The Audyssey Pro Installer Kit Thread (FAQ in post #1) - Page 74

Thanks for this insight. I have a room with 70hz axial mode(s). My mains show this strongly. The dual sub response far less so. They are on side walls.
I just raised the xover of my mains up 10 hz to 70 hz (previously at 60 1st choice) to decrease the mains interactions with this mode. Guitar and bass seem to be more articulate.

80 hz is a third choice . I may go there next. I do not know the characteristics of the xover slopes so I do not know how much the contribution of the mains has been decreased at 70 with the xover at 70.

Room 11.7x16x8.

^^^

you are welcome...

iirc, most avr's xovers are comprised of second order high pass and 4th order low pass filters... but i could be recalling incorrectly... edit: i did. see post 2195...

Same for both sub and mains in modern avrs? I have an integra 80.2

I probably shouldn't even be commenting here because I can't see the graphs, but when you speak of "ringing" are you talking about bass decay graphs or in relation to the FR curve? AFAIUI, they are different things. Regardless, I mention it only because I have been curious about the effectiveness of Audyssey on bass decay AKA "ringing" and I think looking at both the bass decay and the FR curve during optimization may lead to discovering the combination of sub positioning and distance tweaks that are most amenable to Audyssey correction. IOW, different combinations of sub positions and distances that result in similar "pre" Audyssey FR graphs may result in differing post Audyssey bass decay graphs. Or maybe not. I only mention it since I see so little in the way of before and after bass decay graphs that I haven't been able to come to any conclusion one way or the other.

Edit: in fact, since using this forum app I see so little of ANY graphs anymore

a quick measurement of my a100 (1/6th smoothing for clarity), would indicate i recalled backwards...



sure looks like a 2nd order low pass and a 4th order high pass to me... not sure if that holds true for your integra...

That is,ore or less what I wanted. Sounds crisper so moving the xover up 10 hz seems to have decreased the coupling with my axial modes. Thanks for the advice.

Question is why xt 32 chose. 60 1st with 70 2nd given the room modes . Perhaps it decides it can equalize the region so it doesn't matter.

That would be a question for "Ask Audyssey."

Jeff

I look at it this way. Audyssey is looking for the best crossover, so it would want the axial mode out of the crossover. At 60 Hz that mode is not in the mains contribution to the crossover at all. As you move up from 60 to 70 Hz you have now moved that mode into the crossover. Go up to 80 Hz and now the tail of the mains contribution to the crossover will have that mode in it. Since the sub is not impacted by the axial mode, with the crossover at 60 Hz it is the tail of the sub's contribution at 70 Hz that will pass through the crossover. Bottom line, better crossover.

But maybe not better FR curve

Edit: reworded for clarity(I think)

That makes sense.clearly careful listening will be required to choose the optimal. However, I will try some room treatments first to see if I can tame the mode a bit. Then rerun audyssey pro etc.

Good idea, that's always the best way to do it.(treatments)

the conclusion that i am starting to come to is that the logic for choosing the xovers in pro isn't as robust as we might want to hope it is...

Never chirping a main channel with a sub would seem to be a weakness of the system as their interaction at the splice is not evaluated, but that I'm sure is a limitation of the receiver/processor.

Jeff

I think you are right. But, as a practical matter, I think there is more to what sounds best than just frequency and time domain response. There is also distortion, dynamics, power handling, etc. which are issues unknown to Audyssey. Assuming a good sub or subs, I think it is usually best to err on the side of a higher xover frequency, allowing the sub to handle more of the frequency spectrum. Even with XT32, you usually cannot go wrong with just setting everything to 80 Hz or so, even if the other channels can go lower than that.

That is still my recommendation ... regardless the manufacturer's specs.

Jeff

^^^

can't agree more... imo/ime, it's a very rare situation where crossing any lower than 80hz is beneficial...

I would only like to crossover lower for 2-channel music.

Do you listen to music without bass management/mains on Large?

@ccotenj (or anyone else who cares to comment).

Chris, I promised to upload a graph of the other listening seat for your perusal. Here it is, with one of the MLP taken at the same time (both graphs 1/24th smoothing):

First the MLP:



Then the other seat:



You can see how my maximising my Pro mic positions around the MLP makes a difference! If I cared about the sound in that seat I would have to adopt a more neutral mic placement policy. I may do a Pro reading with such a policy and see how it affects the MLP. It might not be too bad in which case I may as well go for a decent overall result.

I also promised you a waterfall - here is one from the MLP taken with the same mic position as the first graph above. I would welcome your comments and interpretations of this please.



Thanks, Keith

I use the Stereo mode on the 5509, so I'm stuck with the same settings for movies - as I don't want to faff around. A music mode would be good (like I used to have on my Arcam) or at least a user preset option which can be changed at the touch of a button (like I used to have on my Yamaha). It's one of the few things that I wish was a bit different on the Onkyo. But having said all of that, I'll soon be back to 2 decent Subwoofers and probably won't be bothered.

Keith,

I am not familiar with Omnimic ... are those milliseconds on the scale on the bottom right that are to indicate time?

Jeff

Hmm. I think so Jeff, but now you mention it there were several different sorts of waterfall to choose from and I wonder if I chose the wrong one? I'll get the laptop out later and fire up OM and have a look. If Chris is around he uses OM so he can probably answer you immediately. I am still very much a novice with OM - although it is incredibly easy to use. It's interpreting the graphs that is the difficult part for us noobs.

Here is a waterfall from a relatively well-behaved room. There is some stuff at the lower frequencies that ring, but nothing like what you've got happening at the top end. From the graph, you room not only rings, but it seems to be ... adding it's own noise up there?

BTW, my question was semi-rhetorical as the scale is always milliseconds ...

What I was referring to your room "contributing" is where marked. The red circled area is sound that decayed below the threshold and the green is where it ... came back up .. for some reason.



I am not an acoustician .. but it strikes me that this is very high frequency and that area usually is absorbed toute suite with the area below Schroeder ringing on. Puzzling.

It's more than likely that I fubarred the graph somehow. The room is relatively inert - it has a thick carpet, an even thicker rug, heavy drapes that fill two thirds of the back wall, two big cinema chairs in suede leather that occupy a significant percentage of the total room volume and the walls are sheetrock on timber. I can't imagine it ringing too much at the top end, but....

Here in orange is the area that puzzles me. Without that, your room pretty much decays like many residential spaces.

I thought the graph looked strange at the bottom end too - not like any other waterfalls I've seen. I bet I cocked it up. I'll have another go tomorrow when Mrs Keith is out of the way.

I'd say that the mic was measuring *something* - what could it have been? Is there anything that would be introducing electomagnetic or RF interference into your laptop and/or measuring system?

I am inclined to interpret this graph as having the area that always rings .. below 400Hz-500Hz .. to be truncated for some reason. Look at the graphic representation of sound decaying to baseline elsewhere and then look at the region below 400Hz. Chopped off ... like that 5K - 15K stuff where time ... "expired."

Actually, the z axis unit of measurement in Keith's waterfall plot is not milliseconds. It is cycles, which are frequency dependent (e.g. 10 cycles at 100 Hz is equivalent to 100 ms, while 10 cycles at 10 kHz is only 1 ms). That different z axis scale is the reason why Keith's waterfall appears wonky in the upper octaves.

AJ

Yeah. Let's assume it's fubar. I'll try again tomorrow. Nothing I know of that could be causing interference of any sort.