A Discovery

[Gary Eickmeier]

I hesitate to mention this for fear that it will look like I am just posting
to get more attention (after the Beolab thread) but I thought this was neat.

I had been wondering how to force some surround sound to decode to the rear
in a Dolby Pro Logic decoder. Last night I decided to try something while
recording a rehearsal of our jazz band. I took out a 4th mike, stood about
10 ft back, behind my main stereo trio of mikes, and set it to a fig. 8
pattern, and went straight to the rear on playback!

So what to do with this newfound knowledge. It is only mono, but it could
be used for rear sound, as in the audience applause but up to now no one has
tried that - that I would know about. Anyway, this mono channel goes to the
rear so solidly it seems like discrete.

Anyone done this before?

Gary Eickmeier






opped parts of my main

[Gary Eickmeier]

"Gary Eickmeier" > wrote in message
...
>I hesitate to mention this for fear that it will look like I am just
>posting to get more attention (after the Beolab thread) but I thought this
>was neat.
>
> I had been wondering how to force some surround sound to decode to the
> rear in a Dolby Pro Logic decoder. Last night I decided to try something
> while recording a rehearsal of our jazz band. I took out a 4th mike, stood
> about 10 ft back, behind my main stereo trio of mikes, and set it to a
> fig. 8 pattern, and went straight to the rear on playback!
>
> So what to do with this newfound knowledge. It is only mono, but it could
> be used for rear sound, as in the audience applause but up to now no one
> has tried that - that I would know about. Anyway, this mono channel goes
> to the rear so solidly it seems like discrete.
>
> Anyone done this before?
>
> Gary Eickmeier

I had some recordings that wre made with my four cardioids tree, so I took
the rear one and inverted it and paired it with the non inverted original,
put them both on separate tracks, and mixed them into the stereo tracks.
Worked perfectly. So what I have is the normal (quite spacious) front stereo
tracks plus this new mono surround track.

Audible result - it doesn't change the stereo at all, and in fact it is a
little hard to tell that it is back there - until you turn it off, and then
suddenely the room left the room... so to speak.

Gary Eickmeier

[Peter Larsen[_3_]]

Gary Eickmeier wrote:

> I hesitate to mention this for fear that it will look like I am just
> posting to get more attention (after the Beolab thread) but I thought
> this was neat.

It is neat and "known and described in the literature", but not everybody
reads it.

> I had been wondering how to force some surround sound to decode to
> the rear in a Dolby Pro Logic decoder. Last night I decided to try
> something while recording a rehearsal of our jazz band. I took out a
> 4th mike, stood about 10 ft back, behind my main stereo trio of
> mikes, and set it to a fig. 8 pattern, and went straight to the rear
> on playback!

> So what to do with this newfound knowledge.

The real thing dolby encodes and decodes it as I recall things, but it is
just a stray recollection and I have occasionally been wrong.

Kind regards

Peter Larsen

[Gary Eickmeier]

This is working out quite well. Last concert, I put four cardioids on my
stand pointing in the cardinal directions, the rear facing one getting the
audience. I download the four tracks from the Zoom H6, download another
duplicate of the rear track, invert it, and then run the two rear tracks to
the right and left channels to drive that track to the rear. Need them at
the same level to get a perfect isolation from the front channels, but it
works with only two channels. Nice surround effect. Poor man's Ambisonics.

Gary Eickmeier

[Tom McCreadie]

Gary Eickmeier wrote:

>This is working out quite well. Last concert, I put four cardioids on my
>stand pointing in the cardinal directions, the rear facing one getting the
>audience. I download the four tracks from the Zoom H6, download another
>duplicate of the rear track, invert it, and then run the two rear tracks to
>the right and left channels to drive that track to the rear. Need them at
>the same level to get a perfect isolation from the front channels, but it
>works with only two channels. Nice surround effect. Poor man's Ambisonics.
>
Is this "nice surround effect" really a worthwhile improvement over, say, David
Hafler's passive pseudo-quadraphonic circuit from the 70's ?

The latter has some practical advantages: two starting channels, so only two
instead of four heavy AT mics loading that flimsy stand-base thread that you had
reported And the matrixing can be done without a computer. :-)
__
Tom McCreadie

[William Sommerwerck]

"Gary Eickmeier" wrote in message ...

This is working out quite well. Last concert, I put four cardioids on my
stand pointing in the cardinal directions, the rear facing one getting the
audience. I download the four tracks from the Zoom H6, download another
duplicate of the rear track, invert it, and then run the two rear tracks to
the right and left channels to drive that track to the rear. Need them at
the same level to get a perfect isolation from the front channels, but it
works with only two channels. Nice surround effect. Poor man's Ambisonics.

What you've done doesn't even remotely resemble Ambisonics.

[Gary Eickmeier]

"Tom McCreadie" > wrote in message
...
> Gary Eickmeier wrote:
>
>>This is working out quite well. Last concert, I put four cardioids on my
>>stand pointing in the cardinal directions, the rear facing one getting the
>>audience. I download the four tracks from the Zoom H6, download another
>>duplicate of the rear track, invert it, and then run the two rear tracks
>>to
>>the right and left channels to drive that track to the rear. Need them at
>>the same level to get a perfect isolation from the front channels, but it
>>works with only two channels. Nice surround effect. Poor man's
>>Ambisonics.
>>
> Is this "nice surround effect" really a worthwhile improvement over, say,
> David
> Hafler's passive pseudo-quadraphonic circuit from the 70's ?
>
> The latter has some practical advantages: two starting channels, so only
> two
> instead of four heavy AT mics loading that flimsy stand-base thread that
> you had
> reported And the matrixing can be done without a computer. :-)

Well, I am thinking that mine is more discrete in that I am recording the
rear sound with its own dedicated microphone, then forcing that track to the
rear on decode. So I am not just extracting ambience from the two channel
recording, I am actually recording what should go back there. My system
would also be grabbing whatever ambient sounds are picked up by the front
and side mikes and processing it the same way as Haffler too, right? What is
interesting to me is that I seem to have a discrete surround system that can
be encoded into a 2 channel recording. Probably not the first, but I haven't
seen it before.

Gary