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In the Forum: Melquiades Amplifier
In the Thread: Single-stage Melquiades vs. DHT amps
Post Subject: The lights look green for the YO tubePosted by Romy the Cat on: 2/4/2009
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Each new idea is an opportunity or a pain to be involved into a new round of custom work. With all my considerations regarding engaging the DHT I more and more biased to have YO186 as the leading candidate, in fact I almost decided to do it.  From a certain perspective the YO186 is Russian-made RE604 that is good itself, considering the mythical quality of sound from RE604 but there is a twist in it. If the YO186 was mane in 1947 then I would say “Yes”, Russians copy the RE604. BUT, first the YO186 looks like none of the Telefunken or Klangfilm tube of the period and second the YO186 came to production in 1932 and this make the story VERY interesting.

The Russia of very beginning of 1930s is an interesting time. The generation old empire engineers among those who do not escape to west or was not killed still were around and it is very possible that Telefunken stolen RE604 from Russians, or at least that they were independent developments.  A commercial public radio was introduced in Germany in 1923 and in Russia in 1926. So, Russian in beginning of 1930s had people and recourses to do the interesting things and they did.  So, the YO186 might be an interesting tube on it’s own.

Anyhow, returning back to the pain of new round of custom works. It looks like I would need another low inductance output transformer 20:1 or even perhaps 5 more.  This sucker needs to be ordered but I kind of debating what I want this time. I have two options: to go for fasters core (amorphous) as I did before and load the tube a bit harder or to go for more mellow core (cobalt, nickel, Mu-Metal, chicken, wood etc) but to let the plate to idea a bit more. With 350V and 30mA I will get around 3W from YO186 – much more then I need, so I can but some power on damping, thankful the gain won’t be an issue with two stages anymore.  The question is how much S2 driver will be able to handle – I have no idea until I try…

The caT

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