Readers will know how much I like the Quad 405 amplifier. In this article, I look at the Quad 405 amplifier service process and what’s involved when a 405 visits Liquid Audio.
Talk about great-sounding amps, this particular Quad 405 is completely original, with its original capacitors and connectors. The new owner wanted me to freshen her up and fit some RCA connectors, so that’s what I did. Let’s look briefly at what’s involved in a Quad 405 amplifier service like this.
Keen in mind this is a Quad 405 service, not a full restoration. Service focuses on reliability improvement and bang-per-buck sonic gains. I start by carefully inspecting the 405 and looking for any signs of parts failure or earlier poorly executed work.
The next step involves removing both amplifier modules and cleaning all the old thermal compound from modules and heatsink.
In a Liquid Audio Quad 405 amplifier service, the modules come out for a little freshening up. Depending on what my customer asks for, I’ll do more or less at this stage of the overhaul. In this case, the original ERO capacitors were absolutely dead.
I pay careful attention to fasteners. In this amp, some of the transistor mounting fasteners were not tight, and the module fasteners were barely finger tight. I remake the solder joints under each transistor after doing this, to remove stresses. Lastly, I clean each board, removing flux where necessary.
If the customer wants something more like a restoration, I’ll remove the output devices, possibly replace them, and remake the thermal interface with silicon thermal pads.
Finally, as part of this Quad 405 amplifier service, I installed some RCA connectors on the back panel. Whilst not strictly necessary, the owner requested it here.