ProBox   Shelf speaker as in K+T 2/2019

Technical data
  • impedance: 6 Ohm
  • sensivity (2,83V/1m): 84 dB
  • size (HxWxD): 370 x 180 x 253 mm
  • frequency range (-8dB): 52 - 24000 Hz
  • crossover frequency(s): 1900 Hz
  • speaker type: bass reflex

ProBox is a two way compact speaker.

ProBox is a bass-reflex cabinet loudspeaker with drivers of Visaton .

The kit is delivered with the following drivers:
- a Visaton G 25 FFL 8 Ohm tweeter
- a Visaton W 130 S 8 Ohm midrange / bass driver

The loudspeaker has been developed by Thomas Schmidt and Holger Barske.

The crossover consists of:
- a 2nd order high-pass filter (12 dB per octave slope) for the tweeter.
- a 2nd order low-pass filter (12 dB per octave slope) for the mids-woofer.

The frequency response of this speaker is nearly linear.

The decay spectrum (waterfall spectrum) shows a decelerated swing-out behaviour in the mid-range.

At low volume, i.e. 85 dB at 1 m, the nonlinear distortions are below 0,5% above 300 Hz and doesn't exceed 1% at 95 dB at 1 m between 300 and 15000 Hz.

Our kit consists of

  • Visaton G 25 FFL, 8 Ohm
  • Visaton W130 S, 8 Ohm
  • Bass reflex tube BR19.24, black
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • 0,25x Damping Sonofil 100 x 35 cm for 20 litres
  • 0,5x Foam N25, 100x50x4 cm, black
  • Binding Post PK31, gold plated (one pair, red and black)
  • 2m Speaker cable 2x1.5 mm2, transparent
  • 1,5x Visaton Countersunk screws 3.5x25, 8 pcs
  • Plan for DIY kit

the crossover components (right),
to be mounted on a small wooden board.

  • Audaphon MKP CAP Superior 6.8 uF / 400 Vdc
  • 2x Audaphon MKT CAP 15 uF / 160 Vdc
  • 1.0 mm air core coil, 1.5 mH/0.63 Ohm
  • 0.7 mm air core coil, 0.33 mH/0.48 Ohm
  • Metal-oxide resistor, 10W 2.2 Ohm (red-red-gold)
  • Metal-oxide resistor, 10W 6.8 Ohm (blue-grey-gold)
  • Metal-oxide resistor, 10W 8.2 Ohm (grey-red-gold)
  • Metal-oxide resistor, 10W 12 Ohm (brown-red-black)

Kit without cabinet, price per speaker   EUR 147,00 excl. VAT: € 123.53 / $ 138.35

Kit with high-end crossover

The high-end kit is delivered with baked varnish air core coils for minimizing microphonic effects. - The current flow through the coil creates a magnetic field which sets the reel of wire in motion. This motion induces a voltage in the coil which adds itself to the signal. The stiffer the reel of wire is, the less the signal will be altered. The capacitors for the Visaton G 25 FFL 8 Ohm are of type polypropylen (MKP) Clarity-Cap ESA 630 V.

Kit with high-end-crossover without cabinet, price per speaker   EUR 171,00 excl. VAT: € 143.70 / $ 160.94

Impedance correction

If you want to use a valve amplifier with this speaker an impedance correction should be employed. In this case the component quality is less important; therefore, we offer only one kit (upon request higher quality components are available).


Price per impedance correction for one speaker, to be mounted on a small wooden board.     EUR 11,70 excl. VAT: € 9.83 / $ 11.01

universal PCB

If you prefer to mount the crossover components on a 140 x 102 mm universal PCB instead on wood:
Universal PCB RA140, order no.. I-2765, price per unit:   EUR 3,70 excl. VAT: € 3.11 / $ 3.48
We recommend one board per kit (two boards for a speaker pair)


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