HT voltage regulation

    Hi everyone. I've recently built an M15 and it's now my primary amp! But... I would like to build a 2 channel preamp for my rack system.

    From building the M15 I think I understand the basics of how a valve amp works but I'm still unsure of how to get the right voltage going into each valve.

    I decided on a "blues preamp" from ax84.com as my clean channel and a version of the "matchless hotbox" for my crunch channel.

    The schematics I've found have the following voltage values...

    Blues preamp: V1 285V, V2 315V (ECC83's)
    Matchless hotbox: V1 245V, V2 255V (ECC83's)

    I am considering using the Musikding torroidal transformer with these specs...

    Primary 230V, secondary 185V 0,04A and 6.3V

    I know the secondary voltage will be higher after a bridge rectifier. How do I calculate how high it will be?

    Also, what capacitors and resistors do I need to use to provide a suitable power supply for these valves? OR what do I change to the original schematics to make them work with this power supply?

    This is the only bit I'm confused with!

    Thanks,

    Paul

    Re: HT voltage regulation

    You have AC 185V, so multiplied with Squareroot of 2 (1,41) you have 260V. That is too less. I would recomend you this transformer. After the rectifier you can expect 370V, because of the low current. This is the same transformator as in the Madamps. That means that you can also build a poweramp with it.

    You can use the ohms law: U = R * I [V=Ohm*A] So if you have you 370V and want 315V, the diffence is 55V. Than you take the current through the resistor (i.E.: 1,5mA per ECC83 triode) and calculate the needed resistance.

    I would say, take the values of the given schemativs for the Cs.

    So much english.. Good training *g

    Stefan :)

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