Archive | June, 2017

The Art Of The Decoder, Pt1

24 Jun

For quite some time now i’ve meant to do a basic introduction to Matrix Decoding. This isn’t going into any mathematics, or how to do, or not to do, and why (not). The main idea is to get you, the reader, up to scratch with what the decoder is, what it’s supposed to do, and anything else that pops up.

So, to start, let’s take a visit to dictionary corner:

ENCODER

An encoder is a device, circuit, transducers, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed or compressions.

DECODER

A decoder is either a hardware device or piece of software that converts coded data back into its original form

So, from the above we can see that a decoder is principly a device to return a previously mathematical encoded message/signal back to its original form.

In the beginning there was…..

So, in an attempt to convince the general public the need for quadraphonic reproduction in their homes, it was decided that such signals needed to be available for playback via the recently introduced Stereophonic Long Playing record. (remember this for later!)

A brief attempt at just using Amplitude matrix encoding, where it was impossible to decoded the four channels back in the same format as they were encoded, showed that there was interest in the general public, but another method was needed to be able to return the four channels back as they were encoded.

When the PAM (Phase Amplitude Matrix) method of encoding/matrixing four audio channel audio into two, using 90 degree phase shifting, was developed by Peter Scheiber, things moved on at quite a pace. There were a number of competing PAM  systems available, but after a short while there were only two systems still being used, these being Sansui’s QS and Columbia’s SQ systems.

They were quite different in their method of encoding, to the point that they were completely incompatible with each other. But one problem they did share was poor separation between the Front and Rear channels

SANSUI QS

Also know as RM, this system utilised all four audio channels to encode them into a compatible stereo signal. This is certainly the easiest of the two systems to decode, mainly because it used all four channels in the encoding process.

COLUMBIA SQ

Invented by Ben Briar whilst working for Columbia, this system took a completely different route by only utilising the two Rear channels in the encoding process. But by doing this caused some problems, most of which were never discussed outside of the companies laboratory. Also to correctly decode the rear channels it had to be done the correct way, there was no other way of doing it,

When is a Decoder not just a Decoder?

The word Decoder has become to mean more that it was originally meant to be. At first the competing companies sold what we would now call ‘Basic Decoders’, but their performance wasn’t that good, for any of the systems. The problem was due to the low level of seperation these matrix systems gave, bepending on system and circumstances, it was between 3db and 7db. Not much, so the companies developed various methods of improving their performance, which we shall just call Logic systems.

Basically these additions to the decoder circuitry varied the four levels from the decoder at such a rate/level, to give the impression that there was a greater level of seperation than there actually was by using the information in the audio itself. Unfortunately, such systems gave variable audible performance and one annoying side-effect….’Pumping’.

Now, as we can see from the above, including the logic circuitry in with the decoder, it became more than the name suggested. I make this point for one very good reason, which is that people seem to have forgotten that any decoder for either system must include both parts, the system decoder and the logic cicuitry designed to work with the information from the decoder.

I’ll leave it there for now so you can chew over what has been put forward in this basic introduction to the world of PAM.

 

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The (dreadful) state of the Quadraphonic community

19 Jun

I’ve been forced to break my silence here because of the continued idiocy of those that are thought to be ‘In the know’ and ‘those to be followed’ in what it believes to be the font of all knowledge when it comes to all things Quadraphonic.

I feel sorry for those who know little, to nothing, of the heyday of quad in that all they have to go on is the tripe that is spurted out by these people held in (false) esteem. It is the one sadness that i have that i’ll be leaving having barely made a dent in these peoples strangle hold on the community.

What has brought this about (again) is the following statement by ‘kap’n krunch’ on a subject he quite obviously knows nothing about, in every respect:

Having done QC for this release, and for some insane reason, not stating ANYWHERE that it’s a DVD-A, I can attest to the fact that it was NOT an SQ decode.

First of all, you can not get that kind of separation even with the best of scripts (just listen to the perfect separation of the drums on the left rear, no way josé that it’s a decode.)

Second, I saw a note written by an engineer who did a transfer from the MASTER of one of Yes’  LANDMARK albums a YEAR after it was recorded and he found all kinds of imperfections; “surface noise”, clicks, etc.
Guys, remember , analog tape is great but it’s not perfect!
And this was a 40 year old tape!!! (and not even the 1st gen master!)

I was quite amused to listen to it and having it sound better than what I remember listening before it was released.

Yes, the cover is VERY sloppy; no info on who did what and the typos that remind me of the ELP BSS SACD (STS anyone??)… LPCDM??? DTX????  oh well..we got it and, as opposed to the “King Arthur” one which is a DISASTER, this one is quite enjoyable…I’ll give it a healthy 8.

So, you can attest that it’s not an SQ decode? Really? How? I certainly don’t remember you contacting ME (the person who actually did the (pre-phoenix) decode for, and used, on that release. The Quad master tapes most certainly were not available for any of the Rick Wakeman releases.

Where have you been living, the separation issue on SQ has long been broken (by myself), and may i state that if you think the level of separation is impressive (thank you for the back-handed complement) then you’ll be shocked just how more impressive the possibilities are now!

You continue to to use scripts from the dark past, wake up, things have greatly moved on in the world. All you do is to show just how little you, and the rest of the know-nothings there, actually know.

That release was/is, in my view, very poor and very badly treated by the compression happy ‘Abbey Road’ studios. That release is an embarrassment, so much so that i made available to a handful (literally) of people a uncompressed Phoenix decode in compensation as Universal were willing to do nothing to right what Abbey Road had done to it.

So people, please be warned, those who confess to know it all in a certain place are of this level. Basically they are technically devoid of anything resembling fact and are to be treated with the highest contempt. Unfortunately there is nowhere i can suggest to go for the facts, if that’s what you are requiring.

 

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