[Don Pearce]

Adrian Tuddenham wrote:
Don Pearce wrote:

Adrian Tuddenham wrote:
Don Pearce wrote:

Edi Zubovic wrote:
On Sat, 02 Aug 2008 07:59:38 +0100, Don Pearce
wrote:

BBC Radio4's Archive Hour tonight at 8pm (UK) is all about Alan
Blumlein, and apparently has a load of his original recordings. Here's a
sample of a stereo test he did in the 1930s - I just grabbed it off the
trailer. There would have been more but Audition is really slow to fire
up when you want it in a hurry.

http://81.174.169.10/odds/blumlein.mp3

d
Thank you, I'd wish you had more of that. These are interesting stereo
recordings to investigate. Try to invert the right channel and sum up
into mono, you'll get some interesting cancellarions.

Edi Zubovicc, Crikvenica, Croatia
You know what? I get a much more stable set of images having inverted
one channel. I wonder if he got the polarity wrong all those years ago.
Or maybe something has happened to it since.

See the pictures of his cutterhead...

http://www.doramusic.com/Binaural%20...%20head%20side
%20view.JPG

http://www.doramusic.com/Binaural%20...%20head%20deta
il.JPG

....he got the polarity right, his recordings used lateral and vertical
modulation for the two channels. What has happened since is that the
BBC has incorrectly played the recordings in 45/45 stereo.


One of Blumlein's original recordings of the Abbey Road stereo tests was
available as a vinyl re-pressing on the 'Symposium' label (Nr: 1028A).
A vector analysis of it only shows strong modulation on one diagonal,
the other diagonal contains a very faint and distorted signal. Some of
Blumlein's tests were performed with spaced omni mics (HB1s?) and the
spacing was varied from zero to various widths, so it seems possible
that this is the test recording made with zero spacing - unfortunately
it was the only one re-issued (although metalwork for the others still
exists).

Not sure - assuming the 45/45 idea is what has happened, I've done the
necessary sum and difference edit to get vertical and horizontal. The
stereo effect disappears entirely, leaving just a rather shaky central
source. Inverting one channel gives a very clear sound stage with the
players distributed evenly across it. So I think they did do a
conversion from V/H, but got it wrong, ending up with one inverted channel.

I think you're right. I wonder where the mistake occurred and why it
wasn't spotted before transmission?



Maybe they just expected nothing better than they got, and failed to
pursue it. They would have had a pleasant surprise had they done so.

d