The Portable Studio – For Radio Reporters


Invented, designed and developed by Christopher Long. Prototype constructed by Velko Gavric.

Control panel (front view) of the "PORTABLE STUDIO" Prototype 2.
4-Channel Stereo Reporter's Sound Mixer/Amplifier/Telelink.
Original design & specification by Christopher Long.
Constructed by Velko Gavric (1992-1993)

Width 21 cm x Depth 23 cm x Height 4 cm

Weight: (TBA)

1 x kettle plug socket to mains 220-250 volts (back panel)
1 x socket to 12 volts (3 amp) car battery adaptor (back panel)
1 x 7.2 volts automatic mains rechargeable battery (internal)

2 x 0.25 inch stereo microphone jacks (front panel)
2 x 0.25 inch stereo tape recorder jacks (front panel)

3 x 0.25 inch stereo headphone jacks (front panel)
1 x 0.25 inch stereo tape recorder jack (front panel)
1 x 0.25 direct (mono) line to phone (front panel)

Technical specifications:
(Currently confidential)

4-Channel Radio Reporter's Mixer/Amplifier/Phone link.

The Portable Studio was conceived in 1992 to meet the practical needs
of a BBC radio reporter who was operating in the Yugoslav war zones
and who found existing equipment unsatisfactory.

A prototype has been built, in London, by a refugee electronics
engineer from Sarajevo.



1. A single, strong, easily portable unit, no larger than a typical reporter's tape-recorder.

2. The ability to carry out most of the basic mixing functions of a conventional sound studio so that live or recorded interviews with 2 or 3 interviewees could be mixed with other live or recorded material and transmitted as a live or recorded package.

3. A safe and reliable integral phone/amplifier transmitting at broadcast quality.

4. Power options to meet the needs of operating in rough or difficult circumstances.

5. Built-in fail-safe logical controls so that it's easy to use for even the most technically incompetent reporter and in the dark if necessary. The controls arranged so that the mixer can be used from a hotel, a car or even from a shoulder bag in a phone-box.

6. Compatibility with all the tape-recorders, microphones, cans and other equipment normally issued to radio reporters.

7. High quality, reliable components that are readily available off-the-shelf for easy maintenance anywhere in the world.


In practical terms the Portable Studio allows the radio reporter:

a) To carry out high quality live two-ways or simply transmit a prerecorded tape.

b) To transmit a live studio-style interview with two or more interviewees at a time, correctly mixed, plus the simultaneous mixing of up to two sources of prerecorded material (e.g. sound effects or a further prerecorded interviewee).

c) To mix an unlimited number of taped sources in 3-machine format to create a finished package ready for transmission or as a direct 'live' broadcast.

d) To use either conventional mains electrical power (from hotels, etc.); direct attachment from a 12-volt car battery (or Sat-Phone); or rely on the integral rechargeable battery which always recharges automatically when attached to any mains supply or car battery.

e) Recharging which can be set for either 'trickle' or 'fast' recharge.

f) To work in the dark because all the functions and meters are signalled by LEDs (Light Emitting Diodes).

g) To use the equipment with minimal training or technical knowledge because the lay-out 'logic' makes it impossible to misuse the controls or forget a vital function. Furthermore, all the inputs, outputs and controls are colour-coded to make correct connections easy.

h) All the controls are on the front panel with only the power and phone-out sockets at the rear so that it can easily be used on a shoulder-strap in a phone box; to use it without removing it from a water-proof shoulder- bag; or even to mount it on a bracket beneath the dash-board of a car attached to the cigarette lighter socket.

i) Optional extra: It would be an easy matter to add a tone/pulse-dialling pad to the unit.

Christopher Long (radio reporter) & Velko Gavric (electronics engineer) would like to improve on the prototype they have created. They would welcome practical and constructive comments or opinions from their colleagues. Please contact them at:

The Portable Studio and its developers Christopher Long & Velko Gavric featured on BBC World Service's programme "Wave Guide" on 30-06-1993.

© (1993-1998) Christopher Long. Copyright, Syndication & All Rights Reserved Worldwide.
The text and graphical content of this and linked documents are the copyright of their author and or creator and site designer, Christopher Long, unless otherwise stated. No publication, reproduction or exploitation of this material may be made in any form prior to clear written agreement of terms with the author or his agents.

Christopher Long

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