EQ'ing your room

[popotoys]

I have read that since most of the audio information is in the midrange of the spectrum, eq'ing your system flat would result in having to much volume in the midrange. Are any of the professional calibrator's taking this into consideration when setting up a system and actually setting the midrange area lower or calibrating with this excess of information in mind? If so, how would you go about this or do you just set it lower by a set db level?

I guess I am asking what a professional calibrator takes into consideration when doing this or do they just rely on spl?

Also, what frequency range is actually considered to be in the midrange? thx

 

[jostenmeat]

I have read that since most of the audio information is in the midrange of the spectrum, eq'ing your system flat would result in having to much volume in the midrange. Are any of the professional calibrator's taking this into consideration when setting up a system and actually setting the midrange area lower or calibrating with this excess of information in mind? If so, how would you go about this or do you just set it lower by a set db level?

Where did you read this? That doesn't make any sense at all to me.

Also, what frequency range is actually considered to be in the midrange? thx

I don't know what it is really considered to be, but I myself will offer 100hz to 2000hz (+/- an octave). I can sing below 100hz, and I pretty much have piss poor "extension" for a bass.

 

[Savant]

popo,

It appears you're describing the idea of a "loudness curve." There are "loudness" buttons or "effects" on some processors, receivers etc., which boost the low and high frequency ranges to compensate for decreased human hearing sensitivity in those ranges. Some people prefer their sound that way. Others do not. The issue is highly subjective.

To answer your question, I would first opine that the "professional calibrator" should not be equalizing a system at all, unless it is to address some very specific problem(s). If the room has been designed well and the loudspeakers are decent, minimal adjustments to the system's frequency response should be required.

If there is some equalizing going on, a real pro won't be shooting for "flat." Systems typically sound best with some boost in the low end. [Accomplished with level adjustments to the sub(s) relative to the other channels, as opposed to using EQ.] If any adjustments to the high end are made, they are usually uniform boosts or cuts above a certain frequency. In my experience, the need for such an adjustment to the high end is rare.

Having said all that, the ears are the best and final judge. If it's flat (equalized or otherwise) and it doesn't sound right, it isn't. Real pros will use a combination of their ears and other (inferior) analyzers to maximize sound quality from a system.

 

[highfigh]

popo,

It appears you're describing the idea of a "loudness curve." There are "loudness" buttons or "effects" on some processors, receivers etc., which boost the low and high frequency ranges to compensate for decreased human hearing sensitivity in those ranges. Some people prefer their sound that way. Others do not. The issue is highly subjective.

To answer your question, I would first opine that the "professional calibrator" should not be equalizing a system at all, unless it is to address some very specific problem(s). If the room has been designed well and the loudspeakers are decent, minimal adjustments to the system's frequency response should be required.

If there is some equalizing going on, a real pro won't be shooting for "flat." Systems typically sound best with some boost in the low end. [Accomplished with level adjustments to the sub(s) relative to the other channels, as opposed to using EQ.] If any adjustments to the high end are made, they are usually uniform boosts or cuts above a certain frequency. In my experience, the need for such an adjustment to the high end is rare.

Having said all that, the ears are the best and final judge. If it's flat (equalized or otherwise) and it doesn't sound right, it isn't.

An acoustical designer or consultant will definitely go for a flat response- flat is the reference and equalizers are made for equalizing the system/room interface's problems that exist because eliminating them may not be economically feasible. An equalizer is for getting a flat response and tone controls are for making it sound the way the listener wants. If the controls don't have the latitude, more decisions are needed.

Far too many people think their ears should be relied upon for final EQ settings, especially after years of high SPL exposure. Experience makes it possible for them to get good results in spite of the threshold shift and hearing damage that results from this kind of work. It doesn't take much time to shift the hearing threshold and trying to EQ a system by ear when the ears are fatigued is a waste of time.

"Real pros will use a combination of their ears and other (inferior) analyzers to maximize sound quality from a system."

No, "real" pros will use the good stuff. The hacks will use the inferior ones and struggle to get the sound right. The space's use determines what response is needed. If it's always high SPL sound, it needs one contour and room treatments vs low SPL use.

You'd be surprised by how good a group of cheap speakers sound when they have been equalized well.

 

[Savant]

highfigh,

Some good points there. I hope you will pardon me for the rather lengthy responses below:

An acoustical designer or consultant will definitely go for a flat response-...

Yes and no. Unfortunately, it's not a realistic goal in most HTs, EQ or no EQ. Even when the squiggly line or bars show ruler-flat, that is no indication that the room/system is actually flat. And, as I mentioned, most listeners prefer some extra low end. At least, that's what I have found. And I'm not talking about 20 dB of boost or something crazy. I'm just talking about a little more than "flat." Of course, there is a huge part of this that is subjective. Toole has shown that, contrary to myth, most people do actually prefer "flat." However, that's all based on data from controlled listening tests in controlled spaces. When people actually get the loudspeakers into their relatively imperfect rooms, I feel their preferences are wont to change. But that's just my opinion, based on my own experiences.

...flat is the reference and equalizers are made for equalizing the system/room interface's problems that exist because eliminating them may not be economically feasible.

Flat is the reference, agreed. What I'm saying is it is often not the preference. And equalizing is a valuable tool below a certain frequency, typically the subwoofer range. But equalizing system/room interface problems at mid and high frequencies is simply not possible. I realize that's probably not what you're getting at, but I wanted to clarify for others.

An equalizer is for getting a flat response and tone controls are for making it sound the way the listener wants.

I think we're talking about the same thing. An equalizer is certainly useful if there is some anomaly present...and present throughout the room, or at the very least over the entire listening area. Another criterion would be that the problem is actually audible. Many things that appear as "problems" on a squiggly line or bar graph are not really anything to be concerned about due to the bandwidth of the ear. I've experienced many "analysis paralysis" situations where an "expert" was obsessed about a "flat" line or bar graph and never stopped to actually listen to the system.

But I digress... In general, trying to correct an entire room/system interface with EQ is fallacious. An exercise in futility, IMH(and professional)O.

Oh, and as for tone controls, if the system is set up well, the user need never touch anything except the volume control.

Far too many people think their ears should be relied upon for final EQ settings, especially after years of high SPL exposure. Experience makes it possible for them to get good results in spite of the threshold shift and hearing damage that results from this kind of work. It doesn't take much time to shift the hearing threshold and trying to EQ a system by ear when the ears are fatigued is a waste of time.

First, good consultants often have (should have, IMO) somewhat regular (every 2-5 years at least; annually if they're over 40, or regularly exposed to high sound levels) hearing tests (audiograms) conducted by an audiologist. If they know what their hearing response is, they know what they're hearing.

Second, if the sound levels are so high during system setup that ear fatigue is setting in, the sound levels are probably too high. There is no reason to have to experience overall, average sound levels over 75 dBA in order to properly set up an HT system. Average sound levels at and below 75 dBA should not cause ear fatigue problems (but all people are different). Additionally, ear fatigue can be avoided by taking frequent breaks - I would suggest 10-15 minutes ever 60-90 minutes, or thereabouts.

Thirdly, if a client or colleague insists on working with average sound levels above 75-80 dBA, it's time to get out the earplugs. And I'm not talking about the $0.25 yellow foam jobs. Custom earplugs with a linear response are available and are a worthwhile investment for audio professionals. Many models, such as those from Etymotic can be provided with different inserts for different levels of protection. The 9 or 15 dB inserts can often provide enough reduction when the overzealous client/colleague wants it cranked up, and yet hearing remains linear (more accurately, all frequencies are attenuated evenly instead of the HF muffling that comes with foam plugs) and informed decisions can still be made.

Finally, I would honestly have to question a consultant's relative worth if they've been hired to set a system up and yet have to rely completely upon squiggly lines or bar graphs because their hearing is shot. A responsible consultant with known hearing problems (which is redundant, btw; a person cannot not know they have a hearing problem) should delegate system setup to someone on the staff with better "tools."

"Real pros will use a combination of their ears and other (inferior) analyzers to maximize sound quality from a system."

No, "real" pros will use the good stuff. The hacks will use the inferior ones and struggle to get the sound right. The space's use determines what response is needed. If it's always high SPL sound, it needs one contour and room treatments vs low SPL use.

My reference to inferiority was with regards to ears (the best analyzer) versus electronic analyzers in general. They are all inferior to ears. (But we do need both, of course.)

You'd be surprised by how good a group of cheap speakers sound when they have been equalized well.

I'm guessing not as good as the same cheap loudspeakers sound when they are used in a well-treated room and not equalized at all.

 

[popotoys]

some good responses...thx

For jostenmet, I think that I read this a few years back in an accredited audio mag. To me, if there is more information in a certain range, then the percieved spl may be higher, but that may not be the case. I do like my system flat with the sub boosted slightly... mayb 2db. I was interested to see what the "pros" would say and I think we have had a few good responses. thx

 

[highfigh]

"Yes and no. Unfortunately, it's not a realistic goal in most HTs, EQ or no EQ. Even when the squiggly line or bars show ruler-flat, that is no indication that the room/system is actually flat. And, as I mentioned, most listeners prefer some extra low end. At least, that's what I have found. And I'm not talking about 20 dB of boost or something crazy. I'm just talking about a little more than "flat." Of course, there is a huge part of this that is subjective. Toole has shown that, contrary to myth, most people do actually prefer "flat." However, that's all based on data from controlled listening tests in controlled spaces. When people actually get the loudspeakers into their relatively imperfect rooms, I feel their preferences are wont to change. But that's just my opinion, based on my own experiences."

Absolutely flat is only possible in an anechoic chamber with speakers that are capable of producing that. The goal is to have an averaged flat response with a minimum of peaks/dips and a tolerance of +/- xdB. As I said, an equalizer is made to equalize the system/room interface but many use it as a way to add/subtract frequencies to tailor the sound to their preferences. There's nothing "wrong" with this, but it's not what equalizers are really made for. If you have access to an RTA, you'll be surprised by how many recordings peak at a flat average response when the signal goes from the source to the RTA. With additional processing (like aural exciters, compression and EQ on each track), it may sound louder/dynamic or have some other characteristics.

"Flat is the reference, agreed. What I'm saying is it is often not the preference. And equalizing is a valuable tool below a certain frequency, typically the subwoofer range. But equalizing system/room interface problems at mid and high frequencies is simply not possible. I realize that's probably not what you're getting at, but I wanted to clarify for others."

If EQ at only low frequencies was best, they wouldn't make 1/3 and 1/6 octave graphic or parametric equalizers that go to the top end of the spectrum. EQ in the mid range is incredibly important and a small amount there is most audible because human hearing is most sensitive between about 300Hz and 6KHz at low SPL and the differences in sensitivity change as the SPL changes. This is also subject to the listener, but on average, the charts in the link are well established and do a great job in explaining why most people will set a graphic equalizer to a Happy Face.

Equal Loudness curves:
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/eqloud.html

Acoustical treatment is something most people don't want to do and aren't usually willing to get into. The majority of equalizers purchased by consumers are used in an attempt to tame room reflections in untreated rooms. This only works to a certain point because a room with multiple reflections is hard to equalize and get a good result. If the first reflections are limited before equalization, less boost/cut is needed. Another problem with drastic boost/cut is that phase shift increases. In a halfway well treated room, a little EQ goes a long way.

"I think we're talking about the same thing. An equalizer is certainly useful if there is some anomaly present...and present throughout the room, or at the very least over the entire listening area. Another criterion would be that the problem is actually audible. Many things that appear as "problems" on a squiggly line or bar graph are not really anything to be concerned about due to the bandwidth of the ear. I've experienced many "analysis paralysis" situations where an "expert" was obsessed about a "flat" line or bar graph and never stopped to actually listen to the system."

There's not a single room that doesn't have some kind of acoustical problem, if it wasn't specifically designed not to. Even in a treated room, equalization is needed to achieve the desired response. I have heard far more systems that sounded bad because of the way they were EQ'd than because of the equipment and the paralysis you mentioned is one reason they couldn't bring themselves to hit the bypass button. Ultimately, listening to it is the final arbiter but starting at flat and using the tone controls is a really easy way to get excellent sound because the people who design receivers also know where human hearing needs a bit of help, so they make the controls work where we need them.

"But I digress... In general, trying to correct an entire room/system interface with EQ is fallacious. An exercise in futility, IMH(and professional)O."

It can be like Con Quixote, that's for sure. Better to have a smooth response, maybe with a little downward tilt from bass to treble but the best way is to analyze the ambient noise and work around that in order to allow the sound to be as ever as possible without masking by the background noise.

"Oh, and as for tone controls, if the system is set up well, the user need never touch anything except the volume control. "

I agree completely.

"First, good consultants often have (should have, IMO) somewhat regular (every 2-5 years at least; annually if they're over 40, or regularly exposed to high sound levels) hearing tests (audiograms) conducted by an audiologist. If they know what their hearing response is, they know what they're hearing."

Exactly. Personally, I think anyone who has audio as a hobby/obsession should be tested regularly, too. Maybe it would explain their/our incessant quest for better sound.

"Second, if the sound levels are so high during system setup that ear fatigue is setting in, the sound levels are probably too high. There is no reason to have to experience overall, average sound levels over 75 dBA in order to properly set up an HT system. Average sound levels at and below 75 dBA should not cause ear fatigue problems (but all people are different). Additionally, ear fatigue can be avoided by taking frequent breaks - I would suggest 10-15 minutes ever 60-90 minutes, or thereabouts."

There's no reason for the person doing the initial system setup to hear the test tones and pink noise. I wear ear plugs during this phase and take them out when I want to find out if it sounds good.

"Thirdly, if a client or colleague insists on working with average sound levels above 75-80 dBA, it's time to get out the earplugs. And I'm not talking about the $0.25 yellow foam jobs. Custom earplugs with a linear response are available and are a worthwhile investment for audio professionals. Many models, such as those from Etymotic can be provided with different inserts for different levels of protection. The 9 or 15 dB inserts can often provide enough reduction when the overzealous client/colleague wants it cranked up, and yet hearing remains linear (more accurately, all frequencies are attenuated evenly instead of the HF muffling that comes with foam plugs) and informed decisions can still be made.

Finally, I would honestly have to question a consultant's relative worth if they've been hired to set a system up and yet have to rely completely upon squiggly lines or bar graphs because their hearing is shot. A responsible consultant with known hearing problems (which is redundant, btw; a person cannot not know they have a hearing problem) should delegate system setup to someone on the staff with better "tools.""

Cheap plugs are great for removing the upper frequencies in loud situations but not for listening. The Stymotic are great for people, like live sound, studio people and anyone else who actually needs to hear the quality of sound but the level can't/won't be reduced. What's the saying? I think it's "Specs are for techs", or something like that. They make it possible to get a lot closer in a short time than trying to EQ by ear and the fine tuning can be done after that point. Fatigue during the rough EQ stage happens really fast, especially if there's a specific problem. I can't think of many sound guys who don't have a major threshold shift or major damage after years of high SPL exposure and when I have talked to them, many just claim that they "just use their ears", which is often the reason I ask in the first place- the sound it so bad.

"My reference to inferiority was with regards to ears (the best analyzer) versus electronic analyzers in general. They are all inferior to ears. (But we do need both, of course.)."

I think a lot of problems in equalization by ear come from people not knowing what information is in each band.

Holy Hand Grenades! What a long post!

 

[highfigh]

"I'm guessing not as good as the same cheap loudspeakers sound when they are used in a well-treated room and not equalized at all."

The cheap speakers I referred to were Atlas 10" ceiling speakers in plywood boxes attached to the 20' high ceiling in some LDS facilities I did work in. The engineer had spec'd a White PC based parametric/graphic equalizer because the LDS higher-ups don't want anyone messing with the controls. They also specify the goals for the system anyone speaking can be heard in all listening positions equally well and sound as natural as if they weren't using a PA. These speakers are nothing special but they do work well in the range where human hearing is best. It sounded very good, unless someone was swallowing the mic.

One sound guy I know, who has had a long career in live and studio work, gets the system set up, does the sound check and does minimal tweaking, usually because the size of the crowd has changed. His live sound is some of the best I've heard and his recordings are just as good.

Another of the sound guys I talked to (briefly) told me that he used his ears for the sound and every time I have been to a gig he worked, he had to constantly fiddle with the controls. At the end of the night, he always looks like he was rode hard and put away wet.

I have heard gigs mixed by both at the same club and there's a night & day difference in quality, with the same house system.

I saw some graffiti one night at a gig done by the second guy- it read "E=MC² ± 3dB" and he said, "I have no idea what that means".

 

[Savant]

highfigh,

All good points. Really.

I think our approaches differ somewhat, but in the bigger picture our goals are the same.

The only other thing I'd really wish to make clear is that I am not saying that ears replace electronic sound analyzers and other tools. People mixing live shows by ear are the main reason why I don't like the sound at most live shows. And exactly for the reasons you cite. Whether mixing a live show or "calibrating" an HT, I feel it is necessary to use all the tools, including the one's on either side of our heads (and the skin-and-bone-encased analyzer in between). It is my belief that the ear/brain mechanism is superior in all ways to any electronic analyzer or tool. That doesn't mean I discard or disregard "the gear" completely. Quite the contrary; I'm always trying to find better tools to enhance the ones with which I was born.

 

[jostenmeat]

some good responses...thx

For jostenmet, I think that I read this a few years back in an accredited audio mag. To me, if there is more information in a certain range, then the percieved spl may be higher, but that may not be the case. I do like my system flat with the sub boosted slightly... mayb 2db. I was interested to see what the "pros" would say and I think we have had a few good responses. thx

Thanks for the thread.

My reference to inferiority was with regards to ears (the best analyzer) versus electronic analyzers in general. They are all inferior to ears. (But we do need both, of course.)

This is very refreshing to hear. Thanks.

Hey highfigh, could you please use the Quote tags when replying in blocks? (I tried to read anyways, as I'm very interested in your response; and so I look for the inclusion, or lack thereof, the " at the beginning of each paragraph, but even then it might be two consecutive paragraphs as typed by Savant).

Anyhoo, I'd appreciate it, and it's only because i am interested. (lots of times I don't read straight thru; I have to jump back up when I'm not sure about what is referenced or any specific at hand).

 

[highfigh]

Thanks for the thread.



This is very refreshing to hear. Thanks.

Hey highfigh, could you please use the Quote tags when replying in blocks? (I tried to read anyways, as I'm very interested in your response; and so I look for the inclusion, or lack thereof, the " at the beginning of each paragraph, but even then it might be two consecutive paragraphs as typed by Savant).

Anyhoo, I'd appreciate it, and it's only because i am interested. (lots of times I don't read straight thru; I have to jump back up when I'm not sure about what is referenced or any specific at hand).

I used " " but I got carried away with that one and it all becomes a blur. If I ever do a post that long again, hit me in the forehead with a ball pein hammer. I should have used the quote button and just copy/pasted it.