LS3/5B   Shelf speaker as in Hobby Hifi 3/2021

Technical data
  • impedance: 8 Ohm
  • sensivity (2,83V/1m): 83 dB
  • size (HxWxD): 308 x 190 x 170 mm
  • frequency range (-8dB): 70 - 32000 Hz
  • crossover frequency(s): 3000 Hz
  • speaker type: closed box

LS3/5B is a two way compact speaker. It is modeled on the LS3/5A near-field monitor of the British broadcasting company BBC. It enjoyed great popularity for decades.

LS3/5B is available with
- closed cabinet
- bass reflex cabinet
- transmissionline cabinet
- subwoofer atellit set

LS3/5B is a closed-cabinet loudspeaker with drivers of Wavecor .

The kit is delivered with the following drivers:
- a TW022WA05 tweeter
- a WF152CU14 midrange / bass driver

The loudspeaker has been developed by Bernd Timmermanns.

The crossover consists of:
- a 3rd order high-pass filter (18 dB per octave slope) for the tweeter.
- a band pass consisting of a 3rd order high pass filter (18 dB per octave slope) and a 3rd order low-pass filter (18 dB per octave slope) for the mids-woofer.

The frequency response of this speaker is nearly linear.

The decay spectrum as shown in the waterfall diagram is exemplary, free of any disturbing resonance.

At medium volume, i.e. 90 dB at 1 m, the nonlinear distortions are below 0,3% above 500 Hz.

Our kit consists of

  • Wavecor silk dome tweeter TW022WA05, 4 Ohm
  • WF152CU14, Wavecor Mid/Woofer, 8 Ohm, paper cone, BD, phase plug
  • Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • 2x Bitumex board 32.5 x 24.5 cm, 4mm
  • Binding Post PK31, gold plated (one pair, red and black)
  • 1,5m Speaker cable 2x1.5 mm2, transparent
  • Pan screws 3.5x17 black, torx, 8 pieces
  • Plan for DIY kit

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

  • Audaphon MKP CAP Superior 2.7 μF / 400 Vdc
  • Audaphon MKP CAP Superior 4.7 μF / 400 Vdc
  • Audaphon MKP CAP Superior 5.6 μF / 400 Vdc
  • 1.0 mm air core coil, 0.47 mH/0.32 Ohm
  • 0.7 mm air core coil, 0.33 mH/0.48 Ohm
  • Mundorf H core coil H71, 3.3 mH/0.47 0hm
  • Metal-oxide resistor, 10W 4.7 Ohm (yellow-violet-gold)
  • Metal-oxide resistor, 10W 8.2 Ohm (grey-red-gold)

Kit without cabinet, price per speaker   EUR 326,00 excl. VAT: € 273.95 / $ 298.61

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 TW022WA05 are of type polypropylen (MKP) Mundorf MCAP EVO Oil.

  • Mundorf MCAP EVO Oil 2.7 μF / 450 V
  • Mundorf MCAP EVO Oil 4.7 μF / 450 V
  • Mundorf MCAP EVO Oil 5.6 μF / 450 V
  • Mundorf baked varnish air core coil BL71, 0.33 mH/0.48 Ohm
  • Mundorf baked varnish air core coil BL140, 0.47 mH/0.19 Ohm
  • Mundorf H core Hepta Coil LH45, 3,3 mH/0.27 Ohm
  • Mresist Classic 4,7 Ohm / 10 Watt
  • Mresist Classic 8,2 Ohm / 10 Watt

Kit with high-end-crossover without cabinet, price per speaker   EUR 427,00 excl. VAT: € 358.82 / $ 391.12

Kit with high-end crossover 2

Since core coils always lead to non-linear distortion due to re-magnetization losses (the Hepta Coil LH45), Dr. Peter Strassacker suggests this kit as an alternative to the high-end kit. It does not contain a ferrite core but Mundorf copper foil coils in series to the mid-woofer.

  • ClarityCap ESA capacitor 2.7 μF / 250 Vdc
  • ClarityCap ESA capacitor 4.7 μF / 250 Vdc
  • ClarityCap ESA capacitor 5.6 μF / 250 Vdc
  • Mundorf copper foil coil CFC16-0.47mH/0.22Ohm
  • Mundorf copper foil coil CFC14-3.3mH/0.50Ohm
  • Mundorf baked varnish air core coil BL71, 0.33 mH/0.48 Ohm
  • Metal-oxide resistor, 10W 4.7 Ohm (yellow-violet-gold)
  • Metal-oxide resistor, 10W 8.2 Ohm (grey-red-gold)

Kit with high-end-crossover without cabinet, price per speaker   EUR 480,00 excl. VAT: € 403.36 / $ 439.66

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).

  • JB, electrolytic capacitor, bipolar advanced, 47μF / 100 Vdc
  • 0.7 mm air core coil, 0.22 mH/0.34 Ohm
  • Ceramic resistor 8.2 Ohm/20 Watt

Price per impedance correction for one speaker, to be mounted on a small wooden board.     EUR 10,40 excl. VAT: € 8.74 / $ 9.53

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.. str-RA140, price per unit:   EUR 4,20 excl. VAT: € 3.53 / $ 3.85
We recommend one board per kit (two boards for a speaker pair)


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