"Official" Audyssey thread (FAQ in post #1) - Page 1951

Thanks for supporting.

I do use the sub, and always set speakers to 80 Hz, but even with this setting the intermodulation distortion of high frequencies was so boring, that took me to investigation. I already described even before I started the measurement that I hear loud vibrating high frequencies when I turn on Audyssey. It boosts highs to some extent too, but this alone is not telling why it sounds harsh and distorted with the signs of clipping. This low frequency boost is describing everything I hear, this is common that boost in this range produce intermodulation, increases chances to get into clipping and basically it is how it sounds - harsh and vibrating, and distorted sounds are known to be perceived even more loud than they are.

So, it is a huge problem even when the sub is present, while setting the crossovers higher evens the sound a bit, it still doesn't make it good, it still sounds much worse than without Audyssey in the same conditions, except the killed room resonances. When the sub is not present - I wouldn't even want to think about what could happen with speakers on high volumes. And for people who have speakers that have -3 dB point at 80 Hz and above - they also cannot escape that by moving crosses higher. And I have such speakers at surrounds!

If your speakers exhibit "intermodulation distortion" run full range, no sub, no Audyssey, than I'll buy it. Otherwise either there's another problem . . .

IM is typically measured using very high frequency signals, because it provides a clearer picture of IMD. Stereophile uses 19Khz plus 20 KHz to set up a "punishing" IM distortion test. FWIW, I don't think I could, by listening, distinguish IM from THD unless I knew the incoming signal was a sine wave (single frequency so nothing to intermodulate . . .) I have come to believe that with complex signals (a note with overtones, or more likely multiple notes with multiple overtones) the distinction between THD and IMD is of vanishingly little importance. While to my ear a guitar amp on the edge of distortion distorts more when I play multiple notes rather than just one, how much of that is due to the added input level versus differences in distortion generation between one note with its related harmonics and multiple notes with harmonics not mathematecally related to those of any other note? IDK. I don't know that anybody knows. Although maybe if you could take apart the processing of something like the Kemper Proflilng amp, maybe you could begein to segragate the effects . . .

 

Ah hah, now I understand.  I agree with you completely that it is very important to make sure that the sampling rate on the soundcard and the REW configuration match.  It is quite easy to have the soundcard at 44.1Khz, and REW at 48Khz, or vice-versa, which would result in false measurements.  As long as both the soundcard and REW are set with the same values, it doesn't matter which of the two sampling rates one chooses.

Exactly!

I'm glad we avoided the cliff of international misunderstanding.

Unfortunately I cannot find a recording where it happened. I don't remember anything about what it was... I should have been noted the name, but I didn't. It was some kind of high-freq. bell, very clear one, practically pure tone. Turning the Audyssey On immediately made it vibrating quite heavily, I am quite sure it is the IMD, modulated by some very low frequency (there was also very deep bass note playing in parallel, basically it was only those two long notes). Sure it is hard to tell something from more complex signals, and on all other recordings I am hearing high-freqs just as "dirty" compared to no-audyssey case. And generally if the content playing is not complex, like bass only or middle-range and high-freq only - it sounds quite clear.

Anyway, there might be something more, the Audyssey is already working incorrectly, so what is hidden behind is unknown. But we have no other ideas at the moment, while the one with intermodulation+clipping caused by the low frequency boost (combined with over-boosting high-frequencies) pretty much can explain everything what I hear. And in full-range the sound also not as clear as with 80 Hz crossovers... It is pretty much understandable, this is why we have 500W and above amps in sub-woofers, the energy in lowest frequencies is highest, and it is much less load to the amp when those frequencies are cut out from the signal it amplifies.

19kHz + 20kHz is used as a standard because first, it is at the end of the audible range where usually the effect is largest (assuming flat freq. response), and 1kHz difference is just for easier reading of the results. It will not always/usually show the worst results across the range, it is just a standard, so we can compare different systems. The effect of intermodulation is often heard when high-freq signal is modulated by significantly lower-freq signal, but measuring it in this way is much more complicated, you cannot just look to the spectral analysis graph and find two very close peaks, and other products of IMD, so the measured and input frequencies are interchanged so the products of IMD is far from the heavy amplitude signals. It is how I understand it.

If something is significantly boosted then those frequencies in input will always show the worst THD and IMD as it is closer to the limits of the amp or speaker or whatever, same as just measuring with higher level signals. And when I listen not-so-loud the distortion is not-so-apparent and the "clipping bits" disappear. With very low volume there is not so much difference with Pure Audio in distorting part of the problem if I correct the tonal balance of Audyssey with tone controls, but it still not as good, but as was noted - Audyssey is already proven to be working incorrectly in my case so there might be myriad of other lesser problems caused by it. No reason to make more guesses, will try another mic. and if it doesn't help and show good graphs - will deal with Onkyo further.

I wanted to post about an issue I found with my receiver today and see what you all think. Here's some background:

Denon 2312 receiver (MultiEQ XT)
2 x PSA XV15

Standard bass management receiver settings (80 Hz speaker crossover, 120 Hz low pass, speakers set to Small, Subwoofer level is at -1)
Sub gain is at 12:00, crossover disabled, phase at 0 on both.

Here's the issue. I've had the subs since October, but only recently started hitting them hard with the movies. I noticed with several movies (The Dark Knight Rises and War of the Worlds) that the subs sounded like they were bottoming out during strenuous bass scenes. At first, I went back and for with Tom at PSA thinking the issue was mechanical, but for the hell of it today I disabled Audyssey, gain matched the subs to 74 dB with my spl meter, and the problem completely went away. The scenes that were bottoming out my subs now sound great.

A little Google reading showed that a similar issue was discovered with Denon receivers back in 2009, but this issue was remedied by having the DVD player decode the signal and pass it to the receiver as PCM. The issue was caused by the receiver double boosting the bass when it received a bitstream signal. I tried this resolution in hope that it would fix my current issues, but it didn't. (Thread reference: http://www.avsforum.com/t/1177104/warning-for-denon-owners-your-xx09-x89-avr-may-have-a-major-bug)

This is the sum of my dilemma. I rather enjoy my receiver and I'm not thrilled with the idea that I can't use Audyssey due to it making my subs sound terrible. If anyone has any idea how to remedy this, I'd appreciate the guidance.
Edited by Lylelljr - 12/28/12 at 6:53pm

Just to exclude most basic things from the equation. Is there any chance you have changed levels of any speaker or sub gain after you've done calibration with Audyssey, so is everything untouched after it?
It is hard to believe you've got -1 dB level from Audyssey at 12:00 sub gain position, or you are very lucky.

@ LyleIIjr,

Your description of the subs bottoming out during heavy bass scenes in the movies is an indication of one or both subs being over-driven. This type of problem is difficult to analyze without digging a little deeper.

If I were analyzing the problem, I would start over. First of all, since you have two identical subs, I would gain-match them. To gain-match the subs, place the SPL immediately in front of the dust cap on the sub's speaker, pointed at the speaker, and adjust the sub gain to 90dB (which I find is a good value to start with). Do the same for the other sub, carefully adjusting to the same 90dB value. Since you are using MultEQ XT, the best results will be if the subs are placed in the room such that they are equidistant from the MLP. Hopefully you experimented with various placements to achieve the smoothest bass at the MLP, with the subs at the same distance.

Now, with the subs properly placed and gain-matched, re-run the Audyssey calibration. When it finishes, check the sub trim value. It should not be at either extreme (-12 or +12dB). If it is, then the 90dB setting during gain-matching was incorrect, and you need to start over using a higher or lower value until the post-calibration trim is at a reasonable level.

Now try the movie passages again to see if the bottoming-out has improved, or hopefully disappeared. The gain-matching procedure ensures that both subs are contributing equally to the bass output, and that one sub isn't running out of steam during the heavy bass scenes.

-1 dB is with a +3 bump - I knew I left out some minute detail.

And as for the gain position on the subs, there has been a good deal of discussion about this on the PSA thread. Their gain works a little different than most subs. I've got 2 subs, equidistant from my main seats in a 3,000 cubic foot room, and my main listening positions are about 14 feet from the subs.

I just remembered one more oddity that I came across while talking to Tom. After Audyssey calibration, my speakers were all reading around 74 dB on my Rat Shack meter. However, my subs combined output only read 70-71 dB on the meter with the level trim at -1. Seems a little odd, but what do I know.


Thanks for the help.

@AustinJerry

Both subs are gain matched at 12:00 on the dial. I've covered most of what you are asking about in my posts and went over it with Tom at PSA. He's certain I'm not over driving the subs with these settings nor my normal listening level of -15 to -12 on my Denon.
Edited by Lylelljr - 12/28/12 at 4:13pm

i just got an apple tv, it plays tv shows, movies via netflix and i can also play music , what do u think i should set the reference level for this device to? because it plays both music and movies.. ?

Well, in your first post, you said level-matched, which to me implies that you measured the sub outputs with the SPL at the MLP.

Can someone weigh in on XT32 and its results on Horn loaded subs ? Specifically I'm about to pull the trigger on a lilmike lil-housewrecker Tapped Horn diy sub.

Lilmike and others have suggested using a minidsp to tame the peaks and to set a high pass filter at 15hz.

I'm wondering if the peaks can be tamed with XT32 on its own ?

I was told the following "To do a tapped horn right - it need's moderately high Q filters to kill the upper resonant peaks."

I will be crossing the sub over at 60 or 80hz. Does XT32 have the ability to kill those peaks or should I tame it with a minidsp and then run Audessey ?

Fair point, I just got the terms mixed up. Original post is fixed, thanks.

Edit:

I did a little testing tonight and confirmed that if I run Audyssey with both subs engaged I get the bloated bass that bottoms out my subs during select passages. I tried running Audyssey with only 1 sub engaged, turned the other sub on afterward and adjusted the level trim by -3, and now everything sounds great. Deep, thunderous bass with no horrible rattling sound. So obviously something was going on with the levels Audyssey was setting when calibrating with both subs. It's probably not an optimal solution, but it's better than buying a new receiver at this point.
Edited by Lylelljr - 12/28/12 at 11:18pm

 

REW does seem very complicated to use - I wonder how many people have it set up incorrectly?   It is way too complicated for me which is why I use OmniMic - none of these tricky setup things to fall foul of.

 

Help me get my head around it - for the simplest possible test, are you saying that if you play the relevant scenes with Audyssey ON and then, without touching anything at all, you replay the same scenes with Audyssey OFF, you 'fix' the bottoming problem?  If so, then it is Audyssey causing the problem by, it seems, applying too much boost to the bottom end (a subject that has been discussed many times).  Also, please confirm is Dynamic EQ is on or off, and if it maks any difference wrt to the problem.

 

No matter how many times you ask this question, nor in how many places, the answer will always be the same: because there is no standard for music mixing, there is no 'correct' setting for Reference Level Offset. You have to experiment and go with what suits you best.

I agree completely. Every time I used REW I had to learn it again. Combined with having to provide it with a calibrated mic and phantom power supply or mic pre-amp made it a PITA.
Edited by Theresa - 12/29/12 at 5:03am

 

Yep. I'm sure that, if I applied myself, I could eventually learn how to use it, but I can't see the need. OmniMic might not be as fully featured as REW, but it does what I want. One cool feature I like in REW and which I wish Bill would add to OM is the ability to measure once and then see all sorts of different graphs based on that measurement. OM is bulletproof though and has far fewer ways to mess up, which for a measurement novice like me is a godsend.

Yes REW is more full featured but that comes at the cost of being complex. I just wish Bill would come out with the multi-channel test tone DVD, I know its in the works but I'm feeling impatient.

To answer your direct question, yes turning Audyssey off made my subs stop bottoming out. I tested Dynamic EQ to see if it was the cause and it made no difference when it was on or off.

Here's what I stumbled upon last night with a little more testing:

Tonight I confirmed that if I run Audyssey with both subs engaged I get the bloated bass that bottoms out my subs during select passages. I tried running Audyssey with only 1 sub engaged, turned the other sub on afterward and adjusted the level trim by -3 (-6 gain for the 2nd sub I get in room and +3 for a little boost), and now everything sounds great. Deep, thunderous bass with no horrible bottoming out sound. So obviously something was going on with the levels Audyssey was setting when calibrating with both subs. It's probably not an optimal solution, but it's better than buying a new receiver at this point.

I agree with you, Teresa. However, the fact that there is a quality, individual calibrated mic involved with REW could be looked at as a plus. Has anyone ever "measured" an Omnimic against a known standard? Are the Omnimic's mics individually calibrated, batch calibrated or not calibrated at all? Does it matter?

Jeff

May be you have chosen wrong positions for the subs, so Audyssey tries to do more aggressive EQing. It is very important that when you use more than one sub they are positioned to even the frequency response in the room, but wrong choices might make the situation worse than with just one sub. It would be very good if you can do acoustical measurements and find the best positions for subs based on that.

Edit: And you have continuous phase control on your subs, this will also help to match them in the room based on measurements.

Electrical measurements are quite easy, and will show right away if there is some heavy boost somewhere.
Edited by IgorZep - 12/29/12 at 8:15am

Sounds like you need a High Pass Filter (HPF) between the receiver and your subs. This is especially true if your subs are ported.

 

Individually calibrated, high quality mic.

Agreed. I don't know if he has any measuring gear though.

As several have mentioned, sub placement may be a factor. An interesting exercise would be to reverse the test you describe above. By that I mean, run Audyssey with the other sub engaged and see if the result is the same.

Hey guys,

I use REW and honestly, it couldn't be easier or more robust.

The newest version, which is of course also free, now has support for Plug-N-Play USB Mics.

You can get an individually calibrated USB Mic from Cross Spectrum Labs for about $99 shipped and there is no pre-amp, phantom power, etc needed.

So there is only one piece of equipment to buy, the mic, and it's plug-n-play, the software is free, and as mentioned in a post above, you can take one measurement, one time, and then manipulate it any way you want to get any data out of it you want and until you learn (there are several threads that go into detail about how to read and interpret each chart/graph) you can also share the measurement file so more experienced folks can manipulate it and analyze it with standard graph settings that most of us use.

You can literally plug the mic in now, tell REW which USB Mic you're using, and take a measurement in less than 5 minutes for less than $100 with an individually calibrated mic.

IMHO it doesn't get any better than this and it's by far the cheapest and most robust solution.

--Jason

Jason, that's really a great post. $300 for Omnimic is too rich for my blood and I was always put off by the complexity of components needed for REW, but $99 and plug and play may be just the ticket! Do you have a link to the USB mic to which you refer?

I'm sure these issues have been addressed in this 2000 page thread, but it's a lot of info to go through to try and find it. I hopefully will use these audiophile adjectives correctly but no promises. Since running audyssey my speakers sound harsher.. I get listening fatigue rather quickly.. maybe I would say the tweeters sound a little too airy? Is there any way to tame that down? Overall things sound better. When I turn audyssey off the sound stage shrinks and things lose their sparkle so I don't want to turn it off altogether. I feel like audyssey jacked a certain band of the audio spectrum a little higher than I personally like. It's a Denon 1713. I can't find anywhere to make minor adjustments.

My second issue I don't imagine there is much to do and it's just a condition of placement, but I figured I'd ask anyways. My subwoofer sounds best (by that I mean loudest) when I stand in the rear corners of the room. I can't move it because of WAF. Is there anyway to work audyssey magic to help make the subwoofer sweet spot in the same place as the speakers sweet spot?

Thanks Fellas.