C+ Bright Reduction - De-mod?

[Restless Rocks]

Just because noone has mentioned this here's an extra .02 cents. The 10pf cap is a buffer between the input and output of the lead circuit . Changing this cap will not have any effect on the sound of the LEAD channel. It will have a dramatic effect on the upper harmonics of the CLEAN channel. Changing the 1000pm cap will effect the Lead Channel and not the clean channel.

 

[Boogiebabies]

You can clip or de-solder it here.

The 10pf or 20pf has to be across the 3.3M resistor in the middle of the PCB.
It cannot be left as just a resistor. As RR mentioned, the 10pf/20pf effects the clean channel.
In lead mode it is basically swamped by the overdrive.

 

[#2121313]

Thanks Boogiebabies!

 

[#2121313]

I stand corrected....
I should just keep my mouth shut on tech issues like this.. sorry #2121313.

No prob gts!

 

[JOEY B.]

I stand corrected....
I should just keep my mouth shut on tech issues like this.. sorry #2121313.

Actually, George, you stand correct. The capacitor is wired parallel to the resistor, so it will not matter which leg is cut. The rear leg is much easier to access with a small pair of cutters, thus the comment by Ed.

On to capacitor #1. If it is a 10pF(modded), and a person wanted to experiment with the original 20pF value, another 10pF could be attached in parallel. This will give you the original value without de-soldering anything from the preamp board.

FWIW, if the amp has a 10pF in the #1 capacitor position, I would personally let it be. My "brightness mod" C+ has ALWAYS had the better clean sound compared to my stock one. The EVM-12L speaker will be plenty bright enough with the 10pF capacitor, trust me. :wink: If you are using your C+ with Celestion speakers, your results may vary from mine. And then again, if you don't have all the brights pulled and have room left on the Treble knob and graphic EQ ........ 8)

 

[Boogiebabies]

George is correct. The one leg is just much easier to clip or de-solder.
As JoeyB said, unless you really have a fine tuned ear and you are very good with a soldering
iron, the 10pf is just fine as is. If you are a super tweaker, the 20pf does effect the gain on the lead channel
slightly IMO.

 

[JOEY B.]

And with all that being said, I would not give back my "mean clean" for all the gain that could be had with any de-mod. :shock:

 

[Restless Rocks]

These are the fun threads.

Now to go even further in the "fizzy to smooth" search: experimenting with the presence cap from the .005 to .01 will really give the amp the agressive mk III snarl or even something different depending on how much you drive your output tubes. Like Joey says your speaker preference and personal taste will play a big role. If it works please don't fix it.

 

[#2121313]

So I performed the Bright Reduction De-Mod yesterday, and...I love it! Definitely the way to go for a Metal player. Has more bite, still smooth as hell, far smoother than any amp I have played/owned...

I always pull my Treble, Drive & Master 1 - always, and I was also pulling my Lead Master and occasionally (at lower volumes usually) having to also pull Vol 1 to achieve the tone I was after. I can now achieve this tone without pulling Vol1 & Lead Master.

I'm happy, I did drop one of my pre-amp tubes in the process of talking the chassis in/out and was hearing some popping noises out of the amp later in the day...I quickly replaced the tube (a Tung Sol re-issue) with a Mesa 12AX7 and the problem went right away...Not sure I like the Mesa tube in comparison, but I plan on replacing my pre-amps asap, probably with high gain 12ax7's from Eurotubes unless anyone can suggest anything better?

By the way, I found the Bright Mod to make my lead tone, which I used for a Metal Rhythm tone, to sound far more compressed than it does now in it's stock form (without the bright mod). Not sure if there is any technical reasons to support this, but that's what my ears hear.

Thanks again everyone, especially Boogiebabies for direction in doing the de-mod - any updates on the C++ mod that's in the works Boogiebabies?

 

[Platypus]

glad you liked it, figured you would 8)

 

[Boogiebabies]

Nothing yet on the C++. I been derailed by other amps at the moment.