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The 5 Loudspeakers described on this and subsequent pages under the heading 'Full Range single Unit High Fidelity Loudspeakers', are all designed to cover the full audible frequency range without assistance from any auxiliary units. In other words all that is necessary to complete the loudspeaker system is to mount one of these units in an enclosure of the correct design. Because the construction of these units is relatively uncomplicated they offer the best 'performance for money' value. Enclosure designs are given and further reference should be made to pages 4, 5, 6, 7 and 8.

Frequency range............................................. 40-15,000 c/s
For amplifiers up to ..................... 6 watts (12 watts U.S.A.)
Fundamental resonance.............................................65 c/s
Flux density................................................... 13,500 gauss
Total flux................................................... 53,000 maxwells
Voice coil...........................1" (2-54 cm) diameter-aluminium
Impedance.........................................................15/16 ohms
Chassis............................................................... Diecast
Overall diameter ............................................. 8^-" (21 cm)
Overall depth...................................................3f" (9-2 cm)
Reflex enclosure volume (Internal) .................. 3,000 cu. ins.
Baffle hole diameter....................................... 1" (17-8 cm)
Fixing holes........................... 4 holes -fg (0-7 cm) diameter
equally spaced on 7§" (19-4 cm) P.CD.
Nett weight ................................................... 4 lbs (1.81 kg)
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Frequency range............................................. 40-15,000 c/s
For amplifiers up to..................... 10 watts (20 watts U.S.A.)
Fundamental resonance.............................................45 c/s
Flux density................................................... 13,500 gauss
Total flux................................................... 53,000 maxwells
Voice coil...........................1" (2-54 cm) diameter-aluminium
Impedance......................................................... 15/16 ohm
Chassis............................................................... Diecast
Overall diameter.......................................... 10" (26-6 cm)
Overall depth................................................ 4" (10-9 cm)
Reflex enclosure volume (Internal)..................... 5,000 cu.ins.
Baffle hole diameter....................................... 8 1/2" (21-6 cm)
Fixing holes.............................. 4 holes (0-6 cm) diameter equally spaced on 9"
(24-4 cm) P.C.D.
Nett weight....................................... 4 lbs 12 ozs (2.16 kg)
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Frequency range............................................. 30-16,000 c/s
For amplifiers up to..................... 15 watts (30 watts U.S.A.)
Fundamental resonance.............................................35 c/s
Flux density................................................... 13,000 gauss
Total flux................................................... 87,500 maxwells
Voice coil........................ 1f" (4-4 cm) diameter-aluminium
Impedance...................................................... 15/16 ohms
Chassis............................................................... Diecast
Overall diameter.......................................... 12"(32-1 cm)
Overall depth................................................ 5" (13-2 cm)
ARU 172 enclosure volume (Internal)............... 7,800 cu.ins.
Baffle hole diameter.......................................... 11" (28 cm)
Fixing holes........................ 4 holes 0-312" (0-8 cm) diameter
equally spaced on 11 J* (298 cm) P.C.D.
Nett weight....................................... 9 lbs 12 ozs (4.43 kg)

Frequency range............................................. 30-16,000 c/s
For amplifiers up to..................... 20 watts (40 watts U.S.A.)
Fundamental resonance.............................................35 c/s
Flux density................................................... 16,500 gauss
Total flux...................................................185,000 maxwells
Voice coil........................... 1 3/4" (4-4 cm) diameter-aluminium
Impedance...................................................... 15/16 ohms
Chassis........................................................ Diecast
Overall diameter.......................................... 12" (32-1 cm)
Overall depth................................................ 6"(15-6 cm)
ARU 172 enclosure volume (Internal)..................7,800 cu.ins
Baffle hole diameter.......................................... 11" (28 cm)
Fixing holes........................ 4 holes 0-312" (08 cm) diameter
equally spaced on 11" (29-8 cm) P.C.D.
Nett weight....................................... 17 lbs 10 ozs (8-0 kg)

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Style and shape may be arranged to suit individual taste provided that the internal volume is within ±10% of the value given in the table. The A.R.U. may be fitted into any of the enclosure walls, but the shortest distance between the A.R.U. and the loudspeaker measured round or over the outside of the cabinet should not be less than one foot.

There should be no obstruction within 3" of the front of the A.R.U. The wooden frame is decorative and is normally fitted outside the enclosure, but performance is not affected if the fitting of the A.R.U. is reversed, e.g. in the front panel to present an unobstructed flat surface for covering with a decorative woven fabric material.

All enclosures should be close jointed and rigidly constructed of timber, chipboard, or material of similar or greater density and rigidity, not less than 3/4" thick. All internal surfaces (except the loudspeaker and A.R.U.) should be lined with 1" thick soft felt or wool, or cellulose wadding, and two curtains of the same material should be suspended from (approximately) the centre of the top of the enclosure, one 2" behind the other.

These curtains should be the full internal width of the enclosure, should extend from top to bottom of the interior and should not be fixed to sides and bottom. For detailed analysis of the operation of the A.R.U. see 'Loudspeaker Enclosure Design1 by E. J. Jordan, Goodmans Industries Limited in 'Wireless World', January and February, 1956. Reprints available free on request.

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AUDIOM BASS units are designed to cover only the bass portion of the musical register and all the features necessary for providing very accurate performance down to the lowest musical frequencies encountered are incorporated in their design. The necessary mid-range and high-frequency units for the completion of multiple systems will be found on pages 14 and 15 and enclosure details on page 6. Alternative versions are also available for Public Address work and for specialised applications such as electric guitars.
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Maximum power handling capacity 15 watts (30 watts U.S.A.)
Fundamental resonance.............................................35 c/s
Flux density................................................... 13,000 gauss
Total flux................................................... 87,500 maxwells
Voice coil.......................................... 1J" (4-4 cm) diameter
Impedance.........................................................15/16 ohms
Chassis............................................................... Diecast
Overall diameter.......................................... 12f" (32-1 cm)
Overall depth................................................ 5-jV' (13-2 cm)
ARU 172 enclosure volume (Internal)............... 7,800 cu.ins.
Baffle hole diameter.......................................... 11" (28 cm)
Fixing holes........................ 4 holes 0-312" (0-8 cm) diameter
equally spaced on 11" (29-8 cm) P.C.D.
Nett weight....................................... 9 lbs 12 ozs (4-431 kg)

Maximum power handling capacity 20 watts (40 watts U.S.A.)
Fundamental resonance.............................................35 c/s
Flux density................................................... 16,500 gauss
Total flux...................................................185,000 maxwells
Voice coil.......................................... If" (4-4 cm) diameter
Impedance.........................................................15/16 ohms
Chassis..................................................................Diecast
Overall diameter.......................................... 12f" (32 1 cm)
Overall depth................................................ 6^"(15-6 cm)
ARU 172 enclosure volume (Internal)..................7,800 cu.ins.
Baffle hole diameter.......................................... 11" (28 cm)
Fixing holes........................ 4 holes 0312" (08 cm) diameter
equally spaced on 11" (29-8 cm) P.C.D.
Nett weight....................................... 17lbs 10 ozs (80 kg)

Maximum power handling capacity 25 watts (50 watts U.S.A.)
Fundamental resonance.............................................25 c/s
Flux density................................................... 14,000 gauss
Total flux...................................................269,000 maxwells
Voice coil.............................................3" (7-6 cm) diameter
Impedance.........................................................15/16 ohms
Chassis..................................................................Diecast
Overall diameter.......................................... 15-fV (38-2 cm)
Overall depth................................................ 6^" (160 cm)
ARU 280 enclosure volume (Internal)............... 9,600 cu.ins.
Baffle hole diameter....................................... 13^" (33-8 cm)
Fixing holes........................... 8 slots i"x-fe" (0-95 cm x
0-8 cm) on 14^" (36-9 cm) P.C.D.
Nett weight................................................ 20 lbs (9075 kg)

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Three versions of the Audiom 51 and Audiom 61 are available. For the majority of High Fidelity and High Quality applications the Audiom 51 (Bass) or 61 (Bass) with 35 c/s fundamental resonance (Bass-Resonanz) is recommended. This recommendation assumes that the loudspeaker will be properly mounted in a correctly designed and constructed enclosure, such as one of those described on pages 6 and 7. Under these circumstances first class reproduction down to below 30 c/s will be achieved.

However, these Bass versions should never be chosen when an incorrect or inadequate enclosure is to be used, as they will not then have the opportunity to achieve this extended bass response and they may also suffer damage from the excessive diaphragm movement permitted by insufficient enclosure loading.

For much Public Address work, and for cases where the conditions of service are particularly arduous, the Audiom 51 or 61 with 75 c/s fundamental resonance should be used. This resonance is also a wise choice for electric bass guitars and similar instruments, especially when these are being used at full power, and with loudspeaker enclosures which, because of the requirements of portability, are smaller than the optimum size and therefore do not provide full acoustic loading for the diaphragm. Under these conditions the Audiom 61 (75 c/s) is the preferable choice.

A fundamental resonance of 55 c/s can be supplied for special applications, on either model. The 15" Audiom 81 has a higher power handling capacity than the 12" Audioms, but requires a larger enclosure for correct operation, as shown on page 11.

An 18" unit, the Audiom 90 is available for very high power applications. It has a handling capacity of 50 watts for normal speech and music signals and it is a standard unit for musical instrument amplifiers, electronic organs, Church belfries (reproduced bells) etc. It should be noted that the power rating must be modified according to the type of signal being reproduced. In addition, the Audiom 90 may be used as a bass unit in multiple unit High Fidelity systems. Enclosure requirements are 11,700 cubic inches internal volume, using A.R.U. 480.

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Dimensions........................ 27" high x 20" wide x 63" deep
(68-6 cm x 50-8 cm X 159 cm)
Frequency range............................................. 35-15,000 c/s
Power handling capacity....................................... 15 watts
Impedance.........................................................15/16 ohms

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The pressure-driven horn-loaded loudspeakers shown on this page have been designed specifically for use with the Audiom Bass units to form very low distortion multiple unit High Fidelity loudspeaker systems. The 12" Axiom loudspeakers (pages 6 and 7) are equally suitable as bass units, and should be used if the 'Stage-Built' System (page 16) is being followed, or if a two-way system only is required, with one of the Trebax High Frequency Units.

The system power handling capacity figures quoted below imply that the units may be incorporated (with crossover frequencies as specified) in multiple systems handling these powers on speech or music programme inputs. To enable Trebax and Midax units to be used with Horn-loaded bass units, if required, sensitivity has been made very high. A more usual application, however, will be in conjunction with direct radiator bass units, such as the Audiom series. In such cases some attenuation of the inputs to the Trebax and Midax units will be necessary to provide a flat overall response. A variable attenuator has been designed for this purpose and is fully described on page 15. A series of crossover networks for use with Trebax and Midax is also shown on page 15.
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Frequency range..........................................2,500-20,000 c/s
Crossover frequency............................................. 5,000 c/s
System power handling capacity... 25 watts (50 watts U.S.A.)
Impedance............................................. 15 ohms at 10Kc/s.
Baffle hole diameter..-........................................ 1 7/8" (4-8 cm)
Fixing holes (Horn flange)......3 holes 0-156" (0-4 cm) diameter
on 3 2^(5-7 cm) P.CD.

Frequency range..........................................2,500-20,000 c/s
Crossover frequency.....................5,000 c/s (built in network)
System power handling capacity..................... 20 watts max.
Impedance............................................. 15 ohms at 10Kc/s.
Construction of Driver............... Aluminium diaphragm and
voice coil with integral air chamber in removable self-aligning assembly
Baffle cut-out........................... 1 1/8" x 2 3/8" (2-9 cm x 6-0 cm)
Attenuator fixing..................3 holes, 0-156" (0-4 cm) diameter
on 2"(6-3 cm) P.CD.
Attenuator cut-out........................... 2 3/16"(5-5 cm) diameter

This accessory is designed for use with the Midax and Trebax units to enable easy and accurate balancing of the two-way or three-way systems. The attenuator is of the constant impedance type, so that at all settings it will present an impedance of 15 ohms at its input, when connected to a 15-ohm load, such as the Midax or Trebax. It is variable in eight steps as follows: - Odb, 2db, 4db, 6db, 8db, 10db, 12db, and off. In the "off" position (fully anticlockwise) the loudspeaker under control is switched off altogether and a dummy load automatically replaces it to maintain correct matching. This position is useful when checking the operation of the various loudspeaker units in a multiple system.
In the systems described on page 14 the settings of the attenuators for level response will normally lie between the 2db and 8db positions, depending on the choice of bass units. There is thus effectively a facility for "boost" or "cut" available with these controls. This enables a system to be adjusted to suit the characteristics of any particular room in which it may be used.

There is also sufficient scope to allow for individual preferences and special requirements. Another useful feature lies in the ability of these controls to "tailor" the response to an extreme degree as it is often necessary, for example, when playing pre-electric recordings. In such cases it is often desirable to remove all response above 5Kc/s; and this is easily done by switching the Trebax attenuator to the "off" position. The attenuator is supplied complete with knob and engraved escutcheon, (cut-out required 2-rV - 5.5 cm.dia.).

The 'Stage-Built' system is a method of building up a multiple unit High Fidelity reproducer having a performance of the highest order. As there are three stages the total outlay for the complete system can be split up into three parts to suit individual convenience. The main feature of the 'Stage-Built' system is that each stage is a complete full range High Fidelity reproducer, which is improved by the addition of the next stage. Thus at no time is the user without an excellent High Fidelity loudspeaker; neither is there any wastage of components, since all parts used in one stage are automatically used in successive stage(s). By this means it will be realised how it is possible to improve the quality of the loudspeaker system in a most economical manner as and when the remainder of the apparatus (pickup, amplifier, etc.) is improved.

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In building up a High Fidelity system you may want to use any or all of these signal sources, but you will only need one amplifier and loudspeaker system! Figure 1 shows very simply the main components of a complete installation.

The 'control unit' is part of the amplifier and is also called a preamplifier; it contains the controls for volume, treble and bass etc., and is usually physically separate from the main part of the amplifier so that it can be installed in a position where the controls are conveniently to hand.

It also contains a selector switch which connects the gramophone pickup, tape recorder, radio or other sound source to the amplifier. All the components shown in the diagram, except the loudspeaker, can be built into the same cabinet, or 'built-in' to a room in any way that you wish (e.g. shelves, room dividers, etc.)

The loudspeaker, however, needs its own specially designed enclosure it if is to perform properly. Details of suitable enclosures are given in this manual. The system in figure 1 is a monophonic system; on page 18 you will find a description of this type of system, and also an explanation of stereophonic systems, and their advantages.

Whatever installation you decide upon, you will have to choose a loudspeaker to do justice to the rest of the equipment. Your choice will be governed by three main considerations.

(1) The amount you are prepared to spend on the loudspeaker system.
(2) The size of the room in which it is to be used.
(3) The possibility of later development of the system.

A useful guide to expenditure on the different parts of a High Fidelity system is to divide the total into three roughly equal parts - so that you spend about the same amount on the loudspeaker and its enclosure as you spend on the amplifier with preamplifier, and about the same amount again on each signal source. (There is an exception here - a radio unit will probably cost less than a pickup and turntable or a tape recorder of comparable quality).

The size of room to be used influences the size of loudspeaker needed. A small loudspeaker (e.g. AXIETTE 8 or AXIOM 10, pages 4 and 5) would be large enough for most small sitting rooms, and in addition the enclosure is compact. However, there is no bar to using a larger loudspeaker (e.g. AXIOM 201 or AXIOM 301, pages6and7) inasmall room, except that the enclosure is rather larger. There is often a fear in people's minds that a large loudspeaker will be 'too loud'. This is quite unfounded, as the loudness is under your control at all times.
A large loudspeaker is capable of producing a larger volume of sound than a small one, so it may be worth considering if it is likely that your 'Hi-Fi' might later be moved into a larger room.

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The introduction of Stereophonic sound reproduction is the most important single step towards greater accuracy and realism of sound reproduction that has taken place for many years.

Until recently every advance that was made simply concerned further refinements of the 'monophonic' system, which is still employed in all radios, and many radiograms and record players.

Always the sound came from one spot only - the loudspeaker - and no matter how large the orchestra or how wide the operatic stage, all were compressed in size into one small area at the receiving end. At best, the situation was similar to having one's sitting room connected directly to the concert hall by a small hole in the wall.

All sense of the position of the different instruments or of the direction of movement of actors was lost. Imagine now that you can put head and shoulders through that hole in the wall. At once the scene broadens, and the ears can take up their function as direction-finders. You are in the concert hall. Stereophonic equipment can do this for you in conjunction with stereophonic records or tape.

The records after 1958 contain two different impressions in the same groove; these represent the signalsfrom two separate microphones spaced apart in front of the performers.

The pickup used in your stereophonic equipment converts these impressions into two sets of electrical impulses and passes them to two separate amplifiers. Thence they go to separate loudspeakers, also spaced apart.

You, sitting in front of the loudspeakers, and roughly equidistant from each of them, will have the whole sound picture built up before you, with everything in its right place. If a performer moved across the stage in the original performance you will hear him do so between your loudspeakers.

It is hardly necessary to dwell on the vast improvement in realism that is gained in this way. It is similar to the difference between an ordinary 'flat' picture and a 'three-dimensional' one, (which again is composed of two separate pictures, taken from different viewpoints). WITH HIGH FIDELITY ADDED, THE PICTURE IS NOT ONLY THREE-DIMENSIONAL, BUT IN FULL COLOUR TOO.

What is needed to install Stereophonic High Fidelity in your Home?
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It does not pay to buy a cheap one; your listening pleasure can be completely spoilt by slow variations of speed (called 'wow') or rapid ones (called 'flutter'), or by a noisy mechanism which will pass noises like distant thunder ('rumble') through to your loudspeakers. A good turntable ('transcription' type), not a record changer, will be almost completely free of all these faults. You may want to play some of your existing 78 r.p.m. records as well (stereophonic records are 33 or 45 r.p.m.) so a 3-speed turntable is a wise investment.

• Anmerkung : Vermutlich hatten die Goodmans Werbetexter die Hannover Messe 1963 nicht sorgfältig genug "abgegrast" und auf der Funkausstellung im Herbst 1963 dann auch nicht genug aufgepaßt. Denn dann wären ihnen beide Male der brand neue DUAL 1009 ins Auge gefallen, der alle diese Macken nicht mehr hatte.

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A good stereophonic pickup is a light and comparatively delicate affair, but it will not be damaged in normal use. Most models have a removable head, which can be put away safely when not in use. A completely separate pickup and arm should be fitted for playing ordinary (monophonic) recordings, and this can be more robust, to withstand normal family use if necessary.

Specialist advice should be sought as to the exact choice of pickups: as a general rule to guide expenditure on the complete equipment it would be reasonable to spend equal amounts on (a) turntable and pickup, (b) amplifier, (c) two loudspeakers.

As mentioned already, the amplifier actually consists of two separate amplifiers though they may be assembled on one chassis. The controls(volume, treble, bass, etc.) for both amplifiers are usually 'ganged' so that there are no more controls than on an ordinary equipment, excepting a 'balance' control which enables the two channels to be adjusted to an exactly equal degree of amplification. For normal domestic installations an amplifier having a power output of 10 watts in each channel will be found quite adequate.

• Anmerkung : Wie wir im Original-Prospekt gesehen hatten (ich habe es hier weggelassen), werden für fast jedes Chassis mehrere riesige Gehäuse zum Einbau vorgeschlagen, sogar samt der Gehäusewand-Stärke. Da könnten mit einem der damaligen mittelmäßigen Plattenspieler diese 10 Watt (an 4, 8 und 16 Ohm !! ) pro Kanal für leise Zimmerlautstärke gerade so ausgereicht haben.

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Since care has been taken all through the recording and reproducing chain to give each of the two signals identical treatment, it is wise to employ two loudspeakers of the same type. Any of the full range High Fidelity loudspeakers or loudspeaker systems described in the earlier pages may be used; the exact choice will be governed by the power handling capacity required (this ought not to be less than the power output of the amplifier) and by the space which can be given up to the loudspeaker enclosures. It will be noticed that several very compact models are available, and these are of especial value when space is limited. The installation of the equipment is comparatively simple, but if in any doubt seek the readily available expert guidance.

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This section describes Goodmans "G" Range High Fidelity Loudspeakers. In addition to the many types shown elsewhere in Goodmans High Fidelity Loudspeaker Manual, Goodmans Industries manufacture a range of luxury specification High Fidelity Loudspeakers exclusively for export to overseas countries, each class of loudspeaker representing a fine example of British craftsmanship and precision engineering.

The "G" Range consists mostly of two-element and three-element types, to span the maximum frequency range with a single loudspeaker. But for those who prefer the facility of middle frequencies also to be reproduced by a horn loaded pressure unit, there are high-powered Audiom Bass loudspeakers, "Midax" midrange and "Trebax" treble horn units, to enable a perfectly matched multi-speaker system to be installed in a normal size enclosure.

The enclosure designs in the Goodmans High Fidelity Loudspeaker Manual are suitable for all Goodmans High Fidelity loudspeakers of the stated size.

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Impedance......................................15/16 ohms
Magnet Weight.........................................fib.
Flux Density...................................13,500 gauss
Fundamental Resonance.............................45 c.p.s.
Power Suitability...........................20 watts (U.S.A.)

The Triaxiom loudspeaker brings professional standard High Fidelity to domestic listening with just a single uncomplicated unit and in the standard A.R.U. enclosure needs but little floor space.

Massive unitary diecast chassis. Plastic terminated "Rigidflex" diaphragm for rich undistorted bass. - Extra-long 3" diameter voice coil for effortless power handling.
High efficiency Feroba II Magnet. - Automatic crossover to high stability mid-range radiator. - Pressure driven horn loaded high-frequency unit, with aluminium diaphragm and voice coil in self aligning assembly with air chamber and phase equaliser. - Pre-wired 5 Kc/s L.C. network and constant impedance L-pad attenuator for H.F. level balancing. - Phased terminals for ease of stereophonic hook-up.
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*Power rating figures show U.S.A. and, in brackets, r.m.s. values. For enclosure particulars and fixing hole diameters, please see Goodmans High Fidelity Loudspeaker Manual.pages 6, 7 and 11.
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Fundamental Resonance.............................35 c.p.s.
Frequency Response in Enclosure down to............30 c.p.s.
Power Suitability for systems not exceeding........., .40 watts (20 watts r.m.s.)
Voice Coil Diameter......................................3"
Tote/ Flux..................................308,000 maxwells
Nett Weight..........................................26 lbs.
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