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Paul C PI Mod

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Andrew Wilson (awilson40)
Username: awilson40

Registered: 05-2006
Posted on Sunday, December 17, 2006 - 01:51 pm:   

I just did the Paul C mod ( Using Ed Goforth's recommended component values) on my Hd130
It really sounds good.
I also replaced the PI tube with a NOS Philips 12AT7.
This gives me more useable range before clipping.
It think the 12AT7 takes to OD/Distortion pedals better also.
It just sounds smoother.

To sum up Ed's instructions.
The changes are :
1.Remove the 1.5K resistor on the cathode of the 2nd half of the PI tube, replace with a jumper.
2.Move the leg of the 1meg resistor that is at the junction of the 33k cathode and the 1.5 k that was just removed to ground.
3.Add a 4.7meg 1/2 watt resistor from point F (340v) to the grid (pin 2) of PI tube.

Works fine, Lasts a long time
:-)
Andrew Wilson (awilson40)
Username: awilson40

Registered: 05-2006
Posted on Sunday, December 17, 2006 - 02:13 pm:   

here is a quick schematic showing the changes.

http://home.earthlink.net/~awilson40/pau l_c_mod.jpg
Ed Goforth (ed_goforth)
Username: ed_goforth

Registered: 06-2006
Posted on Saturday, March 03, 2007 - 06:04 am:   

Very nice work Andrew,
thank you for the drawing. How do you like the mod, I have been doing this mod with great results along with a few preamp and power supply mods, the mods have really given the MM amps a broader spectrum of tones and still keeps its own original voice. The settings are more usable/versatile after the mods.
Andrew Wilson (awilson40)
Username: awilson40

Registered: 05-2006
Posted on Friday, March 09, 2007 - 07:04 pm:   

I love it, its finally sounding like I want...just wish I played well enough to show it off. Thanks for all your help with the amp.
Ed Goforth (ed_goforth)
Username: ed_goforth

Registered: 06-2006
Posted on Friday, March 09, 2007 - 08:33 pm:   

Your welcome Andrew, and thank you for the drawing!
Ed