Are three channels better than two for stereo reproduction?

[LowShelfFilter]

Considering that two speakers cannot accurately reproduce a 3D acoustic event in the first place, would using a center channel summed to mono with LR playing normally provide for a superior/more realistic listening experience than just using LR? Please note that I am not referring to listening to three channel recordings, but rather up-mixing two channel recordings to three channels.

I am considering routing audio as such with a MiniDSP 2x4 product:
Output 1: Right Speaker (Right input channel)
Output 2: Left Speaker (Left input channel)
Output 3: Center Speaker (Right + Left input channels)
Output 4: Subwoofer(s) (Right + Left input channels)

From Floyd Toole's book, there are significant acoustic advantages to using a center channel. Are there any downsides to using LCR for stereo reproduction instead of LR?

 

[MaxwellsEq]

Stereo content has 2 channels of information encoded. Stereo is Greek for solid

 

[dfuller]

Generally speaking? If you have a way to do a stereo to LCR encode, then yes!

Stereo's biggest weakness is that the phantom center is never particularly strong.

 

[Robin L]

Early stereo recordings used three channels with distinct mixes for each channel. The Mercury "Living Presence" recordings used three widely spaced omnis, tracking each into a separate channel. RCA Victor, in their "Living Stereo" series used more complex mixes but still tracked with three channels. I don't know the miking arrays of the Everest 35 mm recordings of that era, but a few appeared as 3.0 SACDs. When SACDs appeared some of the recordings of these series were reissued as three channel recordings. I still have some of the RCA "Living Stereo" SACDs, though I no longer have multichannel gear. My experience, with both 3.0 and 5.1 SACDs, is that the image of the center channel was more solid than that generated by two channel recordings. In two channel stereo, the Redbook layer sounds the same to these ears as the two channel DSD layers. And there was considerable care taken with the RCA recordings to get the best results from these 1950s recordings. Some are very good, some display predictable distortion at peaks.

 

[LowShelfFilter]

Stereo content has 2 channels of information encoded.

Using a MiniDSP 2x4 product, you can route audio as such:
Output 1: Right Speaker (Right input channel)
Output 2: Left Speaker (Left input channel)
Output 3: Center Speaker (Right + Left input channels)
Output 4: Subwoofer(s) (Right + Left input channels)

This is what I am considering doing.

 

[DVDdoug]

Good luck finding a 3-channel recording. The old Dolby Surround on VHS was encoded during recording and steered (panned) during playback. That doesn't work very well with music because you don't want it steered, and it's not produced and encoded to be steered.

From Floyd Toole's book, there are significant acoustic advantages to using a center channel.

Yes, he says the phantom center only works when you're sitting in the sweet spot. He also says immersive surround is even better.

Personally, I do like up-mixing with my 5.1 system to get delayed reverb in the rear speakers and the "feel" of a larger space. The Pro Logic mode I use doesn't seem to enhance the center.

 

[EERecordist]

No for music. If the content was mixed for 2.1, 3.1 is unpredictable. If the content was mixed for 5+.1+, your choice. I would spend on room conditioning.

 

[LowShelfFilter]

Good luck finding a 3-channel recording.

I'm referring to listening to stereo up-mixed to 3-channel. Please see my comment above yours.

 

[Timcognito]

You don't need MiniDSP for that. You can use this:

View attachment 382275

This is the old Hafler set-up. It was created in an era when "ping-pong" stereo recordings were common. However, it's usable (kinda) on modern recordings.

A couple comments:

1`) Experimenting with this will drive you crazy.
2) I started on this with hookup by placing 3 identical speakers side-by-side in front of me, about 10 feet (3m) away. I then carefully moved the right and left speakers wider and wider, keeping them on that arc 10 feet from me. I did this until they were at my exact 90-degree left and right, pointing at each other.
3) I used a few well-known recordings, using each to test for differences in the sound field, and keeping notes on the comparison at each move to widen the speaker array.
4) Doing that will drive you crazy.
5) If the center-fill speaker sounds too bright or too loud, try either laying it on its back, aimed at the ceiling, or even turning it around and aiming it at the wall. Then compare the different recordings again, testing for compatibility.
6) If the center-fill speaker sounds too bright or too loud, you can try moving the L and R speakers closer to your position, taking advantage of the precedence effect.
7) Doing this will drive you crazy.
8) I found, for my own satisfaction, that sitting directly between two opposing speakers yields the best results, but the center needs to have a volume control. For some recordings, the center will be too loud, and for others it will be not loud enough.
9) The necessity of adjusting this system for each and every different recording will drive you crazy.
10) When I did this, I found out a lot about the stereo process and in-room presentation. Namely, I found out that Dolby Pro Logic is just about as good (or just about as bad) and easier to implement ... by far.
11) My friends still say I'm crazy. Well ... doh!

Crazy Jim Taylor.

Is the center out of phase with the L&R?

 

[terryforsythe]

Stereo's biggest weakness is that the phantom center is never particularly strong.

I have had systems that did not image particularly well, and this is common.

However, two of my present systems produce very good imaging and produce phantom center images extremely well. The caveat is that they achieve the highest level of imaging at a specific listening position, not over a wide area.

If you want a strong center image over a wide area, perhaps a center channel is the way to go. I have never used one, so this is just speculation on my part. Perhaps some of the home theater guys in this forum can chime in on that.

 

[Mikig]

I tried with my TV system, which has 3 channels, a central one and the two main ones.
Answer to your question: no, it's not better. Stereo content is difficult to level between the three channels. It is not meant for that application.
Better then multi-channel content already designed and mixed to be broadcast by systems with 5 or more speakers.
As already said by others: if you have a hole in the middle it almost always depends on poorly positioned speakers or on the listening point not being proportionate to the very famous triangle with the speakers.

 

[Jim Taylor]

Is the center out of phase with the L&R?

I just deleted my post. If a user isn't sure about the internal wiring, the hookup can blow their amp. I don't want to be responsible for that happening.

I was familiar with this years ago, when tube amps ruled the roost, and "common" was more assuredly "common." To anyone who copied that post: please ignore it.

Jim

 

[theREALdotnet]

Stereo's biggest weakness is that the phantom center is never particularly strong.

Really? That’s not my experience. My phantom centre is as strong and focused as hard-panned left or right. It does shift with listener position, but it is not weak.

 

[Blumlein 88]

http://decoy.iki.fi/dsound/ambisonic/motherlode/source/7038.pdf

Math involved. Michael Gerzon paper from 1991. Optimally you need to do some frequency contouring, and some mid-side processing. Simplifying that paper some, one obvious result is plopping a center channel down and connecting it with mono combination of L and R will cause a narrow stereo width. A simple way to help with that is to widen the spacing between L and R to at least 90 degrees as viewed from the listeners position. You see lots of people saying just connecting a center narrows the stereo effect.

So simple terms widen your speakers unless you already have something of a hole in the middle. Reduced the center channel vs side channels by 3 to 6 db. Have the center equi-distant from the listener vs side speakers. Another aspect is some recording methods are effected differently than others doing a 2 channel to 3 speaker setup. So it might be better for some, a little worse for others, but without the extra matrix processing etc it won't always be for the better.

 

[LowShelfFilter]

Is the center out of phase with the L&R?

I already have the MiniDSP, but the center would be of the same brand and model as the side channels.

 

[LowShelfFilter]

I have had systems that did not image particularly well, and this is common.

However, two of my present systems produce very good imaging and produce phantom center images extremely well. The caveat is that they achieve the highest level of imaging at a specific listening position, not over a wide area.

If you want a strong center image over a wide area, perhaps a center channel is the way to go. I have never used one, so this is just speculation on my part. Perhaps some of the home theater guys in this forum can chime in on that.

How would it be possible for a system with two channels to have center imaging as strong as a system with three channels as long as the speakers are in phase?

For those saying that stereo can have a good center image, please read section 7.1 of the third edition of Floyd Toole's Book on sound reproduction. I am not necessarily saying there is a bad center image when listening to stereo speakers in a normally reflective room since the comb filtering issue is less than in an anechoic chamber, but it cannot match the timbre of the lead singer being right in front of you, presented by the center channel.

 

[Blumlein 88]

How would it be possible for a system with two channels to have center imaging as strong as a system with three channels as long as the speakers are in phase?

For those saying that stereo can have a good center image, please read section 7.1 of the third edition of Floyd Toole's Book on sound reproduction. I am not necessarily saying there is a bad center image when listening to stereo speakers in a normally reflective room since the comb filtering issue is less than in an anechoic chamber, but it cannot match the timbre of the lead singer being right in front of you, presented by the center channel.

I think you are misinterpreting Toole somewhat.

In simple terms, you have a level difference between a left and right image. If you add an equal level center speaker you are in essence adding equal amounts of left and right to the middle which will end up pulling all imaging toward the center. You will get a strong center image, but it will adversely effect the left to right imaging off center. Things that should be heard wide over one direction will get pulled toward the middle.

 

[rynberg]

Using a MiniDSP 2x4 product, you can route audio as such:
Output 1: Right Speaker (Right input channel)
Output 2: Left Speaker (Left input channel)
Output 3: Center Speaker (Right + Left input channels)
Output 4: Subwoofer(s) (Right + Left input channels)

This is what I am considering doing.

That will be a bit of an acoustical disaster. If you want to "upmix" audio, then you need to use an actual upmixer, like Dolby Surround or DTS Neural. So my advice would be to not use a Mini DSP but an AVR. Since all you care about is audio, you can get an older unit on the cheap -- even better, you can use an older AVR from when Dolby Pro-Logic II was being used, which is the best 2->3 channel upmixer in my opinion. The tradeoff would be that newer receivers have much better room correction/EQ software; that is irrelevant if you can EQ upstream.

 

[Petrushka]

The phantom channel works fine with near field listening. We only have two ears.

 

[Mikig]

I think you are misinterpreting Toole somewhat.

In simple terms, you have a level difference between a left and right image. If you add an equal level center speaker you are in essence adding equal amounts of left and right to the middle which will end up pulling all imaging toward the center. You will get a strong center image, but it will adversely effect the left to right imaging off center. Things that should be heard wide over one direction will get pulled toward the middle.

I absolutely agree: this is what happens with my 3-channel TV system with stereo content and Dolby or multichannel settings. If I keep the central player at the level of the main players, only the central player can be heard, losing depth and space on the sides. It's like listening to a turntable equipped with a mono cartridge.... If I turn the center switch down I feel a strange "delay" effect. If I select the "stereo" mode on the amp it becomes pleasant again, because the center is excluded.