Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mats on September 06, 2013, 08:27:55 am
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I had one Hammond 369EX PT and one 125CSE OT
I wanted to wire up/ try PSE.
So with one 6AB7 and two 6V6, I was on my way.
Took some experimenting but it turned out OK.
369EX rated for about 65-75 mA and about 250 V
Sound Ok with
Plates, 6V6 246V
Screens, 6V6 236V
Cathodes, 6V6 13,5V and 13,1V
About 70mA in total
Plate, 6AB7 102V
Screen, 6AB7 33V
Cathode, 6AB7 1,5V
PT seem to take this, after one hour turned on.
Little hum but not much.
I also would like to say, to all here on forum that, thanks for all your answers and
I have learned a lot here.
Like I have learned here; try it out and see/hear for yourself how your idea turn out.
Have a nice weekend to all of you from me here in Sweden
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Update:
I have tried one or two separate, Cathode Res., for the two 6V6.
The Res. has its own Caps (22uF).
I think theres some tonal difference, not much but some.
Pros and cons for this ?
I have the center tap of 6,3V connected to the Cathode, (One resistor)
But when I have two. I just connected, the same way as before, to one of the Cathodes.
Is this OK and correct ?
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Update:
I have tried one or two separate, Cathode Res., for the two 6V6.
The Res. has its own Caps (22uF).
I think theres some tonal difference, not much but some.
Pros and cons for this ?
I have the center tap of 6,3V connected to the Cathode, (One resistor)
But when I have two. I just connected, the same way as before, to one of the Cathodes.
Is this OK and correct ?
Nothing wrong with using individual K resistors on the power tubes, but unless they're really mis-matched not necessary. But we're hobbyists, so we can do things differently and how we like 'em. :)
Your heater center tap should be fine if I understand you right. You are either connecting your CT to the shared K resistor, OR when you're using separate K resistors you're still just hooking it to ONE of the K resistors.
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Thanks for replay.
I have only one Vol-pot, 1 Meg log between Input pentode and Power tubes, for this so far.
Want to try a "simple tone-control" I looked at Fxxxxrs two caps and one pot.
But then again would like to keep it simple and had a look at Treble cut, one cap and one pot.
Now to my question, I noticed there are two kinds :
1. Cap after the input tube coupling cap and then to pot ( have tried this way before)
2. Cap before the input tube coupling cap (from plate of tube) to pot (this I have not tried)
Value of Caps and pot for shure make a difference but !
Better or worse or just a matter of taste with 1. and 2.
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I would expect either method to produce about the same results.