Plexi 6v6 - Rich Mod II Master Volume

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mspitzer
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Plexi 6v6 - Rich Mod II Master Volume

Post by mspitzer » Wed Jul 11, 2018 10:11 am

Hey guys -

I am working on a Plexi 6v6 build using the Hoffman 6v6 as a guide. I would like to add a PPIMV, and I am really impressed with the Rich Mod II PPIMV using a PEC 500K dual ganged pot as used by George Metropolous.

My question is this - on a standard 50 watt plexi, using a Rich Mod II PPIMV, the 220K resistors stay in place on the board and a 500K dual gang pot is used. On the Hoffman 6v6 layout, the board resistors after the caps that follow the phase inverter are 100K. Can I still use a 500K dual gang pot and wire the Rich Mod II PPIMV the same way as on a 50 watt plexi? Or do I have to change anything because the resistors after the phase inverter are 100K on the 6v6 instead of 220K on the 50 watt?

The Hoffmann layout is here:

http://el34world.com/Hoffman/files/Hof ... 6-V2.pdf

The Valvestorm layout for the 50 watt is here:

http://www.valvestorm.com/Amp Mods/PPIMV


Thanks so much!

Mike

danman
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Re: Plexi 6v6 - Rich Mod II Master Volume

Post by danman » Thu Jul 12, 2018 7:50 pm

Fender normally used 220k in that spot so you would be fine using anything from 100k-220k with the Rich-mod MV. 100k may cut drive to the power tubes slightly but feel free to experiment with either value and let your ears decide.

danman
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Re: Plexi 6v6 - Rich Mod II Master Volume

Post by danman » Thu Jul 12, 2018 7:54 pm

Low end will also be reduced slightly with the lower value grid leaks which may or may not be a good thing depending on the sound you are after.

mspitzer
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Re: Plexi 6v6 - Rich Mod II Master Volume

Post by mspitzer » Fri Jul 13, 2018 8:51 pm

Thanks so much. So using a 500K dual pot would still be fine for the Rich Mod II with the 100K grid resistors?

danman
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Re: Plexi 6v6 - Rich Mod II Master Volume

Post by danman » Fri Jul 13, 2018 9:28 pm

Yes, no harm will occur. You may want to experiment with both values to see which gives you the best sound as well as the coupling capacitor values between PI and power tubes.

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