IMF Super Compact
Small, 3 ways speaker.
Tweeter : unknown; medium : unknown, bass: unknown.
The original IMF Compact Loudspeakers were a great success. Despite opinions to the contrary, the Compact demonstrated that there is a sophisticated strata of the hi-fi buying public who do not judge the merits of a loudspeaker system on a cost versus size basis. The advantages of applying the same attention to design detail as in our IMF Monitor loudspeakers to enclosures of modest proportions are, apparently, obvious even to the novitiate. This demands a loudspeaker that necessarily needs to be made at a price, rather than to a price.
The IMF Compact Il employs a bextrene unit of specified piston area and excursion such as to provide homogenous mid-range and low frequency performance. This is complemented by a dome tweeter and the whole unit integrated by low loss crossover and phase correction circuitry. Bass performance is maintained via a critically tuned and optimumly damped reflex enclosure (see illustration). Indeed, had dimensions of the enclosure or drivers in the Compact Il been greater, it would not have been possible to achieve such smooth and extended response without resort to an additional separate mid-range unit and associate complex electronics such as apply to the IMF SuperCompact. In all, the Compact Il sounds larger than its size, providing wide dispersion and remarkable low frequency extension, and represents superb value for space.
With the Super-Compact, enclosure size is sufficient to accommodate the use of a bass unit with a free air resonance around 25Hz. The drawing illustrates the resistive loading conditions which, whilst not impairing the exceptional bass response, damps the system against 'cone weave' from unwanted subsonic signals The mid-range is isolated in its own short transmission line and this unit along with the tweeter is similar to those we used in our Studio TLS 50 and ALS 40 loudspeakers.
The decision was also made to adopt the same complex and expensive crossover and mirror image configuration as in these larger models. This results in two important advantages. The in-line crossover network has been developed as a no compromise optimum filter for the drive units employed and as such, provides the minimum of colouration and thus the maximum sense of acoustic transparency. Secondly, it ensures that the phase and dispersion characteristics of the SuperCompact are substantially identical to those of the TLS 50 and ALS 40. Thus all three models are compatable for four-channel applications. Research demonstrates that dissimilar loudspeakers cannot be used for four channels any more than unmatched speakers are acceptable for stereo. Even choosing all loudspeakers from the same manufacturer is no guarantee of compatibility unless the speakers have the same phase relationship throughout the range and a substantially similar integrated performance. With an eye to the future, IMF in their Super-Compact have ensured this compatibility and anticipate that many of these speakers will compliment IMF Studio or ALS 40 loudspeakers for rear channel information. Meanwhile the prospective customer can purchase now without .fear of pending obsolescence.
We have said very little about the sound of Compacts, which in a way is a good thing for both have little of the obvious 'hi-fi' qualities about them. Low frequencies are remarkably extended for their enclosures sizes, but are smooth and free from the exaggerations of 'one note bass'. The middle and top has a sense of 'sheen' and continuity - rather than the sound of multiple speakers working in a box. Although of moderate efficiency, such is the freedom from distortion and colouration, that listening at low levels as well as high, gives a sense of balance that reveals all that is worthwhile over a wide variety of programme sources. The speakers are worthy of the best amplifiers and indeed the finest ancilliary equipment. We invite you to audition the IMF Compact II and SuperCompact loudspeakers against others beyond their size category.
18" x 11" x 11 3/4" wide; 46 cm x 28 cm x 30 cm
8" 20.5 cm bextrene bass unit
4" 10cm rolled surround impregnated cone mid-range with domed tweeter
Electrical three way at 375 Hz and 3 kHz
30 Hz 20 kHz
Frequency- Response & Distortion Characteristics
4 - 8 ohms (see graph)
Efficiency Measured via Pink Noise at 1 metre on axis for 40 watts
Driving Power Requirements
20- 50 watts
Nett Weight (each)
Gross Weight Packed (pair)
Subject to alteration without notice.
IMF International, Westbourne Street, High Wycombe, Bucks. Telephone High Wycombe 35576