Did Dolby Surround (1982) implement a centre channel before Dolby Pro Logic 1 (1987)?

[TheRealOC]

I'm writing a wiki article on surround sound for retro gaming consoles, and I've hit a bit of a speed bump in my understanding of the topic...

In this Audioholics video (Understanding Surround Formats in AV Receivers), Gene says that the original Dolby Stereo/Dolby Surround (my understanding is that Dolby Surround was basically the home equivalent of the theatrical Dolby Stereo format) was basically matrixed surround channels - with no centre channel yet - and that it was the Dolby Pro Logic 1 format (1987) that introduced the centre channel.

However, in my journey down this rabbit hole, I've come across video essays that indicate a centre channel was possible using Dolby Surround - such as this video (Sound Formats EXPLAINED by Sound Sack):

"Dolby Surround was originally known as Dolby Stereo when it was introduced to theatres in 1975. It wasn’t the first movie surround format, but it was the biggest and easiest to implement for some time. Dolby Stereo is the first cool reworking of a stereo signal that I’ll mention today. It’s able to produce four channels but they’re not discrete. These channels are left – centre – right and a single surround channel. It’s extracts them from a common stereo connection with a specially encoded signal. Sounds that are common in the left and right channel (aka mono) are routed by the processor to the centre channel. Discrete left and right sounds still go to the left and right speakers. Sounds that are in common but 180 degrees out of phase with each other are routed to the surround channel. Note that while there may be more than one surround speaker, this signal is played equally through them all at the same time. A subwoofer signal could also be extracted using a simple low pass filter."

and also this video, also discussing the original Dolby Surround (Surround Sound On Retro Video Game Consoles, by Mythic Resonance):

"In the early days of home media surround sound, most media was making use of what we would call “matrixed surround”, meaning they were able to send four different channels of audio across the two stereo cables that were already in use with most audio equipment at the time. They did this by piggybacking an inverted phase signal on each of those two channels, which effectively doubles the available channels for a surround mix. So you have your normal Left and Right signals as usual, but one of them is now carrying a rear channel on its inverted phase, and the other is carrying a centre channel. So you now have four different channels for four different speakers that go around you in the room, wherever your listening space is. This is especially clever because it’s backwards-compatible with existing home audio systems – if you had a two channel stereo system, it would just play the Left and Right signals normally, and if you had a mono speaker in your TV, it would mix everything down to that one speaker and you would never know the difference. But if you had an AV receiver capable of decoding and separating those inverted phase signals (or a surround processor unit that would connect to your main stereo amplifier), you now had access to four channel surround – and some in cases 4.1 if your receiver was capable of sending everything below a certain frequency threshold out to your subwoofer."

Would greatly appreciate if someone could explain to me if the Audioholics video was correct in saying that Pro Logic 1 introduced the centre channel? And if so, is there some distinction in the definition of "centre channel" that I'm not understanding? And if it's actually correct that Dolby Surround introduced the centre channel, could anyone please explain what the main innovation of Pro Logic 1 was? (or was it mainly a rebranding exercise?)

 

[lovinthehd]

AFAIK it was originally invented and implemented for movie theaters. Try this https://www.harman.com/documents/HowManyChannels_0.pdf

 

[TLS Guy]

I'm writing a wiki article on surround sound for retro gaming consoles, and I've hit a bit of a speed bump in my understanding of the topic...

In this Audioholics video (Understanding Surround Formats in AV Receivers), Gene says that the original Dolby Stereo/Dolby Surround (my understanding is that Dolby Surround was basically the home equivalent of the theatrical Dolby Stereo format) was basically matrixed surround channels - with no centre channel yet - and that it was the Dolby Pro Logic 1 format (1987) that introduced the centre channel.

However, in my journey down this rabbit hole, I've come across video essays that indicate a centre channel was possible using Dolby Surround - such as this video (Sound Formats EXPLAINED by Sound Sack):

"Dolby Surround was originally known as Dolby Stereo when it was introduced to theatres in 1975. It wasn’t the first movie surround format, but it was the biggest and easiest to implement for some time. Dolby Stereo is the first cool reworking of a stereo signal that I’ll mention today. It’s able to produce four channels but they’re not discrete. These channels are left – centre – right and a single surround channel. It’s extracts them from a common stereo connection with a specially encoded signal. Sounds that are common in the left and right channel (aka mono) are routed by the processor to the centre channel. Discrete left and right sounds still go to the left and right speakers. Sounds that are in common but 180 degrees out of phase with each other are routed to the surround channel. Note that while there may be more than one surround speaker, this signal is played equally through them all at the same time. A subwoofer signal could also be extracted using a simple low pass filter."

View attachment 59591

and also this video, also discussing the original Dolby Surround (Surround Sound On Retro Video Game Consoles, by Mythic Resonance):

"In the early days of home media surround sound, most media was making use of what we would call “matrixed surround”, meaning they were able to send four different channels of audio across the two stereo cables that were already in use with most audio equipment at the time. They did this by piggybacking an inverted phase signal on each of those two channels, which effectively doubles the available channels for a surround mix. So you have your normal Left and Right signals as usual, but one of them is now carrying a rear channel on its inverted phase, and the other is carrying a centre channel. So you now have four different channels for four different speakers that go around you in the room, wherever your listening space is. This is especially clever because it’s backwards-compatible with existing home audio systems – if you had a two channel stereo system, it would just play the Left and Right signals normally, and if you had a mono speaker in your TV, it would mix everything down to that one speaker and you would never know the difference. But if you had an AV receiver capable of decoding and separating those inverted phase signals (or a surround processor unit that would connect to your main stereo amplifier), you now had access to four channel surround – and some in cases 4.1 if your receiver was capable of sending everything below a certain frequency threshold out to your subwoofer."

View attachment 59592

Would greatly appreciate if someone could explain to me if the Audioholics video was correct in saying that Pro Logic 1 introduced the centre channel? And if so, is there some distinction in the definition of "centre channel" that I'm not understanding? And if it's actually correct that Dolby Surround introduced the centre channel, could anyone please explain what the main innovation of Pro Logic 1 was? (or was it mainly a rebranding exercise?)

It goes back a lot longer than that. The credit has to go to Bob Fine and his wife Wilma Cozart. They developed three channel recordings with a center channel in the mid sixties, and by 1967 were making a slew of three channel recordings on three track Ampex magnetic tape recorders and also using optical recorders. These were made for Mercury Living presence. You can hear these recordings on SACD restored by Wilma Cozart, when she was in her nineties. It could be there are examples earlier than that, but I'm not aware of them.

 

[TheRealOC]

AFAIK it was originally invented and implemented for movie theaters. Try this https://www.harman.com/documents/HowManyChannels_0.pdf

Thanks for the quick replies!

I should probably clarify - the article I'm working on is only looking at surround sound formats in the home. Maybe instead of using the word "invented", I should have said - Which home multichannel surround format was the first to implement a centre channel?

Edit: Just figured out how to amend the thread title the earlier history is very interesting though.

 

[TLS Guy]

Thanks for the quick replies!

I should probably clarify - the article I'm working on is only looking at surround sound formats in the home. Maybe instead of using the word "invented", I should have said - Which home format was the first to implement a centre channel?

There were enthusiasts with three channel reel to reel machines in their homes, to play those tapes. Cinemas used the optical system.

 

[TheRealOC]

Don't know how likely this is, but is it maybe possible that Gene meant that Pro Logic 1 introduced a discrete centre channel?

 

[ski2xblack]

Pro logic did not introduce the center channel. I think credit would go to Bell Labs and their research into stereo recording and playback back in the 1930's. Disney's Fantasia was multi-channel, and it came out in 1940. It took a couple decades for home audio to catch up and stereo recordings and broadcasts to become adopted widely, but the benefits of three channel "stereo" were known and accommodated for back then. McIntosh, Scott, and others back in the primordial days of home hifi had kit that sported pre-outs for an extracted center channel. Add in rear channels via Hafler method, and it's getting pretty close to first gen Pro Logic.

 

[rsharp]

I don't have exact details, but hopefully these dates can narrow your search a bit.

I started with home surround in 1989. Cannot remember the brand, but there was some component that you could input the TV's audio out into and then connect three speakers. One front speaker and two surround. Not a center channel, per se, but you had just one up front.

I then moved to Dolby surround I believe later that year. Four speaker setup.

Next up (prob 1991) was a Pioneer receiver (cannot remember the model). I do remember picking up though two Pioneer magnetically shielded speakers to serve as a center channel (placed right next to the sides of my TV). The receiver at the time allowed direct hookup of two center channel speakers. I do remember "Pro Logic" at this point. So I thought that was something to do with the center myself.

These dates don't imply that's when things were introduced to the home market. But shouldn't be too far off.

 

[Kingnoob]

I don't have exact details, but hopefully these dates can narrow your search a bit.

I started with home surround in 1989. Cannot remember the brand, but there was some component that you could input the TV's audio out into and then connect three speakers. One front speaker and two surround. Not a center channel, per se, but you had just one up front.

I then moved to Dolby surround I believe later that year. Four speaker setup.

Next up (prob 1991) was a Pioneer receiver (cannot remember the model). I do remember picking up though two Pioneer magnetically shielded speakers to serve as a center channel (placed right next to the sides of my TV). The receiver at the time allowed direct hookup of two center channel speakers. I do remember "Pro Logic" at this point. So I thought that was something to do with the center myself.

These dates don't imply that's when things were introduced to the home market. But shouldn't be too far off.

What ever happened to those cool Dolby prologic shelf systems ?

 

[gene]

Don't know how likely this is, but is it maybe possible that Gene meant that Pro Logic 1 introduced a discrete centre channel?

Nothing was discrete until Dolby Digital 5.1.

Dolby Surround was 4 channel. Prologic introduced nondiscrete center.

 

[TheRealOC]

Nothing was discrete until Dolby Digital 5.1.

Dolby Surround was 4 channel. Prologic introduced nondiscrete center.

Thanks @gene !

Sorry for what's probably a stupid question, but just so I understand - what's the difference between a "nondiscrete centre" works (as in Pro Logic 1), and how *Sound Sack described a centre channel working in OG Dolby Surround?

*Sound Sack is the first paragraph in Italics from the original post, where he says (about Dolby Surround) "Sounds that are common in the left and right channel (aka mono) are routed by the processor to the centre channel ."

(I'm just being a bit dense here, but if Dolby Surround was 4.0, and you have left front, right front, and single mono surround channel, where would the fourth channel be?)

 

[TLS Guy]

Thanks @gene !

Sorry for what's probably a stupid question, but just so I understand - what's the difference between a "nondiscrete centre" works (as in Pro Logic 1), and how *Sound Sack described a centre channel working in OG Dolby Surround?

*Sound Sack is the first paragraph in Italics from the original post, where he says (about Dolby Surround) "Sounds that are common in the left and right channel (aka mono) are routed by the processor to the centre channel ."

(Or he just completely wrong, and there was no centre of any kind in DS?)

What Gene is saying is that Prologic derived the center from the left and right channels. It was not recorded discretely. 5.1 was the first Dolby discrete center.

The Fine/Cozart recording for Mercury WERE discrete and were ahead of 5.1 by a generation. After I have researched this I find that Fine/Cozart starting making discrete three channel recordings with an Ampex 300 tape machine as early as 1955. So I think the honors go to them.

 

[TheRealOC]

What Gene is saying is that Prologic derived the center from the left and right channels. It was not recorded discretely. 5.1 was the first Dolby discrete center.

The Fine/Cozart recording for Mercury WERE discrete and were ahead of 5.1 by a generation. After I have researched this I find that Fine/Cozart starting making discrete three channel recordings with an Ampex 300 tape machine as early as 1955. So I think the honors go to them.

Okay, I understand that nothing was discrete before 5.1

What I'm still not understanding is what the deal was with a centre channel in the original Dolby Surround? Meaning, did it exist? If so, how did it differ from the non-discrete centre in Pro Logic 1?

If it didn't, what was the nature of the fourth channel in Dolby Surround 4.0 (after the front left, front right and mono rear surround have been accounted for)?

 

[TLS Guy]

Okay, I understand that nothing was discrete before 5.1

What I'm still not understanding is what the deal was with a centre channel in the original Dolby Surround? Meaning, did it exist? If so, how did it differ from the non-discrete centre in Pro Logic 1?

If it didn't, what was the nature of the fourth channel in Dolby Surround 4.0 (after the front left, front right and mono rear surround have been accounted for)?

Somehow you have got confused. There was no Dolby 4.0 essentially. Dolby was a noise reduction company and only got into multichannel audio late in the day with Prologic.

The Quadraphonic craze of the seventies and early 80s were matrix based. There was no center channel. The speakers were in the four corners of the room basically.
There was discrete quadraphonic from commercial reel to reel tapes, for playing on four track tape recorder, not to be confused with the stacked four track stereo which where two channel and you turned over the tape to play the second side. Both sides of the tape where two track stereo, with 2+2 making four. The quadraphonic reel to reel machines had four record and playback amps, and the four tracks were recorded in the same direction and not one forward and one reverse. This was the only way to get discrete four channel, but there was NO center channel.

Now for LP and for VHS and Betamax tapes there were competing quadraphonic matrix systems. SQ Matrix from CBS, the QS Matrix from Sansui, JVC devised the CD-4 which was a carrier signal based system, Regular Matrix (RM), 45J by the National Research Development Council, Stereo 4 by Electrovoice, Dynaquad by Dynaco, and Matrix H by BBC. None of these were compatible, but Electrovoice did come out with a universal matrix decoder, and I still have mine, but do not use it, and have not for years. I do have a number of matrix LP quadraphonic recordings. The results form these matrix systems was frankly not worth the bother and expense and they died out. I will say that the Dolby DD surround up mixer decoder does a far better job, than the original decoders.

Some of these Quadraphonic recordings made from the discrete for channel master tapes have been released by Pentatone on SACD. And by the way Mercury have reissued the Fine/Cozart recordings on SACD and I think I have most of them. Now they are the front three channels and do have a center channel. They are absolutely superb, and a monument to the pioneering professionalism of that husband and wife team. They used an Ampex tape machine for some, and an optical recorder for others. They used three spaced Telefunken electrostatic mics. This Telefunken division morphed into Neumann.

As far as I know Dolby did not get into discrete multichannel recording and playback until Dolby Digital 5.1 and subsequent. Then there was competition from DTS and others.

I should mention as a foot note Ambisonics. This was a UK system developed in the seventies, and amazingly is a forerunner of Atmos. It required a complex single Ambisonic microphone with multiple capsules. It was a true sphere surround format and highly effective. However it was too complex for general distribution. The Ambisonic microphone was massively expensive and only available for a relatively short period of time. The system was totally dependent on that microphone. All the sound sources devolved from that single microphone only. So it was only really suitable for recording orchestras and choirs etc. in large spaces.

So, I think I have now probably written your Wikki article for you. If you do publish, then ethics and etiquette would require I have attribution.

 

[lovinthehd]

Wasn't the Dolby 4.0 surround for a center, l/r and a single rear surround?

 

[TLS Guy]

Wasn't the Dolby 4.0 surround for a center, l/r and a single rear surround?

Not as far as I know. I'm pretty sure that was a somewhat of a misconception, in that when Dolby Prologic came out, it was considered acceptable to use a single rear channel and both rears could be summed to the single rear channel by the software. But as I understand, and remember it, it was Dolby Prologic which was, and is, a matrix system, which is for five channels, but mixing the rear two to one via the software was acceptable under the Dolby license. In any event Prologic was a matrix system playing tricks with phase and was essentially a two channel system and NOT a discrete four or five channel system. In other words it was the original version of the Dolby upmixer from two channel. Dolby 5.1 was their first discrete multichannel system as Gene has pointed out.
Just for the record Dolby Prologic was introduced in 1987. So they came almost 20 years later than the other matrix systems. From 1965 to 1987 Dolby was strictly a noise reduction company for magnetic tape. In that they developed Dolby A, B and C noise reduction systems. Their major competitor was dbx and to some extent Telefunken.

 

[Kingnoob]

Not as far as I know. I'm pretty sure that was a somewhat of a misconception, in that when Dolby Prologic came out, it was considered acceptable to use a single rear channel and both rears could be summed to the single rear channel by the software. But as I understand, and remember it, it was Dolby Prologic which was, and is, a matrix system, which is for five channels, but mixing the rear two to one via the software was acceptable under the Dolby license. In any event Prologic was a matrix system playing tricks with phase and was essentially a two channel system and NOT a discrete four or five channel system. In other words it was the original version of the Dolby upmixer from two channel. Dolby 5.1 was their first discrete multichannel system as Gene has pointed out.
Just for the record Dolby Prologic was introduced in 1987. So they came almost 20 years later than the other matrix systems. From 1965 to 1987 Dolby was strictly a noise reduction company for magnetic tape. In that they developed Dolby A, B and C noise reduction systems. Their major competitor was dbx and to some extent Telefunken.

When was Dolby phantom invented ?
Pro Logic 1 was amazing when I first heard it.

 

[TheRealOC]

Not as far as I know. I'm pretty sure that was a somewhat of a misconception, in that when Dolby Prologic came out, it was considered acceptable to use a single rear channel and both rears could be summed to the single rear channel by the software. But as I understand, and remember it, it was Dolby Prologic which was, and is, a matrix system, which is for five channels, but mixing the rear two to one via the software was acceptable under the Dolby license. In any event Prologic was a matrix system playing tricks with phase and was essentially a two channel system and NOT a discrete four or five channel system. In other words it was the original version of the Dolby upmixer from two channel. Dolby 5.1 was their first discrete multichannel system as Gene has pointed out.
Just for the record Dolby Prologic was introduced in 1987. So they came almost 20 years later than the other matrix systems. From 1965 to 1987 Dolby was strictly a noise reduction company for magnetic tape. In that they developed Dolby A, B and C noise reduction systems. Their major competitor was dbx and to some extent Telefunken.

I give up

Trying to be polite here, but the original question is very simple.... I have two credible sources saying that that Dolby Surround (1982) implemented a centre channel before Dolby Pro Logic (1987) and another very credible source (Gene) saying that a centre channel was added by Dolby Pro Logic (1987). I would like to know which is correct; that is literally all the question was...................

 

[TheRealOC]

Wasn't the Dolby 4.0 surround for a center, l/r and a single rear surround?

Sure looks that way to me..........

 

[Kingnoob]

Sure looks that way to me..........

View attachment 59637

Interesting what year was Dolby stereo 1976 ? That ends up same channels as pro logic 1?
My bad I went off topic lmao, oh it’s on wiki but how accurate is Wikipedia?
I’m sure you already did all the research I’ll wait and read.

Dolby Stereo - Wikipedia

en.m.wikipedia.org