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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Johnny Diaz on July 09, 2011, 06:18:09 pm

Title: PEQ or GEQ
Post by: Johnny Diaz on July 09, 2011, 06:18:09 pm
Which one do you use and for what?  Does one sound better than the other?
Title: Re: PEQ or GEQ
Post by: Taylor Phillips on July 09, 2011, 06:44:29 pm
Which one do you use and for what?  Does one sound better than the other?
They're used for the same thing, and a good GEQ won't sound any better or worse that a good PEQ or vice versa.  The difference is purely functional.  With a graphic EQ, you have a number of sliders centered around a certain frequency with a fixed bandwidth, with parametric, you have a few filters that you can adjust not only the gain, but the centered frequency and bandwidth.  The most common graphic EQs are 31-band and I think the most common parametric is 5-band.  While the GEQ has more bands, the PEQ doesn't need as many because the bandwidth is adjustable.  I think most people on here prefer a PEQ, but because of functionality, not sonic quality.
Title: Re: PEQ or GEQ
Post by: Bob Leonard on July 09, 2011, 07:25:14 pm
As usual, that depends. I have in the past owned a few very well made and expensive PEQs, and own a number of decent GEQs, mostly DBX 2231 series. The best PEQ I have owned was a Rane PEQ55, no longer manufactured. Each of these units has / had a specific job to handle, all based on my needs.

So having said that it's best if you understand the simplistic version of what each type unit can accomplished if used properly.

PEQs are a wondeful tool if used properly and come in a variety of sizes depending on how much money you're willing to spend. PEQs are usually 3 band minimum, the better PEQs being 5 band or more in some cases. Each band should allow you to specify a center frequency, the amount of Q (band width), gain, and slope.

In the example if I were to compare a PEQ to a guitar amplifier with treble, middle and bass control I am in effect using a semi PEQ as the slope and center frequencies are set. If I compare this to a GOOD channel strip then I have control over input gain, high frequency, mid, mid low, and bass frequencies, but should also have the ability to vary the center frequency for those controls as well. On my board, an APB Pro rack house, I also have an adjustable high pass filter as part of the channel strip. All of this obviously gives me enough control of the channel to not warrant the use of an additional PEQ. The APB channel strips are good enough that at this time adding an EQ to the strip would probably hurt more than help.

My system is a dual system with seperate output and signal chain for vocal and backline. So, being that the program material for each will differ significantly, each signal chain has a GEQ in line with the master outputs, but before the DSPs. These GEQs are used to tweek the system very gently IF needed. They are almost flat and are set to taste. When I say set to "taste" I'm saying they are set to enhance the quality of the sound for the overall system and are the last EQ set once the signal chain is set to unity gain and the speakers are set flat. Keep in mind that these EQs are almost NEVER touched. Once set to taste there are few instances where you should need to make any major adjustments unless you find you have no taste at all, and I've seen plenty of that.

The last device in the signal chain before the amplifiers and speakers will of course be the DSP. In my case I recently moved to a DBX 480 which controls 2 inputs for backline, one input for mono vocals, one input for one pair of monitors. Additionally I carry a DBX 260 for use with additional monitors or for use as a backup in the event the 480 should ever fail. The real point here is that each of these DSPs has quality PEQs for every channel. I am not a fan of EQ after the crossover, however, the driveracks allow for that option and I set a very gentle bump in gain around 50hz for my subs after the crossover for the backline only. PEQ with a wide slope used prior to the crossover and set to the correct frequency can actually be used to controll the overall brightness and clarity of the total system output. In the 480 this is actually a selection under the GEQ called Boom and Zizz.

Either EQ can be used to do the job. A PEQ can be used to notch frequencies if the slop is set steep enough, however IMO the GEQ is a better animal for this use. Want control over a wide range with gradual effect then a PEQ may be the best animal. Once again it depends, and only the operator can say for sure which is best for which job. So, once again, it depends, the reason I provided the examples above. Maybe one of those examples will apply, but if not there are thousands more.
Title: Re: PEQ or GEQ
Post by: Bob Leonard on July 09, 2011, 07:34:43 pm
I failed to answer the second part of your question, which EQ sounds better. Any EQ will sound only as good as the EQ itself. Buy a cheap EQ and the entire signal chain pays the price. Use the EQ improperly and the entire signal chain pays the price. Don't cheap out on your EQs. DBX is a safe bet and analog EQs are still as good as any digital EQ IMO. Stay away from the cheaply made and low cost EQs from Behringer, Alesis, etc. and you'll be happy you did.
Title: Re: PEQ or GEQ
Post by: g'bye, Dick Rees on July 09, 2011, 08:45:30 pm
Which one do you use

I use both.

Quote
and for what?

Both can be used in various ways.  Generally speaking:

1.  Tuning your system to the room/environment.  This is a somewhat misleading statement in that the basic "tuning" of the system should be done by proper speaker deployment and DSP.  Beyond that you can use either EQ to help

2.  Compensate for room resonance and "hot" frequencies

3.  Make overall tonal adjustments to your mix.

The graphic EQ will have more and wider filters and I use it for general tone shaping of the mix.

The parametric EQ will have fewer filters but all will be able to sweep from the lowest to the highest frequencies and will have variable filter width.  I use these for "surgically" cutting trouble frequencies, using the narrower, more specific filters to remove the troublesome frequencies without putting gaping holes in the overall sound spectrum.

Either a graphic or a parametric can be inserted on a channel or group as well as being used for the whole mix.  The "single mic" bluegrass setup is made most workable by inserting one or the other of these devices on the required channel for greater and more flexible control.

Quote
Does one sound better than the other?

If the device itself has a "sound" it should be replaced by one which passes signal without coloring it.

I'm not sure what you mean by the "sound" as these devices boost or cut frequencies within the 20-20Khz spectrum and will by definition change the sound.  How cleanly and effectively they do this will, I suppose, contribute to what one might call their "sound".

I agree with Bob that the DBX 2231 is a nice, workable, affordable graphic.  I still use these, but prefer my Klark-Teknik graphics and parametrics.    I also use the Sabine GraphiQ units.  These are digital and are best deployed with computer control.  I use a laptop to run 6 or 8 channels of GraphiQ.  These units have both graphic and parametric sections.

 

Title: Re: PEQ or GEQ
Post by: Patrick Tracy on July 09, 2011, 11:07:13 pm
Which one do you use and for what?  Does one sound better than the other?

I use both. Parametric eqs are more precise. Graphic eqs are easier to use in the heat of battle. If I am setting up a speaker system at the shop I'll spend the time and get the parametric settings right. At the gig I just want to grab for sliders on a graphic.
Title: Re: PEQ or GEQ
Post by: John Roberts {JR} on July 10, 2011, 10:05:48 am
Which one do you use and for what?  Does one sound better than the other?

GEQ are more popular because they are easier to use, but the fixed bandwidth means boost/cut adjustments may affect frequencies you don't want to involve. So in principle PEQ should sound better, when properly used, but they are harder to use properly.

Which to use where, generally depends on time available for adjustment, and your comfort level with complexity.

JR
Title: Re: PEQ or GEQ
Post by: Paul Dershem on July 10, 2011, 03:00:45 pm
<SNIP> I am not a fan of EQ after the crossover<SNIP>

Why not?
Title: Re: PEQ or GEQ
Post by: Jordan Wolf on July 10, 2011, 07:25:45 pm
Which one do you use and for what?  Does one sound better than the other?
For run-and-gun audio, you can't beat GEQs.  If you've got a battle of the bands with 12 bands in the next hour, you NEED that type of functionality.  PEQs are great, but you need time to set them precisely.  For corporate audio, they are indispensible - especially when you have lavs or goosnecks.

I prefer to use both types for the reasons that they shine separately - GEQs are great for general tone-shaping and PEQs let you focus in on frequencies that are particularly annoying.  Also, the different types of EQ shapes in GEQs allow for more creativity.  Check out these Rane articles for some good info:
Perfect-Q Technology (http://www.rane.com/note154.html)
Constant-Q Technology (http://www.rane.com/note101.html)

If something sounds bad through any quality EQ, the reason is most certainly operator error on one end or the other of the signal chain.
Title: Re: PEQ or GEQ
Post by: Geoff Doane on July 10, 2011, 08:03:15 pm
PEQs are usually 3 band minimum, the better PEQs being 5 band or more in some cases. Each band should allow you to specify a center frequency, the amount of Q (band width), gain, and slope.


OK Bob, you got me there  ???.  The PEQs I've owned and used had frequency, Q, and gain, but "slope"?  Did you you mean "peaking/shelving" on the upper and lower bands perhaps?  Digital PEQs will sometimes give you a choice of peaking/shelving/HPF.  In the case of a HPF (or LPF) a slope of x dB/8ve might also be selectable, although I have yet to see it.

GTD
Title: Re: PEQ or GEQ
Post by: John Roberts {JR} on July 10, 2011, 08:14:08 pm
PEQs are usually 3 band minimum, the better PEQs being 5 band or more in some cases. Each band should allow you to specify a center frequency, the amount of Q (band width), gain, and slope.


OK Bob, you got me there  ???.  The PEQs I've owned and used had frequency, Q, and gain, but "slope"?  Did you you mean "peaking/shelving" on the upper and lower bands perhaps?  Digital PEQs will sometimes give you a choice of peaking/shelving/HPF.  In the case of a HPF (or LPF) a slope of x dB/8ve might also be selectable, although I have yet to see it.

GTD

Oh that's a PEC for peculiar EQ...  :o

JR

PS: I did a console back in the '70s with 4 band PEQ with switchable peaking/shelving on high and low bands.. that was an odd duck with with variable Q on the shelfs...It probably makes sense to disable the Q on the shelving sections.  I didn't have enough switch poles.