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-   -   "Technically augmented stereo" (https://www.vintage-radio.net/forum/showthread.php?t=164370)

joebog1 1st Mar 2020 6:35 am

"Technically augmented stereo"
 
2 Attachment(s)
I have a few LP's that are at the turn of stereo/mono.
I have a SUPERB LP as the cover shows, apparently made around 1962.

It WAS mono recorded, but this has been "fiddled with. It's called "Re engineered for stereo, which on my humble/bumble system means that the left channel appears as audio about 20 or 30 mS AFTER the left. ( unless I dont know left from right).
NOW, the quality is excellent, BUT the fact that the reverb is ALSO mono and about ( my guess) 30 mS AFTER the right channel!!.

Is there anybody that can offer REAL explanation of this (mostly American)
blodge of the original mono ?
This is a VERY heavy LP, about 180 Gms, on Roulette label.

Joe

'LIVEWIRE?' 1st Mar 2020 9:11 am

Re: "Technically augmented stereo"
 
To me, some of those 're-engineered for stereo' pressings give the impression that, if vocals are involved, these all appear to come from one channel, whilst all the instruments appear to come from the other. No doubt this has something to do with the way the 'artificial stereo' is created.

Craig Sawyers 1st Mar 2020 9:13 am

Re: "Technically augmented stereo"
 
Thanks for the heads up about the existence of this LP!

I've tracked down a copy that has not been messed with - ie not stereo enhanced and in the original true 1959 mono. No idea how worn or crackly it will be when it arrives, but it looks like a real rarity.

simpsons 1st Mar 2020 10:41 am

Re: "Technically augmented stereo"
 
According to Wikipedia, Duophonic Stereo is the process you are listening to. Better known as "fake stereo", the process cuts bass on one channel and treble on the other, add reverberation and you will give the listener an aural experience of something better left for others to comment on.

Chris

Ted Kendall 1st Mar 2020 10:45 am

Re: "Technically augmented stereo"
 
Basically, there are four techniques available for creating some sort of stereo effect from a mono signal :

Frequency division between left and right - this can be as simple as turning the bass up on one side and the treble up on the other. When applied to 78 originals, as it often was, this caused a deficit in surface noise on one side, so some bright sparks added a loop of surface noise on the quieter side to even things up...! A more sophisticated variant, used in the Orban stereophoniser and the BBC TRU "spreader", is to apply several broad peaks to the signal, route that left and then subtract this from the original and route it right. The beauty of this is that the sum gives you back your original signal.

Time delay between channels - this perforce gives some impression of width, but Haas effect tends to make the earlier channel sound louder, so there are limits to how much you can use, and the mono signal of course goes to pot.

Application of reverberation - the EMT stereo plate had one driver and two collectors, so it was a useful tool for creating a fairly convincing stereo "wash". A variant of this technique, used by Argo, was to use a mono plate but to send its output to the difference channel only - this again gave some sort of stereo "wash", but one which disappeared altogether in mono.

Separation of work parts - by which I mean the technique used on the early Beatles' stereo releases. Studio practice was to use stereo machines, in effect, as two track machines, with backing on one track and leads on the other, to allow manipulation of the balance for the final master, which was in mono. The easiest way of producing a "stereo" sound was therefore to route the individual tracks left and right.

Some issues used all of the above to varying degrees. Record companies were less concerned about mono compatibility than broadcast organisations, where the majority of the audience were listening in mono and had to have a signal which still made sense to them. Techiques which could be cancelled by simple use of the mono button were therefore preferred in the BBC.

One instance I should mention is the Transcription Service issues of The Goon Show in simulated stereo. This was no "shove it through a box" job, but a re-imagining of the action in stereo. The script was first marked up with the position and movement of each character. Then each speech was dubbed with appropraite panning to a stereo tape through a spreader and the speeches edited together to re-form a continuous performance. This called for very precise editing - all on quarter-inch, mark you - and attention to hazards like "flying edits", where the taper of the cut caused a speech to flit to one side momentarily. Effects and music were treated more conventionally, and when the whole was assembled it was played through a stereo plate to simulate PA colouration and give the sound a coherent "frame". A technical tour de force, which brought the shows to a wider market (most FM stations in the USA and Canada were running a "Stereo only" policy by this time), but in my view of dubious artistic merit.

The other notable instance of updating an older recording for stereo was Decca's addition of a stereo orchestral accompaniment to the Kathleen Ferrier record of Bach and Handel arias. This was well received at the time, but the advent of CD showed the seams a little too obviously and all the CD reissues of this material have been in the original mono.

paulsherwin 1st Mar 2020 11:25 am

Re: "Technically augmented stereo"
 
None of the 'fake stereo' techniques were particularly convincing, and the driver seems to have been simple marketing - people were reluctant to buy mono recordings when they had spent lots of money on a fancy stereogram. Nowadays digital techniques allow the creation of a much more convincing stereo mix from a mono master, but listeners are much happier to accept the original mono mix so fake stereo is rare.

Ted Kendall 1st Mar 2020 2:48 pm

Re: "Technically augmented stereo"
 
In some ways, the record companies made a rod for their own backs - for several years they pushed and pushed for "single inventory" - that is, stereo releases only, with no mono equivalent, This made it practically impossible for the majors to release back catalogue in mono until the advent of CD. Even such classics as the Beecham set of La Boheme and Karajan's first Beethoven symphony cycle were "stereophonised", fairly inoffensively as it happens, but they did not trust even material of that quality to sell on its own merits.

Sideband 1st Mar 2020 9:10 pm

Re: "Technically augmented stereo"
 
Interesting thread. Has anyone heard of DES....Digitally Extracted Stereo. I gather this is called 'spectral frequency division' whereby the original mono recording is fed to digital frequency filters and then fairly complex mixing is required to generate what sounds like a very convincing stereo sound. I have had some American compilation CD's that have had original mono tracks processed in this way and they sound just like normal stereo. Eric Records seem to specialise in this technique http://www.ericrecords.com/htf_17.html

If you scroll down to the explanation at the bottom of the screen, it gives you an idea of how DES works. http://www.ericrecords.com/des_explan-htf17.html. There are some audio samples of DES processed mono tracks.....they sound just like normal stereo.

As an example, back in 1962 The Tornados released Telstar but it has never been officially released in stereo. Here is a DES processed recording of Telstar https://www.youtube.com/watch?v=y6NEqCbnBeI. There are some arguably better songs in the samples presented.

Ted Kendall 1st Mar 2020 10:03 pm

Re: "Technically augmented stereo"
 
Digital, analogue or steam-driven, there is only so much that can be done with a single channel of information, and this is basically frequency division with some steering logic on transients. Where it comes unstuck is when two leads are in the same band, so in Telstar you have the hi-hat anchored right and the rest swimming about.

For me the acid test is whether you switch to mono with a feeling of relief, and with all but the mildest examples of fake stereo this invariably happens to me.

Craig Sawyers 2nd Mar 2020 12:33 am

Re: "Technically augmented stereo"
 
Quote:

Originally Posted by Craig Sawyers (Post 1221465)
Thanks for the heads up about the existence of this LP!

I've tracked down a copy that has not been messed with - ie not stereo enhanced and in the original true 1959 mono. No idea how worn or crackly it will be when it arrives, but it looks like a real rarity.

OK - I won it on a best offer. I'll let you know what state it is in, when it arrives. In unmessed with mono.

joebog1 2nd Mar 2020 12:44 am

Re: "Technically augmented stereo"
 
G'day Craig.

Only track one is "messed" with. Rest of the LP is mono. If your copy plays OK you do have a rarity.

The actual sound is so badly messed with that it sounds like she is singing the same song milliseconds apart, and is DEFINITELY not convincing.

The last track on side one, and on side two are by Ted Alevizos and are superb songs in their own right.

Joe

BulgingCap 2nd Mar 2020 2:43 am

Re: "Technically augmented stereo"
 
What is 'plate' as referred to in stereo plate or mono plate?
I have not come across this term before.
Thanks,
BC

suebutcher 2nd Mar 2020 2:56 am

Re: "Technically augmented stereo"
 
The Telstar stereo job is quite convincing, and it makes sense because it opens the recording up so you can hear the tricky production clearly. But I was amazed by their improvement of the sound quality of "You're Gonna Miss Me"; the first 13th Floor Elevators LP is a great record spoilt by poor recording, and I've been hoping that one day it will be restored and reissued.

suebutcher 2nd Mar 2020 3:21 am

Re: "Technically augmented stereo"
 
Quote:

Originally Posted by BulgingCap (Post 1221746)
What is 'plate' as referred to in stereo plate or mono plate?

A reverb plate is basically a plate of steel suspended on springs with a small speaker and microphone attached to the opposite ends. The plate reverberates, giving the effect of an echoing hard walled space. The echo can be softened by moving a pad of felt against the plate. Add another speaker and mike, and you've got a stereo plate.

Nuvistor 2nd Mar 2020 8:10 am

Re: "Technically augmented stereo"
 
Short video of the EMT 140 plate reverb, didn’t realise they were so big.

https://youtu.be/HEmJpxCvp9M

bluepilot 2nd Mar 2020 10:17 am

Re: "Technically augmented stereo"
 
Quote:

Originally Posted by joebog1 (Post 1221734)
The actual sound is so badly messed with that it sounds like she is singing the same song milliseconds apart, and is DEFINITELY not convincing.

A very simple way of producing a stereo effect is to duplicate a mono channel to make a two-channel track and then delay one channel by a few milliseconds. You can do it yourself quite easily. Take something like Audacity and make a two-channel version of a mono recording. Then chop a few milliseconds off the start of one channel. It spreads the sound out a lot but it's certainly not stereo.

TIMTAPE 2nd Mar 2020 12:01 pm

Re: "Technically augmented stereo"
 
Quote:

Originally Posted by joebog1 (Post 1221734)
Only track one is "messed" with. Rest of the LP is mono. If your copy plays OK you do have a rarity.

The actual sound is so badly messed with that it sounds like she is singing the same song milliseconds apart, and is DEFINITELY not convincing.

The last track on side one, and on side two are by Ted Alevizos and are superb songs in their own right.

I listened to some versions on YT of the first track, "On the banks of the Ohio", transferred from vinyl. On one her voice seems slightly to the right of centre, the guitar slightly to the left, so it may have been recorded in stereo. Recording live voice and guitar at the same time can be difficult when the two mics are mixed together.

On some of Bob Dylan's early solo albums recorded about the same time, the voice is hard one way and the guitar hard the other. It's not necessarily to everyone's taste but keeping the tracks on separate stereo channels or even just spreading them apart a little can help avoid the problem of "comb filtering" between the tracks.

Sometimes the delay between left and right channels is a production mistake. An example on a famous track is "Teach your Children" by CSNY where half way through the song the timing between left and right changes.

https://youtu.be/EkaKwXddT_I

Listening in stereo it's not too bad but in mono the harmony voices seem to partly disappear down a hole in the floor. This was probably caused by a head azimuth misalignment between tape machines in production.

So "simulated stereo" is not necessarily intentional. It may just be less that stellar production.

Station X 2nd Mar 2020 12:42 pm

Re: "Technically augmented stereo"
 
I'm sure I have some LP's somewhere which are labelled something like "Mono recording electronically enhanced for stereo". I'll have a look and a listen.

Andrew2 2nd Mar 2020 12:49 pm

Re: "Technically augmented stereo"
 
Quote:

Originally Posted by suebutcher (Post 1221747)
The Telstar stereo job is quite convincing, and it makes sense because it opens the recording up so you can hear the tricky production clearly. But I was amazed by their improvement of the sound quality of "You're Gonna Miss Me"; the first 13th Floor Elevators LP is a great record spoilt by poor recording, and I've been hoping that one day it will be restored and reissued.

Back in the 90's I started making 'karaoke' versions of records (mainly Motown, as most were clean pan-potted mono tracks rather than 'stereo pair' productions). Once the lead vocals were removed by simple phase inversion and addition, the underlying production methods were easy to hear - instruments being roughly punched-in, sloppy edits etc, all of which were normally hidden by the singer's voice.

Andrew2 2nd Mar 2020 1:15 pm

Re: "Technically augmented stereo"
 
Having just read the explanation of DES, I was reminded of a feature I saw on TV about 30 years ago (possibly more). It was about noise reduction in the restoration of old recordings, and it used exactly the techniques discussed in that article. The idea was to allow through only the specific frequencies produced by each instrument and reject the noise 'between' them.
At the time I wondered about the overlapping frequencies of the various instruments, but it seemed to work. I also wondered how they managed to allow the harmonics of the instruments to pass though, as it is these which produce the character and timbre which identifies each one.
Only a short step from noise reduction to sending each instrument to its own place on the stereo stage.


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