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"OFFICIAL" Pioneer MCACC thread - Page 160

post #4771 of 5311
I would expect the signal to the sub to be rolled off. The question is as splotten asked: over the crossover, is the LFE signal sent to the L/R channels, or simply lost? When I ran my test years ago using a broadband (or swept, forgot which) LFE source, my other AVRs (Sony, Denon) sent LFE frequencies over the crossover setting to the L/R speakers but my Pioneer discarded the signal (no output on the L/R channels). I actually measured at the preamp outputs, not speaker outputs.
post #4772 of 5311
The mains were still connected, so yes, everything above the crossover was discarded. I tried the subwoofer "PLUS" setting as well with the same result.
post #4773 of 5311
Thanks rader, seems like they have not changed their LFE implementation.
post #4774 of 5311
Wouldn't the correct way to do the test be turn off the subs, leave the mains on, set the xover as low as possible (50Hz) and send a LFE signal out and see if any sound comes out of the mains??

Here's a picture of a mains/subs test, and LFE test from 0-200hz. You can see the LFE is boosted as it should be, but also continues on past the xover into the mains.

post #4775 of 5311
Quote:
Originally Posted by rader View Post

The mains were still connected, so yes, everything above the crossover was discarded. I tried the subwoofer "PLUS" setting as well with the same result.

OK. Thanks for posting. Do you actually notice the sound changing when moving the cross over up and down? I would think that the discarding of the upper end of the LFE channel would have some audible effect, but maybe im just make a fuzz over a small issue?
post #4776 of 5311
Quote:
Originally Posted by pdxrealtor View Post

Wouldn't the correct way to do the test be turn off the subs, leave the mains on, set the xover as low as possible (50Hz) and send a LFE signal out and see if any sound comes out of the mains??
Sorry, I don't follow. If turning off the subs affects whether bass is redirected to the mains, that surely is no help to those of us using subs? Or do you mean turn off the sub amp itself, not disabling it in the receiver?
Definitely no sound coming out of the mains on my setup when sending direct to the LFE channel, you can see from the measurements how it drops like a rock above the crossover. Looks like 24db/octave.
Quote:
Originally Posted by pdxrealtor View Post

Here's a picture of a mains/subs test, and LFE test from 0-200hz. You can see the LFE is boosted as it should be, but also continues on past the xover into the mains.

Interesting, could you share the receiver model, and settings (speakers large/small)? Was the signal fed over HDMI using REW w/ASIO4ALL or something else?
post #4777 of 5311
Quote:
Originally Posted by pdxrealtor View Post

Wouldn't the correct way to do the test be turn off the subs, leave the mains on, set the xover as low as possible (50Hz) and send a LFE signal out and see if any sound comes out of the mains??

Here's a picture of a mains/subs test, and LFE test from 0-200hz. You can see the LFE is boosted as it should be, but also continues on past the xover into the mains.


Im not sure what the correct test would be, but i believe that in your case, where the LFE seem to redirect to the mains, the redirected LFE should be played back a equal level to the LFE played in the sub. What i see in you graph is that the redirected LFE is played back at ~-10db relative to the LFE played through the sub. That cant be right. Can it?
Say you set a 50Hz cross over. Then "half" the LFE track would be played back at a much too low level.
post #4778 of 5311
Quote:
Interesting, could you share the receiver model, and settings (speakers large/small)? Was the signal fed over HDMI using REW w/ASIO4ALL or something else?

Same receiver as yours. HDMI out of laptop, LFE channel in REW for the +10db line, channels left/right/sub in REW for the -10bdb line.

Speakers small, crossed at 80 hz.

If nothing from the LFE is sent to the mains above the xover point then shouldn't the LFE output signal show a drop off, not a reduction, past the xover?
post #4779 of 5311
Quote:
Originally Posted by pdxrealtor View Post

If nothing from the LFE is sent to the mains above the xover point then shouldn't the LFE output signal show a drop off, not a reduction, past the xover?

Yes, that is what I would expect. I'll need to try overlaying a sweep of the mains over a sweep of the sub to see what I get.
post #4780 of 5311
Is your gear hooked up? Mine is very easy to hookup, but I'm tied up for the day.

You seem familiar with REW, so you are probably aware you can send out content on the LFE channel only. For me it's drop down box 4.

Set your xover to 50hz and do a 0-1000 sweep with the sub turned off. Either the power to the amp, or disconnect the speaker wires.
post #4781 of 5311
I have a perma-REW setup. smile.gif The sub shows up as channel 4 for me as well.
I'm not sure why we see such different results. It could be I'm missing some audio parameters option buried in the receiver menus. Maybe some subtlety of the HDMI connection. I even tried messing around with bass management in Windows to see if that could cause it, I always leave "Disable all audio enhancements" checked otherwise. No dice.
Below is 20-400hz sub sweep with 80hz cross over, 50 hz cross over, and 50hz cross with the sub amp off. No sound with the sub amp off.


Below is a sweep of the sub and the right channel so you can see how it drops off:
post #4782 of 5311
Nice...... thanks for rerunning those.

Seems that's solved. smile.gif

I have no clue what was going on in my graph posted above, but obviously it wasn't set properly for the situation at hand here.
post #4783 of 5311
Quote:
Originally Posted by pdxrealtor View Post

Nice...... thanks for rerunning those.

Seems that's solved. smile.gif

I have no clue what was going on in my graph posted above, but obviously it wasn't set properly for the situation at hand here.

You did not state the nature of your test signal. The internal processing in the preamp might behave differently depending on the incoming signal. Maybe yours was encoded as dolby and radars was PCM?
post #4784 of 5311
Pure direct
post #4785 of 5311
Quote:
Originally Posted by pdxrealtor View Post

Pure direct

Even if you are in pure direct I am not absolutely sure you can assume that PCM and Dolby is treated the same. Was you test signal Dolby encoded?
post #4786 of 5311
AFAIK all REW HDMI output is pcm......... in any event, I am always in pcm when running REW
post #4787 of 5311
Same here, direct PCM.
post #4788 of 5311
And I'm not sure it would make a difference in this topic of discussion anyways..... if Pioneer handles LFE one way it won't matter what the signal is. If there is LFE in that signal it will be handled the way Pioneer handles. it.
Edited by pdxrealtor - 1/10/14 at 6:27pm
post #4789 of 5311
Ok, so what's the verdict?

All recivers throw away information above the crossover dont they? I remember Chris from audyssey saying that's the reason he recommends to set the LFE channel to 120hz so you get all the information from that channel. Obviously with Pioneer receivers there's a universal crossover so it's either 80hz or 100hz all around. I don't know why they don't have a 120hz setting. 150hz is too high.
post #4790 of 5311
Quote:
All recivers throw away information above the crossover dont they?

No. Check the Dolby site for pix of implementation. Most AVRs (OK, at least the Denon, Sony, and Yamaha I was able to check) send LFE content (actually, anything in the sub channel IIRC) over crossover to the L/R channels.

Whether the LFE content above the crossover point, especially the 80 Hz normally used, really matters is up for debate.
post #4791 of 5311
Quote:
Originally Posted by DonH50 View Post

No. Check the Dolby site for pix of implementation. Most AVRs (OK, at least the Denon, Sony, and Yamaha I was able to check) send LFE content (actually, anything in the sub channel IIRC) over crossover to the L/R channels.

Whether the LFE content above the crossover point, especially the 80 Hz normally used, really matters is up for debate.

Any specific link for that? I can't find anything specific to this on the Dolby website itself.

Figure 4 in this article about bass management make it appear that the information above the LPF is discarded, no information from the LFE is delivered to other channels when a subwoofer is used, and that the LPF is employed after the redirected bass from the main channels is mixed with the LFE: Bass Management and the LFE Channel

I also find this statement from page 2 of particular interest:
Quote:
5. There are NO clear rules governing the bandwidth of the LFE channel. The production statutes applied to LFE channels are so varied that determining the upper LFE cutoff frequency for a playback system is often an exercise in futility. Some LFE channels contain no content above 50Hz, while others (usually due to an error in mastering) are full range! The generally accepted safe approach on the playback end is to lowpass-filter the LFE channel at 80 Hz. However, some AV controllers do not apply a lowpass filter to the LFE channel at all, meaning that highly directional bass on some recordings could potentially be produced by the subwoofers. Beware of these controllers, as there is usually no way to add an external lowpass filter without serious repercussions to the main-channel bass.
post #4792 of 5311
Hmmm... I think I was wrong about the LFE content. I looked on my PC and could not find the paper I was thinking about, and wasted a while on the Dolby site looking for a section with technology white papers. It's probably there, somewhere, but I don't know where,,, I also read the S&V article you linked, thank you.

What I found in my search was the diagram for one of my AVR's bass management schemes (not the Pioneer, but I am not sure if it is for the Denon or Sony -- no name on the picture). I probably grabbed it when I was first researching bass management before getting my Pioneer and after learning of Pioneer's scheme. For that AVR, the LFE channel has a 110 Hz LPF (not 120 Hz, don't know why, but that is what the diagram says) before the usual 10 dB gain stage and then a summer for bass from the other channels. The bass from the other channels goes through a second LPF before the summer o the sub, and that is variable as set by the crossover frequency. I found one other diagram for another AVR with essentially the same scheme. In other words, bass from the other channels is rolled off by the user-controllable LPF before being applied to the sub, but the LFE channel goes straight through to the sub. The diagram I have that I think is for my Pioneer shows LPF's for each channel, including LFE, and all the LPF outputs are summed to go to the sub. All the LPF's are in one box and all controlled by the same crossover setting. So, in this case any LFE content over the crossover is lost.

So effectively I can't prove my claim so must redact with apologies. What I have evidence of is two of my AVRs (Sony and Denon as my Yamaha is older and I don't have any details for it) appear to send the LFE channel to the sub using its own LPF. Pioneer's LFE filter is ganged with all the other channels and controlled by the same, global, crossover setting. Here's the bullet list:

  • In one case, the LFE has its own LPF (not user-controllable). All the other channels are summed, then go through a separate (single) LPF before being summed with the LFE signal going to the subwoofer. (Each channel also has its own LPF; seems a little wacky but that's what it shows.) The LFE signal is independent of the channel crossover so nothing is lost.
  • In the second case again the LFE has its own LPF (not user-controllable). Each channel has its own LPF filter and the output of all the individual channel LPFs are summed with the LFE signal to drive the subwoofer. Again no LFE content is lost.
  • Pioneer's scheme places a LPF in each channel, including the LFE, but all the LPF corners are set by a single (user-defined) crossover frequency. Thus any LFE above the global LPF setting is lost.

So in the first two schemes all LFE bandwidth is sent to the sub irrespective of the (user) crossover setting. In the Pioneer, any LFE signal over the (global, user) crossover is lost. Signal frequencies above the LFE crossover are not sent to the mains in any figure I have (except those without a sub, natch, in which case LFE is sent to the L/R speakers). So you are correct AFAIK that LFE is not sent to the mains (unless there is no sub).

Thanks for keeping me honest! - Don
post #4793 of 5311
I've done some searching in this topic in hopes of answering a question I have regarding a SC-71 purchase on the horizon. The following post came closest to an answer.
Quote:
Originally Posted by pdxrealtor View Post

MCACC will not EQ the sub, at all.

I don't think MCACC will apply any EQ to the mains if your xover is above the 50 Hz setting. I know for sure it won't let you adjust the 63 Hz band in pro eq.

What MCACC does do is apply what it calls a standing wave filter which is Pioneer talk for parametric EQ with no option to boost. In other words it only cuts down peaks in the frequency response.

The standing wave is applied the main, center, and subwoofer channels. But here's the thing..... it applies the same frequencies to all three channels and it doesn't dig down past your xover point.

Let me try to describe a scenario.

Sub to 'yes'; xover to 80hz then:

First set the surrounds to large. Then manually apply boost 8-10db to the 63hz band. Set the surrounds to small.

Question - Does applying the 80hz cross eliminate the previously adjustment to the 63hz. band - or - does it just overlay the the 80hz high pass filter on top and leave the boost where it was?

The reason I'm asking is the surrounds I have (infinity SM-65's) have a listed low end of 78hz and I'd like to try to leave the option open to use a 80hz cross. I "MAY" be able to pull it off if I can sneak a little boost at 63hz just on the surrounds. I'm waiting for CSL to open up orders for a UMIK-1 mic so I can use REW to help out but right now I'm just blue skying it.

BTW I'm waiting on a work bonus late FEB to early MARCH for the AVR purchase.

Thanks in advance.
post #4794 of 5311
I have not tried but am pretty sure when you switch the speakers to "small" with an 80 Hz crossover the 63 Hz band is no longer used (not applied and no longer adjustable).

My guess is you will not notice the loss of LF on the surrounds; just not much LF content in them.
post #4795 of 5311
Quote:
Originally Posted by DonH50 View Post

So in the first two schemes all LFE bandwidth is sent to the sub irrespective of the (user) crossover setting. In the Pioneer, any LFE signal over the (global, user) crossover is lost. Signal frequencies above the LFE crossover are not sent to the mains in any figure I have (except those without a sub, natch, in which case LFE is sent to the L/R speakers). So you are correct AFAIK that LFE is not sent to the mains (unless there is no sub).

Thanks for the follow-up. I just accidentally found that article while googling for Dolby Bass Management. I found it interesting in that it's the first thing I've seen that suggests that discarding LFE info above a certain frequency is a good thing. I'm wondering if it may be a THX standard to low pass the LFE channel. I don't believe Sony has ever had a THX certified receiver, and I'm not sure if the Denon you're referring to would be THX certified or not. In any case, Pioneer (or THX) may have implemented it this way specifically to deal with the issues referred to in the article (high frequency, directionally locatable sound from the LFE track being played on the subwoofers).
post #4796 of 5311
NP. Well, it was a pain, but I hate being unsure, let alone wrong.

It may be a THX thing but I did not look at the THX site. I know THX specifies 80 Hz (at least I think I know; that's what I recall). They used to have a bunch of info on their site but last I checked most of the white papers had been moved off the public site and I didn't feel like paying for them.

Technically, since it is the output of a DAC, the LFE always has to have some sort of LPF to reject the out-of-band images. My memory is that the LFE channel is sampled at a lower rate, and perhaps lower resolution (not sure on the latter). IIRC the Dolby spec for the LFE channel is 120 Hz max.

I don't recall the model numbers nor if either AVR (Sony or Denon) is THX-certified. Pretty sure my (pretty old) Yamaha is not, and I know my Pioneer SC-27 is. I could look later but probably not worth the effort (one is out of service and buried, should probably sell it).

Onwards - Don

* edit: Sony STR-DA3400ES, does have a THX sticker on it. Denon AVR-1804, not THX. Pioneer SC-27, THX Ultra. Yamaha RX-V690, what's THX? smile.gif
post #4797 of 5311
Quote:
Originally Posted by DonH50 View Post

Sony STR-DA3400ES, does have a THX sticker on it.

I had to look that up since I didn't remember any Sony receiver ever being THX certified. Looks like it has (and some of the other Sony receivers had) Neural-THX, which is a multi-channel from stereo listening mode similar to Pro-Logic II or DTS-Neo. I may be mistaken, but I don't think including that feature involved or required the THX certification of the entire receiver.
Edited by KC-Technerd - 1/11/14 at 8:41pm
post #4798 of 5311
Quote:
Originally Posted by DonH50 View Post

I have not tried but am pretty sure when you switch the speakers to "small" with an 80 Hz crossover the 63 Hz band is no longer used (not applied and no longer adjustable).

My guess is you will not notice the loss of LF on the surrounds; just not much LF content in them.

Thanks for the quick response. That's what I expect, too. Won't know till I get the 71 and the UMIK. I'll post when I find out for sure.
post #4799 of 5311
Quote:
Originally Posted by KC-Technerd View Post

Quote:
Originally Posted by DonH50 View Post

Sony STR-DA3400ES, does have a THX sticker on it.

I had to look that up since I didn't remember any Sony receiver ever being THX certified. Looks like it has (and some of the other Sony receivers had) Neural-THX, which is a multi-channel from stereo listening mode similar to Pro-Logic II or DTS-Neo. I may be mistaken, but I don't think including that feature involved or required the THX certification of the entire receiver.

Picky, picky... smile.gif I checked again and yes, Neural THX is what the sticker says. I think. Old eyes... I don't know the difference among various THX modes. However, I was thinking the Pioneer I got was my first THX AVR, and that still seems to be the case.

Aside: I was very disappointed with that Sony on several fronts (room correction and lack of power among them). It still lives in our family room system but is not used much.
post #4800 of 5311
the issue of Pioneer's bass mgmt comes up again smile.gif I've been reading the posts & graphs - much thanks for those, guys!! cool.gif

and probably will add more comments or questions but no time until late today at the earliest. but this discussion is very interesting and I would like to know more about the settings used for those graphs, from those that measured.

Dolby Digital? surround format used on the receiver? main speakers Small or Large? maybe some of the graphs showed this but were the mains measured and if so, were measurements made set as Large and as Small to see if they pick up LFE where the sub drops off with either setting? was there any difference in their bass response at the various crossovers between set as Small vs Large?

to me, it would seem plausible that LFE above the crossover, where the sub drops off, would be directed to the mains and therefore not lost but just not played by the sub. because that crossover is where you are telling the receiver that your speakers are capable of handling all bass. if you set it to 80, then < 80 goes to sub and >80 to the mains. I think the preferred way is supposed to be to send all LFE to the sub and just have bass from the normal channels get crossed over & bass managed but that is from reading the same kind of stuff years ago from my memory, probably the same sources that DonH50 remembers wink.gif as long as some speaker gets the bass, I don't think it matters. at least this is how I've assumed Pioneer has done it.

do these measurements support this or refute it? confused.gif if the speakers don't get re-directed LFE, then it would be lost. but that may not be relevant anyway but it would mean that setting a crossover to 50 Hz would not be a good idea smile.gif and it would also mean that crossovers < 80 Hz are "useless" settings and shouldn't be used because as you went lower, you would lose more and more LFE bass. and I have a real hard time believing Pioneer would implement it that way.
Edited by ss9001 - 1/12/14 at 4:18am
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