"Official" Audyssey thread (FAQ in post #1) - Page 184

Originally Posted by Charles R

Here it is... I highlighted the part about the first position and the only reference to different types of listening areas.



You have already included this quote in a previous post. I guess you feel he wasn't addressing large rooms...

Originally Posted by LarryChanin

I also refer you to Chris' response to my question about this two row arrangement. Posting #4967

Please notice he doesn't respond by recommending I place the first measurement in the center of the listening area, but rather agrees that I can place all the microphone measurements in each of the 8 seats.

Originally Posted by hclarkx

"Each sub may have the response you mentioned, but what happens when you combine them? I believe they interact and have different responses when used together.

From what I've read, I don't believe they just sum, although now that I say that, it doesn't sound right. I believe subs are linear systems, so superposition should apply."

Noah,

You are absolutely correct. I went off half cocked. One can't separate phase and magnitude (out-of-phase signals produce a null). Etc. It's a lot more complex than that. Just how complex is apparent here:
http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt3.pdf

I suspect that Sound EQ can do a decent EQ with two subs on one EQ channel or with each sub on its own channel. In either case the EQ feeds a known signal, measures the results, and designs a filter to correct any problems. I lean toward the second option though, partly based on this example:
http://www.audioholics.com/productre...eyMultEQp1.php

and partly because with two different sub locations, I think one channel per sub will break the task down and effectively apply more processing power. I.e., if each sub can be individually corrected to provide flat response and the proper phase, then the two subs should look the same from the seating area and thus provide only an SPL increase when the second one is cut in.

The importance of two subs being equidistant from the listening area is stressed here (last few paragraphs on page 3):
http://www.audioholics.com/techtips/...ProPrimer3.php

Clearly Sound EQ can't correct the huge time error from an out-of-phase sub at 20 Hz so it's important that both subs be not only equidistant but about the same distance as the mains from the listeners. Given a reasonable starting condition, I suspect Sound EQ can achieve near perfection.

Interestingly, the Harmon article on page 22 presents a situation where two subs is problematic and removing one (or stacking it on top of the other one) is better. Of course, the author didn't have the benefit of Sound EQ.

Originally Posted by plhart

I thought a couple of minor clarifications to my Audyssey Sound Equalizer article might help here…

1. You can put two subs on a single channel of the ASEq and ask the Equlizer to derive a single amplitude and phase correction algorithm only if two parameters are met simultaneously>
a. The subs should be placed symmetrically within the room (i.e. at the two 1/3rd distance points across the front wall or to the left and right sides of the listening area and 1/3rd back into a symmetrical rectangular room)
b) Note that in either of these two examples each subwoofer’s distance to the first position should be identical. Note also that if you don’t have a sealed rectangular room but are listening instead in a rectangular room with, for instance, a large arched open entry the symmetry will be lost.

2 If you do have asymmetry in the placement of two subwoofers than you have no choice but to assign a separate channel on the ASEq to each sub. Again refer to my article. The ASEq MultEQ Pro algorithms solve for both amplitude and phase relative to the prime, (first) listening position.

3. My two subs are different distances from my prime (first) listening position. I average the two distances and input that average in the Denon 3806 which I’m using as a pre-pro. Remember, bass wave lengths are very, very long and the speed of sound is 1130 ft/sec so once you’ve got the two bass frequency responses flattened and the two phases relative to the prime (first) listening position correct then the slight differences in distance from each sub to the prime (first) listening position are all but irrelevant.

4. Two identical subs positioned exactly symmetrically will produce +6dB over a single sub in the same room.

Hope this helps....

Patrick Hart

Originally Posted by Hakka

I've been trying different mic positions, trying to calibrate for the primary seat only. I have been saving all the curves to the pc so i can go back to the best one.

The best result so far was:
1 primary
2 4 inches left
3 4 inches right

456 were 2 inches behind 123
78 were 2 inches forward of 123.
I tried wider spacing and different positions but this one worked considerably better than the others.

It's a close spacing but i have a very small room and a comfy spot in my chair that puts my head in the same position every time (tested with laser pointers aimed at ears and video cam for a 2 hour movie).
I have checked results with room eq wizard.
I'm not saying this is the right way but it worked best for me.
I have also been testing different ways to integrate with a BFD and add a house curve. I found doing a large wide cut before running audyssey, and then removing or tweaking the filters after running audyssey gave the best results. I use a pretty decent house curve that audyssey doesn't like. The trick is using cut filters to find a curve for the lower bass that audyssey wont touch. Then you remove the cut and you have a house curve without boosting in the BFD. There's a fair bit of trial and error involved but the results are worth it.

Hakka.

Originally Posted by LarryChanin

Based on his response, which didn't place the first microphone location in the geometric center of the listening area, I am lead to believe there is some latitude in the placement of the first microphone, particularly for larger listening areas.

Originally Posted by audyssey

As for the measurements, since your seating is slightly to the left of the center line I would recommend taking the left-most seat measurements closer to the right side of those seats to avoid going too far off-axis.

Originally Posted by giomania

1. Phase controls on subwoofers apply "delay" at one frequency rather than the needed group delay that is frequency dependent. So, it is best to just leave them at 0.

1. If this is not possible, enter the average of the two distance measurements.

2. When two subwoofers are driven as one unit, adjustments to the physical distance are required so they are time-aligned with each other.
3. Adjusting the physical distance of the two subs effectively adjusts their time delay.

C. The above advice applies only to sealed rectangular rooms without any openings.

B. When calibrating only a primary listening position, use the following placement methodology:
1. The first microphone position (#1) must always be in the center of the listening area.
2. For measurement #2, move the microphone two feet (60cm) to the left of position #1.
3. For measurement #3, move the microphone two feet (60cm) to the right of position #1
4. For measurement #4, move the microphone two feet (60cm) forward of position #1.
5. For measurement #5, move the microphone two feet (60cm) forward of position #2.
6. For measurement #6, move the microphone two feet (60cm) forward of position #3.
7. For measurement #7, move the microphone one foot (30cm) to the left of position #1, and one foot (30cm) forward of the line formed by measurements #1, #2, and #3.
8. For measurement #8, move the microphone one foot (30cm) to the right of position #1, and one foot (30cm) forward of the line formed by measurements #1, #2, and #3.

B. Raise the crossover of the LFE subwoofer in the receiver / processor to 120Hz, if allowed.

Originally Posted by fyzziks

Again, you are suggesting that the average of the two sub distance measurements be entered before running MultEQ measurements. That makes no sense, because MultEQ ignores any distance settings made before you run the measurements, and resets them to its own values afterward.

What you want here is "frequency-independent", not "frequency dependent."

Again, you are suggesting that the average of the two sub distance measurements be entered before running MultEQ measurements. That makes no sense, because MultEQ ignores any distance settings made before you run the measurements, and resets them to its own values afterward.

I'm not sure what you are suggesting here - what do you mean by "adjusting physical distance"? Are you really saying: "If your subs are not the same distance from the prime, move them so that they are"?

I'm also confused by this - do you mean that you should not have equal distances to the listening area from two subs driven from a y-connector if your room has an opening to some other living area?

I suggest adding a statement that microphone positions can be taken in any order, after the first one, because folks are going to ask that (and have, in the past).

Again, that is not a crossover, it's the LFE low pass filter.

Originally Posted by Kal Rubinson

And it adds compensation for the transmission delays of the circuitry, so no manual entry will be a sufficient replacement.

Originally Posted by David Aiken

It sounds to me as if the speakers aren't particularly sensitive or there's something very absorptive in the room that's making it require a lot of boost in order to set things to reference level.

What you can do is reduce ALL of the channel levels by the SAME amount, ie by say 11 dB. That will set all of the channels between the -1 and +1 dB range while preserving the current "gaps" between the various speakers. It's the gaps that are important in order to preserve the balance between speakers so you don't want to change them.

If that ends up making the sound levels too low for you when playing a particular source, go to the input settings and add some boost for the input related to the source you're using.

Originally Posted by giomania

Kal, please see post #5495 above where I am asking for input on this section. I would value your input.

I have tried posting this three times, and nobody has responded. What can I do?

Mark

IV. Dual (mono) Subwoofer Setup
A. Place the subwoofers symmetrically within the room.
B. Place the subwoofers at identical distances from the primary listening position.
1. If this is not possible, enter the average of the two distance measurements.
2. When two subwoofers are driven as one unit, adjustments to the physical distance are required so they are time-aligned with each other.
3. Adjusting the physical distance of the two subs effectively adjusts their time delay.
C. The above advice applies only to sealed rectangular rooms without any openings.

Originally Posted by Charles R

Which unless I read it wrong only addresses the left-most seat measurements and doesn't address the first measurement at all. He simply tried to prevent the measurement locations from being off-axis.

Originally Posted by LarryChanin

The primary listening location, which is almost exactly in the center of the room, is the second seat from the right in the first row.

As I understand it, these pre/pros permit 8 microphone measurements, and since I have 8 seats it seemed logical that each seat should get a microphone position. However, since the speakers are widely spaced I also thought that off-axis considerations might suggest a different approach.

Originally Posted by Audyssey

As for the measurements, since your seating is slightly to the left of the center line I would recommend taking the left-most seat measurements closer to the right side of those seats to avoid going too far off-axis. Other than that everything looks pretty straight-forward.

Originally Posted by Kal Rubinson

Well, if the two subs are driven from the same source, I would think that one has little choice since settings made before Audyssey will be ignored and changes after Audyssey should be made with trepidation since Audyssey's filtering is based on the measurements.
I would change line B to say:
B. Place the subwoofers at identical distances from the primary listening position, if at all possible.
I would eliminate parts 1,2,3. Of course, this is not an issue for the SEQ or other systems where individual subs can be EQ-ed separately.

Originally Posted by giomania

What do you think of this modification?

B. Place the subwoofers at identical distances from the primary listening position, if at all possible.
1. When two subwoofers are driven as one unit, proper time alignment is critical.
2. The two subwoofers will not be properly time aligned unless they have the same physical distance from the primary listening position.
3. Adjusting the physical distance of the two subs effectively adjusts their time delay.
C. The above advice applies only to sealed rectangular rooms without any openings.

Originally Posted by reedace

Thanks David. I'm thinking now that my small, inexpensive speakers don't put out enough sound in my big room to hit the reference levels Audyssey is looking for during auto-setup. I'm kind of disappointed that Audyssey would rather max out the gain on most channels to approach reference levels rather than preserve enough headroom to properly balance the channels _relative to each other_, but I have to say it still sounds great. Someday when I upgrade my speakers I can really fine-tune the balances.

Originally Posted by David Aiken

The test tones are played at a set level and aren't modified. Audyssey measures the SPLs at the mic position. It has no way of telling whether the reason why the measured SPL is low is because the speakers are inefficient or the receiver does not have enough power to drive them to reasonable levels in your room. It simply "acts" on its measurements.

I'm not certain whether it's the receiver manufacturer whose instructions determine speaker gain settings or Audyssey. Audyssey certainly provides the EQ filters but it may not do the individual speaker gain settings, just as it doesn't make the decision about the Large/Small speaker setting. I have to admit that the point where the receiver manufacturer's own functions hands over to Audyssey's functions is a little grey for me on some things.

Originally Posted by audyssey

David,

MultEQ does measure absolute level on all recent products that use the Audyssey microphone (or the Audyssey sensitivity spec applied to the manufacturer's mic). So, yes, the level settings are reported by MultEQ to the AVR such that the "0" volume setting produces reference level playback. This is also critical for all the new systems that have Dynamic EQ. Loudness correction can not operate correctly without knowing what the absolute SPL level is. You are right, though, MultEQ doesn't know if the level is due to the speaker sensitivity or some other factor (e.g., amp gain). It can only respond to what it measures at the mic...

Chris

Originally Posted by audyssey


In situations where there is only one listener and they always sit off axis from the center speaker I can justify starting in that position and measuring in a tighter pattern around that seat.

Chris

Originally Posted by David Aiken

Chris,

I'm running an older receiver, a Denon 2807, without dynamic EQ.

You said "Loudness correction can not operate correctly without knowing what the absolute SPL level is" and I can understand the reasons for that. Does Dynamic EQ work properly at levels below reference level? I assume it will since the system will be aware of the volume setting and how far below reference level it is.

Just one of those people who never runs his system at reference level and may want to upgrade sometime in the future. My normal playback levels tend to run between -20 and -30 dB. I find reference level way too loud for my tastes.

Originally Posted by jesyjames

In an "on axis" "one listener" position, how tight of a spacing would you recommend? Or is 2 ft. still the best for even just one person?

Originally Posted by tocaje

I have 7 small speakers (each one has two 4 1/2" midrange drivers and a 1/2" tweeter and rated to -3db at 90hz) and a 12" 200 watt powered sub.
If the LFE can reach up to 120hz why does Audyssey (Chris) recommend 80hz as a guide for the crossovers on small speakers? Why not set the speakers to 120hz to match the LFE? (I'm still waiting for my Denon 1909 to ship so I have no idea what the AVR is going to set these to)
Thanks for anyone's reply.

Originally Posted by ddingle

Anyone notice an increase in sibulance on voices when using Audyssey. I just equalized my seven channel system for the first time. I had been listening to 2 channel with Audyssey for a few days.Standard Rolloff and Midrange comp. checked.
I may have noticed it with 2 channel as well. I would guess the tweeters are kind of reacting badly to the "balancing" of the response? Overdriven or the like.
It goes away when Audyssey is off.
I searched for "sibulance" on this thread and did not get any results.
Just getting started with the pro version. As mentioned earlier the results are pretty spectacular. The sibulance is a little annoying. Steve Winwoods voice on the Eric Clapton 2007 Guitar Fest is an example. Like the microphone is overloading,but as mentioned it goes away with the Audyssey off.
I wonder if a different rolloff like the SMPTE might be better. I may try it tomorrow.
Thanks

Originally Posted by audyssey

Because the 120 Hz LFE filter has nothing to do with the speaker-to-subwoofer crossover.

A crossover is really two filters. A high pass (allows high frequencies to pass through it and stops low frequencies) and a low pass (allows low frequencies to pass through it and stops high frequencies). These two filters are combined to form a crossover. So, when we select an 80 Hz crossover for a speaker channel that means that anything above 80 Hz will be sent to the main speaker and anything below 80 Hz will be sent to the subwoofer.

The bass management system has additional stuff happening. It takes the low frequency components from all the speaker channels that passed through their respective crossover filters and sums them. It then takes the separate LFE track found on DVDs and HD and applies a low pass filter to it at 120 Hz (note: this is only a lowpass so it is not a crossover. Crossovers apply to speaker channels not to the LFE track that is just a content track). After that it adds 10 dB to the LFE track (as required by the decoder) and adds it to the bass content it collected from the other channels. The sum of bass content plus low-passed LFE track is the signal that is sent to your subwoofer.

Chris

Originally Posted by geodon005

So, Chris, what is the advantage of increasing the LFE to 120 Hz (as has been suggested throughout this thread) in the first place? After having run MultEQ on my 5 matching Niles Audio ceiling speakers and SVS sub, it set the crossover at 40 Hz and the LFE to 80 Hz. I like how it sounds just fine, but am curious as to any advantages that a higher LFE setting might have.

Originally Posted by Hakka

I've been trying different mic positions, trying to calibrate for the primary seat only. I have been saving all the curves to the pc so i can go back to the best one.

The best result so far was:
1 primary
2 4 inches left
3 4 inches right

456 were 2 inches behind 123
78 were 2 inches forward of 123.
I tried wider spacing and different positions but this one worked considerably better than the others.

It's a close spacing but i have a very small room and a comfy spot in my chair that puts my head in the same position every time (tested with laser pointers aimed at ears and video cam for a 2 hour movie).
I have checked results with room eq wizard.
I'm not saying this is the right way but it worked best for me.
I have also been testing different ways to integrate with a BFD and add a house curve. I found doing a large wide cut before running audyssey, and then removing or tweaking the filters after running audyssey gave the best results. I use a pretty decent house curve that audyssey doesn't like. The trick is using cut filters to find a curve for the lower bass that audyssey wont touch. Then you remove the cut and you have a house curve without boosting in the BFD. There's a fair bit of trial and error involved but the results are worth it.

Hakka.