Drop preamp voltage

[Guitarist]

Hi, this an '800 style pre (English Muff'n) and as the output is too high/hot and it could use more distortion, I'd like to add a dropping resistor. It could use to shed 100 Volts before the plate resistors (from nearly 200V). Might even add two resistors in order to isolate V1a and V1b if you think that may help.
So only the first tube as the V2 is fine as is. Perhaps a 470K 1 watt? I don't like 150K plate resistors so the 100k's stay.

I remember reading an ultimate Marshall had 100 V on its plates.
Thanks.

[eschertron]

So are you changing a PSU node resistor? Are you adding a node (resistor and cap)? Unless the two stages of V1 had exactly the same amplitude signal - exactly out of phase - on their plates, there'd be some odd stuff happening with an added resistor/no cap. Almost like adding the 470k onto the 100k plate resistor, but not quite.

Not to mention that 470k will drop almost a thousand volts if there's 2+ mA running through it!

[Chuck H]

As long as nodes of like phase aren't shared at any filter node you shouldn't need to separate the first tube triodes unless you just want to stagger the voltages.

100Vp sounds really low to me. But I've never experimented that low so I can't comment really. If you don't have Duncan PSUD you should download it. Works really well if you program it right.

PSUD2

[eschertron]

MEF member Alan0354 mentioned dropping a Marshall preamp rail. I can't find the exact thread, but some searching might bring it up.

[Guitarist]

"Are you adding a node (resistor and cap)?" Yes exactly, I'll likely parallel a 1uF poly as well with the 10 or 22uF electrolytic.
If it was inside a amp head it would be fine but it's playing fair on the pedalboard. Its MV must be set so low that the bass and balls are gone. I see that Alan has asked MANY great Qs, but can't locate this particular one.

thanks!

[Guitarist]

I just added a 10K 1 watt resistor in series with R24 a 3.3K 1 watt. There's another cap and 18K .5 watt resistor for V1. Thus node voltages are now 298, 217, giving 108 on V1 plate with 100K.
Just a quick test but his seems to have helped. Creamy. It wasn't really useable prior and now it is! Recorded example in my other Silver Dragon post.