[78-L] Binaural, duophonic, etc.

[Michael Biel]

On 4/21/2011 2:40 PM, Steve Williams wrote:
> Mike Biel is correct.  I was referring to the Blumlein "Matrixed" method of
> using a unidirectional wide pattern cardoid facing forwards, which is summed
> with the left-pointing cardoid and subtracted from the right-pointing mic -
> Or something like that.. :-)

I believe that some of the experiments were recording the front mic on 
one track and the sidewards mic on the other track and doing the 
matrixing on playback.  OR you could do the matrixing before recording 
and record the left on one track and right on the other.  See what I 
also say below.

>   But anyway David is right, that is not a
> correct method of capturing accurate "two-ear" imaging but can provide
> exceptionally realistic sound for playback on two speakers.  (I was at work
> and typing hastily.) When referring to Binaural, Stereo etc. I was going by
> current-day understanding of their meaning, I realize the terms were used
> differently in the past.
>

David mentioned that coincidental pair systems of miking give no time 
displacement clues to the brain, only level differences.  The brain 
needs both for binaural (using the modern meaning of the word.)  (I 
think we are losing a lot of our audience here with all this geekiness!!)

> I have the 1952 Mercury Wilbur DeParis Cook "Binaural" LP, and wonder how on
> earth anyone expected to get proper results using a twin spiral.


You mean Atlantic, don't you?  If so, I have this too, along with a real 
single groove stereo issue of the recordings that Atlantic issued in the 
late 50s.

>   (Many many
> years ago I stumbled upon a hoarder-of-anything who happened to have a NIB
> Cook arm among his detritus.  I begged and pleaded to get it from him, who
> didn't even know what it was, to no avail.)

That is closer than I have ever gotten to a Cook binaural arm.

>   But regardless, having two
> channels is just the start of the equation; most critical is that accurate
> timing of the two channels is necessary to maintain accurate phasing to
> preserve the imaging used by the ear to judge direction and distance of the
> source.  All early forms of record-playback equipment, except multitrack
> film, could not preserve that accuracy.

I would really like to have a cook arm to see how much the phasing would 
be affected by the traxcking era that must occur with that arm.  I would 
assume that Cook cut his masters with a normal straight-line lathe which 
would maintain accurate syncing of the two tracks ONLY if played back on 
a similar straight-line arm like a Rabco -- and no dual head arm like 
that was ever made.  Of course it IS possible that Cook had a special 
RADIAL cutting arm with the two cutting heads which would match the 
tracking era of the playback arm.  I've never seen anybody discuss this, 
especially Cook.

Most early miltitrack film equipment recorded the different tracks on 
separate films.  Because film is sprocketed it does not slip like tape 
can.  The recorders are synchronized with locked three-phase motors 
which also does not allow slippage.  (Once locked, if you turn the motor 
shaft of one and the others will also turn!)   In playback and editing 
the films can be passed thru synchronizers which are multiple sprocket 
wheels on one shaft.  The picture film is also synced this way.  By the 
1950s most multitrack optical or magnetic film were recorded on one 
film, but of course they still have to be synced with the separate 
picture film.

> Even early CD players which used
> only one DA convertor were anathema to Golden ears who could detect the
> timing error introduced between the two channels.

Most people don't realize that there is only one digital stream on CDs 
with the samples of the left and right tracks interlaced.

>   Staggered-head tape
> machines were getting there, but still fussy, until finally stacked audio
> heads and single-track record cutting were developed.

Right.  There can be spacing irregularities between the two heads, and 
tape stretching or shrinkage will also mess it up.

>   I guess the Decca
> vertical-Horizontal matrixed method of cutting was similar to the Blumlein
> matrixed mic pickups, and FM radio with the AM sideband subcarrier providing
> the difference signal to the FM summed channel.
>
> Steve Williams..
>

Both Blumlein and Western Electric experimented with vertical-lateral 
single groove stereo.  I believe -- but do not know for sure -- that it 
can be played back with a standard 45-45 stereo cartridge.  I don't 
remmber how these different companies experimented with having the two 
directions being the discrete left and right signals, or which had the 
lateral be the sum of both with the vertical being the difference.  I'd 
have to pull out a whole bunch of books and articles to remember all of 
this!
Pearl had sold pressings made from Blumlein masters, but I was not able 
to buy some in time.  Anybody here have them?

Mike Biel  mbiel at mbiel.com



> Date: Wed, 20 Apr 2011 14:02:08 -0700 (PDT)
> From: DAVID BURNHAM<burnhamd at rogers.com>
> Subject: [78-L] Binaural, duophonic, etc.
> To: 78-L at 78online.com
> Message-ID:<414652.32411.qm at web88103.mail.re2.yahoo.com>
> Content-Type: text/plain; charset=us-ascii
>
> Dan Van Landingham wrote:
>
> "Binaural" refers to a method of recording that mimics the human
> ear. - "Two Sounds." The microphones are literally mounted on a Styrofoam
> head in some cases, or a single crossed-8 cardoid stereo mic is used.  The
> listener wears headphones.
>
> ~~~~~~~~~~~~~~~~~~~
>
> As dl has pointed out, Duophonic was a Capitol term for simulated stereo.
>   Binaural recordings have to be made using microphones spaced approximately
> the
> same distance apart as the distance between a pair of ears, just like stereo
>
> photography uses two cameras which are eye-spaced apart.  In both cases the
> signal for the left ear/eye cannot reach the right ear/eye or it won't work.
>
>   That's why headphones or some sort of glasses must be employed respectively
>
> BUT the second half of the above statement is not only wrong, but is
> confusing.
>   There are several different kinds of mikes, based on polar patterns;  two
> of
> these are Cardioid and figure of 8.  Crossed figure of 8, (or bidirectional)
>
> mics will yield superb stereo recordings reproduced on speakers.  This is
> known
> as an XY system and was regularly used by BBC and EMI in the early days of
> Stereo.  The system was invented by Alan Blumlein and bears his name.  A
> bidirectional mike is also known as a cosine mike because the level of
> pickup is
> proportional to the cosine of the angle of incidence on the mike.  This may
> sound confusing but what it means is that this particular pickup is ideal
> because when your position to the mike is 90 degrees, which in an XY system
> is
> the direction from which the right signal will be arriving to the left
> channel
> mike, the output is theoretically zero, (the cosine of 90 degrees is "0").
> At
> 45 degrees, which is the angle at which each mike will be picking up a
> centre
> sound source, the output of each mike is reduced by half.  If a speaker
> walks
> from the extreme left to the extreme right of an XY pair of figure 8s, his
> voice
> level will not vary and the direction of the image will be identical to his
> position on the sound stage.
>
> Crossed cardioids, on the other hand, produce a less than ideal stereo
> image.  A
> cardioid mike is only down a couple of dBs at 90 degrees so a signal from
> the
> right side of the sound stage will produce a considerable signal to the left
>
> channel mike.  If the same speaker walks across a XY pair of cardioid mikes,
> the
> image will never be at the extreme left or right and the voice will be
> louder
> when he is at the centre, (called centre channel build up).
>
> In any case, neither of these situations will produce binaural recordings
> because the inter-channel time difference which is required for binaural
> reproduction is totally absent when using a coincident stereo mike.
>
> db
>
> ------------------------------
>
> Message: 9
> Date: Wed, 20 Apr 2011 19:26:35 -0400
> From: Michael Biel<mbiel at mbiel.com>
> Subject: Re: [78-L] Binaural, duophonic, etc.
> To: 78-L Mail List<78-l at klickitat.78online.com>
> Message-ID:<4DAF6BAB.7040701 at mbiel.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 4/20/2011 5:02 PM, DAVID BURNHAM wrote:
>> Dan Van Landingham wrote:
>>
>> "Binaural" refers to a method of recording that mimics the human
>> ear. - "Two Sounds." The microphones are literally mounted on a Styrofoam
>> head in some cases,
> Let me mention again that this use of the word was not solidified until
> the 1960s.  Prior to this binaural was used for just about any
> two-channel recording, including some that have w-i-d-e separation.
>
>>    or a single crossed-8 cardoid stereo mic is used.  The
>> listener wears headphones.
>>
> The explanation below is quite good, but I think that the above
> description might have been mis-understood because the wording is a
> little confusing.  Blumlein and others didn't always use a pair of
> bi-directional with one facing forward and the other facing sidewards.
> Sometimes a cardioid is used facing forward and the bi-directional
> pattern is facing sidewards.  I think this is what is meant in this
> description.  Using a cardioid as the forward facing mic instead of a
> bi-directional reduces pickup from the rear, such as audience noise and
> hall reverberation.   Stereo mics like the AKG C-24allowed for the
> changing of the patterns -- in the case of the C-24 even from the
> control room while listening to the results live!
>
> Mike Biel  mbiel at mbiel.com
>> ~~~~~~~~~~~~~~~~~~~
>
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