Quad 405 405-2 Upgrade Quad 405PE

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 silver plated copper cable and input wiring is replaced with screened MonoCrystal cable. Output wiring is replaced with MonoCrystal speaker cable. The mains voltage is set to 240V (other voltages may be specified as required). This upgrade can be applied to any Quad 405 version as we completely re-build the amplifier modules.

All wiring is soldered directly to the amplifier modules.

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

New high current 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 module components are replaced and the following modifications are carried out:
Current Limiting Removed. (DC Offset protection is retained.)
TR1 constant current circuit improved.
Later stages are all re-configured to use the class A constant current source.
IC power supply improved.
Op Amp replaced with Burr Brown OPA227.
Bridge components are matched to minimize dumper switching noise.
Additional power line decoupling is added to each module.
Output transistors replaced with MJ21194
Driver transistors replaced with MJE15031
All other transistors are 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 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.