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In the Forum: Melquiades Amplifier
In the Thread: GM70 vs. 6C33C

Post Subject: Give the GM70 the best shot.Posted by KOTriode on: 4/28/2012

It is impossible to make two amp with the same quality with such big difference in output tubes , the transformer design are vastly different, a 10Kohm transformer would never have a good bandwidth as a 600ohm transformer. I just have to experiment quite a few thing to make the best possible result for the GM70and compare the two amplifier. But I do have what I think the best output transformer for the GM70 to squeeze out its maximum sonic capabilities to give the 6C33C a best shot.
Regarding caps, I think I know why you found the lower octave mushy, the problem is that it might not have adequate capacitance. My rule of thumb regarding capacitance is 500uF per 100ma of current, with 6C33C you will need close to 1000uF to get tight bass, and it is impossible to get quantity of oil&film cap in one chassis. This why I chose to use the voltage regulator, the amount of capacitance needed reduced to less than 100uF which is more reasonable to realize with oil and film. It is much easier and cheaper to use electrolytic at high voltage( you just series a number of them and get the voltage you want), but I prefer what the oil &film does sonically and chose the difficult path for the power supply.
After playing through this GM70 amp, I will experiment the 6E5P which I just bought 20 of these for the 6C33C, the Melquiades circuit is in the work for a pr of 6C33C amplifier, there are so many things to try and it will take time....

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