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Kontakt 40 amplifier



Generously build stereo amplifier with good performance.
This amp was made in
Japan by Comet Electric "Cometro" company, and sold by Aurora-Kontakt company in Holland.



Brand Information:

Kontakt & Aurora, are brands of Klein's Handelmij CV.
The company was founded in 1909 and is located in Amsterdam in the Netherlands.

There was a mail order department in Amsterdam as well, and Klein had stores in Amsterdam,
The Hague, Rotterdam and Utrecht the Netherlands.

Some products were imported from Japan and rebranded with the "Kontakt" brand,
also the type# was freely chosen by the company as this "Kontakt 40" on the amplifier.

The Aurora-Kontakt company still has a shop in Amsterdam at the Vijzelstraat today.
Kontakt website:


Yesterdays shop and todays shop in Amsterdam ^

In 2009: 100 years in business ^


*Aurora-Kontakt magazine 1967 in pdf format click here

*Aurora-Kontakt magazine 1970 in pdf format click here


This "40" amplifier is a early transistor amplifier and a perfect example of "rebranding" of a Comet Japan amp.
Kontakt issued a tube amplifier as well with type# SA-40 that is a totally different amp from a different manufacturer.

Comet Electronics company Japan made many amplifier and tuner models for European, British and USA companies:
big and small electronics companies as Tandy, Dixons, Roelofs, Tempofoon, Canwell, Eagle, AudioSonic, Robin, Kontakt, etc.
They also issued audio gear under their own names, like 'Comet', 'Camet', 'Cometro', etc.
The typical build of this amplifier is found in many models this Comet company designed in the early HiFi audio age,
if you find an amplifier with this kind of build you know for 95% sure that its a Comet - Cometro design.

Commercial of the company ^

Add for a 2x 2 Watts rebranded Kontakt amp (here the original click) ^

Transistor pocket radio's ^


Special futures:

Loudness switch incorporated on the Power switch.

High & low filter switch.



Output power: max. 2x 15 Watts RMS per channel, max output 20 Watts per channel at 4 Ohms.
Distortion: THD 20 Hz - 20 kHz  < 0.1% at rated continuous output per channel.
Speaker recommended impedance: 8~16ohms.
Tone control: Bass: 40Hz, @ +/-10dB, Treble: 10000Hz, @ +/-10dB
Tone filter: low filter: 40Hz: -10dB, high filter: 10kHz: -10dB
Input sensivity: 4 mV at 47 kOhms for Phono, 300mV for Aux & Tuner at 10 kOhms,
                       150 mV for X-tal at 100 kOhms, 300mV for Tape at 47 kOhms, rec out 150 mV.
Signal/noise ratio: 70 dB RIAA phone amp, 90 dB power-amp. section.
Channel separation: Tuner, Tape, Xtal: >60dB
Damping factor: 30 @ 8 Ohms.
3 x DIN inputs, 2x Din ouputs.
Mains: 220V / 240V.


User Manual:

Click here to download the user manual PDF format (construction)


  Front right Front left



This amp was originally designed for TO-66 power transistors,
later models do not have the NEC 2SD154, but plastic transistors.
This amp has a class B output section, the bias-current through the power transistors is only a few mA.
The power section is OTL and DTL, but is assymetric with output condensers.
Some values of used parts may slightly differ from values on the schematic diagram:
in this amp the power supply cap is 3300 µF and the ouput caps are 1500 µF.

NEC 2SD154 ^

*Click here to download the schematic of the Kontakt 40 in PDF format.



Set the mains voltage on the transformer to 240 Volt in Europe.

Set the Voltage on the ouput capacitors + connection to half the supply voltage:
27V when supply voltage is 54V/55V, and to approx. 25V when supply voltage is around 52V when mains set to 240V in EU.
Check bias-current through the power transistors by measuring the voltage on the emitter resistors, a few mV should be measured.

Some wiring can be improved and the ground wiring may be optimized.


Interior: extra RCA connections made by the previous owner ^


Main pcb copper side , output caps and supply cap, measure all still within specs ^


Components pre-amp with 2SC945 ^


Power stages with the drivers ^


 NEC 2SC853 & 2SA545 complementary driver transistors ^


The pcb component side, good quality parts used ^



The sound is very good.


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© PE1MMK Hans Hilberink last update:  25-10-2020.