Hey everyone! Longtime lurker here. Seems like a very friendly and extremely informative site. PLEASE, any and everyone complement...give me some responses here. Even if others more qualified have responded , I would like to hear YOUR two cents. Here's my question(s). I apologize for the length.
I am EXTREMELY interested in buying a XXX2 or JSX. I have played a triple xxx mk1 quite a bit. I love the tone of the two high gain channels. It is my understanding that it is a few very minor mods to have the crunch and lead channel of the jsx match the xxx. I have heard that the jsx, while being in the same realm on the lead channel, is a bit TOO refined, polished, smooth in comparison to the original xxx. I hear there is less low end on tap, and less grunt in the lower mids, with more of the "cocked wah" frequencies seemingly being more prominent. I am very interested in the aesthetic and versatility of adjustable resonance and presence controls of the JSX.
1. Can someone tell me... DEFINITELY...the differences in the JSX and original XXX? Component wise? What i should change? 2. Assuming I'm able to do that, any suggestions to maybe remove (or be able to dial out) the cocked wah frequencies that are STILL present post modification? 3. Any tips to get a tiny bit more low end/ low mid girth ala an OG 5150? I absolutely love the XXX, but if I can get it in a more attractive (to my peculiar eyes lol), versatile package via the JSX, and a little thicker without sacrificing clarity , all the better.
Here is the inspiration for my post, and why Im hesitant to dive in. A guy on another forum did the mods in the second part of the post, in an attempt to get his jsx to xxx values/ tonality, and said it absolutely DESTROYED the tone. Said it completely neutered if to the point of being virtually unusable in his opinion. ANY help you offer is greatly appreciated. I am NOT up to the challenge of reading an amp schematic, and sure as heck not modding one. Thank you all
Here are the posts:
#1
"The JSX is a slightly modified triple X design wise. There is only a few parts and values that are different sound wise. The JSX is different from the XXX in that the JSX cuts more low mids.
Between the first 2 triodes is where the differences are. In the XXX there is a 220K inline resistor with a switchable 2.2n cap in parallel followed by a 220K reference to ground.
On the JSX there is instead a 2.2n cap in series with a 2.2M resistor, and this in in parallel with another 2.2n cap. This is part of the JSX FAT switch. When the fat switch is on, it bypasses the 2.2M resistor so that both 2.2n caps are in parallel. This in the JSX cuts bass all the way from about 1.0Khz with the Fat switch off, to 700hz with the fat switch on.
The plate resistors have differening values in a few places as well which lead to more distortion and less headroom in that gain stage.
There is also a pot value difference on the crunch channel of the JSX its a 50k pot versus the 1M pot on the XXX."
#2
"I actually just played a jsx and xxx side by side at a music store today. The xxx is a little more compressed cause of the extra gain, but compressed in a good way. Kinda has a fuller sound. The ultra channel on the jsx is close to the crunch on the xxx but still not quit the same. I personally like both the gain channels on the xxx but then again I used to own one so I am pretty familiar with how to tweak it. A while back I found some info about modding the jsx to xxx. Below is the copy and paste:
Peavey jsx/xxx/ultra differences 2
the differences between the JSX and XXX/Ultra series are small, but meaningful.
JSX R6/56k
XXX R6/220k
(JSX drops way more gain to ground)
JSX C35/10nF
XXX C35/22nF
(JSX boosts frequencies above 10k, XXX boosts lower)
I also found this about the tone stack:
FYI to turn the JSX tone stack into an XXX tone stack:
Crunch
remove R16 R106 C67
Ultra
remove R107
switch R44 240k ->220k "