H.M.V.'s NEW RADIO GRAMOPHONE

Radio Record, Volume VIII, Issue 23, 14 December 1934, Page 23

H.M.V.'s NEW RADIO GRAMOPHONE

\ Sets as Used by Duke of ‘ Gloucester Now on Sale QNE of the most elaborate and up-to-date H.M.V. radio gramophone combinations yet produced by this famous Mnglish firm was landed recently in Wellington by the \New Zealand agents, His Master‘s Voice (N.Z,) Ltd. This model 580 Duo-Diffusion Autoradiogram, as it is described in the catalogue, is identical with the receiver installed on the H.M.S. Sussex for H.R.H. the Duke of Gloucester’s personal use during his journey to Australia. It was recently transferred to the 1.M.A.S, Australia, the warship on which his Royal Hightness is coming to New Zealand. -{The combination, which is housed in a beautifully finished walnut cabinet, incorporates every latest improvement and convenience of both radio and gramophone. The receiver chassis accommodates a powerful nine-valve superhet using the following combination of Marconi valves:-VMS4B r-.f. amplifier, MX40 mixer, VMS4i.f. amplifer, MS4B second if, amplifier, MHD4 second detector and first audio stage, MHé4 silent tuning control, PX4 output (2) and MU14 rectifier. The circuit refinements are many. ‘Delayed amplified automatic volume control is incorporated, ensuring. a \. minimum of fading on overseas trans‘missions and a complete absence of "blasting" on. local stations. Silent tuning is provided for by the inclusion of an inter-station noise suppression control, which operates in conjunction with a fluid light, tuning indicator. With this control operating, the. tuning knob can be rotated from the top to the bottom of the wave-band with not the slightest trace of inter-station "mush." Stations, both distant and near, appear and disappear at substantially the same volume. Provision is made for fitting a matched transmission. type of screen aerial. lead-in if desired, to eliminate local interference. However, in locations free from power interference, the outside aerial can be dispensed with and the mains aerial device used. Tone compensation is provided, so that when. the volume on either radio or gramophone: is turned down to low levels, the high quality of reproducyion is not impaired. The push-pull output valves deliver an output of 5 watts to the moving coil speaker, which has an oval cone of special design to give extended frequency range. Quality of reproduction, both on radio and gramophone, is beautifully balanced, while the reserve of power is such that-up to four extra speakers can be attached, a . switch being provided to enable any, or all, speakers to be played at will. A tone control permits the tonal balance to be adjusted to individual tastes, but without reducing the frequency range. However, the reproduction of the receiver is normally so good that the main uses of this control are to reduce "mush" on outside stations and to eliminate needle scratch when old or worn records are being played. The

tone control is ingeniously combined with a selectivity control. Rotating the knob gives a variation of tone, while it may either be pulled out to give high fidelity, or pushed in to give super-selectivity for reception of distant stations. The set covers the long waves in addition to the broadcast band, and the wave-change switch also serves'a dual purpose, being combined with the "super-silent" or noise suppression control switch. There is only one dual control jn front of the instrument, a combined volume control, which operates on both radio and gramophone, and a "reject button," used to reject or omit a record. The record changing device is especially ingenious. The magazinc holds eight ten or twelve inch records

which the instrument plays through automatically. Any record can be omitted or rejected by pressing the push button located in the centre of the volume control knob on the front of the cabinet. After the last record has been played through, the pick-up comes to rest automatically on the support provided for it, and in so doing euts off the gramophone motor. A switch Jabelled "Hand-Auto-Repeat’ permits records to be played either in the ordinary way by hand, automatically, or else repeated indefinitely. Both on the radio and gramophone sides, the model 580 is precision-built throughout of the finest quality components and materials,.and is an outstanding example of high-class British workmanship.