Listening to Mono tracks

Rich Satch

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Apr 15, 2002
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5.1 and other surround formats are great and all, but I really hate listening to mono tracks. Typically, I've left the surround on and just listened to it through the center speaker, but tonight I turned off the surround and listened to it in the two fronts and it sounded a lot better. Is this ok? Is listening to it through the center channel the correct way to listen? Which do you prefer?
 

Guy Martin

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Rich-

Sending a mono signal to multiple speakers is fine. You're not altering the signal in any way. In fact most mono theaters actually had many speakers throughout the theater, they just received the same signal. Mono didn't mean that the sound only came from a single speaker behind the screen, just that there was only a single signal sent everywhere. So if you prefer listening to soundtracks this way, knock yourself out.

- Guy
 

Dan M

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I agree with Guy, but I'm sure there are many an audiophile zealot out there that would cry heresy for listening to mono through multiple speakers.

I have a nice center channel speaker but I prefer to spread the sound out throught the mains when it comes to mono sound. It's sounds warmer and fuller to my ears.
 

Patrick McCart

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1.0 is the essential way to listen to a mono soundtrack. The sound is more like it's coming from the image, rather than complementing it on the sides.

The problem with spreading the 1.0 or 2.0 mono to the entire 5.0 system is that you can get distortion. Now...if your reciever can keep the rear channels from the "echo" effect, it'll probably work alright.
 

Aaron Reynolds

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I agree with Guy, but I'm sure there are many an audiophile zealot out there that would cry heresy for listening to mono through multiple speakers.
...and there are the ones who would cringe at the thought of needing a centre channel speaker in the first place.

Another downside of listening to mono tracks in prologic through the centre channel is that certain parts of the sound become muffled during decoding. Running the sound to the front two channels with no processing avoids this.
 

Larry Geller

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The problem with spreading the 1.0 or 2.0 mono to the entire 5.0 system is that you can get distortion. Now...if your reciever can keep the rear channels from the "echo" effect, it'll probably work alright.
If your system places sound anywhere but the center channel ONLY during a mono program, than your decoder is not working properly. The only time ANYTHING should be coming out of any of the other 4 speakers would be if it is a stereo program.
 

Vic_T

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It is not wrong to send mono tracks to more than one speaker. Mono need not be center channel only. That is the way mono 1.0 tracks will be sent by default. Mono 2.0 will go to the R&L front speakers. I would not suggest using Pro-Logic, cause I think it sucks, but there should be no ill effects on the sound of the track at all by sending it dry to other speakers. It is, in fact, common place to do so in many applications, including theaters.
 

TedD

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In fact most mono theaters actually had many speakers throughout the theater, they just received the same signal. Mono didn't mean that the sound only came from a single speaker behind the screen, just that there was only a single signal sent everywhere.
Here we go again!!!

The standard configuration for theaters running mono optical tracks is to route the signal to ONE speaker located behind the screen centered laterally behind the screen with the horn mid/tweeter (anything above 500 Hz) positioned 2/3rds of the way up the screen. This was the ONLY configuration used for mono optical sound before 1954, and was also the standard even in theaters equipped with 4 track mag installations after 1953.

Theater sound systems that pre-date Dolby Stereo are HARD WIRED in this configuration.

This is still the standard, even today, as specified by the SMPTE.

Any deviation from this standard is just that, a non-standard installation, and is very rare.

There was a system in the mid 50's called Perspectasound that utilized three subaudible tones (30, 35, and 40 Hz.) to steer a mono optical track to three speakers located at the normal Left, Center, and Right locations behind the screen. However this system requires a control unit (called a Perspectasound Integrator) to decode the control signals and route the mono signal and also requires a special print containing the control signals.

In case you are wondering, the integrator had filters to prevent the control tones from being audible, and even if a Perspecta print was run without an integrator, very very few theaters had any usable bass below 60 Hz. Of course, this all predates subwoofers and Sensurround.

As a professional projectionist for many years, I was involved in the installation, maintenance, and operation of these sound systems, so I speak from personal experience.

Ted
 

Dan M

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If your system places sound anywhere but the center channel ONLY during a mono program, than your decoder is not working properly. The only time ANYTHING should be coming out of any of the other 4 speakers would be if it is a stereo program.
The decoder in my receiver works fine. It gives me several options on how to listen to mono tracks.
I can set the receiver to isolate mono (1.0 or 2.0) directly to the center speaker OR I can set it to be directed to the front L&R mains (which is how I prefer it).
If I leave it in ProLogic mode it will send 1.0 to the center channel and 2.0 to the mains.
It also has a Mono Movie Mode. It sends it to all 5 speakers and has reverb control and re-equalization to simulate how it might sound in an actual movie theater. I tend to stay away from this one.
I have an Onkyo TX DS989 BTW. Very nice receiver
This thread is beginning to sound like might belong in hardware!
 

Chris Shelly

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How come they just don't put mono button on modern receivers? Many older films were mixed in such a way that required the high end be rolled off (I think it is -2db per octave above 2000) and the low end be rolled off (-6db below 50). This was refered to as the academy filter. It was necessary because of the distortion in optical soundtracks. Even today Dolby processors in movie theaters have 01 optical mono with this filter. If we could have this on our receivers that sent sound only to the center speaker and rolled off the low and high ends older movies would sound alot more genuine.

Chris
 

Roger Dressler

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Another way to listen to mono soundtracks is with Pro Logic II's Music mode. You can then use the Center Width control to adjust the exact proportion of signals across the three front speakers. For example, rather than steering all the signal to the center, some can be spread to L/R at a lower level, thus adding a sense of width or scale but without the hole-in-the-middle effect of dual mono.

Aaron wrote: >>Another downside of listening to mono tracks in prologic through the centre channel is that certain parts of the sound become muffled during decoding. Running the sound to the front two channels with no processing avoids this.>Many older films were mixed in such a way that required the high end be rolled off (I think it is -2db per octave above 2000) and the low end be rolled off (-6db below 50). This was refered to as the academy filter.
 

Paul Linfesty

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The standard configuration for theaters running mono optical tracks is to route the signal to ONE speaker located behind the screen centered laterally behind the screen with the horn mid/tweeter (anything above 500 Hz) positioned 2/3rds of the way up the screen. This was the ONLY configuration used for mono optical sound before 1954, and was also the standard even in theaters equipped with 4 track mag installations after 1953.
I was under the impression that some of the larger palaces would place TWO stage speakers next to each other

(but still centered) to help get more power out) since many of these ALTEC Voice of Theatre speakers were only being run on 5-10 watts.
 

TedD

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I was under the impression that some of the larger palaces would place TWO stage speakers next to each other
No. Placing two of them next to one another would create combing effects and very uneven coverage of the auditorium.

But there were many models of the Altec "Voice Of The Theater" system. The largest one had 4 15" woofers and a 3x5 segment multicell horn used for anything above 500 Hz. (There might have even been a 4x5 segment horn available, but the largest one I have seen was the 3x5.) The multicell horn bolted to the driver via a throat section that was configured as an "I" to use a single driver or a "Y" that used two drivers.

The magnets on these drivers must have weighed at least 20 lbs.

The woofer magnets probably weighed 35 lbs.

Incidentally, before Alnico was used, many theater speakers used electromagnets powered from 90 volts DC taken from the amplifier.

Ted
 

Rich Satch

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HMMM, I just realized why Mono 2.0 is called Mono 2.0. Because it should be spread out across the two fronts. However, when my reciver is in pro-logic mode it sends all mono tracks even 2.0 to the center fro some odd reason. Any way to fix this, what's going on?
 

Scott_MacD

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May 13, 2001
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Rich -

Pro-Logic is a matrixing technique that redirects stereo sound to 4 speakers.

When a signal is in phase (when elements from left and right are in equal phase) and at the same volume, the Pro-Logic decoder sends this signal to the center channel.

This is what is happening. Two equal signals in left and right, from the Mono 2.0 track is being identified as material that belongs to the center channel. And as such, this material is being decoded to the center channel.

Switch off the Pro-Logic decoder and listen to it in stereo if you wish to listen to it in 2.0
 

Ken Garrison

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Jun 1, 2002
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IF I had a center speaker for my Pro Logic system and a Mono Movie came on, I Love Lucy, or The Three Stooges, I'd definently turn the center speaker off and listen to it with the front mains. BTW, how come when you go to the Information menu on Directv to I Love Lucy and it says STEREO? Lucy is not a stereo program. Why are they lying to us? On a prologic system, if you decide to keep the center turned on when watching a mono program, it will still send bass information to the right and lefts, because that's where a sub is usually hooked up to.
 

Larry Geller

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BTW, how come when you go to the Information menu on Directv to I Love Lucy and it says STEREO? Lucy is not a stereo program. Why are they lying to us?
It's because the STATION is broadcasting in stereo, they're just playing a mono program (just as if you are playing a mono CD like Please Please Me, for example, the same signal is going thru 2 channels), but the commercials are in stereo. It's also getting MTS stereo's noise reduction regardless of how many channels of audio there are in the signal, and the signal is put out that lights up the "Stereo" light or indicator on TV. This is just like FM stereo, which lights up as stereo regardless of whether the source is stereo or mono.
 

Ken_McAlinden

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Another good reason you may want to use your fronts for mono is if you have full range fronts, but normally rely on your receiver's bass management for the center channel. Similarly, if you have a satellite & sub system where you follow the manufacturer's instructions and set your fronts (wired through the sub) to "Large", your center to "small" and your subwoofer to "none", depending on your receiver's bass management, with center channel mono you can get trace elements of the bass signal in your front L/R speakers in addition to the sub which can be distracting.

IMHO, mono soundtracks should always be encoded as 1.0 on the disc, though. It eliminates a potential failure mode and makes optimal use of the bitrate. Hey, if Roger Dressler is still monitoring this thread, I would be interested to know if that is true or not. It seems that given 192 kb/s, that 1.0 would be more efficient, but the DD codec may be able to take advantage of the redundancy to make 192 kb/s 2.0 mono nearly as efficient. Roger?

Edited for really bad spelling

Regards,
 

Kevin M

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I personally would prefer all mono & stereo surround soundtracks to be uncompressed PCM (where applicable space-wise), or at the very least use the highest DD or DTS bit rates available for 2.0 compressed soundtracks, I have heard a few DD 2.0 tracks at 384 kbps (Image's MST3K-TM was a recent surprise) and they sound pretty good compared to PCM...well...reasonably good anyway.
 

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