Treble and Bright caps

[Kapo_Polenton]

Deisel throw up a pic of your module. Let the wizard do his work! and check the value of cap you have in C3. The Brahma has a funky series of caps and resistors which give it the sound and that sound is great. Great classic Marshall plexi crunch to my ears.

 

[JKD]

Eureka.. MUCH better! 2 value changes and bam. Usable module. excellent mid range crunch and fatter sounding than my brahma. This thing has now earned it's spot among the rotation. Friedman should have consulted you before releasing this thing! Now that mode switch, who knows why it has such a volume drop, sounds great though. :idea:

Any chance of a recording? I actually like my GTO (in both modes) but am naturally curious module whore!

 

[Kapo_Polenton]

See what I can deliver if I can get some time this week... maybe throw a cheesy backing track on and let er rip.

 

[SacredGroove]

Eureka.. MUCH better! 2 value changes and bam. Usable module. excellent mid range crunch and fatter sounding than my brahma. This thing has now earned it's spot among the rotation. Friedman should have consulted you before releasing this thing! Now that mode switch, who knows why it has such a volume drop, sounds great though. :idea:

Nice! Glad it worked out.

 

[SacredGroove]

@ Sacred Groove. Yes , there was a 10k resistor in R25 and R31. And those are stock values in my PLEXI i just bought a few weeks ago from M.F. And it's dated " 1104R1146 ". Kinda weird, huh? I changed both of those to 33k and can't hear any difference . . . . . . . This is NOT a great sounding module.

Which module are you working on, Plexi or SL+? Are you still going for the cranked Plexi tone?

 

[Deisel401]

Yea I'm working on the PLEXI. It has way too much lower mids and the treble feels more Fendery than it does Marshally. I changed out the .022 in C3 for an Orange Drop .001 too get rid of the boominess. It helped a little but it's still more boomy than I want. I also changed out C8, C9, C16, and C17 to Orange Drops same value. And I added a .22 polarized cap to C13. In C13 I first tried a 22, then a .68 but those were adding too much of everything so I settled on the .22 to get just a hint of "more". Not hearing any significant differences with these changes. This PLEXI just has too much lower mids for my liking. And I broke my SL+ because I wasn't smart enough to stop tweaking when it sounded good enough. And, yes, I really want that cranked Plexi sound with a bit more of everything but not so much that it makes it muddy and unclear. Thanks for listening to my whining. lol. oh. . . there was a 33k in R25 and a 10k in R31 on the Plexi pcb. The schematic of the Plexi on the Grailtone website shows the Plexi having a 56k resistor in R31 which is directly behind the "middle" knob. On MY Plexi , in that location, is R25 with a 33k res.

 

[Kapo_Polenton]

Why don't you start with a module that you like... then compare. Are you saying that at some point your SL+ was working? The changes you asked about and liked, they were on the SL+ that now doesn't work? I am going to suggest a Brahma.. go from there. The gain and mids I added to mine (thanks to SacredGroove) took it that much further though I love my other stocker as well. The SG "juror" mod I just did will give you the Marshall bark and is tight.

 

[Deisel401]

Yea my SL+ WAS fine. I did a few tweaks too it and , to my ears, made it a bit better. Then I made a few more changes and accidently broke off the "Middle" knob and messed up the pcb trace that connects C3. I wasn't smart enough to leave well enough alone. But my last few posts were in reference to my Plexi which I'm being ridiculously careful with so I don't screw this one up too. I get what you're saying about comparing other modules and then making changes, but I only have my SL+, my Plexi, and my Blackface. So I really have nothing to make comparisons with and the schematics on Grailtone are not 100% accurate. Thanks for the suggestions tho'.

 

[Deisel401]

WTH ? That SPAM ? ^

 

[Jaded Faith]

WTH ? That SPAM ? ^

I took care of it.

 

[Deisel401]

Everyone has been very helpful to me so I'd like to share my tweaks I've done to my PLEXI. But this is probably info most of you already know about. And these are changes discussed in this thread. I removed C1 on the riser board; more highs. With Bright Switch off, not enough highs. With Bright Switch engaged, too much high. Removing C1 behind gain knob, highs are just right to my ears. I took the cap I removed from the riser board and installed it in C2 behind the gain knob. I couldn't hear any difference so I removed it. I removed C7 because I read in a different post that that could increase gain. Couldn't hear any difference. Put it back in. Installed a 22uf polarized cap in C13; def made a thicker tone and a bit more gain, but created too much low mids that kinda overwhelmed the tone so I took that back out and tried a 2.2uf polarized cap. To my ears, that sounded the same as the 22uf so I removed that and left that spot empty. In C3 I've tried .0015 and .001 to get rid of the "boominess". I went with .001. Definitely tighter and works for me. My Plexi sounds a little better after these tweaks but I'd still like to get a bit more gain somehow. I've read a post about removing R7 to get more gain, but my pcb does NOT have an R7. So, after all is said and done, the only tonal difference is I'm happier with the treble response and the low end is a bit tighter.

 

[SacredGroove]

Everyone has been very helpful to me so I'd like to share my tweaks I've done to my PLEXI. But this is probably info most of you already know about. And these are changes discussed in this thread. I removed C1 on the riser board; more highs. With Bright Switch off, not enough highs. With Bright Switch engaged, too much high. Removing C1 behind gain knob, highs are just right to my ears. I took the cap I removed from the riser board and installed it in C2 behind the gain knob. I couldn't hear any difference so I removed it. I removed C7 because I read in a different post that that could increase gain. Couldn't hear any difference. Put it back in. Installed a 22uf polarized cap in C13; def made a thicker tone and a bit more gain, but created too much low mids that kinda overwhelmed the tone so I took that back out and tried a 2.2uf polarized cap. To my ears, that sounded the same as the 22uf so I removed that and left that spot empty. In C3 I've tried .0015 and .001 to get rid of the "boominess". I went with .001. Definitely tighter and works for me. My Plexi sounds a little better after these tweaks but I'd still like to get a bit more gain somehow. I've read a post about removing R7 to get more gain, but my pcb does NOT have an R7. So, after all is said and done, the only tonal difference is I'm happier with the treble response and the low end is a bit tighter.

Try the 22uF at C7, and leave C13 empty. The 22uF might not be so overwhelming to you there. 2.2uF is a good choice too at C13.

R7 should be right above the bright switch.

C2 isn't active until the Bright switch is engaged. If you used the one from the tube board it may be a different value than what should be in C2 to make a difference.

Removing C7 will decrease gain.

Your SL+ sounds like an easy fix, if you hadn't done it already. You'll just need some wire to reconnect wherever the traces are disconnected. If you need help, I'll be around tomorrow. Today is an early Christmas.

 

[Deisel401]

Thanks bro. That info def helped. I "jumpered" the contacts on the traces I screwed up a few days ago. But I also broke off the MIDDLE pot because I was clumsy when flipping the board over. Can't find a replacement locally so that's gonna have to wait till I can find the right part online. And thats the SL+ by the way. Gonna try your ideas on the PLEXI and hopefully that'll get me what I want so I can just leave it alone before I mess up that one too. Thanks again. BTW, hope things are getting better for you and Happy Holidays. As soon as you are back in action I'd like to send my modules to you just for the basic upgrades and maybe fix my SL+.