MANUFACTURERS SPECIFICATIONS:
Bass unit: 12 inch.
Treble: Two 2 inch cone types.
Crossover: 1,300 Hz, (mechanical)
Frequency response: 30 Hz to 21 kHz +.4.5 dB.
Nominal impedance: 6 ohms.
Size: 25 by 14 by 12 1/4 inches deep.
Price: $139.00.
The infinity 1001 is a rather unusual system on two counts: one, it employs a 12 inch bass unit crossing over at 1,300 Hz and two, it uses two 2 inch tweeters--one front mounted and the other "firing" at the rear. Usual crossover point for a 12 inch woofer is around 400 Hz because of the difficulties in controlling response irregularities at higher frequencies. Infinity solve that problem by using a plug at the cone apex which also functions as mass loading to reduce the system resonance. The upper roll-off is so smooth that no crossover inductance is used with the bass unit. System resonance is 44 Hz, lower than usual for this size enclosure. The object of the rear firing tweeter is to use wall reflections to give the effect of a larger sound source-the front unit is said to be the transient speaker and the rear is called the ambience speaker.
A H.F. (high-freq.) level control is provided. The enclosure itself is a resistance loaded reflex which Infinity call a terminated line.
The walnut cabinet is solidly constructed with an unobtrusive black grille cloth which will harmonize with any decor.
Fig. 1--Response with one-third octave pink noise. A was taken on axis at
3 positions of the HF control, B was taken 30 degrees off-axis and C at 60
degrees.
Fig. 2--Low frequency distortion and some SPL measurements.
Fig. 3-Tone burst responses: A is 100 Hz, B, 500 Hz and C, 5,000 Hz.
Fig. 4-Impedance characteristics.
Measurements
Figure 1 shows the response measured with one-third octave pink noise. A was taken on-axis with the tweeter level switch at normal, minimum and maximum. B shows the response at 30 degrees off-axis and C at 60 degrees. Under normal room conditions, the frequency response will be modified by wall reflections from the rear speaker. Figure 2 shows low-frequency distortion with some SPL figures. Tone burst characteristics at 100 Hz, 500 Hz and 5,000 Hz are shown in Figure 3 and the impedance curves are given in Figure 4. Lowest point was 4 ohms with the tweeter control at maximum. White noise tests showed very little coloration. Sensitivity was around average for this kind of system and an amplifier power of at least 20 to 25 watts per channel is recommended.
Listening Tests
Overall sound was very good with a clean, solid bass which would put many larger systems to shame. Because of the low coloration, the sound had a transparent quality--in other words, the 1001 did not sound too much like a loudspeaker! The open quality is partly due to the rear radiation and it is recommended that the systems be placed four to six inches from the wall for best results. As mentioned earlier, it is quite difficult to design a good system having such a high crossover point for a 12 inch bass unit but Infinity have certainly succeeded with the 1001. Especially since the price is only $139.
-T.A., G. W. T.
(Audio magazine, Apr. 1973)
Also see:
Infinity SERVO STATIK 1A speakers (ad, Aug. 1975)
Infinity 9 Kappa Loudspeaker (Auricle, Jan. 1988)
Hitachi HS-300 Speaker System (Equipment Profile, Mar. 1975)
Hegeman H-1 Loudspeaker (Oct. 1973)
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