Indus   Shelf speaker as in K+T 3/2021

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 90 dB
  • size (HxWxD): 600 x 250 x 300 mm
  • frequency range (-8dB): 47 - 28000 Hz
  • crossover frequency(s): 1800 Hz
  • speaker type: bass reflex

Indus is a two way compact speaker.

Indus is a bass-reflex cabinet loudspeaker with drivers of Audaphon and Mark Audio.

The kit is delivered with the following drivers:
- a Audaphon AMT 1i air motion transformer (ribbon-tweeter)
- two Mark Audio Pluvia 11 Gen 1 woofers

The loudspeaker has been developed by Dennis Frank and Daniel Gattig.

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 woofer.

The frequency response of this speaker is perfectly linear.

The decay spectrum is perfect.

At low volume, i.e. 85 dB at 1 m, the nonlinear distortions are below 0,3% above 500 Hz and doesn't exceed 0,6% at 95 dB at 1 m between 300 and 15000 Hz.

An excerpt from the Klang+Ton review (Translation of the author into English)

"And the Indus is so much fun that one likes to exhaust those 95 decibels (and more) from time to time. The bass range is not ultra-deep - but it can be if you dare to move the speakers a little closer to the back wall. With the tweeter at ear level, you can achieve an extremely precise and very realistic spatial image, which, in combination with the lack of any colouration, also recommends the Indus as a work device for the home or professional recording studio. The tweeter with its dynamics is beyond all doubt, but the two Markaudios with their metal membranes and plenty of volume behind them are more than equal partners."

Our kit consists of

  • Audaphon AMT-1i
  • 2x Mark Audio Pluvia 11 generation 1, soft chrome, one piece
  • Bass reflex tube HP70, 70x220m, black
  • 2x Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • 0,5x Damping Sonofil 100 x 35 cm for 20 litres
  • Binding Post PK28 I Ni, nickel plated (one pair, red and black)
  • 2m Speaker cable 2x1.5 mm2, red-black, 1 m
  • Plan for DIY kit

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

  • Audaphon MKP CAP Superior 2.2 μF / 400 Vdc
  • Audaphon MKP CAP Superior 6.8 μF / 400 Vdc
  • Audaphon MKT CAP 15 μF / 160 Vdc
  • 1.4 mm air core coil 1.2 mH/0.32 Ohm
  • 0.7 mm air core coil, 0.68 mH/0.70 Ohm
  • Metal-oxide resistor, 10W 6.8 Ohm (blue-grey-gold)
  • Metal-oxide resistor, 10W 15 Ohm (brown-green-black)

Kit without cabinet, price per speaker   EUR 962,00 excl. VAT: € 808.40 / $ 864.99

Kit with high-end crossover

The high-end kit is delivered with baked varnish air core coils on important parts of the crossover 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 Audaphon AMT 1i are of type polypropylen (MKP) Clarity-Cap CSA 630 V.

  • ClarityCap PWA capacitor 15 μF / 400 Vdc
  • ClarityCap CSA capacitor 2.2 μF / 630 Vdc
  • ClarityCap CSA capacitor 6.8 μF / 630 Vdc
  • Mundorf baked varnish air core coil BL71, 0.68 mH/0.71 Ohm
  • Mundorf baked varnish air core coil BL140, 1.2 mH/0.34 Ohm
  • Metal-oxide resistor, 10W 6.8 Ohm (blue-grey-gold)
  • Metal-oxide resistor, 10W 15 Ohm (brown-green-black)

Kit with high-end-crossover without cabinet, price per speaker   EUR 1039,00 excl. VAT: € 873.11 / $ 934.23

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).

  • Audaphon MKT CAP 33 μF / 160 Vdc
  • 0.7 mm air core coil, 0.10 mH/0.27 Ohm
  • ceramic resistor 8.2 Ohm/20 Watt

Price per impedance correction for one speaker, to be mounted on a small wooden board.     EUR 14,40 excl. VAT: € 12.10 / $ 12.95

universal PCB

If you prefer to mount the crossover components on a universal PCB instead on wood
PCB 150x115 mm, tin plated, price per unit:   EUR 4,70 excl. VAT: € 3.95 / $ 4.23
We recommend one board per kit (2 boards per speaker pair)


measurmentsMeasurements on this speaker

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