The Kenwood KD-650 is an amazing turntable. It really is one of the very best decks to come out of the 1970’s and 80’s and if you ever get a chance to purchase either the KD-650, with Kenwood tonearm, or the KD-600, usually with an SME series 3, you should go for it.
The KD-650 is one of the best-performing turntables you can own for sensible money. Featuring a superb brushless and slotless direct-drive motor, quartz phase-locked speed control, high-inertia 3 kg machined and balanced aluminium platter and the now iconic ARCB synthetic composite chassis, this is a seriously heavy hitting turntable.
This is literally space age engineering of course, compared to the wobbly ‘pipe and slippers’ belt-drive decks you could buy at the time. No wonder the market was literally torn open when decks like these appeared! According to Kenwood, the deck exhibited the following features:
High inertia platter: 550kg.cm2
Quartz PLL servo speed control
Electronic controlled braking system
Special anti-vibration rubber platter sheet
Integrated high-performance tonearm
ARCB limestone resin concrete base
The unit is also available as the KD-600 which is supplied with two tonearm bases, one designed for the Ortofon AS-212 mkII and the other for the SME 3009 or Infinity Black Widow laboratory reference tonearms.
This particular KD-650 needed some repairs to the speed lock indicator, touch control switches, a motor service and a general tune-up. The deck came up very nicely after having apparently not worked and sat in the shed for many years.
Drive: quartz PLL direct-drive system
Motor: 20-pole 30 slot brushless DC servo motor
Platter: 33cm, 2.6kg aluminium alloy die-cast
Speeds: 33.33 and 45rpm
Wow and flutter: less than 0.025% WRMS
Signal to noise ratio: more than -75dB
Tonearm: static-balance type, s-shaped pipe arm, eia plug-in connector
Effective length: 245mm
Stylus pressure range: 0 to 3g
Usable cartridge range: 2 to 12g
Dimensions: 490 x 165 x 460mm
Inside the Deck:
This shot of the insides of the KD-650 is worth further discussion. Top and centre, you will notice the power supply board. I sometimes upgrade this by replacing the single axial electrolytic capacitor with a better quality part, featuring higher capacitance, lower impedance and longer service life.
To the left, we have the mains transformer, which is rubber mounted so that it hangs and rests against soft rubber bushes when the deck is sitting right way up. You want to check that it is free to move and not binding on the rubber mounts, as this transformer is a source of mechanical hum which can be coupled dthrough to the cartridge. The best option would really be to remove the transformer from the chassis and mount it externally.
To the right, we have the control board and Kenwood didn’t skimp here. There are four adjustments, but don’t go fiddling with these unless you have access to a dual channel oscilloscope that you know how to use, and a precision multimeter. Two of the pots set the absolute speed, whilst the other two are involved with the phase locked loop control and electronic braking.
In the middle, you can see the large direct drive motor. Access to the bearing is via the circular metal plate and screws. You will see the rubber gasket protruding from around the edges of the cover plate. This gasket does deteriorate with age. I reworked the mating surfaces of the plate and bottom of the motor to improve the seal on my KD-600. On this deck though, I cleaned out the bearing and added synthetic bearing oil before carefully re-tightening the plate. This will be sufficient on most KD-600/650s.