Cumulus C BPA

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 85 dB
  • size (HxWxD): 430 x 150 x 350 mm
  • frequency range (-8dB): 55 - 22000 Hz
  • crossover frequency(s): Hz
  • speaker type: bass reflex

Cumulus C BPA is a two way compact speaker.

Cumulus C BPA is a bass-reflex cabinet loudspeaker with drivers of Omnes Audio and Tang Band.

The kit is delivered with the following drivers:
- a Omnes Audio CX 3.1 coaxial driver
- two Tang Band W4-657 woofers

The loudspeaker has been developed by Thorsten Fischer.

The crossover consists of:
- a 2nd order high-pass filter (12 dB per octave slope) for the tweeter.
- a band pass consisting of a 2nd order high pass filter (12 dB per octave slope) and a2nd order low-pass filter (12 dB per octave slope) for the mids-woofer.
- a 2nd order low-pass filter (12 dB per octave slope) for the woofer.

The frequency response of this speaker is nearly linear.

An excerpt from the Hobby HiFi review of the old Cumulus C

Conclusion of the magazine Hobby HiFi:

Our kit consists of

  • 2x Tang Band W4-657 unshielded 12 cm full range
  • Omnes Audio, coax driver CX 3.0/3.1
  • 2x Bass reflex tube Streamline 30
  • 2x Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • 0,25x Damping Sonofil 100 x 35 cm for 20 litres
  • Terminal T105 Au, with brass, gold plated
  • 2,5m Speaker cable 2x1.5 mm2, transparent
  • 1,5x Pan screws 4x20 black, 8 pieces
  • Plan for DIY kit

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

  • ClarityCap PWA capacitor 160 Vdc
  • ClarityCap PWA capacitor 160 Vdc
  • Audaphon MKP CAP Superior 400 Vdc
  • Mundorf, electrolytic capacitor, etched 100 Vdc
  • 1.0 mm air core coil
  • 0.7 mm air core coil
  • 0.7 mm air core coil
  • 0.7 mm air core coil
  • Metal-oxide resistor, 10W
  • Metal-oxide resistor, 10W

Kit without cabinet, price per speaker   EUR 201,00 excl. VAT: € 168.91 / $ 190.87

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 fullrange driver are of type polypropylen (MKP) Clarity-Cap PWA 160.

Kit with high-end-crossover without cabinet, price per speaker   EUR 222,00 excl. VAT: € 186.55 / $ 210.81


Home