My AVR-3806 Audyssey experience! (measurements inside)

[Nick250]

Originally Posted by audyssey

I have edited my post to remove any comments that may be taken in a negative fashion. Let's move on and talk about fun stuff.

Best regards,
Chris

Your forgot to edit the post below. I will be ready to move on when I get a public apology and this post is deleted. Just to keep facts straight, the few days you were away from this thread was 7 days and I am not the only person who figured you up and abandoned the thread without notice.

Originally Posted by audyssey

Nick,

I was on travel and did not have internet contact for a few days. I am surprised at your language given how many of your messages I have answered. I had a higher opinion of you as a sophisticated person, but apparently I was wrong. I have no interest in engaging in discussions with people that use this type of abusive language.

Goodby and good luck.

Chris

[joekoz]

Originally Posted by Nick250

Your forgot to edit the post below. I will be ready to move on when I get a public apology and this post is deleted. Just to keep facts straight, the few days you were away from this thread was 7 days and I am not the only person who figured you up and abandoned the thread without notice.

Nick, don't you think you may be taking this too far. Just like you, audyssey is entitled to his opinion. I for one, am grateful for his participation, and demands such as yours don't do anything but take away from a quality thread. Please consider your posts prior to using the reply button. I understand your frustration, but you post is ridiculous. I have been on many different forums where the quality of postings have been, shall I say, less than quality. AVS, for the most part, hasn't been one of them. I'm sure audyssey needs no defenders, just wanted to put my .02 cents in here FWIW.

[noah katz]

"Your forgot to edit the post below. I will be ready to move on when I get a public apology and this post is deleted."

You've got to be kidding.

Unless you were treated outright rudely, there's no justification for posting with the language you used; and even if you were it's still pointless.

[kromkamp]

I agree. Nick, Chris was and is under *no* obligation to answer questions on this forum. The fact that he did does not obligate him to further continue to do so, nor does he need to warn you in advance when he may stop.

Chris I want to thank you again for all the valuable advice you have contributed.

Thanks,

Andy K.

[sdurani]

Originally Posted by Nick250

the few days you were away from this thread was 7 days...

I don't understand where this sense of entitlement you seem to have is coming from. Can't you at least be grateful that the CTO of Audyssey tried to personally help you and others overcome the limitations of the Denon manual? Certainly more than what Denon is doing for you.

The last thing any of us need to do is create an environment where industry reps feel uncomfortable participating; and that includes counting the days Chris may be away from this thread. Please understand that he isn't on some sort of leash tied to AVS Forums.

Best,
Sanjay

[joekoz]

Originally Posted by sdurani

I don't understand where this sense of entitlement you seem to have is coming from. Can't you at least be grateful that the CTO of Audyssey tried to personally help you and others overcome the limitations of the Denon manual? Certainly more than what Denon is doing for you.

The last thing any of us need to do is create an environment where industry reps feel uncomfortable participating; and that includes counting the days Chris may be away from this thread. Please understand that he isn't on some sort of leash tied to AVS Forums.

Best,
Sanjay

BRAVO!!!!!!

[audyssey]

Originally Posted by dmccombs

Chris,

You are right, I re-ran my comparasons and the bass are the same in the Audyssey and Flat settings. Both settings really knocked my Bass down. The bass was taken down -4DB at 125hz, and -8DB at 63hz.

You mentioned that Flat should be used for THX. The 3806 does not have THX decoding correct? Can you elaborate on this a bit?

Many Thanks,
Darrell McCombs

-----------------------------------------------------------------------------------------------

Hi Darrell,

I want to make sure that this is not related to bass management. What you are describing seems to indicate that your speakers are being bass managed at near 125 Hz and what you are seeing is the slope of the bass management filter.

Can you please check the speaker settings for:

1) Are the speakers set to Large or Small
2) Is the subwoofer mode set to LFE+Main or Fixed

More details about this and other questions can be found on the audyssey website at
http://www.audyssey.com/faq.html
This is similar to the FAQ I wrote for Denon's website, but also contains some more info. It will be updated from time to time as questions come up.

Regarding my comment about THX and Flat, I was referring to those receivers that have THX (not the 3806 as you said).

Best regards,
Chris

[dmccombs]

Chris,

Thanks for the the link to your FAQ. I have already read it a few times.

Based on the recommnedations in this thread, I ran the Audyssey, then set ll my speakers to small. Audyssey set my crossovers to: Front 40hz, Center 40hz, Rears 80hz, and the LFE to 100hz. Audyssey set the sub to LFE mode (not LFE+Main). Do these settings sound ok?

Is it true that when my speakers are set to small the system is basically in a LFE+Main mode, even if the Sub setting is set to LFE?

Regards,
Darrell McCombs

[audyssey]

Hi Darrell,

First, I want to make it clear that Audyssey doesn't set LFE or LFE+Main. That is handled by the Denon bass management. What MultEQ does is to report the values that it finds to the microprocessor that subsequently communicates with the Denon bass management system.

From your description it sounds like the system is set up correctly. When the speakers are set to Small, the sub setting defaults to LFE mode. LFE+Main can be used if you want to keep your speakers at Large and redirect the bass below 80 Hz to the subwoofer. Since you have already set the speakers to Small, you can leave the sub mode to LFE.

When you mentioned the values at 63 Hz and 125 Hz where did the dB numbers come from? Are they from the OSD display under Parameter Check? If so, please do not pay too much attention to those as they are extremely coarse and don't really show you what is going on. That's the best that we could do to display some sort of result given the extreme limitations of OSD graphics. In retrospect this has backfired because many people think that MultEQ is like a parametric EQ that only works on those bands and does not operate below 63 Hz. Also, since there is no subwoofer parameter display many (including reviewers...) have said that MultEQ doesn't filter the subwoofer.

It's not uncommon to have a standing wave at 80-100 Hz that causes a large peak. It could be that MultEQ is trying to knock that down and this is the reason for the cut. It's difficult to say without taking some measurements of before and after.

If you have a way of uploading some pictures of your room (or PMing them to me), I can get a better idea of what may be going on. Please also indicate where you are placing the mic, how many positions you are measuring, etc.

I am writing some of this in the form of suggestions for the FAQ that this thread has requested. Maybe we can use your room as an example if that's OK with you.

Best regards,
Chris

[dmccombs]

Chris,

Thanks for the detailed explanations. You are really helping people make the Audyssey system a plus. The system does do nice things for the overall soundstage.

When I said the bass was -4db lower at 125hz, and -8db at 63hz, I looked at the EQ settings after I had copied them to the Manual EQ set. These numbers seem about right based upon what I am hearing.

I would be happy to have you use my room as an example if you think it would be helpful for others. I can send pictures tonight.

I have a Radio Shack SPL meter and an Avia DVD. That is the extent of my test equipment. Will that be enough for the before/after tests you want to do?

Regards,
Darrell McCombs

[mojomike]

I've been lurking here on this thread for a while so I thought I'd jump in here. I've had a AVR-2807 for about a week now and have had enough time time tweak and tune to my preferences. Overall, I think the Audyssey system is pretty good. I'm not crazy about how "Flat" sounds with any material, but the "Audyssey" curve sound great with movies and I prefer the "Front" curve with music. I would think this preference heavily depends on the nature of the front speakers.

What's nice about this arrangement is that it is like having two separate speaker systems, one optimized for movies and one optimized for music.

I have all speakers set to small, fronts x-ed at 80, center at 100, ss at 100, sb at 120. I did raise the level of the sub a couple of db's do to my preference.

Overall, I'm very pleased.

[pmccaffrey]

Originally Posted by pmccaffrey

If one decides to rerun the autosetup, it is as simple as just starting over. Or does the avr need to be reinitialized/reset?

Bump, in case the my question got lost amidst all of the bickering .

[Jase H]

Originally Posted by pmccaffrey

Bump, in case the my question got lost amidst all of the bickering .

You can just re-run it without resetting the Amp.

[Yves Smolders]

I'll just throw in my 2 cents here...

As I understood from previous threads -

- Audissey first calculates what the frequency response is from all the speakers.
- Audissey finds best XO for every speaker and communicates this to the Denon bass management
- If you change XO frequencies, no problem for audissey - it 'knows' the speakers and alters the curves of the material played back, so that it becomes as flat as possible (or as close to the target curve as possible)
- Now the Denon BM comes into play:

- Large speakers are speakers with ideal XO points under 80hz
- Small speakers are speakers with XO points of 80hz and higher
- Large speakers react to the LFE setting - LFE means that large speakers are "uncrossed"
- Large speakers + "LFE+main" means that the part that the Large speakers can't handle is sent to the LFE - I believe the large speakers are then rolled off, but bass is only added up to the "crossover point" that is shown next to the large speakers when in LFE+main. Kinda puzzles me why this isn't just regarded as "small" with a lower x-over.

Anyway, for the moment I'm running 2 B&W N804's, 2 N805's, a yama SW300 and a HTM2 centre. Set amp to LFE+main - all speakers detected as large - crossovers for the large speakers are set at 40hz. Changed sub settings: sub crossover set to max, volume to 50% as demanded by audissey. (Audissey handles Xover)

Strange points - LFE is detected at >6.5 metres distance while it is much closer (perhaps some kind of phase problem) - sounds good though. Other distances seem to be correct!

Sounds all pretty good to me, I prefer the "flat" curve, sometimes audissey, but only for movies. Imaging (already good on 804's) is improved, detail comes out, stereo is amazing, but the finesse of the 804's in direct is missing. So audissey is movie-only for me. Bass is much lower than I manually set it before (hearing only, no measurement) but I guess this is right. Some movie soundtracks still rumble the house when needed. However there isn't much bass being sent from the mains to the sub, in my opinion (for example, dolby prologic tracks seem thin now)

As for stereo, I run "direct" to avoid any bass management, unless I go for dance music - then I select stereo, have enabled crossover in advanced stereo playback (or something like that...) - have upped the Xover from 40 to 60, introduces some boominess but that's good for dance, not looking for perfect playback.

At enhanced stereo, 40,hz the sub "works" but way too silent - like there's no <40hz material in the music at all - should try this with organ music or something. at 60 it's pretty bass heavy.

Haven't tried to change my speakers manually to small.

[s2silber]

Chris,

Like others in this forum, my Audyssey set-up detected all five of my speakers as "large" and set the crossover on all of them to <40db. I suppose this is fine for the fronts (Paradigm Studio 60 V.3) and even the center (Paradigm CC470), but why would it think that my in-ceiling surrounds should be crossed over at 40db??

[Kal Rubinson]

40dB? Or 40Hz?

Kal

[audyssey]

Originally Posted by s2silber

Chris,

Like others in this forum, my Audyssey set-up detected all five of my speakers as "large" and set the crossover on all of them to <40db. I suppose this is fine for the fronts (Paradigm Studio 60 V.3) and even the center (Paradigm CC470), but why would it think that my in-ceiling surrounds should be crossed over at 40db??

Hi,

It's not that unusual to find a number close to 40 Hz. In-wall speakers can measure lower because of the extended baffle created by the wall, or because of a resonance caused by the cavity they are in. My suggestion would be to manually switch the speakers to Small and allow Denon's bass management to do its job.

Regards,
Chris

[s2silber]

Originally Posted by Kal Rubinson

40dB? Or 40Hz?

Kal

Of course I meant Hz. Sorry.

[s2silber]

Originally Posted by audyssey

Hi,

It's not that unusual to find a number close to 40 Hz. In-wall speakers can measure lower because of the extended baffle created by the wall, or because of a resonance caused by the cavity they are in. My suggestion would be to manually switch the speakers to Small and allow Denon's bass management to do its job.

Regards,
Chris

Should I set all of the speakers to Small, or only the in-ceilings, which are Paradigm Reference SR15s with 8" woofers?

[joekoz]

Originally Posted by audyssey

I am writing some of this in the form of suggestions for the FAQ that this thread has requested. Maybe we can use your room as an example if that's OK with you.

Best regards,
Chris

Man this thread kinda died, huh? I just wanted to check in on audyssey's progress with that FAQ he was putting together for us. I hope this thread hasn't run out of gas. I want to understand as much as I can about this room correction system and any setup tweaks I as the end user can do to enhance it's performance. I have a bunch of custom room treatments arriving shortly from bpape on this forum, and I'm hoping that the marriage of those treatments and Audyssey will be acoustical nirvana. I have an AVR 5805 matched to a complete Paradigm Studio 100v.3 7.1 setup, including the Servo 15 sub.

[172av8r]

Yeah, i'm bummed out if this thread died. I'm still struggling to get the performance from Audyssey on my 3806 without losing all that bass! Can anyone explain to me what FRONT mode of Audyssey really does? is it just not EQing the FL & FR speakers? or what exactly does it do differently?

[adri]

Audessey Front mode does not apply any EQ to the Font L+R speakers.
The EQ applied to the Center and Rear speakers tries to match their frequency respons as close as possible to the Front L+R speakers.

Adri.

[audyssey]

Here is a list of tips based on several discussion in this and other forums about MultEQ. I will add to it from time to time as new questions come up. Some additional information can also be found on the Audyssey website.

Best regards,
Chris
CTO, Audyssey Laboratories



Microphone Placement

• The microphone has been calibrated for grazing incidence and so it must point to the ceiling during calibration. Any other orientation will produce incorrect results.

• The microphone response has been calibrated to match (on average) the response of an industry-standard ¼” instrumentation microphone. It is critical to use the microphone that came with the receiver and not one from another model that may have a different calibration curve.

• It is also important to place the microphone on a tripod or other stand so that it is at ear height. We strongly recommend against holding the microphone in your hand because this can give rise to low frequency handling noise that will cause the MultEQ filters to compensate by cutting those frequencies. Furthermore, it is not recommended to place the microphone on the back of the couch or recliner. If a tripod is used, care must be taken to ensure that the microphone is placed at a height just above the seat back so that reflections from the seat do not cause problems at higher frequencies.

• The first microphone position is used to calculate the distances to each loudspeaker and subwoofer and set the delays. It is also used to measure and set the trims. So, it is important to place the microphone in the main listening seat for the first measurement.

• MultEQ measures the background noise level in the room before playing the test signal from each speaker. For the measurements to be valid, the signal to noise ratio must be above a certain threshold. If it is not, the test signal from that speaker will repeat at a higher level. If the noise in the room happens to be higher during some of the speaker measurements, then the test signals from those speakers will sound louder than the test signals from the other speakers. This does not affect the calculation of trim levels. If the room noise is too high even after the test signals increase in level, then an error message will be displayed warning the user that measurements can not be completed.

• After the first position is measured, MultEQ measures other positions in the room around the listening area. These do not necessarily have to be in each individual seat. The idea is to capture as many points around the listening area as possible so that the acoustical problems that affect the quality of sound within that area are minimized.

• For example, we recommend taking 3 positions on the couch facing the TV and then 3 more positions about 3 feet in front of the couch and parallel to the first three. Measurements up against the back or side walls should be avoided.

• Some loudspeakers have rather problematic responses when measured off-axis (i.e. more than 15° away from the imaginary straight line that points to the listening position). In these systems, measurements taken too far away from the center line will show a reduced high-frequency response that may result in overcorrection and thus overly bright sound. Although it is difficult to predict which type of loudspeaker will have these off-axis problems we have most often observed them in poorly-designed multiple-driver arrays that exhibit very high off-axis lobing. In these situations we recommend a tighter calibration pattern centered around the main listening position and making sure that the mic is not placed in extreme locations and certainly not outside the plane of the front main speakers.

Checking the Results

• Once MultEQ calibration is complete the results are stored in the receiver memory.

• It is important to activate MultEQ by selecting one of the target curves. This is not performed by default after the calibration is finished and must be selected by the user. In a THX system we recommend using the “Flat” setting that allows the re-equalization to work as intended. In other systems, we recommend “Audyssey” for movie playback and “Flat” for music playback. Unfortunately, the music industry does not have any mixing standards like the movie industry so some music program material may sound better with the “Audyssey” setting. “Front Align” also uses the Audyssey process, but it does not apply the filters to the two front loudspeakers. “Manual” is not an Audyssey setting and does not use MultEQ filters. It is a simple parametric equalizer and will be subject to all the limitations that come with parametric EQ.

• Small vs. Large speakers. This is the most commonly discussed topic by MultEQ users. The first thing to understand is that it is not a personal insult to your system if your speakers were detected as “Small”. It simply means, that in the room they were measured the – 3 dB point was detected at 80 Hz or above. This may happen even if the manufacturer’s spec shows that the speaker is capable of playing lower. In fact, there are several benefits at crossing the speakers over at 80 Hz that have to do with power handling and headroom in the bass region that will be handled by the subwoofer amplifier.

• The second most common question also relates to Small vs. Large. In the Denon receivers, MultEQ will designate as “Large” any speaker that has a –3 dB point below 80 Hz. For non-THX speaker systems this is an arbitrary definition that often causes confusion. All it means is that the speaker will not be bass managed unless the user tells it to be. Because Audyssey is not in charge of bass management, we have to abide by the manufacturers’ rules and simply report the information found by the measurements to the bass management system.

• In situations where the speakers do not play significantly below 80 Hz, an additional step must be taken to make sure that there is no loss of bass information. The user must set the speaker to Small manually so that bass management is performed properly.

• Polarity: MultEQ checks the absolute polarity of each loudspeaker and reports it to the user. This is simply a report and does not affect the subsequent calculations in any way. It just asks you to check the wiring to make sure it is connected properly to each speaker. Sometimes we get false alarms. This is usually because the speaker has a driver (usually the mid-range driver) wired out-of-phase intentionally to make up for some problems at the crossover region. If a phase warning is shown, it is not a cause of alarm. Simply check the cables and hit “Skip” if everything is fine. Again, this does not have any effect on the EQ results.

• Subwoofer distance: in many active subwoofers it is not possible to defeat the low-pass filtering. That means that the pre-pro bass management filters will be on top of the low-pass filters inside the subwoofer. The built-in low-filters introduce a delay to the signal coming in (because they have poles). This delay is seen by MultEQ as acoustical delay and is reported in the results. That is why sometimes the subwoofer distance is reported to be longer than the physical measured distance. The setting should not be changed because the blend between the sub and the satellites has been designed based on this time delay.

• The design constraints for MultEQ were that it (1) must fit within a small portion of the DSP so that other processes can also run and (2) it must use FIR filters because of the well-known artifacts that IIR filters cause particularly in the time domain response. As it turns out, these two requirements are contradicting. In order for FIR filters to be effective and capable of correcting to low frequencies, they must consist of several thousand coefficients (taps). The problem is that the CPU power required increases with the number of taps, hence the dilemma. What we did at Audyssey was to come up with a different way to partition the frequency axis so that we can use fewer taps and yet not completely give up on low frequency resolution (and therefore low frequency correction). This allows us to take a 512 tap filter that would normally have a resolution of 94 Hz (meaning that any peak or dip narrower than 94 Hz would be missed) and significantly improve its resolving power. The resolution of the filter actually varies continuously with frequency and starts at around 10 Hz. Does this mean that MultEQ can correct an arbitrarily narrow peak or dip at 30 Hz? Of course not. The reality is that in the MultEQ XT version found in receivers, we can correct broader features below 100 Hz better than narrow ones. For example, a lump that is half an octave wide at 50 Hz can be fixed. A narrow dip or peak that is 1/3 or 1/6 octaves wide and centered at 30 Hz will be improved, but not eliminated.

• The on-screen display in the receiver has very limited graphics. Therefore it is not possible to really show what the MultEQ correction filter is doing at all frequencies. It appears to only be operating on 9 bands like a parametric equalizer, but this is not the case. What is shown is a very crude approximation to the MultEQ correction and it should not be used to read exact values of cut or boost at the 9 frequencies shown.

• Furthermore, there is no display for the subwoofer filter. This doesn’t mean that there is no subwoofer correction. It was not added to the display because of interface and memory considerations.

[Nick250]

Originally Posted by 172av8r

Yeah, i'm bummed out if this thread died. I'm still struggling to get the performance from Audyssey on my 3806 without losing all that bass! Can anyone explain to me what FRONT mode of Audyssey really does? is it just not EQing the FL & FR speakers? or what exactly does it do differently?

Interesting, Audyssey set my sub about 5db to hot. I have run the auto EQ a couple of times with the sub in different locations and I always with the same results ie 5db too hot. My experience is that it sounds best to me when after I run auto eq I manually set all speakers to small and cross them over at 80Hz. Audyssey had set all my speakers (mains are Paradigm Studio 20s) to large and crossed them over at 40Hz. I then turn the sub down about 5db to get it right and I am done. It sounds great with music, I have not done much movie watching recently so I can not comment on that.

Nick

[Nick250]

Chris, great FAQ! It really fills in a lot of the blanks that the manual does not cover.

I would like to see this over at AudioHolics. If you don't mind I would like to start a thread over at there and do a cut and paste of everything including your opening comments. Hope all is well.

Regards, Nick

Originally Posted by audyssey

Here is a list of tips based on several discussion in this and other forums about MultEQ. I will add to it from time to time as new questions come up. Some additional information can also be found on the Audyssey website.

Best regards,
Chris
CTO, Audyssey Laboratories



Microphone Placement

• The microphone has been calibrated for grazing incidence and so it must point to the ceiling during calibration. Any other orientation will produce incorrect results.

• The microphone response has been calibrated to match (on average) the response of an industry-standard ¼” instrumentation microphone. It is critical to use the microphone that came with the receiver and not one from another model that may have a different calibration curve.

• It is also important to place the microphone on a tripod or other stand so that it is at ear height. We strongly recommend against holding the microphone in your hand because this can give rise to low frequency handling noise that will cause the MultEQ filters to compensate by cutting those frequencies. Furthermore, it is not recommended to place the microphone on the back of the couch or recliner. If a tripod is used, care must be taken to ensure that the microphone is placed at a height just above the seat back so that reflections from the seat do not cause problems at higher frequencies.

• The first microphone position is used to calculate the distances to each loudspeaker and subwoofer and set the delays. It is also used to measure and set the trims. So, it is important to place the microphone in the main listening seat for the first measurement.

• MultEQ measures the background noise level in the room before playing the test signal from each speaker. For the measurements to be valid, the signal to noise ratio must be above a certain threshold. If it is not, the test signal from that speaker will repeat at a higher level. If the noise in the room happens to be higher during some of the speaker measurements, then the test signals from those speakers will sound louder than the test signals from the other speakers. This does not affect the calculation of trim levels. If the room noise is too high even after the test signals increase in level, then an error message will be displayed warning the user that measurements can not be completed.

• After the first position is measured, MultEQ measures other positions in the room around the listening area. These do not necessarily have to be in each individual seat. The idea is to capture as many points around the listening area as possible so that the acoustical problems that affect the quality of sound within that area are minimized.

• For example, we recommend taking 3 positions on the couch facing the TV and then 3 more positions about 3 feet in front of the couch and parallel to the first three. Measurements up against the back or side walls should be avoided.

• Some loudspeakers have rather problematic responses when measured off-axis (i.e. more than 15° away from the imaginary straight line that points to the listening position). In these systems, measurements taken too far away from the center line will show a reduced high-frequency response that may result in overcorrection and thus overly bright sound. Although it is difficult to predict which type of loudspeaker will have these off-axis problems we have most often observed them in poorly-designed multiple-driver arrays that exhibit very high off-axis lobing. In these situations we recommend a tighter calibration pattern centered around the main listening position and making sure that the mic is not placed in extreme locations and certainly not outside the plane of the front main speakers.

Checking the Results

• Once MultEQ calibration is complete the results are stored in the receiver memory.

• It is important to activate MultEQ by selecting one of the target curves. This is not performed by default after the calibration is finished and must be selected by the user. In a THX system we recommend using the “Flat” setting that allows the re-equalization to work as intended. In other systems, we recommend “Audyssey” for movie playback and “Flat” for music playback. Unfortunately, the music industry does not have any mixing standards like the movie industry so some music program material may sound better with the “Audyssey” setting. “Front Align” also uses the Audyssey process, but it does not apply the filters to the two front loudspeakers. “Manual” is not an Audyssey setting and does not use MultEQ filters. It is a simple parametric equalizer and will be subject to all the limitations that come with parametric EQ.

• Small vs. Large speakers. This is the most commonly discussed topic by MultEQ users. The first thing to understand is that it is not a personal insult to your system if your speakers were detected as “Small”. It simply means, that in the room they were measured the – 3 dB point was detected at 80 Hz or above. This may happen even if the manufacturer’s spec shows that the speaker is capable of playing lower. In fact, there are several benefits at crossing the speakers over at 80 Hz that have to do with power handling and headroom in the bass region that will be handled by the subwoofer amplifier.

• The second most common question also relates to Small vs. Large. In the Denon receivers, MultEQ will designate as “Large” any speaker that has a –3 dB point below 80 Hz. For non-THX speaker systems this is an arbitrary definition that often causes confusion. All it means is that the speaker will not be bass managed unless the user tells it to be. Because Audyssey is not in charge of bass management, we have to abide by the manufacturers’ rules and simply report the information found by the measurements to the bass management system.

• In situations where the speakers do not play significantly below 80 Hz, an additional step must be taken to make sure that there is no loss of bass information. The user must set the speaker to Small manually so that bass management is performed properly.

• Polarity: MultEQ checks the absolute polarity of each loudspeaker and reports it to the user. This is simply a report and does not affect the subsequent calculations in any way. It just asks you to check the wiring to make sure it is connected properly to each speaker. Sometimes we get false alarms. This is usually because the speaker has a driver (usually the mid-range driver) wired out-of-phase intentionally to make up for some problems at the crossover region. If a phase warning is shown, it is not a cause of alarm. Simply check the cables and hit “Skip” if everything is fine. Again, this does not have any effect on the EQ results.

• Subwoofer distance: in many active subwoofers it is not possible to defeat the low-pass filtering. That means that the pre-pro bass management filters will be on top of the low-pass filters inside the subwoofer. The built-in low-filters introduce a delay to the signal coming in (because they have poles). This delay is seen by MultEQ as acoustical delay and is reported in the results. That is why sometimes the subwoofer distance is reported to be longer than the physical measured distance. The setting should not be changed because the blend between the sub and the satellites has been designed based on this time delay.

• The design constraints for MultEQ were that it (1) must fit within a small portion of the DSP so that other processes can also run and (2) it must use FIR filters because of the well-known artifacts that IIR filters cause particularly in the time domain response. As it turns out, these two requirements are contradicting. In order for FIR filters to be effective and capable of correcting to low frequencies, they must consist of several thousand coefficients (taps). The problem is that the CPU power required increases with the number of taps, hence the dilemma. What we did at Audyssey was to come up with a different way to partition the frequency axis so that we can use fewer taps and yet not completely give up on low frequency resolution (and therefore low frequency correction). This allows us to take a 512 tap filter that would normally have a resolution of 94 Hz (meaning that any peak or dip narrower than 94 Hz would be missed) and significantly improve its resolving power. The resolution of the filter actually varies continuously with frequency and starts at around 10 Hz. Does this mean that MultEQ can correct an arbitrarily narrow peak or dip at 30 Hz? Of course not. The reality is that in the MultEQ XT version found in receivers, we can correct broader features below 100 Hz better than narrow ones. For example, a lump that is half an octave wide at 50 Hz can be fixed. A narrow dip or peak that is 1/3 or 1/6 octaves wide and centered at 30 Hz will be improved, but not eliminated.

• The on-screen display in the receiver has very limited graphics. Therefore it is not possible to really show what the MultEQ correction filter is doing at all frequencies. It appears to only be operating on 9 bands like a parametric equalizer, but this is not the case. What is shown is a very crude approximation to the MultEQ correction and it should not be used to read exact values of cut or boost at the 9 frequencies shown.

• Furthermore, there is no display for the subwoofer filter. This doesn’t mean that there is no subwoofer correction. It was not added to the display because of interface and memory considerations.

[audyssey]

Hi Nick,

No problem. That would be very helpful.

Regards,
Chris

[longshanksdvd]

Chris,

Thanks for all your support, can you address the issue with how Audessey is not working properly when then denon receivers are being used as a preamp (i.e. seeing phantom speakers)

[audyssey]

Originally Posted by longshanksdvd

Chris,

Thanks for all your support, can you address the issue with how Audessey is not working properly when then denon receivers are being used as a preamp (i.e. seeing phantom speakers)

Hi,

I am not aware of any such issue. By "phantom" do you mean when feeding another amp via the line level outputs of the 3806? Please give me some more info about what set up you are using and what problems you are having.

Regards,
Chris

[longshanksdvd]

Chris thanks for the response.

I am running a 4306 as a preamp (connected to a 5 channel amp) and with 5 indentical M&Ks 150s (only speakers I have on the system-5.1).

When I run Audessey with 4306 acting as a preamp it finds rear surrounds which do not exist in my system and set them as well (complete with a different distance than the sides). It plays the signals through my 2 side surrounds including running additional signals for A+B together (all through the single set of side surrounds).

When I use the interal recievers amp It sees only the 5.1 set up that actaully exists.

What am I doing wrong.

i believe 2 others in this thread are experiencing the same.

[atdamico]

Originally Posted by longshanksdvd

Chris thanks for the response.

I am running a 4306 as a preamp (connected to a 5 channel amp) and with 5 indentical M&Ks 150s (only speakers I have on the system-5.1).

When I run Audessey with 4306 acting as a preamp it finds rear surrounds which do not exist in my system and set them as well (complete with a different distance than the sides). It plays the signals through my 2 side surrounds including running additional signals for A+B together (all through the single set of side surrounds).

When I use the interal recievers amp It sees only the 5.1 set up that actaully exists.

What am I doing wrong.

i believe 2 others in this thread are experiencing the same.

I use a 3806 as a preprocessor and have the exact same issue. It sees two side speakers that don't exist.