updated schematics

 


Changes to the circuit since the previous schematics:

* input section: voltage divider (attenuator) ahead of boost circuit, to moderate the level of boost when activated.

* vmeq section: redesigned back to my older "cathodyne" circuit (v1-b).

* M-drive section: cold switch has three settings: 10k, 39k, 2k.

* fx loop section: feedback resistor in second return stage reduced to 2M, to trim overall gain close to unity.

* power amp: 13 kHz LPF between vol pot and 5k6 grid leak resistor, to suppress parasitic oscillation.

* relay control section: LED resistors increased to 56k on green (K3) and blue (K5) LEDs, to normalize brightness.

* power supply: initial 1k resistor ahead of first electrolytic ("sag resistor") removed, other resistors changed from 10k to 1k.

* all 12AX7 tubes: 10pF snubber caps across pins 1,3 and 6,8.

* EL84 tube: 10pF snubber cap across pins 3,7.


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