Sofia AMT 12   Shelf speaker as in K+T 6/2023

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 90 dB
  • size (HxWxD): 600 x 230 x 370 mm
  • frequency range (-8dB): 44 - 31000 Hz
  • crossover frequency(s): 2100 Hz
  • speaker type: passive radiator
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Sofia AMT 12 is a two way compact speaker.

Sofia AMT 12 is a loudspeaker with drivers of Mundorf and Wavecor. Passive radiators provide deep bass.

The kit is delivered with the following drivers:
- a Mundorf AMTU160W1.1-R air motion transformer (ribbon-tweeter)
- two Wavecor WF182BD14 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 nearly perfect.

At low volume, i.e. 85 dB at 1 m, the nonlinear distortions are below 0,4% above 300 Hz and doesn't exceed 0,5% at 95 dB at 1 m between 300 and 15000 Hz.

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

Conclusion of the magazine Klang+Ton:

Our kit consists of

  • 2x Wavecor Mid/Woofer WF182BD14 kevlar/carbon, die cast, 8 Ohm
  • 2x Wavecor PR182BD02 Passive Radiator, die cast
  • Mundorf AMTU160W1.1-R
  • 2x Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • 1,5x 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 black/red
  • 1,5x Pan screws 3.5x17 black, torx, 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 2.7 μF / 400 Vdc
  • Audaphon MKP CAP Superior 6.8 μF / 400 Vdc
  • Audaphon MKT CAP 2.2 μF / 160 Vdc
  • Audaphon MKT CAP 6.8 μF / 160 Vdc
  • Audaphon MKT CAP 15 μF / 160 Vdc
  • Audaphon MKT CAP 33 μF / 160 Vdc
  • 1.4 mm air core coil, 1.0 mH/0.29 Ohm
  • 0.7 mm air core coil, 0.12 mH/0.29 Ohm
  • 0.7 mm air core coil, 0.15 mH/0.28 Ohm
  • 0.7 mm air core coil, 0.47 mH/0.50 Ohm
  • 0.7 mm air core coil, 1.8 mH/1.15 Ohm
  • Metal-oxide resistor, 10W 1.8 Ohm (brown-grey-gold)
  • Metal-oxide resistor, 10W 2.7 Ohm (red-purple-gold)
  • Metal-oxide resistor, 10W 10 Ohm (brown-black-black)
  • Metal-oxide resistor, 10W 12 Ohm (brown-red-black)

Kit without cabinet, price per speaker   - not available

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 AMTU160W1.1-R are of type polypropylen (MKP) Clarity-Cap CSA 630 V.

  • ClarityCap PWA capacitor 33 μF / 160 Vdc
  • ClarityCap PWA capacitor 2.2 μF / 400 Vdc
  • ClarityCap PWA capacitor 6.8 μF / 400 Vdc
  • ClarityCap PWA capacitor 15 μF / 400 Vdc
  • ClarityCap CSA capacitor 2.7 μF / 630 Vdc
  • ClarityCap CSA capacitor 6.8 μF / 630 Vdc
  • Mundorf baked varnish air core coil BL71, 0.12 mH/0.25 Ohm
  • Mundorf baked varnish air core coil BL71, 0.15 mH/0.28 Ohm
  • Mundorf baked varnish air core coil BL71, 0.47 mH/0.57 Ohm
  • Mundorf baked varnish air core coil BL71, 1.8 mH/1.22 Ohm
  • Mundorf baked varnish air core coil BL140, 1.0 mH/0.30 Ohm
  • Mresist Classic 1,8 Ohm / 10 Watt
  • Mresist Classic 10 Ohm / 10 Watt
  • Mresist Classic 12 Ohm / 10 Watt
  • Mresist ultra 2,7 Ohm, 3/30Watt
  • Mresist Ultra cooling rod 6,5K/W + Accessories (Set 1)

Kit with high-end-crossover without cabinet, price per speaker   EUR 1426,00 excl. VAT: € 1198.32 / $ 1306.17

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 22 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 12,20 excl. VAT: € 10.25 / $ 11.17

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 / $ 4.31
We recommend one board per kit (2 boards per speaker pair)

Measurements

measurmentsMeasurements on this speaker

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