it, instead of cut. Then it really sticks out like a sore thumb when you've found the it, and can save you some time. Of course, don't forget to cut the freq once you've found it! :cool:
 
#45

How to get a clean mix

I expect that many here will know this, being bass players. But if you can’t hear the bass in the mix, or things sound muddy in general, the problem is simple: There is too much low frequency information emanating from other sources. The solution is simple in theory: Roll out the bass of all channels except the bass guitar and perhaps the kick drum. Once the bass is the only thing carrying the bottom end, you’ll come through loud and clear.

Notice I said “simple in theory.” In practice this can be difficult to achieve. You can expect the other musicians to start howling in protest if you limit their bottom end. Keyboard players, guitar players and drummers all seem to like that full, rich sound, and excessive low end helps achieve it.

However, they have to realize that you don’t EQ a full band the same way you would if they were the only instrument on the stage. For instance, with a solo singer playing a guitar or piano, you’d need a nice full low end to balance out the sound. But when a bass guitar is added, the piano or guitar no longer needs to carry the bottom end, so their lows need to be EQ’d out. If not, it just muddies up the sound.

Good audio professionals know these things, and it shows up in their work. Next time you hear a well-produced CD where the bass comes through clear and clean, pay attention to the other instruments and vocals when they are solo’d all alone – like in the intro of a song, for instance. Notice that they will sound fairly “thin,” with virtually no lows at all! Same thing with a recording where the bass sounds muddy and indistinct. When other instruments are solo’d, you’ll probably they find they’re bottom heavy. Multiply that by every other instrument, and you have sonic mush, plain and simple.

Keep in mind the ultimate goal and purpose of a high-fidelity audio reproduction system: It should sound natural, only louder. With that in mind, listen to say, the acoustic guitar totally unamplified, then through the PA. Does it sound deeper through the PA? Well, that’s not the way an acoustic guitar sounds naturally. Reduce the bass.

Same thing with vocals: Do they sound deeper through the PA than without it? That’s not the way voices sound naturally. Reduce the bass. To achieve a clean mix, voices should typically be high-passed at about 200 Hz; keys and guitars perhaps a bit lower.

Same with the drums, to: Listen to them unamplified, then through the PA system. Unlike most other instruments on stage, drum's natural response does reach down in to the “bass guitar zone.” However, there’s not a kick drum in the world with 40 or even 60 Hz fundamentals!

A common problem with the tom-toms in drum kits is that often they have a “hot” frequency that takes a long time to decay. This is especially true if they are poorly dampened (some drummers seem to like that). And typically that “overhang” is in the lower-frequency fundamentals where the bass guitar lives. The problem is easy to fix with the course quasi-parametric EQ controls you typically find on the channel strips of most mixing consoles: Just cut the gain a few dB and sweep the frequency knob. When you hit the tom’s “hot” frequency, it will suck the “overhang” right out. Typically you’re looking in the 80-125 Hz range.

If you manage to get all the other instruments on stage under control, you still have the problem of lows generated from the stage itself, via the monitors or backline amplifiers. Naturally, these sources need to be bass-limited as well.

Regards,
Wayne A. Pflughaupt


Administrator, Pedulla Club #45
Administrator, Tobias Club
Big Cabs Club #23
Pedulla Club #45

 
#46
WayneP said:
Here’s my tried-and-true method for eliminating feedback...

...nothing is better for feedback control than a parametric EQ. A parametric EQ can cut ringing frequencies with surgical precision. By contrast, a 1/3-octave EQ is a poor substitute. It just cuts too wide a path and sucks out much more than the offending frequency.
Click to expand...

Can I just give massive props to this technique (again). I tried it today and I can safely say that PEQ is infinitely better for ringing out fedback than GEQ.
 
#48
I think I can get into this thread. Its been quite some time I've had to run sound - I retired from it about 6 or 7 years ago.

Luckily, I had it pretty easy, as far a mixing was concerned. After slugging it out in clubs running monitors for crummy cover bands in the Philly area, I landed a gig with Disney on Ice. The audio was preprogrammed tracks, so the mix was, well, quite easy. I had a keyboard I used as a MIDI trigger to do cartoonish sound effects live and on the fly.

Biggest hassle was the rigging. This was before line arrays, and we had to hang speakers every where. We had clusters over the ice for the floor seats, a ring of speakers on the truss around the ice for the lower bowl, and delay pairs for the cheap seats. Every load in I ran mics around the arena to ring out the system. It was all Meyer, so we used SIM (I have no idea what you guys use these days).

FOH was right on the floor in front of everyone, so the 3 times in 5 years the sound went out, life sucked - it was always power related. Just had to sit there and wait until the electricians got it fixed. Nothing worse than 10K+ people staring at you and asking you what happened.
 
#49
Looks like a cool thread here. I mix concert FOH and road manage for many national contemporary jazz artists. I hear ya on the bass being a mess. I find it generally occurs more with indoor venues where you have all sorts of nightmare room problems. I love outdoor shows, nothing but air to deal with (except DB limits!)
Eq is everything.WayneP is right. You really have to know the frequency ranges of instruments and vocals. And more often than not, more cutting than boosting. Usually the concert systems run the subs on an aux send. Kick, bass, toms, and keys are what make it to to the subs for me. I also prefer a mic and DI on the bass. The mic gets a good fat bottom and the clarity from the DI. Remember you don't have to turn things up to make something jump out of the mix. Turning another instrument down or cutting a frequency can make something jump right out at you. Also when the bass solo comes up I'm generally pulling the bass out of the subs more as I turn it up.

Also I'm not a big fan of compressors. Some guys I see comp everything, I prefer to get a natural sound and actually mix the band. I only use them for problems. Of course this is dealing with jazz/ R&B, there are a lot of dynamics going on....
 
#50
rdmjazz said:
Also I'm not a big fan of compressors. Some guys I see comp everything, I prefer to get a natural sound and actually mix the band. I only use them for problems. Of course this is dealing with jazz/ R&B, there are a lot of dynamics going on....
Click to expand...

Lately I've only used compression on vocals, kick drum and snare. The guitarists have their own compressor pedals they can use if they like, and I just leave the other instruments uncompressed.
 
#52
Keys have such a wide range sonically (depending on the patch being played) and sometimes the keyboard players lay down a synth bass line. If I have a particular patch giving me trouble in the low end, I'll just roll off some bottom... Generally my keyboard eq's are flat with a bit of high end boost...
 
#54
rdmjazz said:
Keys have such a wide range sonically (depending on the patch being played) and sometimes the keyboard players lay down a synth bass line. If I have a particular patch giving me trouble in the low end, I'll just roll off some bottom... Generally my keyboard eq's are flat with a bit of high end boost...
Click to expand...

That makes sense. The keyboard in my case was a Hammond B3 and I wanted him out of the bass range. But it makes sense if the keys are going to provide bass. I am also guessing you where working with more professional players ;)
 
#55
WayneP said:

First, nothing is better for feedback control than a parametric EQ. A parametric EQ can cut ringing frequencies with surgical precision. By contrast, a 1/3-octave EQ is a poor substitute. It just cuts too wide a path and sucks out much more than the offending frequency.
Administrator, Pedulla Club #45
Administrator, Tobias Club
Big Cabs Club #23
Pedulla Club #45
Click to expand...

+1 for parametric. How I wish my school's rack had a PEQ :crying:.
 
#56
Thought I'd resurect this...why not, eh?

just got back from a rehearsal I was running sound for; I experimented with snare mic positioning, which was fun. I love being 'on the board' at practices, as you have a great chance to mess about and experiment with a set of live sources, and nobody cares if something doesn't work out.
 
#57
Got a question that may help with the resurrection. I have a Yorkville Powermax 16, which is pretty nice as powered boards go. It has two 875 Watt amps for mains and two 275 Watt amps for monitors. The band runs four 12 inch monitors, two 15 inch mains and two 18 inch subs. At our NYE gig I had planned to run the subs from the auxiliary out into a spare power amp I have bridged to 1200 Watts. The idea was to be able to just send the kick and bass to the subs and have independent control of the output. The power amp got no signal from the auxiliary out so I ended up having to get the signal from the line out which worked OK, just not as well as I was hoping for. What did I do wrong?
 
#59
iamoldschool said:
What did I do wrong?
Click to expand...

Good question.

First, double check the obvious things; damaged cable, correct output, aux master up?

Other than that it could be a few things:

Would it be worth trying to plug the aux send into another amp, just to see if you can get an output of some description? It could be that the aux itself isn't functioning porperly; it's a pity the aux send on that desk doesn't have an AFL (or 'solo') like the monitor sends do. Another way of checking is to max a channel in the aux and see if you can make the 'peak' light flash.

The other possibility is that the aux output isn't line level, and therefore the signal simply isn't strong enough to drive the amp in question. Which amp is it by the way?
 
#60
Jimbob Jones said:
Good question.

First, double check the obvious things; damaged cable, correct output, aux master up?

Other than that it could be a few things:

Would it be worth trying to plug the aux send into another amp, just to see if you can get an output of some description? It could be that the aux itself isn't functioning porperly; it's a pity the aux send on that desk doesn't have an AFL (or 'solo') like the monitor sends do. Another way of checking is to max a channel in the aux and see if you can make the 'peak' light flash.

The other possibility is that the aux output isn't line level, and therefore the signal simply isn't strong enough to drive the amp in question. Which amp is it by the way?
Click to expand...


The amp is a Crown XLS402. I eliminated the cable being the culprit by using the same cable for the line out. I tried maxing out the aux on a channel, as well as the aux master and could get nary a light on the signal strength indicator of the Crown. Moved to the line out and got plenty of signal. Frankly, I'm a bit puzzled but I do suspect it has to do with the signal strength (or lack thereof) of the aux out.
 

Latest posts

Top Bottom
Back