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Author Topic: EQ for Monitors  (Read 7719 times)

Matthew Donadio

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EQ for Monitors
« on: March 30, 2011, 11:43:34 am »

Hi all,

I arrived to mix a service this week to a bad feedback problem in our band's monitors.  This wasn't happening before, so I suspect somebody changed something.

I tracked the problem down to a particular mic (the PZM on a piano) so I think I can fix the problem with better gain staging and monitor placement.

Anyway, we don't have an EQ in the monitor path, and this problem has me thinking that we should be considering one.  We have two monitor mixes coming off auxes from the board.  The actual monitors are rather small stand mount ones (probably 6") and not normal floor wedges.  Each one also has a passive attenuator for setting the volume.

I have two questions about EQs.

1.  Is a 31-band graphic EQ worth the extra cost for monitors?

2.  Is a unit w/ feedback detection worth the extra cost?

Based on our budget (this would be a non-budget item...), I am mainly considering the ART 355 and HQ231.  The 355 rather than the 341 is not really because of the number of bands, rather that it has the HP/LP so I can chop out the frequencies that the small montiors just can't reproduce.

Thanks for any thoughts.
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Mike Spitzer

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Re: EQ for Monitors
« Reply #1 on: March 30, 2011, 12:02:26 pm »

That's a tough one. I don't personally think that the 31-band is worth the extra cost. For floor wedges, it's rare that the tones have to be perfect for the musician. Many vocalists can be very picky, though.

That said, the ART 355 is actually a really good EQ for the price (I've been very happy with mine). It's quiet, responsive, and, like you said, has the high and low-pass filters. It could be a nice, cheap solution. For about half the price, you could get a dual 15-channel Peavey, but I don't care for them as much. May not matter on your monitors, though. If they're cheap enough, you won't be able to tell the difference.

As for feedback detection, I've found those are more worth it if you're moving from place to place, due to the extra cost. If you're always in the same room and your setup is always similar, you should be able to dial in on the feedback problems and fix them all at once. The feedback detection probably won't help you much after that. If you find that feedback is consistently a problem, it might be worth it to you.

I'll also add that although I generally prefer the ARTs over the Peaveys, I think the Peavey feedback detection is better.

-mS
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Matthias Heitzer

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Re: EQ for Monitors
« Reply #2 on: March 30, 2011, 02:16:03 pm »

That's a tough one. I don't personally think that the 31-band is worth the extra cost. For floor wedges, it's rare that the tones have to be perfect for the musician. Many vocalists can be very picky, though.

I've got an completely opposite opinion on this topic:
The notch should be as narrow as possible. A 1/3 octave EQ (30 or 31 band) is already quite broad, a parametric EQ with High Q is a lot better for fighting feedback.

Each filter of a 15-band EQ has a bandwith of 2/3 octaves, that's a lot. If you cut ~6dB somewhere in the vocal range, the singer can almost completly loose his pitch reference.

1/3 octave Eqs are roughly matched to the critical bandwith of the human hearing, this makes them easy to use.

15-band Eqs are a nice thing for home Hifi.

For feedback detection i use my ears, god gave me two of 'em.
after some time you'll know which fader tames that particular squeal

There is an easy way to set up parametric Eqs:
turn the channel up until the fedback starts then back it down by ~3dB
Then set the Q as high as possible (i.e. very small  bandwith) and give ~4db of boost.
Now sweep through the spectrum and once the feedback starts again, cut this frequency.
Then you can continue to increase the volume until the next feedback starts.....
... when you've reached the point where the feedback is not a single or small number of tones, you've found the limit of your monitorsetup.
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Buck Roberts

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Re: EQ for Monitors
« Reply #3 on: March 30, 2011, 05:14:35 pm »

The first thing - I would lose the PZM in the piano - get a decent small diaphragm condenser (or a pair). The things other folks said to you is true about EQ's so I won't repeat. You need to look at your monitor mixes themselves - try to reduce what you throw into them. Its amazing that worship team folks always want something "turned up" instead of down! If you'll go with a minimal approach to stage monitors - put in only what is necessary, you'll greatly eliminate feedback issues. Feedback eliminators are not worth it - I don't put the things in systems I build.
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g'bye, Dick Rees

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Re: EQ for Monitors
« Reply #4 on: March 30, 2011, 05:25:59 pm »

Feedback eliminators are not worth it -

Not as such.  However, once you get past the "feedback eliminator" terminology to the "automatic parametric equalizer" level of understanding you may well find that such units can in fact be utilized to gain a good bit of the desired system control.  Even the humble B********** units have their use if you understand how to use them as a parametric. 

If you think they are a magic box which will automatically solve your feedback problems the answer is no.  If you are open to applying their capabilities properly, then the answer can be yes.  So as with any other piece of equipment it is the ability of the user to apply the piece properly which will give acceptable results.  The prejudicial nature of the title "feedback eliminator" raises false hopes and expectations.  But it is the expectation which is at fault, not necessarily the piece itself.
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Brad Weber

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Re: EQ for Monitors
« Reply #5 on: March 30, 2011, 06:12:35 pm »

That's a tough one. I don't personally think that the 31-band is worth the extra cost. For floor wedges, it's rare that the tones have to be perfect for the musician. Many vocalists can be very picky, though
 
That said, the ART 355 is actually a really good EQ for the price (I've been very happy with mine). It's quiet, responsive, and, like you said, has the high and low-pass filters. It could be a nice, cheap solution. For about half the price, you could get a dual 15-channel Peavey, but I don't care for them as much. May not matter on your monitors, though. If they're cheap enough, you won't be able to tell the difference.
This seems to be missing that there are soemtimes multiple reasons for applying equalization and that while the subjectively desired response is one of them, another is to try to improve gain before feedback.  In the latter role EQ, and especially parametric EQ with adjustable bandwidth, center frequency and depth, can be very effective.

As for feedback detection, I've found those are more worth it if you're moving from place to place, due to the extra cost. If you're always in the same room and your setup is always similar, you should be able to dial in on the feedback problems and fix them all at once. The feedback detection probably won't help you much after that. If you find that feedback is consistently a problem, it might be worth it to you.
While aspects such as the phsyical relationships of the microphones to monitors and the house speakers are critical to feedback even much smaller factors such as a singer cupping a mic or wearing a hat with a brim can affect feedback.
 
Automatic feedback detection and elimination is quite useful in some cases, however it is generally much better to try to address the underlying issues if at all possible.  One challenge with such devices is that if you insert the device on an output then any equalization applied affects not just the offending source but every source.  If you insert it on an input then it affects only that source, which is good, but it affects everywhere that input is routed, for example any equalization applied to prevent feedback in the monitors would also be applied to the main output as well as to any recording or other sends.
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Matthew Donadio

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Re: EQ for Monitors
« Reply #6 on: March 30, 2011, 08:20:07 pm »

Thanks for the replies.

The main reason for asking about about a box with feedback detection is because of the different levels of skill that exist in the volunteer pool that runs sound.  We have some people who are very knowledgeable, and others who basically just know to mute/unmute channels.  I was thinking that with something like the Art HQ231, it would be pretty easy to tell someone "if the monitors feedback during the service, pull back the band that is lighting up on front, and then tell me so I can fix it afterwards". 

The particular situation was one mic open and one mic in the monitors, and happening a good 10 dB lower than the normal level I run the monitors at.  I know something was really wrong, but I didn't have enough time to fix it.  I am going to redo and ring out the system and get to the bottom of it.

The PZM.  Yeah, it isn't ideal, but we wouldn't be able to get someone to place an SDC in the proper place week to week.  Thankfully, the piano fills the room and this mic is mainly used for monitors and secondary outputs; it almost is never used in the mains.

Parametrics.  Are there any affordable boxes geared for live-sound?  I didn't see any on the Sweetwater site, but didn't check out Full Compass yet.  I have considered a used DriveRack PA, too, but I find that the live filters can be too aggressive and turn on too quickly, and the front panel interface can be slow for fixing something quickly.

Again, thanks.
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g'bye, Dick Rees

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Re: EQ for Monitors
« Reply #7 on: March 30, 2011, 08:50:52 pm »

Matthew.....

One very easy and effective way to mike up a grand piano is to simply put an SM57 in one of the holes in the lyre/frame of the instrument.  Depending on the size of the instrument it is usually the second or third hole from the hammers.  Most grands will have holes in the lyre.  Some do not.  It does require using a stand with the boom extending over and into the piano.  The mic should go right into the hole and about an inch to an inch and a half from the sound board.

The first time I saw this done I was quite skeptical but find it a very practical solution and very easy to implement.  Placement is quite easy and easily repeated by even the newest novice assistant.
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Brad Weber

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Re: EQ for Monitors
« Reply #8 on: March 31, 2011, 11:13:28 am »

The main reason for asking about about a box with feedback detection is because of the different levels of skill that exist in the volunteer pool that runs sound.  We have some people who are very knowledgeable, and others who basically just know to mute/unmute channels.  I was thinking that with something like the Art HQ231, it would be pretty easy to tell someone "if the monitors feedback during the service, pull back the band that is lighting up on front, and then tell me so I can fix it afterwards".
My mistake, you said automatic feedback detection and I assumed that was referring to equalizers with automatic feedback detection and elimination such as the Sabine Graphi-Q units.
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