Quad 405-2 Upgrade Quad 405-2PE

This upgrade provides a complete re-build of the amplifier modules along with a new 'Dual Mono' power supply. All primary and secondary wiring is replaced with solid core OFC cable and input wiring is replaced with screened OFC cable. The mains voltage is set to 240V (other voltages may be specified as required)

Phono inputs are added and the input sensitivity changed to 1.5V (Optional but recommended items).

New speaker sockets are fitted.

Power Supply:

New 'Dual Mono' power supply fitted, with 2 bridge rectifiers and 4x 10000uF capacitors. All primary and secondary wiring is replaced (the voltage selector switch is by-passed). The amplifier 0V is separated from the chassis by connecting the amplifier modules directly to the 'Dual Mono' power supply (rather than through the chassis as standard). The 0V is then connected to the chassis ground via a resistor and capacitor (in parallel) in the same way as in the Quad 306 and 606.

Module Re-Build:

All components are replaced and the following modifications are carried out:
Current Limiting Removed. (DC Offset protection is retained.)
TR1 Constant current circuit improved.
IC power supply improved.
Op Amp replaced with Burr Brown OPA227.
Additional power line decoupling added.
Output transistors replaced with MJ21194
Driver transistors replaced with MJE15031
All other transistors replaced with low noise audio transistors.
The inductors used are high current EPCOS types.
All resistors are low noise types and all capacitors are either film or polystyrene capacitors or Elna Silmic for electrolytic capacitors.
(The DC Offset protection circuit uses a non-polarized ELNA capacitor).

Full bench test.

This amplifier is not suitable for use with un-modified ESL57s, otherwise there are no usage restrictions.

The cost for this upgrade is £480.00 including return tracked and insured shipping to the UK. Please enquire for shipping to other locations.

Please refer to our Payments and Shipping pages for additional information.