June 1973 25p AND BROADCAST ENGINEERING SURVEY: AUDIO DELAY GENERATORS BROADCASTING: BBC RADIO BLACKBURN FIELD TRIAL AND REVIEW OF THE AKG BX20 REVERBERATION UNIT www.americanradiohistory.com 'atever the recording lever or wherever, a need for sound control Ile systems, stereo or quadrophonic, to the t performance specifications in all modes on, the first choice of Europeans is pgic function selection by push - the audio systems, including `Mies eliminating the need for 'er to change giver from -mix. www.americanradiohistory.com studio sound AND BROADCAST ENGINEERING EDITOR DAVID KIRK ASSISTANT EDITOR JOHN DWYER JUNE 1973 VOLUME 15 NUMBER 6 ADVERTISEMENT MANAGER TONY NEWMAN AMERICAN REPRESENTATIVE STEPHEN H. LAMPEN Editorial and Advertising Offices: LINK HOUSE, DINGWALL AVENUE, CROYDON CR9 2TA. Telephone: 01 -686 2599 American Office: P.O. Box 99569, San Francisco, THIS COLUMN is not often used as a vehicle for book California, 94109, U.S.A. reviews but a recent HMSO publication has so much to offer ©Link House Publications Ltd 1973. All rights reserved. the electronic communications industry that such treatment seems justified. The publication in question is Sir Ernest Gowers's The Complete Plain Words,* newly revised by Sir Bruce Fraser. CONTENTS Copies of this eminently readable work should be on sale in FEATURES the Performers' Lounge at audio and broadcasting industry conventions. Audiences might then be subjected to less of the AES ROTTERDAM convoluted word -mongering that so often passes for wisdom. By John Dwyer 22 A typical example deposited on visitors to the recent AES CONSTRUCTING A QUADRAPHONIC MICROPHONE Rotterdam Convention ran: Part Two `Electrical equalisation of monitor systems was examined as By John Fisher 28 a means of minimising the differences between locations so SURVEY: AUDIO DELAY UNITS AND that equivalent musical judgements might be made at these REVERBERATION GENERATORS 44 locations'. A grain of sense there perhaps but we fail to see the point of delivering: COLUMNS `When considering the specification to which a control room NEWS 16 should be designed, certain parameters and criteria should be PATENTS 18 considered'. Although Plain Words gives many examples of verbal garbage BROADCASTING: BBC RADIO BLACKBURN irrelevant to this (`It By Douglas Oakley 26 industry was here that the Emperor liked to put on his grand alfresco spectacles'), others demonstrate VIDEO: VIDEO TAPES COMPARED the misuse of technical jargon at its most decadent. `Using the By Roderick Snell 30 indexed sequential method on an exchangeable disc, the time AROUND THE STUDIOS: ADELPHI involved in accessing a record by searching several levels of By Adrian Hope 34 index, and seeking index, data and overflow areas can amount DIARY to well over 200 ms. It is possible to improve upon these By John Dwyer 36 timings by systems optimisation.' Accessed the information FIELD TRIALS: ARP ODYSSEY level of that? By David Kirk 40 AKG BX20 Her Majesty's Stationery Office, £1. By Angus McKenzie 50 REVIEWS SUBSCRIPTIONS AKG BX20 STUDIO SOUND, published monthly, enables engineers and studio keep By Hugh Ford 52 management to abreast of new technical and commercial developments in electronic communication. The journal is available BROOKDEAL 9471 without charge to all persons actively engaged in the sound recording, By Hugh Ford 56 broadcasting and cinematographic industries. It is also circulated by paid RAC AUDIO MODULES subscription to manufacturing companies and individuals interested By John Fisher 60 in these industries. Annual subscription rates are £3 (UK) or £3.30 ($8 or equivalent) overseas. STUDIO SOUND is published on the 14th of the preceding month AND ARTICLES CORRESPONDENCE unless that date falls on a Sunday, when it appears on the Saturday. All STUDIO SOUND correspondence should be sent to the address printed on this page. Technical queries should be concise and must Matters relating more than one include a stamped addressed envelope. to PAST ISSUES department should occupy separate sheets of paper or delay will occur in replying. A small m.mber of certain past issues may still be purchased from Link House, price 31p each including postage. Articles or suggestions for features on all aspects of communications Photostat copies of any STUDIO SOUND article are available at 25p and musical engineering will be received sympathetically. including postage. Manuscripts should be typed or clearly handwritten and submitted with rough drawings when appropriate. We are happy to advise potential authors on matters of style. BINDERS Total average net circulation of 7,374 per issue ABC during 1972. Loose binders for annual volumes of STUDIO SOUND are -leaf AUOIT available from Modern Bookbinders, Chadwick Street, Blackburn, Lancashire. ewu, .,. ox Please quote the volume number or date when ordering. STUDIO SOUND AND BROADCAST ENGINEERING, INCORPORATING TAPE RECORDER, JUNE 1973 3 www.americanradiohistory.com An example of the Midas modular system mixers. Medium scale chassis, with space for sixteen inputs. The input modules shown include, sensitivity control and fader, pan and output group switch, fold back with pre-fade/post-fade switch, bass, treble, presence equalisation and reverb/ echo mix. The top level has four output modules with PPM calibrated Vu Meters and compressors. The middle level accommodates the fold back output, talk back and headphone facilities, acoustic compensation filters and triple range crossover network. The lower level also includes a send and return panel. Specifications Inputs 0.2 mV into 200 ohms, 10 mV into 50K ohms. Outputs normally OdbM into 600 ohms. Overload range 60 db, low and high Z, channel outputs 16 db above Odb, Vu indication. Line outputs Max level + 16 dbM Signal to noise Ratio At maximum channel gain 66db, Typically 80db at normal gain settings Distortion Less than 0.1% THD Midas Professional Amplication. 87, North Grove, London, N.15. Telephone 01- 800 6341 COMMUNICATION ACCESSORIES & EQUIPMENT LIMITED 77 AKEMAN STREET, TRING, HERTS, U.K. G.P.O. Type components on short delivery JACK PLUGS -201, 310, 316, 309, 404 JACK STRIPS -310, 320, 510, 520, 810 JACK SOCKETS -300, 500, 800, B3 and B6 mountings PATCH PANELS -made to specifications LAMPS & LAMP STRIPS -SWITCHBOARD No. 2 LAMP CAPS 10 way PO 17 20 way PO 19 BALLAST PO No. II HOLDER No. 12 CORDS, PATCHING & SWITCHBOARD -made to specifications TERMINAL BLOCKS DISTRIBUTION -20 way up to 250 way LOW PASS FILTERS-type 4B and PANELS, TELEGRAPH 71 (15 x 4B) UNISELECTORS- various types and manufacturers both PO and miniature LINE TRANSFORMERS /RETARDATION COILS-type 48A, 48H, 149H, 3/16, 3/216, 3/48A, 3143A, 48J, etc FUSE & PROTECTOR MOUNTINGS -8064 A/B 4028, H I5B, H40 and individual I COILS -39A, 40A and 40E, etc PO TYPE KEYS-I000 and PLUNGER TYPES 228, 279, etc 19" RACKS -VARIOUS SIZES Telephone: Tring 3476/8 STD: 0442 -82 Telex: 82362 Answerback: Batelcom UK Tring STUDIO SOUND, JUNE 1973 www.americanradiohistory.com I.T.A. STUDIO STANDARD RECORDERS TEAC A3344 72 - 15 IPS As for HS2340 but with 10f spool capacity £485.oó TEAC SEMI PRO HS2340 7 2 -15 IPS TEAC INDUSTRIAL RECORDER 72 -15 IPS Frequency response high 20Hz - 25kHz Signal/ Special noise ratio 55dB performance version of Particularly suitable for domestic A3340 - 30kHz use in Mini Studios and Response 20Hz for replay of Signal /noise ratio 63dB quadraphonic tapes Currently being used in many recording studios Sole U.K. Supplier Now available to the general public £382.oó Sole U.K. Supplier £492.oó SPECIAL PRICES TO PROFESSIONAL USERS !TA 10 input 14 output mixer specially designed SPECIAL LOW PRICES ON for use with TEAC range SCOTCH 207, 3600 ft TAPE now available Details on request INDUSTRIAL TAPE APPLICATIONS *Prices exclude VAT 105 High Street, Eton, Windsor, Berks. Credit facilities available Tel: (95) 52663 5 www.americanradiohistory.com Now Altec speakers systems and stereo components are designed to offer you finer specifications for better listening and the available latest features for better control of what you hear and the intheU.K.- newest innovations for professional recording studios. the world And that's why we say they're built a little better. renowned ALTEC LANSING range. Built a little better ALTE[ LANSING For further details write to sole U.K. Distributors: ACOUSTICO ENTERPRISES LTD., 6 -8 Union Street, Kingston- upon- Thames, Surrey. Tel. 01 -549 3471/3 (3 lines). .. AUDIO CONNECTORS APOLLO ELECTRONICS BROADCAST PATTERN JACKFIELDS, JACKCORDS PLUGS & JACKS. QUICK -DISCONNECT MICROPHONE CONNECTORS. AMPHENOL (TUCHEL) MINIATURE CONNECTORS WITH COUPLING NUT. HIRSCHMANN BANANA PLUGS & TEST PROBES. XLR COMPATIBLE PROGRAMME IN -LINE ATTENUATORS. LOW COST SLIDER FADERS BY RUF. EXPANDER FUTURE FILM DEVELOPMENTS LTD. model EX60 90 Wardour Street WIV 3LE plug -in unit 01 -437 1892/3 This plug -in unit that contains 14silicon planar transistors and an equally reliable IC is capable of reducing electronic noise, tape hiss, hum, rumble, scratch, microphone feedback and crosstalk by as much as 60 db. Designed to operate at zero or +6 dbm line level offers Series 7 +19 dbm maximum input and output level, more than 90 db Modular Sound Systems S/N ratio, better than 0.5% output distortion, IO K input and 50 ohms output impedance, 20 microseconds attack time, as well as a 0 -60 db expansion range control, 100 msec -4.5 sec release time control and zero to -22 dbm threshold level control, GRAMPIAN REPRODUCERS LTD all three of them continuously adjustable. HANWORTH TRADING ESTATI. Price: Very