*Gross price for private customers. Industrial prices are available on request.
Technical Data
Recommended cabinets
Amplitude & Impedance Frequency
Directivity pattern
Rated power 50 W
Maximum power 80 W
Nominal impedance Z 4 Ohm
Frequency response fu–8000 Hz
(fu: Lower cut-off frequency depending on cabinet) .
Mean sound pressure level 86 dB (1 W/1 m)
Opening angle (-6 dB) 72°/4000 Hz
Excursion limit +/−10 mm
Resonance frequency fs 36 Hz
Magnetic induction 1.0 T
Magnetic flux 314 µWb
Height of front pole-plate 4 mm
Voice coil diameter 25 mm
Height of winding 12.5 mm
Cutout diameter 148 mm
Net weight 1.1 kg
D.C. resistance Rdc 3.2 Ohm
Mechanical Q factor Qms 2.16
Electrical Q factor Qes 0.51
Total Q factor Qts 0.41
Equivalent volume Vas 38 l
Effective piston area Sd 129 cm²
Dynamically moved mass Mms 12 g
Force factor Bxl 4.4 Tm
Inductance of the voice coil L 0.6 mH
Connections 4.8 x 0.8 mm (+)/2.8 x 0.8 mm (-)
Volume/Principle BR-Channel fb fc/QTC
20 l/closed - - 61 Hz/0,70
20 l/bass reflex BR 19.24 (length 14 cm) 44 Hz -
30 l/bass reflex BR 15.34 (length 12 cm) 39 Hz -
50 l/bass reflex BR 15.34 33 Hz -

Used in / Accessories:


The ALTO I is a 2-way shelf-mounted speaker with a cabinet volume of 13 litres. Apart from the 20 mm tweeter cone, the cabinet contains a 17 cm diameter mid-bass cone.

The sound qualities of the ALTO I are "warm" but with crisp, high-range reproduction.

This kit is ideally suited to replacing the more basic speakers often supplied as standard with low-priced hi-fi systems and thus improving the overall standard of the system.

Since the bass ports are at the front, the ALTO I can be hung on the wall or placed in bookshelves, facilitating good bass response even in rooms with difficult acoustics.

Art. No. 5966


This 2-way column speaker, ALTO II, designed as a 30 litre vented system, is another suggested application from the Alto series. The same driver arrangement has been selected as for the ALTO I but, here, the lower range octaves benefit from the enlarged cabinet volume and optimum bass frequency to produce powerful, responsive bass.

ALTO II is also well-suited to improving the sound of low-priced compact hi-fi systems.

The ALTO II can be positioned freely anywhere in the room, producing clearly defined spatial sound character.

Art. No. 5967

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