XTC Mod Project Discussion

[SacredGroove]

Craig,

I just noticed something looking at your picture. R14 is 29k, not 43k. I looked at mine and it is the same. The pcb diagram shows R14 being 43k. Weird.

Scott

 

[khingpynn]

I've noticed oter dicrepancies aswell... namely the vlaue of C1.

For other ppl viewing this R14 is the resister to the left of the white circular sticker with the numer 12 on it. Right below the screw hole and the stamped charaters.

 

[SacredGroove]

I am going to change that R14 tonight and see what happens. I don't think I have 43k, but I do have 47k.

 

[Jaded Faith]

The PCB layouts here are from the initial release of the modules and many improvements have been made by Randall through the years. Anyone with a 2005 Silverface module will be able to tell you the new ones are much better in general.

I wouldn't use those as "spec" values to build towards. The changes were generally made in the name of progress.

Regarding R14 here, 43K is stock. 47K would be stock in a UXL and can work well here, I used it in my mods for a while but I really do prefer the 43K.

 

[khingpynn]

I'm interested to know the results from the 47 k and JF has me interested in the 43K... thansk for the input with this module guys.

 

[SacredGroove]

I'm interested to know the results from the 47 k and JF has me interested in the 43K... thansk for the input with this module guys.

I'll probably try this because the curiosity will eventually kill me. I really like the way it is, with the 29k. The 43k will take away some of the highs/clarity.

The pcb layout is more than likely outdated if both of us have 29k values. Now that I think about it, I may just "upgrade" the cap (C14), just so it feels like I've done something for the better good of my module...LOL.

 

[khingpynn]

I'm trying more C1 caps as well.

 

[Jaded Faith]

43K is a stock value for R14 and I am certain it's in 2008 and 2009 modules since I just did a few. I have seen some older ones with 33K and other lower values in the past. 47K is a little thinner sounding to me, 33K is more of a Marshall-y vibe to the mids (also depends on you cap value). 43K is a good voicing on this module and probably my favorite right now.

 

[SacredGroove]

43K is a stock value for R14 and I am certain it's in 2008 and 2009 modules since I just did a few. I have seen some older ones with 33K and other lower values in the past. 47K is a little thinner sounding to me, 33K is more of a Marshall-y vibe to the mids (also depends on you cap value). 43K is a good voicing on this module and probably my favorite right now.

:?

 

[Jaded Faith]

:?:

 

[khingpynn]

JF thanks for your input... you have done extensive work with many MTS mods... you are a great resoarce for this and other mod threads.

 

[Jaded Faith]

My pleasure guys, glad to help out. :wink:

In geek speak for you, the difference in those R14 resistors is a shift in the midrange level around 750Hz with all other things remaining constant. Going from 29K to 43K causes a dip of around -2db's if all tone knobs are set to noon.

 

[headown]

I just wanted to say that I love Rob?s new XTC mod !!!
It can sound a little like my new Einstein.
Great module !

 

[chop883]

Hey Guys, I thought I would get in on this one since the XTC is by far my favorite. I have my last "Chop's personal grail tone" now for sale on the forum because I have no MTS gear to stick it into! Anyway, for me, the XTC sounds like what the SL+ SHOULD sound like. It is just about perfection in my book. I play Gibson Les Pauls or LTD EC-400ATs through it with an MTS head (JJ 6L6s) into an MTS cab with V30s. My perception of the module and set up I was running was that my XTC was actually too bright. I like to run the treble up to get the sizzle, but without thinning out the sound too much. So my high frequency roll off circuit performed this function perfectly. ALso, opposite the "muddy" issues with mine is that is was voiced alot like a Marshall with very little low end. So I made a change to give it a little more bottom end. This is not the C3 cap change. Anyway, if you run the gain down to about 2 or 3, you now have a texas blues machine with a strat. Very versilte module

So, my point is writing on this thread was actually to share my sectret weapon. I mod amps, guitars, and modules constantly, but the best medicine for a muddy sound would be one of two things.

I am not a pedal guy and only use a total of 4, including my TU-2 tuner. But if you want to give a little boost to the treble to help get defined clarity, the Boss Blues Driver is you machine. I actually don't even use it as a "driver", i keep the gain low, but it is a great adjustable treble booster - no soldering iron required, and no risk of lifting the PCB pads on these lead free modules.

If you want to boost the mids, and get a slight increase in treble (or not), the Barber Direct Drive drives the mids like a mo' fo', but without getting honky like a TS-808. Plus, the Barber has trim pots on the PCB to finely tune "Prescence" and "Bass", in addition to the single tone control. This pedal, I can assure you, will cure a muddy Recto Module without ever turning on a soldering iron.

I love to modify things myself, but I relay so heavily on these two pedals as EQ tools (no so much for drive tools).

If you have an MTS system with a Recto or Ultra, the Barber Direct Drive could be your best friend. I never needed it with my XTC since it has abundant mids, but it will cure a muddy XTC too.

 

[Vince]

I am fairly new to this whole concept but I must say out of the Plexi, SL+ and XTC.... the XTC gives me everything the other modules do plus more!

The plus side of all this is that I have 2 modules I can send for mods! :lol:

I would love to see a whole forum dedicated to modding these ourselves. I am very handy with a soldering iron and have built several pedals but lack preamp circuit knowledge.

Anyway.... I hope this catches on!

 

[chop883]

The modules are certainly fun the modify, because you slide out of the chassis and have the PCB in your hand. How cool. I have been modifying amps for years, and I am accustomed to a 1+ hour tear down to pull 1-2 preamp boards out, etc just to get to a stinkin cap or resistor or whatever. These are much easier for preamp mods.

I salute the pro guys that do this for every day. Most of the preamp modules are ROHS compliant, which means they were built with lead free solder. Leaded solder normally melts around 600 degrees, however, lead free has a much higher melting point around 750. You have to transfer so much heat into the solder joint to depop the component, you sometimes break down the adhesive holding the pad in place, and lift the pad too (bad).

Enjoy.

 

[khingpynn]

chop 883 your post is very appreciated... thanks for sharing.
I'm still working on my XTC. I make a change and play it for a while.. make a change and play it for a while. I'm not in it to make $$$ and I'm being real picky making sure i wear the new shoes for a while.
Admittedly I've not worked on it for a few weeks now as I'm very busy with Sonic Diplomat and the Guitar Cable Face Off.
The XTC is a allready well concieved stcok module and is fun to tweak... it has so much potential

 

[khingpynn]

I'm selling trading my XTC. Great mod but not a fit for me.

It's currently modded as per page 3 in this thread. Please read view my post with thew photo of the mod.

I will include the origional parts or I can return to origional cct your choice.

make me an offer.

 

[Daryl]

I'm disappointed that this thread died off. I want to learn more about modding my own modules. I've been amassing information for a while now and looking to decode the circuits. I know that the common PCBs make it a lot easier to map out the signal path, gain stages, and tone stack. I have an XTC modded per page #3 of this thread. I put a 43K resistor in R14 and I have a .001uf "Orange Drop" in C1. Very tight pick attack and nice even note separation with the gain up. It ***** slaps a stock XTC. There are many more mysteries to me about the tone stack and gain stages. If anyone out there cares to generously share their knowledge and make it easier for everyone, please jump in. I think the Pro-modders are doing a fabulous job and they aren't going to be replaced by the DIY crowd. Just the work you guys do to get a module's voicing and gain balanced is a testament to your craftsmanship. Much respect.