Marshall Super Lead with Mods - Too Bright

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Cap217

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I have an amp that has the inputs jumped internally so only the top left input works. It also has a ppiv master on the back. The standard layouts show a bright cap on Volume 1 but my amp does not have a cap on Volume 1, only Volume 2. I see the Dookie mod is like this as well and is 4700pf. Im not sure what mine is and will have to look on the other side of the disc but once I get in there, I assume I can clip one leg and see what it does, then experiment with different values if needed.

The lower value, the more frequencies (to the mid and lows) is passed, correct? So if its 4700 and I use a 2200 it would be less harsh and more mids/lows?

But my other question is how does the PPIV master on the back effect brightness? I usually play the amp with V2 and V2 at 7 and the master at 2-3. Does the masters lower volume have anything to do with brightness of the amp?
 
Cap217 said:
The lower value, the more frequencies (to the mid and lows) is passed, correct? So if its 4700 and I use a 2200 it would be less harsh and more mids/lows?
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Higher the value the more gets through.

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TheRealDonnie said:
Higher the value the more gets through.

View attachment 99836
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So the lower the value, the darker the amp. But not because it allows more lows but blocks highs?

It seems that all values in your chart would block the same amount of lows, so you cant adjust for lows with a bright cap at all, right? Its just subjective on how many highs are heard.
 
is there a book I can study so I can learn to understand this stuff and how to work on tube amps ? I’d love to get this knowledge and don’t have it now
 
Cap217 said:
So the lower the value, the darker the amp. But not because it allows more lows but blocks highs?

It seems that all values in your chart would block the same amount of lows, so you cant adjust for lows with a bright cap at all, right? Its just subjective on how many highs are heard.
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The chart is mainly showing just high frequencies but I'm pretty sure the equation is the same
as you go down in Fr.
 
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Smaller the value bright cap across the pot, the higher the cutoff frequency, meaning the more highs that are passed and the more lows that are attenuated due to being forced through the resistive voltage divider within the potentiometer.

It will sound more harsh on the top end. The larger the value, the more mids and eventually lows you’ll be bypassing. The cap is out of circuit when the pot is on 10/10. The cap and pot make an RC filter that adjusts what lows, mids, and highs are targeted.
 
glpg80 said:
The cap is out of circuit when the pot is on 10/10.
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Isn't there still some filtering (extremely slight) still happening?

I THINK :rolleyes: I noticed something for sure playing a guitar with the single tone pot on 10 vs removed from the circuit.

???
 
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TheRealDonnie said:
Isn't there still some filtering (extremely slight) still happening?

I noticed something for sure playing a guitar with the single tone pot on 10 vs removed from the circuit.

???
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No filtering, it’s a dead short between the legs with the full value of the pot referencing ground.
 
regarding the ppimv, I’ve had 2 different ones on my 1987 clone and I felt both really took away the warmth of the amp, made it really scooped sounding. I had much better luck with an attenuator.
 
glpg80 said:
Smaller the value bright cap across the pot, the higher the cutoff frequency, meaning the more highs that are passed and the more lows that are attenuated due to being forced through the resistive voltage divider within the potentiometer.

It will sound more harsh on the top end. The larger the value, the more mids and eventually lows you’ll be bypassing. The cap is out of circuit when the pot is on 10/10. The cap and pot make an RC filter that adjusts what lows, mids, and highs are targeted.
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This.
 
Cap217 said:
I have presence and treble on 0. Literally 0.
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Try using a coiled cable over 30 feet direct to amp with no buffer. That will tame the high-end somewhat as is why many hard rock Marshall users played with coiled cable. There is a degradation of the high end.

This is also why coiled cables or long cables aren't very good with country, blues and rockabilly because they can damped the high end. You need a buffer in front like Wah if you use long cables. It explains why Boss Pedal tuners are buffered.

The degradation is measurable. Longer the cable the less high end you get.
 
TheToneDig said:
Try using a coiled cable over 30 feet direct to amp with no buffer.
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True! But testing has found it's not so much because of the coil but all the extra conductor
needed to make them since a coiled cord stretched fully out is what, like 100' long?

So if you hate the look or vibe of coiled cords try experimenting with 100' of straight cable
and the subtle effect should be similar.
 
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