EQ Horse Hockey?

[Jack N]

I hope I posted this in the right forum because it has both an opinion and a question. So excuse me while I get up on my soap box. There. Ok, I’m ready now. I belong to a few different home theater forums and I’ve read quite a few comments about how “EQ”s shouldn’t be used. Frankly, I just don’t understand that philosophy. Isn’t the whole idea behind home theater to get the sound and picture the way you like it? Even though I’m not an audiologist or a doctor, I can guarantee that everyone’s ability to hear any given frequency is going to be different, and we haven’t gotten into personal tastes yet. Between those two, the thousands of audible frequencies, and any given driver’s or amplifier’s idiosyncrasies, the possible number of combinations are staggering. How anyone can say that any given curve is the only right one, is beyond me. Or that if you have to “lower” yourself to using EQ’s, use a parametric instead of a graphic. What’s up with that? Anybody that’s serious about home audio is going to realize that there’s pro’s & con’s to each type. Personally, I think it’s about time that this snobbish horse hockey attitude towards EQ’s get tossed in the toilet where it belongs. I wouldn’t have a system without EQ’s.

There, now that I got that off my chest – excuse me while I get down off my soap box. Ok. Now I’ve got a question. Not too long ago, someone made a comment that graphic EQ’s limit dynamic range/headroom because you’re working within the confines of the +/- db range of your particular EQ. After thinking about that for awhile, I’m thinking this is another piece of horse hockey. If that statement were true, then how does the EQ know when you want to turn the volume up or down? Wouldn’t it want to keep the volume within the +/- db range the unit? And why only graphic EQ’s? A parametric performs the same function as a graphic, it just adds the ability to alter center frequencies and octives. To me, it doesn’t sound sensible. Is there anyone out there who can factually verify this condition one way or the other?

 

[m1abrams]

I think the biggest issue with EQs is that they add another potential to degrade the sound. The fewer paths the better. Which is a good idea. And alot of people use EQs for purpose beyond what you have stated which is bad. Also some people have actually built speakers that REQUIRE an EQ to function correctly which is bad.

However to balance a room using an EQ is IMHO quite ok. Many people can not build that perfect room, our wives wont let us.

 

[Rob Babcock]

I think that for any application except subwoofer use, analog EQ should be avoided whenever possible. When you can X-over the signal & send just the low-pass to an EQ to feed the sub(s), there's no downside, only advantages.

This doesn't apply, however, to digital EQ. While manipulation of an analog signal usually leadly to degradation, information in digital form is quite robust, and can be processed & manipulated substantially without any degradation whatsoever. Provided you use a good "computer" (lack of a better word) to perform the maniputations, you can acheive remarkable things in the frequency & time domain with DSP.

Parametric EQ is by far the superior option, mostly because having to make boosts and cuts only where your graphic EQ fixes the center to be is like being forced to wear shoes given only even sizes to pick from(eg size 6,8,10,12, etc). One size doesn't fit all, and the ability to pick not only the Q but the bandwidth is a potent advantage. There's nothing a graphic EQ can do that can't be done with parametric EQ, but you can't credibly claim that the reverse is true.

 

[Jack N]

“alot of people use EQs for purpose beyond what you have stated which is bad. Also some people have actually built speakers that REQUIRE an EQ to function correctly”

Good points. I guess I should have clarified that there have been quite blatant misuses of this type of equipment which has given EQ’s the “black mark” so to speak.

“Many people can not build that perfect room, our wives wont let us.”

Although it sounds funny, unfortunately it’s true.

“This doesn't apply, however, to digital EQ. While manipulation of an analog signal usually leadly to degradation, information in digital form is quite robust, and can be processed & manipulated substantially without any degradation whatsoever.“

For what it’s worth, from my own personal experience, any good quality analog EQ doesn’t audibly degrade the signal. I’m not familiar with “digital” EQ’s. The only one that I personally have seen that was digital was one that the now defunct SAE made back in the late 80’s, which sold for about $650. A very nice unit that still pulls in big resale prices even though they’re a good 15 years old now. Are the ones that you’re talking about made for professionals? Can you expand on this, and list some manufacturers, websites, or links? Thanks.

“Parametric EQ is by far the superior option”

I’ll agree with that to a certain extent. If we’re talking about only having to manipulate a single area of the frequency range, a parametric is clearly the way to go. No doubt about it. However if we’re talking about having to manipulate more than one area, multiple band parametrics can carry a pretty hefty price tag. Obviously, if we had a parametric that could handle as many areas as we needed, that would be the ideal way to go. However many of us need to keep tabs on our pocket books as well. And let’s face it, when it comes to using any EQ the way it was meant to be used, we’re not talking about making wholesale changes to the audible spectrum. Usually we’re only going to be tweaking a couple of db here and there as the huge majority of related audio equipment is made to hold the audio band flat to within +/- 3 db at most. For small changes like that, a graphic EQ is often quite capable in carrying out this task, especially if you have an idea of what frequencies you need to deal with. And if we’re talking about using multiple EQ’s, as is getting to be more and more likely as surround continues to garner more followers, the difference in price can add up quickly. Yes, there are multiple channel EQ’s, but they’re not exactly cheap either. So, I do agree that parametrics are better for precision tailoring to any given system. However for those of us who can’t afford them, by carefully analyzing of what frequencies need to be altered, one can save money by using a graphic.

 

[Rob Babcock]

I remember the old SAE models you mention- despite the wording of the ads, they weren't really digital in the sense we mean today.

I'm not an expert on DSP (or anything else! ) but some of the digital EQs: Rives (full function EQ & room correction), Z-Systems (potent & expensive models), Tact (make Digital amps & room correction, Perpetual Technology (room/speaker correction they calls "SOCS") & Behringer (mostly known for Pro stuff, there are some digital whiz's out there modding the digital Behringers for audiophool use- the claims I've heard have really got my attention).

You're right of course about the price. Mulitiband parametric EQ can be spendy, although the modded Behringers, if they live up to the hype, could really kick the door wide open.

The beauty of parametric EQ is that with it, you can do anything you would do with a graphic EQ. Just more precisely. It would be a remarkable coincidence if the width of the peak (for example) that you wanted to cut was just precisely the width of the band controlled by the slider of a graphic eq. With parametric EQ, you could set the width to boost or cut by a couple whole octaves if you wanted to, or as narrow as a 1/16 of an octave, or more.

I don't want to make too sweeping a generalization as to how transparent analog EQ is. I'll just point out that many people *claim* to be able to hear differences in wire, power conditioning, green pens on the CD, tennis balls under the CD player, phase of the moon, etc etc. Speaker designer Brian Cheney once said that in the sound of speakers "everything makes a difference." Based upon that type of philosophy, I'd advocate keeping the analog portion of the signal as pristine as possible.

No, scratch that. I'd really like to see there not be any analog portion! All digital, all the way to the speaker. That's gonna be The Next Big Thing.

 

[Jack N]

Doing a quick search on the equipment that you mentioned – looks like really nice stuff. Unfortunately I can’t afford that kind of money.

“many people *claim* to be able to hear differences in…” LOL ! I know what you mean. I think they’ve been reading too many reviews. I wonder if they sleep with their audio magazines?

“I'd really like to see there not be any analog portion! All digital, all the way to the speaker. That's gonna be The Next Big Thing.”

I think you’re right. Although I think the digital speaker thing will be a ways off.

Anybody out there have any input on my question about EQ’s limiting dynamic range?

 

[Rob Babcock]

The Behringer isn't very expensive, under $450 or so. Even unmodded, it might give you a taste of what's possible. The other ones are awfully steep, although the prices will eventually fall as the line between audio/video gear and computers blurs even further.

As far as limiting dynamic range, I think that idea stems from the assumption that EQ users are going to make the familiar "smiley face" curve: this probably began with the old 70's & 80's rack systems that featured graphic EQs & speaker w/paper woofs & tweets. Pretty much everyone tried to boost the lows to get some decent bass and boost the treble to try to coax something resembling highs out of the 2" paper tweeter! Of course, anytime you use EQ to boost instead of cut, you're cutting into the dynamic range. In almost all cases, boosting is ineffective and risky. Very modest boosts may work, but much more than a dB or two and you're just pouring power into a hole.

 

[Jack N]

What is “unmodded”?

“Of course, anytime you use EQ to boost instead of cut, you're cutting into the dynamic range.”

Can you explain why/how it would be cutting into the dynamic range? And why only boost? Isn’t dynamic range the difference between loud & soft?