Desk-Top BB4   Shelf speaker as in Hobby HiFi 1/2016

Technical data
  • impedance: 8 Ohm
  • sensivity (2,83V/1m): 81 dB
  • size (HxWxD): 250 x 150 x 200 mm
  • frequency range (-8dB): 48 - 28000 Hz
  • crossover frequency(s): Hz
  • speaker type: bass reflex

Desk-Top BB4 is a 1 way loudspeaker that employs a Omnes Audio BB 4.01 fullrange chassis. The frequency response smoothing can be realised passive, or with an DSP. Desk-Top BB4 has been developed by Bernd Timmermanns.

The crossover consists of a 1st order low-pass filter (6 dB per octave slope) for the fullrange driver to smoothen the frequency response. In addition four parallel RCL absorption circuits smoothen the frequency response.

Between 60 Hz and 20 kHz, the frequency response of this loudspeaker is flat on axis. The decay spectrum is nearly perfect. At low volume, i.e. 90 dB at 1 m, the nonlinear distortions are below 1% above 250 Hz and below 0.3% at 80 dB/1m.

Our kit with passive crossover consists of

  • Omnes Audio, full range BB 4.01
  • Bass reflex tube HP35, 35x125 mm, black
  • Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • Binding Post PK31, gold plated (one pair, red and black)
  • 1m Speaker cable 2x1.5 mm2, transparent
  • Pan screws 4x20 black, cross recess, 8 pieces
  • Plan for DIY kit

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

  • Audaphon MKT CAP 0.33 uF / 160 Vdc
  • Audaphon MKT CAP 1.0 uF / 160 Vdc
  • Mundorf, electrolytic capacitor, etched, 15 uF/100 Vdc
  • Mundorf, electrolytic capacitor, etched, 22 uF/100 Vdc
  • Mundorf, electrolytic capacitor, etched, 100 uF/100 Vdc
  • Mundorf air core coil L50, 0.33 mH/0.75 0hm
  • Mundorf air core coil L50, 0.47 mH/0.93 0hm
  • Mundorf air core coil L50, 0.68 mH/1.16 0hm
  • Audaphon M core coil M12, 2.2 mH/0.2 0hm
  • Mundorf ferrite core coil F50 10mH/3.49Ohm
  • Metal-oxide resistor, 10W 8.2 Ohm (grey-red-gold)
  • Metal-oxide resistor, 5W 2.7 Ohm (red-purple-gold)
  • Metal-oxide resistor, 5W 6.8 Ohm (blue-grey-gold)
  • 2x Metal-oxide resistor, 5W 5.6 Ohm (green-blue-gold)

L2 has a DC-impedance of 3.5 Ohm. In the journal has been a printing error.

Kit without cabinet, price per speaker   EUR 98,00 excl. VAT: € 82.35 / $ 95.53

Kit with high-end crossover

R2=6.8 Ohm because L2 has a lower DC-impedance.

Kit with high-end-crossover without cabinet, price per speaker   EUR 161,00 excl. VAT: € 135.29 / $ 156.94

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 4,55 excl. VAT: € 3.82 / $ 4.44

universal PCBs

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 / $ 3.61
We recommend one board per kit (two boards for a speaker pair)

Desk-Top BB4 mit digital signal processor (DSP)

Instead of a passive crossover we also deliver a pair of loudspeakers with digital signal processor (DSP). The DSP does his work between preamplifier and power amplifier.

Our kit consists of

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

Kit without cabinet, price per pair   EUR 254,00 excl. VAT: € 213.45 / $ 247.60

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