![]() If the function of the capacitor is only DC filtering, or decoupling, then increasing the capacitance 2X-3X for small caps is usually not an issue (also keep in mind that caps in vintage equipment were often rated at -10%, +50%). Generally, if appropriate to the circuit, and there is sufficient space on the board, replacement capacitors will have higher capacitance and sometimes increased voltage (especially if the original voltage rating is just marginally higher than actual voltage). Surprisingly, the original main capacitors (C42 and C43) are listed as 470♟/25V in the schematic, but were actually 1000♟ rated at 16V the problem is that the rectified secondary voltage is 20V! They also cost the same as regular diodes their use won't hurt and will likely contribute to better sound. The "soft recovery" property of these diodes generates less noise and hence there is less potential noise to be amplified by the circuits. The original diodes were replaced with UF4005, ultra fast, "soft recovery" types. ![]() The resistors were replaced with same value metal film types. The power supply provides a regulated output of +14 V and -14V for the phono and line stage as well as the 20V needed by the muting stage. As with the phono stage upgrade, it was not just a "part for part replacement", but along with the the use of modern parts (e.g., low ESR capacitors, stacked film capacitors, metal film resistors, "soft recovery" diodes), the circuit was examined to see where simple improvements could be made without modifying the pcb (e.g., increasing or decreasing capacitance of capacitors, elimination of capacitors where possible, op-amp replacement). ![]() I had previously successfully upgraded the phono stage, see for details. I have a Toshiba SY-335 (same as Aurex SY-330/335) preamplifier which is a good candidate for modifications/upgrades since it has a relatively simple signal path that uses op-amps as active devices.
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