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Reducing NFB what to expect

6/27/2005 5:04 AM
Reducing NFB what to expect
What to expect if I reduce my NFB resistor currently it is a 100K (marshall) I would like it to sound more fenderish as it is a combo ?
6/27/2005 1:14 PM
Mark Lavelle

It should get a little cleaner, but you'll also lose some volume, particularly in the bottom end.
6/27/2005 2:04 PM
Carl Gigun
Maybe you meant "increase the resistor" since marshalls usually have more nfb than fenders? With less nfb you'd get more gain, more character from the speaker and output stage, and a looser sound.
6/27/2005 4:55 PM
Yes you will notice more gain, however, on the  
flpiside, some weird characturistics may show  
up upon max volume setting. Listen carefully  
to any artifacts that may crop up during note  
deminishings at max volume in low drive or high drive modes.
6/27/2005 5:09 PM

JCM 800 have 100K where as the plexis had 47K I want my amp to sound a bit more fenderish.
6/27/2005 5:36 PM
Well, lowering the size of the feedback resistor will not make el-34's sound like 6L6's, and won't change all the other design differences between marshalls and fenders, but it will make the amp a bit cleaner and tighter in the bass. If cleaner is what you mean by "fenderish" then go for it. If you still don't like the tone, then let us know a bit more about what it is about the sound you want to change, and we'll try our best to help you.  
6/27/2005 5:57 PM

I do like the sound of the Marshall however it is very  
piecing at times. I have taken out the 470pf Caps etc I actually want to lose a bit of gain out of it. It sounds great when the Master volume is up and preamp on about 3.
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