2009年11月15日 星期日

Marzant 7C



OVERVIEW
This DIY kit is designed with referenced to the classical Marantz 7C. It give out sweet and detail sound. AUDIO series capacitor is used for high voltage filtering. To enhance power supply unit performance (shorten power routing path to minimize its impedance), the components of the built-in rectifying and regulating circuits are packaged closely together and far from the amplifier core. Also the R14 and R30 are no need to install.These resistors are used for setting the biasing for vacuum tubes and left there for DIYer fine tuning.

Low voltage dropout regulator of Linear technology LT1085C IC is used regulating power supply for tubes filament, which gives a maximum output driving current of the IC is 3A and far enough for filament power supply.

FEATURES
1. Components design value with reference to Walt Jung of American Audio Amateur Magazine.
2. Shuguang 12AX7B x3.
3. WIMA MKP10 series 2.2uF/100V as output coupling capacitor.
4. BHC filtering, WIMA capacitor.
5. Dale resistors.
6. PCB thickness 2.5mm, 2oz copper wires.

Optional: Toroid transformer T30
Primary voltage: 110/220V 50-60Hz
Secondary voltage: 12.6V(1A), 200-220V (200mA)




ASSEMBLY GUIDE
1. Unplugged the vacuum tubes and without applying input signal, the voltage supply of J1 connecter (marked with 200-0) should be 200VAC for high voltage supply and J2 connector(marked with 12.6-0) should be 12.6VAC for filament power supply. Toroid transformer T30 can provide these AC power supply for this DIY kit
2. Turn off the power supply after turned it on for 1 second and quickly measure the residue voltage between the terminals of C13 (back of the PCB) to see whether it is 150-240V or not. If the voltage is 0V, need check again whether the components are mounted correctly by comparing with the schematic.
3. If the high voltage supply part works properly, turn on the power supply and measure the voltage different between the pin 4 and 5 of the tube socket. It should be about 12.6V. if not (higher than 14V or below 10V), need recheck the mounting of the components of the filament rectifying part correct or not.

If everything ok, you can plug the tubes in the socket and turn on the power supply and enjoy it!

SIMULATION RESULTS
DC Analysis:


AC Analysis:


Noise Analysis:

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