Quad 34ST

This upgrade addresses all areas of the 34 performance. All analogue circuits are upgraded and improved by using high quality ICs and discrete components. The power supply is also improved with better and larger capacitors and the phono and digital power supplies are upgraded using linear voltage regulators rather than zener diodes.

This addresses every area of amplifier performance producing a Quad 34 at its very best.

The phono module is completely re-built using low noise resistors, low noise audio transistors and polystyrene capacitors for cartridge loading. The feedback capacitors are either film caps or Elna Silmic depending on the module specification. Modules can be MM or MC and have sensitivities from 100uV to 6mV. With resistive and capacitive loading to match you cartridge exactly.

All operational amplifiers are replaced with Burr Brown OPA227 or OPA2227 (Dual Amps). These are far superior to the original Op Amps giving a much more neutral sound and far lower distortion. De-coupling capacitors are added at each op amp location for maximum stability.

All bilateral switch ICs are replaced.  These are electronic switches used to transfer the selected input signal to the main pre-amplifier circuits and also to select filter levels. The originals are cheap ICs with a very high distortion rate. The replacements are the best I can find and have a very low 'On' resistance and a distortion rating of 0.008%.

All signal path electrolytic capacitors are replaced with film capacitors or wire links! We increase the size of several film capacitors in the signal path to ensure good base response, this includes the parts of the phono stage on the motherboard. The various stages of the Quad 34 are usually linked with large electrolytic capacitors to block any DC offset from one stage to the next. By using very low offset Op Amps we can eliminate the need for these coupling capacitors. The only exception being the tape output where we use a bi-polarised electrolytic capacitor.

The motherboard phono input module power supply is upgraded with linear voltage regulators and the capacitors are replaced with ELNA Cerafine capacitors.

All power supply electrolytic capacitors are replaced with ELNA Cerafine except that a Rubycon ZLH capacitor is used for the main capacitor, all larger capacitance than original.

The bridge rectifier is replaced with fast Schottky diodes. Also further RF de-coupling is added to all power supply lines.

Note at the moment we are using the even better Elna Silmic caps and a Panasonic FC capacitor for the main cap in the power supply and phono circuits.

The cost for this upgrade is £285.00 plus £15.00 return shipping for the UK. Please enquire for shipping to other locations.

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