• 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.

Ready To Build the Other

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Previously known as kingden
Joined 2008
I will start construction on the second MKIII unit tonight.

http://www.diyaudio.com/forums/tubes-valves/236172-dynaco-mkiii-mod.html

The whole point of the exercise was to:

- Engineer out all solid state electronics except for the bias diode.
- Install individual bias controls.
- Develop a circuit with similar performance characteristics to Shannon Park's Poseidon driver circuit, minus the CCS though. Welcome back to the 50s gents.

Minor issues and annoyances you all can assist with:

- A Third wire ground loop between my laptop and the amp introduces all kinds of digital noise. Can this be remedied without an input transformer?

- The GZ34 tube. I have had shorting issues with the JJ's. How are the units from tube amp doctor (TAD)?

What do you think about the construction?
 

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Previously known as kingden
Joined 2008
The schematic is here.

Known Issues:

- Pins 4 and 5 are tied on V1 and V2, unlike what the schematic shows.
- The 5U4 is a 5AR4 now.
- Component reference designators need reworking.

My THD numbers are around 0.3% at 1k, maybe lower. It can vary depending on line voltage, warm up time, the tubes chosen, etc. What do you all think a reasonable number to shoot for is for HiFi?
 

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