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Auto Eq... The nuts and bolts of use
Ok, This assumes you understand the basics of Auto EQ, and you have read the other articles about Auto EQ. Now that your getting the idea about Auto EQ.. and it's use, lets recap..
Do the AutoEQ in close proximity (or the new indoor method)..this eliminates the majority of the reflections due to the pure preponderance of the signal coming directly from the speakers.. even 4' might not be too close...(especially when dealing with hung speakers and those darn 2X15\" 4' tall behemoths...
Do the Auto EQ with a FLAT -0- response curve to get as flat a response as possible...
Transfer the majority of what the GEQ does to the PEQ's available...(NOT the reverse, but exactly... as best you can.. start with the ones that have the largest cuts/boosts over the widest frequency range first, and work towards the ones that only effect a small frequency portion...
YES if you run another auto EQ pass and it does VERY LITTLE to the GEQ you have done VERY well! that is what you WANT!
Once you have that done, next save that to a preset as a FLAT system response... this is very useful for;
1.very live and reverberant spaces where any excess energy will excite the room and cause unstable sound reinforcement
2. Comparison to room auto EQ passes that will show what the room is doing to the sound, and show where nulls and cancellations are for which frequencies.. and if you know your physics, and math.. what surfaces are likely to have caused that problem.. Oh and look ... if we move that speaker 1 \" to the left.. it will no longer blast off that duct! who would have thought... but that' an essay for another diatribe.. right?
3. Starting points for a preset where you season the system response to taste...and save that for those special occasions where you really want to impress someone! LOL
A flat frequency response is when ALL sounds that emanate from the speaker are at the same volume... that is not to say that everything sounds the same, but if a tone was played that had the same voltage at EVERY frequency.. it would all be at the same volume.. you know ,,, 3K is not boosted by 3db,, and 80hz isn't 10 db down...flat response allows the speaker to not have hotspots and obvious frequencies that are missing.
There are limitations to all speakers... your average run of the mill top speakers have a low limit (the lowest frequency they will reproduce faithfully) that start to fall off rapidly at about 100 hz... typically, the more expensive the speaker, the lower it will go...actually, that means that the speaker will start to NOT be able to reproduce the lows below 100 hz as well as they do above ... so... the lower we go below 100 hz, the less the speaker can reproduce... so guess what .... the Driverack will have to BOOST those frequencies in an effort to get as much sound pressure as there is above 100 hz... there will be a point where the speakers will NOT reproduce the sound no matter HOW much you boost them...the Driverack can only boost the frequencies 12 db so when that level is reached the frequency band will be MAXED out... the Driverack can IGNORE up to 4 bands maxed out.. ( an allowance if you will for frequency response limitations of the speakers) but more than that will produce a NOT DONE message when the auto EQ process has ended... Another thing that will cause that message is if you have chosen dual mono or unlinked stereo... and it wants to process the other channel...
ANY maxed out or cut band is SUSPECT! Even one that is CLOSE to maxed out is suspect..(below or above the -10db point of the speakers published response) if the speaker TRULY did that bad in the Auto EQ (close proximity, or new indoor method) it would NOT BE WORTH USING... and tha'ts PERIOD!!!!
Once you have a flat response, and move the mic into the room make NO MISTAKE... setting the mic in the middle of the room WILL open a can of worms...you may never get closed... A mic on a mic stand 5 feet off the floor will have so many multiple reflection paths that all frequency sound.. like PINK noise.. will likely produce a sound that is nearly UNBEARABLE...ESPECIALLY in the high frequencies...it is a matter of reflections...wherever a frequency arrives exactly 1/2 wavelength out of phase with the original.. it will CANCEL.. 100%.. that means that the mic DOES NOT HEAR THAT FREQUENCY!!!!! move an inch at the higher frequencies.. and that cancellation is gone and another takes it's place....So make no mistake.. you will NEVER have all frequencies at one place at one time.. BUT do you really want that held 2K guitar note to be totally missing at the mix position? Believe me neither does the audience...
Much worse problems can happen in the LF response with the Auto EQ.. that would be standing waves, power alleys and comb filtering...this can have the Auto EQ seeing WAY TOO MUCH bass at some spots due to the coupling of low frequency energy...this can double.. triple the amount of bass in certain locations..and that would cause the Driverack to think the room had WAYYYY TOO MUCH BASS.. and it will KILL the bass...
So we would say that the main area that the Driverack will help the sound is in the 170> - <700 hz area... the other room response changes the Driverack makes are NOT to be taken seriously...those changes above and below should be done by ear... After all we just spent a whole bunch of time flattening and then sweetening to taste didn't we? Use the flat/to taste curve, and compare what the Auto EQ did with the flat curve...then make judgments based on the differences in what we know flat is.. to what the room does. If the Auto EQ maxes out say a 975 hz...and we play an ever increasing tone through the system.. when 975hz came the sound pressure (volume) would decrease dramatically for that frequency, and then get noticeably louder when going above the frequency... especially if you put your ear right where the capsule of the measurement mic was. As you move away from that spot you will notice gradually louder sound the farther you get away.
Gadget
Do the AutoEQ in close proximity (or the new indoor method)..this eliminates the majority of the reflections due to the pure preponderance of the signal coming directly from the speakers.. even 4' might not be too close...(especially when dealing with hung speakers and those darn 2X15\" 4' tall behemoths...
Do the Auto EQ with a FLAT -0- response curve to get as flat a response as possible...
Transfer the majority of what the GEQ does to the PEQ's available...(NOT the reverse, but exactly... as best you can.. start with the ones that have the largest cuts/boosts over the widest frequency range first, and work towards the ones that only effect a small frequency portion...
YES if you run another auto EQ pass and it does VERY LITTLE to the GEQ you have done VERY well! that is what you WANT!
Once you have that done, next save that to a preset as a FLAT system response... this is very useful for;
1.very live and reverberant spaces where any excess energy will excite the room and cause unstable sound reinforcement
2. Comparison to room auto EQ passes that will show what the room is doing to the sound, and show where nulls and cancellations are for which frequencies.. and if you know your physics, and math.. what surfaces are likely to have caused that problem.. Oh and look ... if we move that speaker 1 \" to the left.. it will no longer blast off that duct! who would have thought... but that' an essay for another diatribe.. right?
3. Starting points for a preset where you season the system response to taste...and save that for those special occasions where you really want to impress someone! LOL
A flat frequency response is when ALL sounds that emanate from the speaker are at the same volume... that is not to say that everything sounds the same, but if a tone was played that had the same voltage at EVERY frequency.. it would all be at the same volume.. you know ,,, 3K is not boosted by 3db,, and 80hz isn't 10 db down...flat response allows the speaker to not have hotspots and obvious frequencies that are missing.
There are limitations to all speakers... your average run of the mill top speakers have a low limit (the lowest frequency they will reproduce faithfully) that start to fall off rapidly at about 100 hz... typically, the more expensive the speaker, the lower it will go...actually, that means that the speaker will start to NOT be able to reproduce the lows below 100 hz as well as they do above ... so... the lower we go below 100 hz, the less the speaker can reproduce... so guess what .... the Driverack will have to BOOST those frequencies in an effort to get as much sound pressure as there is above 100 hz... there will be a point where the speakers will NOT reproduce the sound no matter HOW much you boost them...the Driverack can only boost the frequencies 12 db so when that level is reached the frequency band will be MAXED out... the Driverack can IGNORE up to 4 bands maxed out.. ( an allowance if you will for frequency response limitations of the speakers) but more than that will produce a NOT DONE message when the auto EQ process has ended... Another thing that will cause that message is if you have chosen dual mono or unlinked stereo... and it wants to process the other channel...
ANY maxed out or cut band is SUSPECT! Even one that is CLOSE to maxed out is suspect..(below or above the -10db point of the speakers published response) if the speaker TRULY did that bad in the Auto EQ (close proximity, or new indoor method) it would NOT BE WORTH USING... and tha'ts PERIOD!!!!
Once you have a flat response, and move the mic into the room make NO MISTAKE... setting the mic in the middle of the room WILL open a can of worms...you may never get closed... A mic on a mic stand 5 feet off the floor will have so many multiple reflection paths that all frequency sound.. like PINK noise.. will likely produce a sound that is nearly UNBEARABLE...ESPECIALLY in the high frequencies...it is a matter of reflections...wherever a frequency arrives exactly 1/2 wavelength out of phase with the original.. it will CANCEL.. 100%.. that means that the mic DOES NOT HEAR THAT FREQUENCY!!!!! move an inch at the higher frequencies.. and that cancellation is gone and another takes it's place....So make no mistake.. you will NEVER have all frequencies at one place at one time.. BUT do you really want that held 2K guitar note to be totally missing at the mix position? Believe me neither does the audience...
Much worse problems can happen in the LF response with the Auto EQ.. that would be standing waves, power alleys and comb filtering...this can have the Auto EQ seeing WAY TOO MUCH bass at some spots due to the coupling of low frequency energy...this can double.. triple the amount of bass in certain locations..and that would cause the Driverack to think the room had WAYYYY TOO MUCH BASS.. and it will KILL the bass...
So we would say that the main area that the Driverack will help the sound is in the 170> - <700 hz area... the other room response changes the Driverack makes are NOT to be taken seriously...those changes above and below should be done by ear... After all we just spent a whole bunch of time flattening and then sweetening to taste didn't we? Use the flat/to taste curve, and compare what the Auto EQ did with the flat curve...then make judgments based on the differences in what we know flat is.. to what the room does. If the Auto EQ maxes out say a 975 hz...and we play an ever increasing tone through the system.. when 975hz came the sound pressure (volume) would decrease dramatically for that frequency, and then get noticeably louder when going above the frequency... especially if you put your ear right where the capsule of the measurement mic was. As you move away from that spot you will notice gradually louder sound the farther you get away.
Gadget
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