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Posted by Welborne on
04-29-2017
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Hello Roman,
Hola from Hong Kong! How are you? Haven't been here for long time. I have a question at the back of my mine for long time, and it may have been covered elsewhete in your blog before. I am asking it here but do point me to the thread if it has already been discussed.
I have read and re-read your writing and description about where the Melquiades sound come from. Especially when you compared the one stage Mel and your proper 6e5p-6c33c they seem to sound super close, which means the output 6c33c stage is very neutral and transparent and its job is to give more horse power to the Melquiades effect from the "gas tube biasing 6e5p" portion. This got me thinking..... here comes my question, naturally. Is it possible to turn a neutral low distortion "low character" sounding power amp such as other tubes or even solid state output stage into Melquiades-effect generating too by incorporating the gas biasing 6e5p stage in it? The question I ask this is because I have been exposed to some latest class d (particularly tpa325x family from Texas Instrument) and they sound very very good, neutral, dynamic, very good soundstage, detailed....in other words Transparent. So I am thinking about a Melquiades Hybrid project....
For the record, I myself have been a huge fan of 6c33c se sound. Mine is a D3a-6c33c, and these years many gears came in and went without taking down the throne of this 6c33c. The closest and my second favourite (very very close) happens to be a tpa3255 class D put together by a friend, which has the Korg Nutube incorporated in this input stage.
Any advice (for or against) on this idea is welcomed.
P.S. my speakers are Klipschorn, and (my absolute favourite) a pair of open bafle using Raal 140-15d ribbon and Telefunken/Altec/Tesla drivers which I followed from Fikus's Project 24 (aka Lampizator).
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Posted by Romy the Cat on
04-29-2017
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Welborne, I do not think
that I can give you an expert answer. You see, the gas tube biasing around 6e5p
was in a way an accident. It was something that made the 6e5p to sound very
interesting but I am not convinced that this type of biasing will be beneficial
for other tubes. For instance I did try to bias 6C33C in the same way but it
was very bad result. I think the things need to be experimented further. The
Milq biasing implies a grid resistor biasing and the “unnecessary” gas tubes
power supplies, it is possible that for some tubes only grid resistor as a “virtual
battery” will work out. I never went for anything further as my objective was
not to define a universal rule of amplification design but just to build an amp
for myself.
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Posted by Welborne on
04-29-2017
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Roman,
Thanks for your prompt reply!May be my last wordings have misled you. I didnt mean I was interested in expetimenting gas tube biasing for D3a or another tube. Instead, I am rather interested in putting a gas tube biased 6e5p in front of a ss amp and in my case a TI Tpa3251 class d. I have this idea after reading your impression on your one stage Melquiades vs Full Melquiades, which seems to point to the possibility that the Melquiades effect is from your 6e5p stage, if the output stage is transparent and neutrap enough....
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Posted by Romy the Cat on
04-29-2017
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Indeed I did not understood you.
If you would like Milq’s front end to drive something else then it is perfectly
fine solution. We have it to drive 6C33C, GM70, many DH tubes, SS push/pull. I
do not know about the Class D module current requirement however. I generally
not a big fun of class D but the question is not about my view on class D but
an ability of Milq’s driver to drive other than Milq output stage.
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