• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Clone Marantz 7C power supply

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kmtang

kmtang

Member
Joined 2004
My friends around me all have their Marantz 7C line amp. Most of the using tube regulated power supply. I just tried something special using choke input passive filter for the power supply.


250Vac CT Power Tran - 6X5GT rectifier - 4H 120mA choke - 68uF capacitor - 20H 120mA choke - 47uF blackgate capacitor (12AU7 buffer) - 3.3K resistor - 47uF blackgate capacitor (2 x 12AX7).

With this power supply circuit, the amp sound very lively, bright and excellent dynamic.

I ran the Duncan's PS software and it seems the circuit is not quite stable. I will try to replace the 4H choke with 20H one.

I like this passive filter because the noise level is significant lower and with very fine resolution.


Your comments are most welcome.


Johnny
 
SY

SY

Ex-Moderator
Joined 2002
SYclotron.com
Cascaded chokes like that are an engraved invitation for instability. PSUD's results may go a long way to explain the "lively" and "bright" colorations you observed. Some carefully applied snubbing or damping resistances could go a long way toward getting your supply rails to look more like DC under dynamic conditions.

Of course, if you like those colorations, you'll be unhappy with the sonic results of power supply stabilization.
 
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