Trio Kenwood KA-2000 amplifier

 

General:

Around 1972 issued amplifier made by 'The Trio Kenwood' company Japan.

This Kenwood amplifier is identical to the Trio KA-2000 amplifier.

front of the 2 phono version ^

Trio front ^
 

Owners manual:

Brochure of the Kenwood KA-2000 amplifier

 

interior not updated ^
 

interior updated ^
 

special futures:

Light and small footprint amp. Metal case.
Well build and good parts used. High quality early Sanken power transistors, Elna capacitors, Hitachi transistors.
This amp employs all early silicon transistors. Rugged version amplifier made for intensive use.

The first Kenwood amp with exclusive safety circuit (US Patent) which provides complete protection
for power transistors, preventing damage which might otherwise result from an excessive input
signal or an output terminal short.

Several versions were produced of this amplifier, USA version, multi voltage version, 2 phono version, 2 aux version.

Early Sanken power transistors ^

 

Specifications:

Power output: 13 watts per channel into 8 Ohms (stereo)

Frequency response: 20Hz to 50kHz

Total harmonic distortion: < 0.5% At RMS output,

Damping factor: 20,

Input sensitivity: 2.5mV (MM), 150mV (aux), 100mV (tuner)

Signal to noise ratio: better than 65dB (MM), 75dB (aux)

Speaker load impedance: 4 to 16 Ohms (minimum)

Semiconductors: 19 x transistors, 10 x diodes

Dimensions: 260 x 105 x 237mm

Weight: 10 lbs

Year: 1972/73

 

Early silicon Sanken 2SD91 power transistor, 60 Volts / 3A capability ^

 

 

Schematic:

click here to download the service manual of the Trio Kenwood KA 2000

click here to download the schematic diagram of the 2 phono input version of the Trio Kenwood KA 2000

click here to download the schematic diagram of the 2 aux input version of the Trio Kenwood KA 2000

 

 bottom view not updated ^

 bottom view of the updated amp ^
 

Modifications:

You may replace some capacitors in the power supply and power rail.
A full restauration of this amp is very rewarding and recommended.
After modification this amp is capable of producing 2x 15 Watts RMS at less than 0.5% distortion.
You may improve the damping factor after modification to 30,
The frequency bandwidth to 10 to 50KHz after modification.
Apply thermal grease to the power transistors for optimal heatsinking.
Realignment of the power amp-section is advised, usually in unrestored amps the idling current is set too high.

 

Backpanel of the USA - 2 phono version ^

Updated back with new speaker connections, multivoltage version ^

 

Sound:

The sound is very good for such a small amplifier.

Woodcase imitation ^

Sucessor of the KA-2000, the KA2000A, the same amp in a different case.

© Hans Hilberink - PE1MMK ® 2003 - Last update: 16-04-2018.