Seaton Sound SubMersive1 - Page 263

 

Yes - important point. FR is only part of the story.

 

Thanks for the clarification. I guess the headroom is a function of amplifier power. I have always made sure I have more than enough to give me all the headroom I can possibly need - I agree with you that it is important for dynamics in real content. I still can't see though why the OP has two graphs that look all but identical and yet hets such a disparity between the sounds.

BTW, now that I'm on my laptop and not my phone, it's easier to copy and paste and post so for those who missed my post about #5794:
As you can see, those were graphs of the full FR from 5Hz to 20kHz. Guess my memory is a little rusty. With my 40Hz crossover, the effect actually appears to begin at ~50Hz on down, but the important point is that both measurements are full FR and as is obvious, the differences above 50Hz are pretty much unimportant (I won't say non-existent as there are minute differences in the traces, which serves to show that they ARE 2 separate measurements, but for all intents and purposes, the differences are insignificant).

And to make it easier to find if anyone decides to search, I'm just going to add a bunch of terms that folks might use in the search engine

Submersive HP SubM graphs program 1 prgm 1 vs program 2 prgm 2 setting
REW graph
Program 1 vs program 2 tweak
prgm1 prgm2 house curve
Calibrate Audyssey with Program 1 then switch to Program 2 without recalibrating recalibration


Max

P.S. edited to add:

Also thought it would be pertinent to point out that Keith is using a 100Hz crossover in his setup with the measured results below, where I'm using a 40Hz crossover, but the Prgm 1 to Prm2 effect in both graphs clearly demonstrates that the effect is confined to the 50Hz and under region with no difference in the higher frequencies.

Net effect = Yep, Mark Seaton and his products ARE THE ABSOLUTE BOMB. What other sub out there not only has the power to be able to produce this, AND has such an easy means to create this house curve for deep bass lovers? That's right, NONE
Edited by djbluemax1 - 2/13/13 at 7:08am

Sorry,I don't follow?

It depends on the measurements and the display. If the display is too coarse significant differences can be visually minimized, and more likely, measurements limited to just the subwoofer can hide major interaction issues with the main speakers which would be very audible. Alternately, measurements of only the speakers and sub could mask significant differences in the sub response. While less likely, Audyssey could be doing something different in the time domain which would be minorly visible in a magnitude response but quite audible. This would be the least likely cause, but not impossible.

In the vast majority of cases this is handled by the surround processor's bass management. Unless otherwise noted, most use a 4th order low pass (24dB/oct) for the sub and 2nd order high pass (12dB/oct) for the high pass. Being that these are fixed for most processors except a few, that wouldn't affect differences being referenced.

I think he was referring to the "crossovers" on some subs. He likes to play around with those, even though he's also using the Bass Management in his receiver. Once again, he shows that he simply doesn't understand the adjustments he's making. His shotgun approach has gotten him to the point where is system is "Fouled Up Beyond All Recognition, (or FUBAR'd.) In another thread, he posted that after all his efforts, he can now listen enjoyably with the MVC at -60. He has obviously "fouled" up the calibration if -60 provides an enjoyable listening level. In my system, (which is properly calibrated for Dolby/DTS Reference Level), -60 is almost inaudible.

If he ever buys one of your subs, Mark, you need to go to his house and set it up for him... and then find some way to lock his system so he can't mess it up.

Craig

Wow, how many mod-deleted posts is it going to take?

Thanks Mark.

I don't have ETC's because XTZ doesn't do them. I do have some waterfalls, but they're different than what you're used to looking at. They're "2D waterfalls" with time on the X axis and frequency on the Y axis. SPL is depicted by color with purple being the same intensity as the original sound, red being 10 dB down, yellow 20 dB down, cyan 30 dB down dark blue 40 dB down and black being 50 dB down. Here is my 2D waterfall without Audyssey. (You can see the color scale on the right-side Y axis.)



You can see that at about 25 Hz, there is a lot of energy that resonates for a long time; it's red out to 100 ms, and still yellow at 150 ms. Also at 125 Hz, there is another resonance, but it doesn't last as long as the one at 25 Hz. In the small frequency response graph in the upper right corner, you can see the peaks associated with the resonances. I have circled them here for clarity:



The next graph shows the effect of Audyssey in the time domain:



Note that the resonances are significantly tamed. The 25 Hz resonance is shorter and it has significantly less energy. The 125 Hz resonance is virtually gone. Audyssey sets filter taps in the time domain and these waterfalls are direct evidence that it works.

It is easy to get used to the sound of these resonances, and to notice when they're gone. Some will say, "Audyssey killed my bass." Again, I say, "Not so... Audyssey fixed the bass." The detail and articulation that is allowed to come through when these resonances are removed is astonishing.

Crabalocker, did you get to take any more measurements?

Craig

No not yet, been busy at work and just got my ChromaPure and D3 meter. I'm going to be calibrating my W7000, see how that goes. I had my JVC X-55 professional calibrated and it looks pretty awesome. Hope I can do a half as good on the BenQ. When that's done I'll start the ugly business of Audyssey....I can hardly wait!

Brilliant. Thanks for that Craig.

craig john,

Isn't there a minimum level that energy should resonate to sound accurate?

Otherwise you wind up with the equivalent of an over treated room.

Obviously I'm not Craig, but I I don't know if that applies to bass. In my room, if I could get ZERO ringing in the lower registers, I would be happy. And at least one acoustician agrees with that since in his position you can never have too many bass traps -- that is Ethan Winer from Real Traps (at least that is what he told me). I'm sure other "acousticians" might feel differently.

First, we are talking about the bass response, which is dominated by the modal response in the room. What happens in a room above the "transition frequency", (the point where the response transitions from modal to reverberant), is a whole different discussion. The psycho-acoustics of the modal response are completely different than the reverberant response.

Room modes or resonances occur in a room when the wavelength of a soundwave is close to a room dimension. The soundwaves bounce back and forth between the room boundaries and they reinforce each other. These resonances occur over very narrow bands of frequencies, as you can see in the graphs above. When those narrow bands of frequencies are louder and they decay longer than the rest of the frequencies, they dominate the sound you hear. Instead of hearing all the notes with articulation, you hear everything as one note, the note of the resonance. This can sound boomy or muddy or sloppy. Removing the resonance allows you to hear every note with the same intensity, (SPL), and decay as every other note. This increases the articulation and detail of the bass.

I can't imagine that there is ever any benefit to having a small band of frequencies dominate the response.

Craig

Interesting you bring up Ethan Winer. In one sentence he will tell you that you need massive bass trapping to reduce modal ringing; in he next sentence he will tell you that Audyssey can't possibly do what it does... only bass traps can work to reduce resonances: http://www.realtraps.com/art_audyssey.htm

Now, admittedly, this was from 2007, using a version of Audyssey, (MultEQ), that has since been superseded twice, by MultEQ XT and XT32. XT32, which is the version I'm using, has 256X the filter resolution on the mains and 4x the filter resolution on the subs. Nonetheless, he hasn't taken this down, nor backed off this stance.

Just sayin...

Craig

Good posts Craig. I think what Ethan is getting at is that Audyssey can't change the room, and the room causes the resonances. When you pull down the peaks you have attenuated the resonsances as they are having less energy excite them. On your graphs you can see how the levels are eq'd down ~6db, and at 25hz it is starting out pink and after aud. is orange-red. This can be seen with manual eq devices as well such as here between the antimode and the bfd. I am sure you already know this, just putting it out there. Obviously room treatment combined with eq will give best results in the time domain.

http://www.hometheatershack.com/forums/electronic-processing-equalization-devices/11699-testing-dspeaker-anti-mode-8033-a.html#axzz2KkqHQN3y
Edited by Luke Kamp - 2/14/13 at 7:51am

Craig: I have the version of Audyssey that Ethan is referring to (in our family room) and it does little to nothing to reduce bass ringing. On the other hand, my guess would be that if I removed all of my bass traps (in my theater) my bass ringing would get worse.

But lest we forget, Ethan is in the business of selling physical product so room correction that reduces the need for that is not his friend. Plus, the "audiophools" (some of whom are Ethans prospects) don't believe in room correction (pure signal path and all of that).

I hope to have Dirac Live running on my server this weekend so it will be interesting to see how it does.

A good audio buddy just installed it and can't stop raving about. He also has Audyssey X32 on his Integra 80.3 so is familiar with it.

It makes sense, to me, that the less digital correction you need to do by first correcting the room with traps, absorbers and diffusers, the better digital processing should work.

I think maybe I'll try and measure the SubM without Audyssey or any other EQ and see if I can treat my room to correct the peaks and nulls that Audyssey might be over correcting then try Audyssey once again. Maybe this is a better approach.

Don't forget subwoofer placement and listening position optimization. Those is the most important determinants of the transfer function, (the transfer of the sound energy from the subwoofer(s) to the listening position.) Optimize your placements first, then run Audyssey.

And listening position is just as important as subwoofer placement. If your seating is against a wall, move it as far off the wall as possible. If it's in the center of the room, move it out of the center. These will make just as big a difference as the subwoofer placements.

Craig

Sorry, for the off topic post...
But do boom mic holders come with the adaptor or holder that will work with the audyssey mic?

Yes, it's a spring clip. Here's an example:

http://www.bhphotovideo.com/bnh/controller/home?Q=&A=endecaSearch&InitialSearch=yes&N=0&O=&Ntt=Microphone+Spring+Clip

Craig

@SOWK - Just in case you're asking if the boom mic holder comes with a low profile boom mic stand like I suggested in a prior post, then the answer is no.  You might want to consider investing a little more in something like this to provide greater flexibility with the Audyssey mic positioning as it threads directly into the Audyssey mic.  For something like an Omnimic, EMM-6 or UMM-6 mic, the adapter that comes with the mic can be screwed directly into the end of the boom arm.  Hope this helps.

 

The problem with 'bass traps' as usually described is that they aren't really any such thing - they are broadband absorbers and they do next to nothing for the very deep bass frequencies, say 30Hz down. If you have persistent ringing there it is very hard to eliminate, as I have found myself. This is even more so if you have a small room like mine, with limited placement options for *everything*.  For example, it's a good idea to move the seats away from the walls and a bad idea to have the seats in the centre of the room. In my room, you don't need to move the seats very far from the wall and they ARE in the centre of the room :)

 

I am investigating what can be done about 20-30Hz ringing but I am not optimistic and may just have to live with it. It looks worse on waterfalls than it sounds to my ears.

They actually have almost no effect below 80Hz. Make sure it's broke before you try to fix it. If you haven't made waterfall charts of your in-room response there's no way of being absolutely sure of what's going on. Even if you have response peaks that doesn't mean you have ringing at those frequencies. If do you have very low frequency ringing the source is most likely the flexing of the room walls, floor and ceiling, and you can't realistically do much of anything about that.

 

Indeed. I have graphed the response in REW using waterfalls. I have no problems until I get down to about 30Hz, which isn't so bad, then more at 20Hz or so, which is, as expected, worse. My main problem is my room - it is too small, a bad shape and offers little room for alternative placements of speakers, subs and seats. Unless or until we move house, I just have to live with it. I guess we all make compromises. I am fortunate that even in this crappy room the SQ is better than I woud have hoped in my wildest dreams thanks to good quality speakers and subs, room treatments and Audyssey XT32. I just wish I could deal with that very low end problem. Actually, it graphs worse than it sounds. 

Unless I really missed something in your posts , KB, small rooms don't have to sound bad. I mean unless you have a WAF, treatments should not be an issue either. I have 8 treatments in my 9 1/2x12 1/2 x8f room. That plus proper speaker placement and XT32 has given me fantastic sound. I have treatments hanging on the all and the ceiling. Trust me, I did not want to do it and then when I did decide to do it I was only going to put 4 up. But after talking to a number of people, I ended up with 8. If you can't take pictures down for some reason or another, then you are just left with what a RC system can do for you. But my room went pretty far just with treatments. Even with my chairs very close to the back wall which I know is a no no. I could tell right away just by listening and looking at some measurements. With treatments and EQ, my combined FR is not too bad(sub is really flat). Plus it sounds really good. Craig can confirm this since he was the one that did all the EQ'ing. Don't let the fact that you have a small room make you think you are destined to have bad sound.

A poor crosssover can make you a bad sound.

How about solid concrete bunkers, all 4 walls , floor and ceiling solid 10-12" concrete?