Rear and Side fill equalization

[Dual-500]

I mentioned this topic in another thread, but it really deserves a thread all it's own - so, here goes.

I've not put any eq correction on rear and side fill channels in the past and don't have any eq capability on current setup.

Running 5 channel system. For the rears, two are on the back wall and two are on the side walls about 3' from the back wall.

Anybody doing eq tuning corections on rear and side fill speakers? If so, what are you doing? Eq type and basic tuning technique used.

EDIT: System is full component.

[Sir Terrence the Terrible]

I mentioned this topic in another thread, but it really deserves a thread all it's own - so, here goes.

I've not put any eq correction on rear and side fill channels in the past and don't have any eq capability on current setup.

Running 5 channel system. For the rears, two are on the back wall and two are on the side walls about 3' from the back wall.

Anybody doing eq tuning corections on rear and side fill speakers? If so, what are you doing? Eq type and basic tuning technique used.

First, Steve you have to get your terminology more HT related, as this sounds like a question one poses to a live performance audio engineer on a PA related site.

What type of system do you have, as different setups will require a different approach to EQ.

[dakatabg]

If you have a surround receiver, I have no idea how you will hook up equalizer to the rear channels.

[Sir Terrence the Terrible]

If you have a surround receiver, I have no idea how you will hook up equalizer to the rear channels.

If the receiver has pre outs on all channels, that is how it can be used.

[Dual-500]

First, Steve you have to get your terminology more HT related, as this sounds like a question one poses to a live performance audio engineer on a PA related site.

What type of system do you have, as different setups will require a different approach to EQ.
Let's not play vernacular or semantic games TT. The little bitty speakers on the back and side walls at the rear of the listening room.

Do you or do you not run equalization on rear or side channels?

If so, tuning them in terms of mic placement and such.

[Dual-500]

If you have a surround receiver, I have no idea how you will hook up equalizer to the rear channels.
Yes, that's true on some receivers - maybe most. It would require pre-outs and ins on the rear amp signal path.

Or a component system - I have a component system and have edited my original post.

Thanks!

[Sir Terrence the Terrible]

Let's not play vernacular or semantic games TT.

Steve, when in Rome you speak Italian, and when in France you speak french. It keeps confusion to a minimum, and keeps you from having to explain yourself over and over again. Right surround, left surround, left back and right back in HT is what is called rear and side fill in live reinforcement sound. If you go into live sound reinforcement circles talking about surround left and surround right, they are going to look at you crazy. The same goes for the HT crowd when you talk about side and rear fill, that is not vernacular that is familiar to HT folks.




The little bitty speakers on the back and side walls at the rear of the listening room.

That would be left surround, right surround, left rear, and right rear. Sometimes those speakers are not all that small.

Do you or do you not run equalization on rear or side channels?


If so, tuning them in terms of mic placement and such.

I usually tune for one "sweet seat" and also try and get good sound in as many seats as I can. In HT there really is only one perfect fusion spot, and I try and maximize for that position. So the microphone starts at the point where all of the speaker center axis lines up.

For HT, imagine a circle. At twelve o clock, that is your center. at thirty degrees from center go the left and right mains. At 90 degrees from center go your left and right surrounds, and at 150 degrees goes you left and right rear. In the center of that circle is where you put your microphone facing straight up towards the ceiling. The subwoofer should go in the corner in large rooms, and in the center of the front wall in small rooms.

This is the basic technique i use for most home theater setups that I have done. If the room is much larger, there is a different technique I use for those systems.

[Dual-500]

.....I usually tune for one "sweet seat" and also try and get good sound in as many seats as I can. In HT there really is only one perfect fusion spot, and I try and maximize for that position. So the microphone starts at the point where all of the speaker center axis lines up.

For HT, imagine a circle. At twelve o clock, that is your center. at thirty degrees from center go the left and right mains. At 90 degrees from center go your left and right surrounds, and at 150 degrees goes you left and right rear. In the center of that circle is where you put your microphone facing straight up towards the ceiling. The subwoofer should go in the corner in large rooms, and in the center of the front wall in small rooms.

This is the basic technique i use for most home theater setups that I have done. If the room is much larger, there is a different technique I use for those systems.
Thank you TT.

I don't have any eq on the surrounds at this time - but, am considering adding as I have the hardware. (of couse it would add to the 75% of the unneeded stuff :) )

So system focus is into the center of the room from the points specified? This is a basic system map for a small room? I have what would likely classify as a small room. And, by hook or crook ended up with a focus a little behind center of the room - more towards the sofa I listen from. That can be easily changed - all on adjustable mounts.

Focus to the center of the room? MIc placement in the center of room. About ear high or a ratio from floor to ceiling assuming 8' ceiling?

What about eq type? Parametric? Graphic? Or notch filter type? i.e. electronic feedback elimination type?

If you use standard eq's for rear/sides do you just cut the resonant spots or boost some areas to flatten them out overall?

Pink noise RTA or test tones?

Test/tune all in unison or individually?

Sub and entire system is corner loaded into room.

[Sir Terrence the Terrible]

Thank you TT.

I don't have any eq on the surrounds at this time - but, am considering adding as I have the hardware. (of couse it would add to the 75% of the unneeded stuff :) )

I usually don't use EQ unless I really need it. Most of the time I need it, but there are times when it is totally unnecessary, like when I watch movies in my smallest system, in the smallest room in one of my houses. I sit in the circle so close to my speakers ( 7 mini monitors from 5'4" away), that the room plays very little role in what I hear. I do use bass traps in that room, but that is to get a little bass energy out of the room, there was too much.


So system focus is into the center of the room from the points specified? This is a basic system map for a small room? I have what would likely classify as a small room. And, by hook or crook ended up with a focus a little behind center of the room - more towards the sofa I listen from. That can be easily changed - all on adjustable mounts.

If the sofa is generally where you listen from, then the focus should be on that seat.


Focus to the center of the room? MIc placement in the center of room. About ear high or a ratio from floor to ceiling assuming 8' ceiling?

You put the mike right where your ears would be when seated.


What about eq type?

I used to use graphic on the mains, and parametric on the bass. Now I use the Audussey system which uses software based processing.



If you use standard eq's for rear/sides do you just cut the resonant spots or boost some areas to flatten them out overall?

I never boost, as that would cut the systems headroom dramatically. I have only used boost on my subwoofers to create a house curve, and I do this with utmost caution. I cut resonant spots, and ignore nodes because I cannot do anything about them except move the listening seat. I first measure before I do anything. After I correct something, I measure again. Measure, correct, measure, correct is how I do it.


Pink noise RTA or test tones? A combination of pink noise and sine waves.


Test/tune all in unison or individually?

Individually


Sub and entire system is corner loaded into room.

Do you use a 5.1 system or a 7.1?

[Dual-500]

I usually don't use EQ unless I really need it. Most of the time I need it, but there are times when it is totally unnecessary, like when I watch movies in my smallest system, in the smallest room in one of my houses. I sit in the circle so close to my speakers ( 7 mini monitors from 5'4" away), that the room plays very little role in what I hear. I do use bass traps in that room, but that is to get a little bass energy out of the room, there was too much.

If the sofa is generally where you listen from, then the focus should be on that seat.

You put the mike right where your ears would be when seated.

I used to use graphic on the mains, and parametric on the bass. Now I use the Audussey system which uses software based processing.

I never boost, as that would cut the systems headroom dramatically. I have only used boost on my subwoofers to create a house curve, and I do this with utmost caution. I cut resonant spots, and ignore nodes because I cannot do anything about them except move the listening seat. I first measure before I do anything. After I correct something, I measure again. Measure, correct, measure, correct is how I do it.

A combination of pink noise and sine waves.

Individually

Do you use a 5.1 system or a 7.1?
Well, it's a 5.1 technically, but I don't use the sub out - that's done in the DBX Drive Racks.

So, it's a 5.1 setup in 5.0 mode and I use 4 x rear speakers. Two on the back wall and two on the side walls about 3' forward of the back wall.

Thanks for the input. We do identical techniques all the way to the test tones and doing each rear as I have never eq'd the rears yet nor used test tones.

Well, Im pretty pleased about this. Nice to know I'm in the ballpark with what I've done.

So in some rooms you use eq on the rear/sides and other rooms not.

I'll run some pink noise through mine and see what it looks like.

Where can I read about these:?
Audyssey Sound Equalizer
Audyssey Sub Equalizer
These are software driven - anything beyond parametric notch filters?

2 custom 4 way horn hybrid monitors
1 custom 2.5 way horn hybrid center monitor
8 custom 2 way horn hybid surrounds
4 custom 15" H-PAS servo subs

Speaker specs - horns, crossovers, etc.

[pixelthis]

Well, it's a 5.1 technically, but I don't use the sub out - that's done in the DBX Drive Racks.

So, it's a 5.1 setup in 5.0 mode and I use 4 x rear speakers. Two on the back wall and two on the side walls about 3' forward of the back wall.

Thanks for the input. We do identical techniques all the way to the test tones and doing each rear as I have never eq'd the rears yet nor used test tones.

Well, Im pretty pleased about this. Nice to know I'm in the ballpark with what I've done.

So in some rooms you use eq on the rear/sides and other rooms not.

I'll run some pink noise through mine and see what it looks like.

Where can I read about these:?
Audyssey Sound Equalizer
Audyssey Sub Equalizer
These are software driven - anything beyond parametric notch filters?

2 custom 4 way horn hybrid monitors
1 custom 2.5 way horn hybrid center monitor
8 custom 2 way horn hybid surrounds
4 custom 15" H-PAS servo subs

Speaker specs - horns, crossovers, etc.

SOMETHING TO PLAY WITH, I guess.
But since most of the sound comes from the front, the rears are usually not worthy of that much trouble, just set the levels and go, usually, but to each his own.:1:

[Sir Terrence the Terrible]

SOMETHING TO PLAY WITH, I guess.
But since most of the sound comes from the front, the rears are usually not worthy of that much trouble, just set the levels and go, usually, but to each his own.:1:

More stupid advice. I hate to bring this to ya VI, but the rears are just as important as the fronts regardless of how much information comes from the front.

When objects are panned from the front to the rear, you do not want any power or timbre skewing going on, or it will snap you out of the effect, making its transition ineffective.

In a 5.1 mix, all channels are created equal. This is not the days of pro logic and Dolby surround.

[Dual-500]

STtT.

I pinked out (Pro Audio Vernacular :) ) the rears last night and attempted to take a couple of shots of the analyzer, but the camera flash washed out the picture. I'll replicate testing today and see if I can get a pic by shutting off camera flash.

I tested individually as you recommended.

Rears had somewhat of an "S" curve if you will with a dip in the 500hz region followed by a hump in the 1.5k region which tapered off. Nothing drastic in the plot. It varied on the order of 5-10 db overall. They looked better than I would have guessed.

How about the fronts? Assumption is the L&R mains are swept (more PA jargon :) ) together and not individually? Just making sure on this as I swept them together as if it were a music only system. Center of course was done independently.

Eq type. I'm thinking a dual 15 band outta handle the rears ok. Is a 1/3 octave necessary? What do you typically use in your installs and personal setups?

Another thing. I set the system overall balance using a test tone function in the AV receiver. Use a basic Simpson SPL meter held in front of me where I can read the meter while seated in the "Sweet Spot".

[Sir Terrence the Terrible]

Well, it's a 5.1 technically, but I don't use the sub out - that's done in the DBX Drive Racks.

So, it's a 5.1 setup in 5.0 mode and I use 4 x rear speakers. Two on the back wall and two on the side walls about 3' forward of the back wall.

So you are splitting the right and left surrounds to four speakers instead of two. I get it.


Thanks for the input. We do identical techniques all the way to the test tones and doing each rear as I have never eq'd the rears yet nor used test tones.

Well, Im pretty pleased about this. Nice to know I'm in the ballpark with what I've done.


So in some rooms you use eq on the rear/sides and other rooms not.

It really depends on what the measurements tell me. If the measurements tell me that I need to correct a boundary reinforcement from having the rear/sides too close to the wall, I correct that. I do not use EQ above 200hz though, that is the area where room treatments are more effective, and it keeps electronic equalization out of the most sensitive area of our hearing mechanism.


I'll run some pink noise through mine and see what it looks like.

It is better to measure the bass, mids and highs at different resolutions when using an RTA. Bass should be measured at 1/6 octave resolution, and the mids and highs at 1/3 octave resolution. There is a more complex interaction of room modes and nodes at lower frequencies than at higher ones.


Where can I read about these:?
Audyssey Sound Equalizer
Audyssey Sub Equalizer
These are software driven - anything beyond parametric notch filters?

Actually Audyseey is beyond parametric notch filters.

http://www.audyssey.com/


2 custom 4 way horn hybrid monitors
1 custom 2.5 way horn hybrid center monitor
8 custom 2 way horn hybid surrounds
4 custom 15" H-PAS servo subs

Speaker specs - horns, crossovers, etc.

The main speakers have a frequency response of 20-40khz -+1.5db, and can playback at levels over that entire frequency band in excess of 120db. Crossovers are DSP based, and use linkwitz/riley crossover slopes of 24db oct for the coaxially mounted mid bass(in front of the subwoofer) unit to the mids, and from the mids to the supertweeter. There is no crossover in the critical band between 500-8khz, and no crossover from the sub to the midbass driver. This is a time phase and frequency correct loudspeaker with a constant directivity from 200-20khz.

The center speaker frequency response goes from 40-40khz -+1.5db achieve playback levels of over 115db in that band. The crossover is DSP based, with the same linkwitz/riley alignment as the mains. This speaker is also time, phase, and frequency correct with a constant directivity horn on the mid/tweeter driver. There is no crossover between 900hz all the way to the top of the tweeters operating frequency

The surrounds have a frequency response of 80-40khz-+1.5db, achieve a playback of over 110db over that entire band frequency band. The crossover is also DSP based with the same alignment as the main and center. It is also time, phase, and frequency correct, and there is no crossovers used above 900hz. The horn on the mid/tweeter is a constant directivity horn.

The subwoofers are a new design using a variation of the HPAS(or high pressure acceleration system) enclosure design. It is a cascading design of a inverted horn, and transmission line hooked together. Its frequency response is 19-80hz-+2db with corrective eq. A single sub can playback 120db over that band with a 150 watt amp. It is 30x17x17. I use four tightly clustered(two side by side and two stack on them) to get the maximum proximity gain, and use 600 watt per channel amps for each sub. Each driver has a servo control to keep the woofers moving in a piston like fashion over its entire operating band.

The mid/supertweeter drivers of all of the speakers are made of Berylium, and the cones of all of the speakers are made of carbon grahite fibre. All drivers are custom made for high quality, high power, low distortion operation.

[Dual-500]

What is DSP? Digital System/Sound/Signal Processor?

I use a DSC to control L&R front monitors. Digital System Controller.

[bfalls]

Audio Control has two Home Theater equalizers, the Rialto and the Bijou. These are manually adjustable not automated like Audissey. For the hands-on audiophile or audio enthusiast.

The Rialto:

"The world's first 7 channel equalizer gives you total control of your home theater's acoustical environment with 11 equalizer controls for the front and center channels, 7 for the stereo subwoofer channels and 5 for the surround channels. A 24dB/octave Linkwitz-Riley alignment electronic crossover allows hook-up to a subwoofer even without separate subwoofer inputs. Module frequency programmability permits the crossover to be customized to any speaker combination imaginable. New 5.1 surround system ready."

The Bijou:
* Five Channels of Equalization
*
First Consumer 1 / 6 Octave Subwoofer Equalizer Provides Unparalleled Control
*
Compatible with Dolby Digital Surround Systems
*
Independent 1 / 3 Octave Equalization for Left, Center and Right Channels
*
Stereo Surround Equalization
*
Constant-Q Equalizer Design
*
THX DB-25 Common Audio Connector
*
Security Cover (Optional)
*
Rack Mount Brackets (Optional)

[Sir Terrence the Terrible]

What is DSP? Digital System/Sound/Signal Processor?

I use a DSC to control L&R front monitors. Digital System Controller.

They are proprietary to the speaker design. They are 64/352.4khz bit and sample rate. The Digital system controller is in my processor listed in my sig.