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Pete Cornish's work for Queen from 1972 to 1992
All text and photographs copyright ©Pete Cornish 2005 and may not be
copied or used without first obtaining permission in writing
GUITAR/ECHOS/AMPS ROUTING SYSTEM:
My involvement with Queen started in 1972 when I was chief engineer at Grafton Electrical and Music Industries (GEMI) who were the proprietors of the “City” group of retail outlets (Sound City, Music City and Drum City). My duties included the maintenance and repair of Amplifiers and Guitars and also the design and building of new equipment and connecting cables. All work carried out for Queen after June 25th 1976 was through my company “Pete Cornish Musical Accessories”.
My first commission from Queen was to eliminate the ground loop hum caused by the interconnection of 3 X Vox AC30 Amps and 2 X modified Echoplex EP3 Delays. In January 1972 I designed and built special circuitry to isolate the amps and echoes, which successfully eliminated all the hum problems. This system was used for their first and subsequent tours up until 1982, also the recording of their albums during this period.
By January 1976 Brian May was using 9 X AC30 amps on stage and the same 2 Echoplex EP3 Delays (see photo9 X AC30 + EP3s) – this required an enlarged Routing System which I designed and built. Despite the large number of Vox AC30's then in use my system successfully eliminated all Ground Loop hum and noise.
Both the above Routing Systems were built into many individual boxes so that for each show the Tech had to wire the system and this was very time consuming!
In June 1982 I was requested to build an integrated system for Brian May’s stage set up, with the majority of the wiring permanently installed, in order to reduce the “rigging” time. The system comprised a Footboard (plus1 spare) (see photoB.May 2 X F/Board also B.May FX Board 1, FX Board #2, F/X Board #3, and F/X Board #4) connected to the main Routing Unit (situated behind the AC30s) (see photos B.May Rout. Unit #1 and B.May Rout. Unit #2) via a 25M multicore cable (see photo B.May System Jun’82). The AC Power for the amplifiers, the Routing System and the Echoes needed to be stabilized at a constant voltage and I designed and built a Power Distribution System (see photos Brian May PSU #1 and Brian May PSU #2) fed from a Power Isolation Transformer (see photo B.May Isol. Trans.).
The stage set-up now consisted of 12 X AC30 amps and 2 X MXR DDL II (which replaced the Echoplexes) plus a Remote Footboard, which Brian operated on stage. The 12 X AC30s were arranged in four groups of three:
3 X AC30 for Dry or Direct Guitar
3 X AC30 for 1st Delay Signal
3 X AC30 for 2nd Delay Signal
3 X AC30 for Chorus Signal
A further problem existed: as the stage sizes had increased it was necessary to provide Brian May with 100ft (33m) long guitar cables. This huge length caused excessive losses of the guitar signal and to prevent this I designed a Mini Line Driver System that was attached to his guitar strap and powered from the footboard (see photoB.May F/Board + L/Driver). We still produce this Mini Line Driver System and it has most recently been successfully used by Sting on his World Tours.
Brian Mays 1982 System
The Mini Line Driver is currently available as a set including a 30m link cable (click here forMini Line Driver info)
I was asked to design a new Treble Boost to replace the unreliable and noisy one then in use. My first design was rejected, as it did not distort!! The second design I prepared had the required frequency and distortion characteristics, plus the following improvements:
High Gain (+33dB @ 3KHz)
High Output (+10dBm)
Much reduced noise (-92dB ref: max output)
Total absence of any radio station interference due to the inclusion of my RFI filter.
My Treble Boost design, in conjunction with my Double TB version and TB with Bypass and Volume Control version, was used for the rest of the time that Queen toured.
In 1977 I designed a new miniature version of the TB, with exactly the same characteristics, and this is the one that I am still building – now known, by Queen fans, as the “Original TB-83” and the “TB-83 Extra” (with volume and bypass switch). (The Miniature Single TB and the Double TB Extra are shown on the photo“B. May Old Board + 3X PC TB”). Another sighting of the Double TB is on the Queen album "JAZZ" - see the gatefold picture: It's on the extreme right side, on top of a flight case.
The reason for using a Treble Boost pedal with the Vox AC30 amps is that the early models did not have any built in Treble Boost. The “normal” channel has a flat frequency characteristic that makes the guitar sound “muddy”. The later version of the AC30 with built in T&B Boost has some problems, mainly concerned with phase shift in the added tone circuit. Even modern AC30 amps still sound better with the TB-83 into the “normal” channel.
All versions of the TB-83 and TB-83 Extra are currently available to order (click here for"Vintage Series" info). Pictured are current TB-83s alongside the original Treble Boost (see photo 5 X TB-83 plus Fireplace) and my current Double TB-83 (see photo TB-83X Duplex)
VOX AC30 AMPS:
All the AC30 amps used by Brian May were modified by me to improve their reliability; I removed all the valves (tubes) that were in the "Bright” and “Vib/Trem” preamps and also the “Vib/Trem” oscillator and modulator valves. This reduced the drain on the power transformer with consequent reduction of temperature rise in the amp cabinet. I also replaced all the valve rectifiers (GZ34) with solid state rectifiers and upgraded the smoothing capacitors. This increased the amp power stage headroom giving a much clearer sound. I increased cooling for the amps by enlarging the top air vents in the cabinets which, combined with the reduced amp temperature rise, made a vast improvement in the life and reliability of the amps.
I modified and maintained up to 18 of these amps while Queen were touring during the period 1972 to 1992. The maintenance included replacement of all Mullard EL84 output valves at the start of every tour (see photo:used Mullard EL84's removed from BHM's AC-30's); re-cone of damaged loudspeakers; repair to the chassis and cabinets and replacement of out of spec components.
THE RED SPECIAL
On many occasions I was asked to repair the Red Special guitar mainly replacement of noisy pots and switches or repair to broken wiring. On two occasions I replaced the special jack socket used on this guitar (see photo:Red Special Jack Sockets); due to the very thin body of this guitar a standard Switchcraft type 11 will not fit in the body cavity and the only socket I could find to fit was a Bulgin paxolin model.
THE RECORDING AMPLIFIER:
Although I cannot be sure of the date (possibly 1973/4), during my tenure as Chief Engineer at the Sound City group of companies, I was asked to build a small, battery powered amplifier to be used with the treble boost for recording. I built this amp from parts obtained locally in Soho - Lisle Street was a very good source of electronic components in the early 70's - but sadly all details of this amp were lost when the Cities Group closed in July 1975.
In October 1976 I was asked, by Brian May's then Tech, Richie Anderson, to build a low power amplifier that could be used with my Treble Boost for recording. I utilized a small bookshelf loudspeaker cabinet and added a battery powered amp module that I modified to have the same frequency response as the Vox AC30 “normal” channel (see photoRecording Amp X 2). Richie explained that the technique used to record this tiny amp was by placing it face down on a pillow and setting up the microphone very near the back panel.
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All text and photographs copyright ©Pete Cornish 2005
and may not be
copied or used without first obtaining permission in writing