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24.34.17.88
In Reply to: I had the 6AN4 on hand... posted by grhughes on March 2, 2007 at 06:18:11:
I have got plenty of 6DJ8s so I would probably go that route first.
Follow Ups:
and he seemed to fear the prospect of loading the cartridge with DC offsets on turn on. It's probably necessary unless you use an input transformer and maybe necessary even if you use one if you don't want DC in the secondary winding. I use a Grado MM and use it direct in with no transformer. There is also a variant used by Studer in their C and J 37 tape preamps in which they used the 6DJ8 on the bottom and a weird Euro 12ax7 type up top as the grounded grid. They didn't use a input coupling capacitor. But I think it's safe to use one. Ray
"I take you as you are
And make of you what I will,
Skunk-bear, carcajou, bloodthirsty
Non-survivor.
Lord, let me die but not die out." THE LAST WOLVERINE by James Dickey
http://www.diyaudio.com/forums/showthread.php?postid=1083419#post1083419
Post #49 the gif at the bottom. Ray
"I take you as you are
And make of you what I will,
Skunk-bear, carcajou, bloodthirsty
Non-survivor.
Lord, let me die but not die out." THE LAST WOLVERINE by James Dickey
Ray,Thanks for the link. Some interesting ideas in that thread. I would probably start with the basic circuit on Steve's website first and modify from there. Also, thanks for the info on the input capacitor. I think a few of the builders have left it out with no ill effects.
"no ill effects"
If removing the input cap,
could DC at the input demage the transformer (Lundahl 9206), or MC cartridge (expensive !!), or are there only a risk for sound degration caused by saturated transformer core ?
Regards
Pix
or a protection should a tube expire if you are using the preamp direct in from a phono cartridge. Moving coil cartridges mostly are low impedance devices. My Ortofon MC30 can drive a 2 ufd capacitor with no signs of instability. If you're using an input transformer, I don't think it would damage the input transformer. It might magnetize a winding depending on high a voltage got into the secondary winding. Audio transformers normally don't like DC.
"I take you as you are
And make of you what I will,
Skunk-bear, carcajou, bloodthirsty
Non-survivor.
Lord, let me die but not die out." THE LAST WOLVERINE by James Dickey
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