The restoration of a rare surround treat from the 70s

Bas Möllenkramer

Procol Harum Quadraphonic Concert on BBC Records : the restoration of a rare surround treat from the 70s

Disclaimer: it is illegal to trade BBC Transcription records. This article is placed
here for research and entertainment purposes only and not for trade of any kind.

As most readers of the Procol Harum website will be aware, the BBC recorded many superb rock concerts in the 60s and 70s. These shows were broadcast by the BBC themselves obviously, but often the shows were also licensed to other broadcasters around the planet. An efficient and cheap way to distribute the shows to other stations was to send them LP records. These are known as BBC Transcription discs. They were accompanied by typed sheets indicating playing times of the songs and perhaps a note of two about the spoken introductions. Sometimes suggestions were made for the local radio announcer to add some comments.

Procol Harum played for the BBC in 1974 at the Hippodrome Theatre in Golders Green. The announcer was Bob Harris. The show is known as “Stereo Pop Special – 66 (i & ii), Pop Spectacular featuring Procol Harum in Concert”. This recording was made just as quadraphonic sound was gaining in popularity. In the early and mid 70s there were three main competing technical systems for presenting four channel sound from a single stereo record groove, known as CD4, QS and SQ. There were a few other less well-known systems too like UD4 and EV. CD4 and SQ were the best known at the time and SQ records had the advantage that no special needle or turntable was required to play them. Quadraphonic Sound or simply Quad was of course an important forerunner of the surround systems of today.

The Procol Harum 1974 BBC show was recorded in Quad and distributed on an SQ-Quad LP record. The BBC’s catalogue number for the disc is CN2023/SQ. There is a note on the text sheet which states “THIS RECORDING IS IN SQ MATRIXED QUAD AND IS FULLY COMPATIBLE IN STEREO AND MONO. IT IS ESSENTIAL TO USE A STEREO PICK-UP. The matrix numbers are 135128-SQ and 135129-SQ. The duration of side one is 25:00 and of side two 27:25. This meant that the disc could be broadcast as two half-hour shows or as a single one-hour show. The songs are:

The band consisted of Gary Brooker, Chris Copping, BJ Wilson, Alan Cartwright and Mick Grabham. Keith Reid was also present.

A plan was made to investigate the possibility of transcribing this LP to CD in such a way that it could be enjoyed in its proper surround sound format on modern systems. There are a number of surround formats available and for reasons of technical simplicity and availability the DTS format was chosen early on. DTS is a surround format that can be burnt on ordinary CD-R discs. First however the LP record had to be transcribed into the computer. This was done on a self-assembled record player (now known as a vinyl engine!) based on a Technics SP10 MkII drive, an SME3009 MkII arm with fluid damper attached and a Stanton 981 LZS professional cartridge. After amplification, this signal was played into a Platinum sound card. After a very thorough cleaning (and some nervousness!) the disc ultimately revealed a very good clean sound indeed. The computer recording of the disc was done as if it were stereo. The decoding into four channels comes later. The computer files were de-clicked in two stages. First the light setting of automatic click removal in Adobe Audition 1.5 was used and then a few remaining loud clicks were gently edited out by hand, using the same superb software.

Next the files were burnt on to a CD-R, once again as if they were stereo recordings. Indeed the programme can simply be played in stereo and enjoyed fully. But proper decoding is needed to reveal the surround sound hidden in the grooves. Many commercial SQ decoders were made throughout the 70s and part of the 80s, each with increasingly powerful processing to improve channel separation. Simple earlier SQ decoders sound all right but lack full channel separation. Later models got cleverer and used special algorithms (tricks) to improve separation, culminating in a very clever and expensive box, known as a Fosgate Tate SQ-decoder. The “Tate” is the most desirable SQ decoder around today and correctly functioning second-hand units routinely fetch four-figure sums on internet auctions. Since I don’t have one, I sent a CD-R of the entire record to Tab Patterson who lives and works in the USA and is regarded by many as one of the most knowledgeable quad-gurus around today. He kindly agreed to decode the programme into four channels using his valuable Tate and of course his skills and experience.

The last step in the process is to use a special software package to take four channels of audio and code them into DTS files. All modern DVD players will also play standard audio CDs and if the player has the DTS logo visible somewhere on the front panel, then it will also play CD-Rs encoded with DTS material. Of course the output signals of the DVD player will need to be attached to some type of surround amplifier and at least four loudspeakers. For auditioning the final results a Pioneer DV-656A DVD player was used and its six-channel discrete outputs were connected to a Denon AVR-1803 Surround Receiver. Either box is capable of DTS decoding but in this setup the decoding is left to the DVD player to perform. There are other ways to play DTS CDs but that is left for the reader to discover.

So how does it all sound? This show can be played off vinyl into a standard stereo system, or can be enjoyed in stereo off a CD-R containing a copy of the vinyl. It can be played into a simple SQ decoder straight off vinyl with medium separation, and finally it can be enjoyed in DTS format on modern surround systems. However you listen, it was certainly a great show, with Procol Harum in great form. The music is wonderful and the sound is nice and heavy. The drums aren’t always loud enough and it is thought this is simply due to the BBC balance engineers needing some time into the show to get it right.

In DTS surround sound, after all the processing described above, the sound is superb, and the listener appears to be a guest onstage. Surround Sound has the advantage that the contribution of individual instruments becomes easier to distinguish without giving the impression of musicians playing separately. The listener is truly immersed in the sound and almost feels a part of the band. Finally, this record sounds better the louder you play it!

In 1999 a standard stereo CD of this show was officially released. This album is entitled Procol Harum: Live at the BBC and is on the Strange Fruit label. This CD contains two additional songs from the show that are not present on the SQ-QUAD LP. These are Beyond The Pale and Grand Hotel. It is just conceivable that this CD was taken from exactly the same tapes used to press the BBC Transcription disc which is the centrepiece of this story. If that is true, then in theory it should be possible to take this new CD, play it into the Tate or any other high quality SQ decoder equipped with sophisticated decoding logic, and get true four channel QUAD sound. As a copy of this CD was not available at time of writing, it is not known whether this is indeed the case. We might publish a future addendum to this story, once this analysis has been made.

Unless one of the readers of this website beats us to it. You are hereby officially challenged to take up the gauntlet – until then enjoy the great music of Procol Harum!

Bas Möllenkramer
Soest
The Netherlands