RetroWave 275   Shelf speaker as in Hobby Hifi 4-5/2023

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 88 dB
  • size (HxWxD): 800 x 440 x 350 mm
  • frequency range (-8dB): 25 - 30000 Hz
  • crossover frequency(s): 2000 Hz
  • speaker type: bass reflex

RetroWave 275 is a two way compact speaker.

RetroWave 275 is a bass-reflex cabinet loudspeaker with drivers of Mundorf and Wavecor.

The kit is delivered with the following drivers:
- a Mundorf AMTU110W1.1-R air motion transformer (ribbon-tweeter)
- a Wavecor WF275BD01 woofer

The loudspeaker has been developed by Bernd Timmermanns.

The crossover consists of:
- a 2nd order high-pass filter (12 dB per octave slope) for the tweeter.
- a 3rd order low-pass filter (18 dB per octave slope) for the woofer.

The frequency response of this speaker is perfectly linear.

The decay spectrum is perfect.

At medium volume, i.e. 90 dB at 1 m, the nonlinear distortions are below 0,35% above 100 Hz.

An excerpt from the Hobby HiFi review

Conclusion of the magazine Hobby HiFi:

Our kit consists of

  • Wavecor Mid/Woofer WF275BD01 paper / glass fiber, 4 Ohm
  • Mundorf AMTU110W1.1-R
  • 2x Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • 0,5x Damping 30 1100 x 470 mm, adhesive
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • Damping Sonofil 100 x 35 cm for 20 litres
  • Binding Post PK31, gold plated (one pair, red and black)
  • 2m Speaker cable 2x2.5 mm2, transparent
  • Allen wood screws, black, 5x30 mm, 8 pieces
  • 0,5x 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 1.5 μF / 400 Vdc
  • Audaphon MKP CAP Superior 6.8 μF / 400 Vdc
  • Audaphon MKT CAP 22 μF / 160 Vdc
  • Mundorf, electrolytic capacitor, etched, 680 μF/63 Vdc
  • Mundorf air core coil L140, 0.33 mH/0.15 Ohm
  • Mundorf air core coil L140, 1.5 mH/0.38 Ohm
  • 1.0 mm air core coil, 0.56 mH/0.36 Ohm
  • 0.7 mm air core coil, 0.12 mH/0.25 Ohm
  • Mundorf H core coil H50, 15 mH/2.32 0hm
  • Metal-oxide resistor, 10W 2.2 Ohm (red-red-gold)
  • Metal-oxide resistor, 10W 3.9 Ohm (orange-white-gold)
  • Metal-oxide resistor, 5W 4.7 Ohm (yellow-violet-gold)

Kit without cabinet, price per speaker   EUR 881,00 excl. VAT: € 740.34 / $ 799.56

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 Mundorf AMTU110W1.1-R are of type polypropylen (MKP) Mundorf MCAP EVO Öl 450 V.

  • Mundorf MCAP EVO Oil 1.5 μF / 450 V
  • Mundorf MCAP EVO Oil 6.8 μF / 450 V
  • Audaphon MKP CAP Superior 22 μF / 400 Vdc
  • Mundorf, electrolytic capacitor, etched, 680 μF/63 Vdc
  • Mundorf Hepta Coil II45, 0.56 mH/0.30 Ohm
  • Mundorf baked varnish air core coil BL71, 0.12 mH/0.25 Ohm
  • Mundorf baked varnish air core coil BL71, 15 mH/4.45 Ohm
  • Mundorf baked varnish air core coil BL180, 0,33 mH/0.10 Ohm
  • Mundorf baked varnish air core coil BL180, 1,5 mH/0.28 Ohm
  • MResist Supreme 3.9 Ohm / 20 Watt
  • Metal-oxide resistor, 5W 4.7 Ohm (yellow-violet-gold)

Kit with high-end-crossover without cabinet, price per speaker   EUR 1023,00 excl. VAT: € 859.66 / $ 928.44

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, 68μF / 50 Vdc
  • 0.7 mm air core coil, 0.15 mH/0.28 Ohm
  • ceramic resistor 6.8 Ohm/20 Watt

Price per impedance correction for one speaker, to be mounted on a small wooden board.     EUR 9,70 excl. VAT: € 8.15 / $ 8.80

universal PCB

If you prefer to mount the crossover components on a 240 x 165 mm universal PCB instead on wood:
Universal PCB RA240, order no.. str-RA240, price per unit:   EUR 8,60 excl. VAT: € 7.23 / $ 7.81
We recommend one board per kit (two boards for a speaker pair)


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