EV-4: The Mystery Solved? – Part II

16 May

Something i should have added in the first part of my investigation is that not all of the ‘QD’ releases are subject to having been released in EV-4 and QS formats. The last EV-4 encoded release appears to have been 5051 (Enoch Light – Big Hit Movie Themes) so it’s fair to say that any album from 5052 onwards marked QD is QS.

Now i will attempt to show how it is ‘possible’ to distinguish an EV-4 encoded album from a QS one, although i must state that when it comes to QS encoded albums the pictures may not be so clear cut, the visual phase response is just a snapshot of a rather complex mathematical  equation, so if you attempt to try this method yourselves, please take your time! Hopefully you’ll see why.

Unfortunately i don’t have more than one copy of any of the Project 3 quad albums so i’m unable to show how a particular albums visual phase response difference compares between the two, but i’m sure that the two albums chosen will give an adequate picture, so to speak.

We’ll start with one of the demonstration albums that were only released using EV-4. This is the album i released a few days ago, ‘Enoch Light – 4 Channel Stereo’. The first picture shows the standard waveform of the complete album that was used for decoding purposes, and included on the release.

The next view is a snap shot of the waveforms spectral phase. It would be very easy to take too much notice of this as it only shows a visual representation of what the program sees and isn’t truly correct, but for the purpose of this experiment it will be more than adequate.

As you see, there is a large amount of zero phase information on almost every track, surrounded by large amounts of random phase information, including some small amounts of out-of-phase information on a couple of tracks.

This could be considered fairly standard for a stereo album and normal for an Amplitude Matrix system like DY and EV-4. As will be seen later, there is no evidence of any +-90 degree information above or below the zero degree line.

Now for the next album marked QD, which is ‘Tony Mottola – The Best Of’

and its spectral phase

I’m sure that you’d agree the difference is instantly obvious, there being less ‘random’ phase information and a slightly lower level of zero phase information. But more importantly there is evidence of +90 degree information on two of the tracks.

Although it is QS encoded, due to the way the audio is encoded and this being just an overview snap shot, there is no guarantee that there will always be such marked proof as shown here. Closer examination by expanding the view horizontally per track would probably show up smaller groups of ‘information’ on either the -90 or +90 degree line.

Because of this it’s not advisable to go by just one track from an album, but at the bare minimum one half of it, preferably the whole album.

To end  i’d like to re-emphasise that this issue is probably why many state that their ‘previously thought to be EV-4 album’ decodes perfectly well through a QS decoder is because it is QS.

The program i have used is Adobe Audition 3, which was once a paid for programme but has, in the last few years, been officially available as a free download. To save having multiple links i’m making the whole package (including updates) available.

 

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2 Responses to “EV-4: The Mystery Solved? – Part II”

  1. Owen Smith May 17, 2018 at 00:42 #

    I think there was also some effect caused by decoder manufacturers saying “Yes of course our new QS decoder can decode all your existing quad albums, buy with confidence” while the techies of these companies knew full well this was a lie. But business demanded compatibility, and EV-4 and DY decoders did such a vague job in the 1970s anyway that provided something came out of the rear speakers through a QS decoder the customers were happy. Once this and the confusion of LP labelling you have explained got entrenched it was too late to fix the misunderstanding, and it wasn’t in anyone’s commercial interest to fix it anyway.

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