Quad 909 reveals itself Quad 909 reveals itself

We just had to have a look inside this recently part exchanged Quad 909 power amplifier - a powerful beast, superbly constructed from the finest materials.

The Quad 909 is a further development of the original Quad 606 power amplifier, as designed by Quad in the 1980's - the basic current dumping circuit design has stood the test of time very well - sound quality is still to a very high standard.

Quad 909 top view Quad 909 top view

The huge central toroidal mains transformer and four reservoir capacitors dominate the casework - a generously sized power supply is essential when 140W per channel into 8 ohm loads is on offer.

Each power amplifier channel is constructed as a physically separate mono block Each power amplifier channel is constructed as a physically separate mono block

On the left and right of the power supply are mono power amplifier circuit boards, each with it's own heatsink to dissipate excess heat generated by the output stage.

 

Connections for two pairs of speakers, left and right phono inputs Connections for two pairs of speakers, left and right phono inputs

 

The rear panel provides speaker binding posts and RCA phono inputs to allow the connection of a stereo preamplifier. Quad bus link passes audio and remote control signals between other Quad 99 series components such as the CD-P2 CD player preamp.

 

Amplifier circuit board and heatsink bracket Amplifier circuit board and heatsink bracket

Three pairs of MJ15003 output devices per channel comfortably handle the currents needed to deliver 140W to the loudspeakers.

Three pairs of output transistors per channel bode well for long term reliability Three pairs of output transistors per channel bode well for long term reliability