Fidele Audio
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Fidele Audio
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Quad 606 GE2 Service and Upgrade - Full Details The main power supply capacitors are replaced with 4 x 15,000uF (originally 6,800uF) capacitors for the MkI and 4 X 22,000uF (originally 15,000uF) capacitors for the MkII. Small polyester capacitors are fitted to the main capacitors to de-couple high frequencies. 4 x 220uF capacitors on the amplifier circuit boards are replaced with 470uF ELNA Cerafine capacitors. The Op Amp is replaced with a Burr Brown OPA227. Key resistors in the Op Amp and feedback circuits are replaced with very low noise types. The bootstrap capacitor is replaced with a Nichicon Muse BP type. Replacing the Op Amp and the Bootstrap capacitor improves the distortion of the amplifier, while using larger main capacitors will tighten and firm up the bass response. The additional RF de-coupling will reduce the effects distortion attributable to RF interference from the mains and general environment. The output transistors are upgraded with very high quality highly linear devices (MJ21194 x 12) and also the driver transistors with a complementary device (MJE15031 x 4). Resistors are changed in the current sensing circuit to increase the maximum output current from 12 amps to 18 amps. All in all this service and upgrade will revive and significantly improve your 606 with lower overall distortion and even better base response and firmness. It is also possible to fit a Mark II power supply unit to the 606 Mark I. The Mark II power supply consists of a new toroidal transformer, 4 x 22,000uF main capacitors, new mounting hardware and additional HF filtering. This upgrade is additional the MK 1 upgrade listed above. |
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