Home » Sponsored » Pi Speakers » flanking subs with small mains
Re: flanking subs with small mains [message #75629 is a reply to message #75628] Sat, 23 February 2013 17:17 Go to previous messageGo to next message
dheflin44 is currently offline  dheflin44
Messages: 47
Registered: November 2012
Location: Carrollton, TX
Baron
Ok, thanks Wayne. I have a pair of Yung plate amps on order, but they are on back-order until April, so it will be a while before I can post any results.

Thanks,
Darrell
Re: flanking subs with small mains [message #75734 is a reply to message #75629] Wed, 06 March 2013 16:58 Go to previous messageGo to next message
zheka is currently offline  zheka
Messages: 80
Registered: June 2012
Location: Chicago burbs
Viscount
Hi Darrell,

Do you have a specific mixer in mind for this set up?
Re: flanking subs with small mains [message #75735 is a reply to message #75734] Wed, 06 March 2013 17:35 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

A long time ago, back when I had black light posters all over my walls, I used to run my oscilloscope with its two channels connected to the right and left channels of my stereo. I'd setup to make Lissajous patterns like a little laser light show. One thing I noticed was nearly all music had low frequency content the same in both channels. Of course, there were a few exceptions but they were rare.

So ever since then, I've made a working assumption that the deep LF content of most music material is summed in the mix. That was on my mind when I first recommended the flanking subs approach. While there is the possibility that LF content could be localized in one speaker or the other, in practice it is rare.

That's why I've always suggested that the flanking subs would be part of the multisub approach when distributed subs were run using a summed channel. I am make the assumption that most times, the LF content is summed anyway.

I think it is probably a little more of a concern in movie soundtracks but I'm not entirely sure those would have LF content panned hard to one channel either. It's an unnatural situation, one that doesn't happen in "real life". So I would hope (expect) the sound editors to put deep bass content in all channels in the mix.

Just my 2¢. Well, not quite 2¢ worth there, but maybe a penny.

But hey, while we're on the subject, let's link in Andy's thread here too:
I kinda think you guys are on to something there. Even though I don't expect much material with deep bass panned hard to one channel, your sound mixer / processor idea ensures it is distributed properly. I think that's a great idea.

Re: flanking subs with small mains [message #75737 is a reply to message #75734] Wed, 06 March 2013 18:14 Go to previous messageGo to next message
dheflin44 is currently offline  dheflin44
Messages: 47
Registered: November 2012
Location: Carrollton, TX
Baron
zheka wrote on Wed, 06 March 2013 16:58
Hi Darrell,

Do you have a specific mixer in mind for this set up?


Hi zheka,

I was planning to use the L/R line-level summer built-in to my plate amp. It seems most sub plate amps these days have at least two line-level inputs so this option should be readily available. The one I'm going to use is the Yung 300W:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=301-510

-Darrell
Re: flanking subs with small mains [message #75738 is a reply to message #75735] Wed, 06 March 2013 20:27 Go to previous messageGo to next message
zheka is currently offline  zheka
Messages: 80
Registered: June 2012
Location: Chicago burbs
Viscount
Wayne Parham wrote on Wed, 06 March 2013 17:35

I think it is probably a little more of a concern in movie soundtracks but I'm not entirely sure those would have LF content panned hard to one channel either. It's an unnatural situation, one that doesn't happen in "real life". So I would hope (expect) the sound editors to put deep bass content in all channels in the mix.



I suspect LFE channel in today's MCH tracks contains distinct signal that is not duplicated in any of the main channels.
The more I think about Darrell's idea, the more I like it.

dheflin44 wrote on Wed, 06 March 2013 18:14

I was planning to use the L/R line-level summer built-in to my plate amp.


this is just perfect. for some reason I thought a mixer is needed but probably a simple stereo-to-mono coupler is all it takes.

something like this for example

http://www.edcorusa.com/p/5/s2m
Re: flanking subs with small mains [message #75739 is a reply to message #75738] Wed, 06 March 2013 22:13 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

The subwoofer output is merely a summation of all channels low-passed, including the LFE channel, of course. I imagine some Dolby Digital tracks put content in the LFE that isn't anywhere else. But that's not the case in other tracks, like Dolby Surround and Pro Logic. So I know there are modes that can be used that do not present any content to the subwoofer output that isn't present in at least one of the mains, and more likely, in all of them summed together.

But I do think you're probably right when running Dolby Digital and perhaps DTS that the LFE channel sometimes has content that isn't present in any of the mains - whether in large or small mode - and this content is summed in the subwoofer output. So for home theater, when running the Dolby Digital mode, if you want LFE infrasound in the mix, I think what you're saying may be correct.

I can't help but wonder though: If you configure the processor to have no subwoofer, wouldn't it necessitate sending the LFE channel to the mains? Seems like any processor that failed to do that would be defective, an oversight in firmware, at the least. That's the mode I always use, and then run the subs off the preamp outputs for the mains, through an external low-pass filter, of course. I don't believe I am missing any LFE content that way, although to be candid, I haven't checked. I assumed LFE content was sent to the mains when "no subwoofer" was selected.

In any case, modes where the LFE signal is unique is where I think the blending approach you guys are talking about makes a lot of sense. It's not needed for stereo, and it's not needed for the formats that don't rely on an LFE channel. But for the formats that do, this subwoofer/mains mixer sounds like a great idea. It's the way the "full" or "large" mode should mix the signal going to the mains, low-passed for flanking subs. And certainly in cases like what Darrell is talking about - where he selects "small" mode to provide high-pass for his mains, but then high-passes low enough (60-80Hz) to get blending for flanking subs - this subwoofer/mains mixer approach seems very attractive to me.

Re: flanking subs with small mains [message #75745 is a reply to message #75739] Thu, 07 March 2013 23:18 Go to previous messageGo to next message
dheflin44 is currently offline  dheflin44
Messages: 47
Registered: November 2012
Location: Carrollton, TX
Baron
Hi Wayne,

I'm not sure if I'm following the discussion. When you talked about not needing a summing circuit depending on LFE content, are you assuming the mains are set to 'Large'? In my system I have to set the mains to 'Small' (because they are) to limit bass extension. Coming out of the AVR, this setting results in no blending between the sub and main channels, independent of LFE content. The purpose of the summing circuit then is to blend mid-bass frequencies from the high-passed main channel into the flanking subs. Note in the summing circuit diagram, the signals at the top represent the main and sub channels after bass management is applied.

Thanks,
Darrell
Re: flanking subs with small mains [message #75747 is a reply to message #75745] Thu, 07 March 2013 23:31 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

What I was talking about in my last reply to Zheka doesn't really apply to you. I was talking about using the "large" mode with subwoofer set off. That should send all LFE content to the mains. But I think Zheka makes the argument that he is not sure that is true. I think he believes the LFE content may simply be missing in some cases if the subwoofer is set to off, even if the mains are set to large. In any case, I do realize that what you are trying to accomplish is a way to configure the system (using the "small" setting) that provides 60-80Hz high-pass for the mains, but yet still provides a suitable flanking subwoofer signal, and that would require a mixer of some sort as you have described. I think it's a great idea.

Previous Topic: 7pi plans
Next Topic: Pi Cornerhorn Aesthetics
Goto Forum:
  


Current Time: Thu Mar 28 17:46:59 CDT 2024

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest