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Re: PP amp design

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akltam

(A)

In Reply to: Re: PP amp design posted by KevinC on September 12, 2003 at 14:39:09:

Kelvin,
I checked from the spec for 6C45, they said the internal plate is only 1200 OHM. But certainly the real implementation and listening experience does matter.
The reason I don't want to go for what you have done (6sn7 and 6BM8) is that I do not want to expand my tube collection choice.
What about two stage 6H30 but doing the other way, to step it down after the two stages - using ration 2.25+2.25:1+1 ? I am just exploring other possibilities.
Alan

Follow Ups:

Thank you! - akltam 01:38:15 09/14/03 (0)
Kelvin and others,
I am thinking about 5687 and 7044 also. They also have low plate resistance and large current (less than 2K).
Kelvin, it seems that what I am going to do will end up very similar to yours. Thank you
Alan
Re: PP amp design - KevinC 10:56:24 09/13/03 (2)
I like the 6H30 idea better. You could choke or resistor load the first half of the 6H30, then direct couple to the grid of the second (interstage transformer loaded) half of the 6H30, using a bypassed (Black Gate) cathode resistor. This keeps small value coupling caps out of the path.

Kevin Carter
K&K Audio
www.kandkaudio.com
- Re: PP amp design - Tre' 22:03:46 09/18/03 (1)
  With the first half of the 6H30 direct coupled to the second half, won't the cathode resistor be a larger value allowing the use of a film bypass cap?
  - Re: PP amp design - KevinC 04:42:37 09/19/03 (0)
    Yes, it might at that. I haven't done the careful math to know what the exact value would be, but at 20mA and 100v a 5uF capacitor would get the roll-off below 10Hz.
    
    Kevin Carter
    K&K Audio
    www.kandkaudio.com
Re: PP amp design - Horn-a-copia 10:32:54 09/13/03 (0)
I think you may be on the right track with the 6H30P. This tube has a fabulous voice, a low Rp and loves to be loaded with a coil. I agree with Kevin about avoiding a step up between the driver and the output. Stay with 1:1 or even a step down and the sound will really open up. You could use both halves of this tube to get two gain stages in one bottle if you need.

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