Marshall Brite Caps!!

[MarshallDog]

So, whats with Marshalls brite caps?

I play Gibson Les Paul Standards with DiMarzio 36th Anniversary pups with new old stock PIO Sprague BB caps. Bridge pup volume at 9/10 and tone at 6. Amp EQs = bass 1, presence 6, mids 6, treble 4, gain at edge of break up and ALL my Marshall amps have had to have the brite caps reduced to 68 - 100 pF to reduce those really high brittle ear numbing high freqs. I also play through either vintage GBs or new G12M-65s. Neck tone is never an issue!

With this set up I can get a nice slightly edge of break up tone, thick, rich and not ear fatiguing tone with plenty of cut/presence!

So looking at my amps in my signature, my question is WHY does Marshall use such a high value brite cap where to get a nice tone ones EQ and tone knobs need to be set to 0-1 excluding the bass knob...I dont get it...what am I missing here?

 

[shredless]

I wanna know this too

 

[AlvisX]

My observation, based on nothing but what my ears like/dislike , is that it's the treble peak caps ,the ones over the input resistor and mixer that are the culprits of brutality . Ive done stuff like lift a leg one OR both ....or Ive cut the value in half . I dont like the stock values ,that's for sure . I think currently on my favorite amps I have a 300 to 470pf brite cap over the pot and NO peak caps

Not sure what the Marshall engineers based their values on .....coulda been math , coulda been using a neck pickup ,I don't know . What I do know,that whole "clip the brite cap" thing is not the way ..... you gotta tune that sh*t ...My 2c anyway

 

[thetragichero]

more treble means the guitar is more louder when your bassist (with svt) and coked up drummer kick in. also a lot of times the tones that sound "fantastic" by themselves are awful in a full band mix (this coming from someone who is primarily a bassist and learned via a high pass filter that the low midrange is where i fit best, not trying to fight the drum kit for low end supremacy)
but yeah mostly i'm guessing it's to make the amp sound louder

 

[MarshallDog]

My observation, based on nothing but what my ears like/dislike , is that it's the treble peak caps ,the ones over the input resistor and mixer that are the culprits of brutality . Ive done stuff like lift a leg one OR both ....or Ive cut the value in half . I dont like the stock values ,that's for sure . I think currently on my favorite amps I have a 300 to 470pf brite cap over the pot and NO peak caps

Not sure what the Marshall engineers based their values on .....coulda been math , coulda been using a neck pickup ,I don't know . What I do know,that whole "clip the brite cap" thing is not the way ..... you gotta tune that sh*t ...My 2c anyway

Interesting Alvis! I believe you are referring to the “treble peaked” cap right? I have not tweeted this one yet! I agree that if you take the Brite cap 100% out it sounds BAD dull!

 

[Chris-in-LA]

I built 2 JTM45’s and played them side by side. The one with the 500pf cap on the treble volume pot sounded more alive than the one with the 100pf cap. It might be a matter of taste.

I also have to agree with statement that a warm living room sound doesn’t necessarily cut through in a band situation when I listen to my band recorded in rehearsal.

 

[neikeel]

I’ve commented on this before.
If you use the 5000pF on the volume pot it is not really designed as a bright cap. It is there to bring the volume in with a bang low in the sweep of the pot rather than by 7 or 8 on the dial because by that stage it is painfully loud. Look at a tone stack calculator and you will see the frequencies that are being boosted.
Worse culprits would be In the 250-1000pF range for allowing mainly highs through.
I like 100-150pF for quieter noodling but when the amp is cranked it is out of the equation
Have a listen to George Metros clips of his 12series vs clones with and without the cap on youtube and you will hear subtle benefits of a big cap.

 

[MarshallDog]

I built 2 JTM45’s and played them side by side. The one with the 500pf cap on the treble volume pot sounded more alive than the one with the 100pf cap. It might be a matter of taste.

I also have to agree with statement that a warm living room sound doesn’t necessarily cut through in a band situation when I listen to my band recorded in rehearsal.

I know what you mean by it wont cut through in a band situation but I have found with lower brite caps I still have no issues cutting through and if I want a briter cleaner tone I just turn the tone pot up on the guitar.

 

[Chris-in-LA]

I know what you mean by it wont cut through in a band situation but I have found with lower brite caps I still have no issues cutting through and if I want a briter cleaner tone I just turn the tone pot up on the guitar.

Right. It’s independent of the cap.

 

[XTRXTR]

I'm gonna play around with values on this "bright cap" Things change with gain for sure. I noticed this with switching values on the cold clipper. This cap is a high pass filter, the lower value of cap the higher the corner frequency. Another way to put it is; in the 20Hz to 20kHz spectrum, left is 20Hz and right is 20kHz, then from right to left more of the frequencies on the right side get passed as the cap value gets higher. On the spectrum dial, much like a radio dial, when dialing from right to left you increase the value of capacitance to scroll to the left.

|| farad F > 0.f millifarad mF > 20Hz microfarad uF > nanofarad nF > kHz picofarad pF ||

As you clip more and more in the preamp you lose your high end on the clipped portion of the signal in an asymmetrical clipping circuit so you have to dial up your highs to hear through the muddier tone.

 

[shredless]

I tried a 1000pf and l didnt like it... I've gotten to really like my amp the way it is lately. So I can't say I gave it a really fair try

 

[1967owner]

Don't they make the 100 watt plexi RIs hiss like a snake in the high treble channel?

 

[Gene Ballzz]

Much easier to tame too much high end than it is to put back in what isn't already there. Remember that the whole tone stack style in "most" Marshall amps actually "cuts" selected broad bands of frequencies and does not boost them! Also, those three tone pots can be extremely interactive upon each other. It's not unusual to actually lose some bass by boosting the treble and vice/versa. If you take away too much treble/brightness in the earliest stages, there's nothing left to put back in or "un" cut!
Just My For Clarity!
Gene

 

[matttornado]

This is interesting. I been playing my 100 watter for over 20 years with the stock 5000pf brightcap removed because I always used to complain that the amp was to bright.
Last week after some maintenance, I put back on and really liked it! The amp sounded more alive and the gain sounded better too, maybe more focused? Not by a whole lot , but very noticeable.

I usually have that volume I pot cranked up between 6 and 9 though.

 

[myersbw]

I like 100-150pF for quieter noodling but when the amp is cranked it is out of the equation

...THIS (above) exactly. The bright cap we often refer to on those 50-100 watters is there with the purpose of restoring high end frequencies lost with the volume control is rolled back on the amp. Your particular flavor of cap will all depend on how you play through it, what pickups, speakers, etc.

If you run the preamp full up, the cap is literally electrically removed from influence. But, I, for one, like a lot of low level playing (as do many in this SW Ohio area), so I've modded many with 100-120pF caps. Playing at lower levels inserts for pure resistance, which will shift the frequency response and cut some highs. Thus, the insertion of a cap to let those upper freqs bypass the added resistance.

I'm also wondering if 'old technology' also comes into play with those early designs (weaker pickups of old, speakers that weren't as sharp in the upper register reproduction, etc.) and just maybe our modern pickups & speakers lend to better low volume results by reducing the cap and, thus, preventing too much upper freqs to come through.

 

[dslman]

...THIS (above) exactly. The bright cap we often refer to on those 50-100 watters is there with the purpose of restoring high end frequencies lost with the volume control is rolled back on the amp. Your particular flavor of cap will all depend on how you play through it, what pickups, speakers, etc.

If you run the preamp full up, the cap is literally electrically removed from influence. But, I, for one, like a lot of low level playing (as do many in this SW Ohio area), so I've modded many with 100-120pF caps. Playing at lower levels inserts for pure resistance, which will shift the frequency response and cut some highs. Thus, the insertion of a cap to let those upper freqs bypass the added resistance.

I'm also wondering if 'old technology' also comes into play with those early designs (weaker pickups of old, speakers that weren't as sharp in the upper register reproduction, etc.) and just maybe our modern pickups & speakers lend to better low volume results by reducing the cap and, thus, preventing too much upper freqs to come through.

Very good points!