Why do so many automatic configuration systems set centers/rears to "large"? (1 Viewer)

[LanceJ]

Besides HTF, I've never been a member of any other dedicated HT forum. I stopped posting at both AudioAsylum & AudioReview (their new format drove me nuts) more than three years ago.

Why anyone would need to personally insult each other over *entertainment* electronics is beyond me.

 

[Andrew Pratt]

Agreed Lance.

 

[Kevin C Brown]

OK, I actually think this should be easier than it is. (And I proposed it to a company that already does auto EQ. Will see if anyone ever does it. )

Some of the questions that could be answered are:

1) Large vs small
2) Crossover freq
3) Phase

For auto EQ, a receiver or pre/pro has to have a mike. It plays tones through your speakers, and then listens to the tones. So ... all it has to do is freq sweeps for each speaker, say 20 Hz to 200 Hz. Because it knows what the original signal looks like, it can compare the signal it's "hearing" back from the speakers through the mike. I.e., it can tell how much distortion is added. So if a speaker is rated to say 80 Hz, - 3 dB, it would almost definitely see the roll off too. So ... large vs small. And then it *should* be able to pick a good crossover, because it could look for distortion added to the signal as the speaker has more and more difficulty reproducing lower freqs.

As far as phase, it does freq sweeps through the *applied* crossover for each speaker to the sub. The phase is the best when either you get:

i) the maximum output of the speaker plus sub combo (max constructive interference)

ii) the flattest freq response measured through the crossover freq of the sub plus speaker

So in essence, you're setting the phase of the sub wrt the speakers.

Doesn't seem like rocket science to me...


Andrew- You now have the Sherwood pre/pro. I will have to remember that.

 

[LanceJ]

Kevin: those sound like good ideas. Do you know if such a system would need a high-speed processor chip to analyze the waveforms? I'm just wondering because while it's common now for a $500 home computer to have a 2gHz Pentium, would such a procesor be cost prohibitive in a sub-$2000 receiver/preamp?

 

[Andrew Pratt]

I've got a dialog going with Jeff Hipps at Sherwood regarding some of these questions and I'll report back what I find out.

 

[Bobby T]

Excellent discussion. I would like to add a sidebar.

Why do auto calibration systems set the sub distance farther away than it really is. I know at least the Yamaha and Pioneer
auto setups do this. My Yamaha sets the distance 2 feet farther than it actually is. I left mine set this way as it sounds good. But I wonder what the reasoning behind it is.

And for the discussion the YPAO on my Yamaha 4600 sets all of my speakers to large and crosses over at 60.

 

[Kevin C Brown]

Lance- I know that PC audio programs like ETF5 can already do this stuff. The trick is integration with a receiver's or pre/pro's "operating system". And then the user interface.


Ahhh, because there are 2 ways of getting the phase correct between a speaker and a sub. One is to have a phase knob or switch on the sub. The second, which does exactly the same thing, is to vary the distance setting. So ... when a receiver sets some wierd distance for the sub, all it is presumably doing, is optimizing the phase for the sub wrt the speakers. But then if you go a step further, having the signal *time aligned* between the sub and speakers is a different beast that most receivers probably don't check for...

 

[Bobby T]

But the YPAO on the 4600 does a phase check also, or the phase can be set manually. Not disputing you Kevin. What you say makes sense. But the YPAO does the distance/time alignment and phase check for the sub and all speakers. That's the reason for the question, why both.

 

[LanceJ]

You mean like connecting the computer via a USB cable or something to the receiver on a temporary basis, so then the receiver wouldn't need all that processing circuitry? And the manufacturer could supply the analyzer software via a download from their site. Then you just need to add a good microphone (and soundcard of course with a mic input).

 

[LanceJ]

Cool.

Meanwhile, people can check out this report on Denon's auto setup system over at Stereophile's site. I didn't know this article was going to talk about this issue until five minutes of reading into it.

And I still don't understand why six cables is considered by many to be such a big deal. :frowning: But since I don't believe in *exotic* cables, maybe that's the difference.

 

[JeremyErwin]

6 analog cables. And if you want to apply equalization, those analog sources need to be converted back into digital, run through the DSP, and converted once more into analog for amplification, with all the attendant possibility of errors.

Besides, it adds to the rat nest.

 

[Kevin C Brown]

Bobby- There is phase between the speakers of your HT, and phase between the speakers and sub. That distance setting to the sub is an alternate way of setting the phase to be correct between the sopeakers and sub.

Lance- I mean integration of RTA-type software *within* the software of the receiver or pre/pro. How to do that, and then how to make its functionality easily accessible to the user. GUI, ergonomics, and all that.

 

[LanceJ]

You're right of course.

But until more receivers start including hi-res PCM & DSD DACs with bass management systems accessible via the Firewire method*, I think any potential - and very probably very subtle - problems with an extra analog > digital > analog step are compensated for by the very audible advantages gained by fixing the EQ, phase, etc problems that an automated system offers.

Kevin: O.K., I see watch you're saying.

* and seeing how crummy 5.1 music sales are, I don't see this happening anytime soon. :frowning:

 

[Bobby T]

Sorry Kevin I wasn't clear. The phase on the 4600 is a sub phase. That's where the mystery lies.

Lance I should have listed my speakers, that would have helped
mains Klipsch RF7
center Klipsch RC7
surround Klipsch RS7
surround back Klipsch RF3-II
Pioneer 59Avi connected via firewire
B&K Ref 200.5

 

[LanceJ]

Bobby: wow now I can see why your receiver classified all of your speakers to large & with that 60Hz xover, especially the front three!

I'm really starting to think *most* movie soundtracks are mixed so they don't include low bass in anything but the LFE channel, and that to avoid any potential electrical problems (filter phase issues, etc), b.m. is only used when neccesary.

 

[Bobby T]

I think you may be right on that Lance. Right now I have my fronts, center, and surround back set to large. Crossover at 60 and bass out to front+sub. So far this has sounded the best, especially on music. And really noticeable on multichannel music such as SACD.Bass heavy movies such as the opening of Star wars 2 aotc when the ship flies over sound great. Not to much bass to the fronts, and plenty to the sub.

 

[LanceJ]

Yesterday I emailed Pioneer, Yamaha and Denon concerning this issue and included a link to this discussion.

And just to cover the bases, I also did the same with a few organizations that deal with soundtracks. I quickly realized Warner Bros., Universal etc don't provide conviently available email addresses for people like myself, so I had to (almost) randomly choose organizations to contact:

The Cinema Audio Society

Post Plus Sound, Inc.

Abbey Road Studios (yes, the one in England)

The THX people.

Independent Feature Project

And I just sent one to Genelec, a hi-end studio monitor manufacturer that also builds home HT gear. FYI: for the tradionalists out there, in addition to conventional HT systems, they also build old skool "box" speakers, including one with a 15" woofer. But they are all internally bi or triamplified designs, so no large outboard power amp is needed.

I doubt most will reply, but that's why I asked so many.

 

[Brian L]

If anyone is so inclined, the current WSR (has Zathura on the cover) has a transcript of a conference held during the last Home Theater Cruise.

The subject was the call for a standard for MC music mixing. On the panel were several heavy weights, including Elliot Schiener.

Very fascinating reading. Lets just say that these guys were less than kind to their host. Gary took a couple shots to the chin regarding some of his beliefs, that's for sure. Lets just say that the industry as represnted by these dudes don't subscribe to Gary's "holosonic" approach for MC mixing.

Brian

 

[Kevin C Brown]

I have read, and am familiar with Gary's views. But he upholds the 5 identical full range speakers equidistant from the listening position approach. Which I think is completely untenable for most people in most rooms. There has to be allowance for different distances (this *is* what delay and time alignment is for after all) and crossing over from less-than-full-range speakers to a sub. Both of those things can (and are) successfully done today.

Plus, let's say I'm a music engineer or producer. And someone tells me that I have to adhere to some "standard" for mixing multichannel music. I'm going to say, nope, I'm going to do things my way for how I want my recordings to sound to the people who I think are going to buy them and listen to them. There aren't any "standards" for 2 channel stereo, and I don't believe that they are necessary for multichannel either. There are quite a few good multichannel music discs out there now, which were mixed and produced in the absence of any "standard".

 

[Bobby T]

Equipment manufacturers need to implement firewire or hdmi for multi channel audio in more pre/pros, receivers, and source components. Then time alignment and bass management could be done by the proccesor. As well as applieing DPL2x, Logic 7, or THX music modes.