Hi guys, after being a Kemper owner and forum member for four and a half years I’ve finally got round to uploading my profiles of my modded Marshall amp.
A little background on the amp.
It’s a 100 watt Marshall 2203 JMP Super Lead Mark II made in 1980 that been quite heavily modified by Steve Dawson of Root 2 Amplification and formally R&D Design Engineer for Marshall between 2005 to 2014.He is the guy that designed amps such as the Vintage Modern, JTM45/100 reissue, Super100 Jimi Hendrix, JMP1W head and combo, 1962 Bluesbreaker combo reissue and the Astoria to name just a few.
The pre amp circuit has been modified to very closely resemble the Friedman BE-100 but has the negative feedback circuit modified to similar values as the Mesa Boogie Dual Rectifier, giving the amp quite a bit more modern thump and thickness in the bottom end.This negative feedback is also adjustable by a pot on the rear which softens or tightens the feel of the amp almost identical to how the definition control works on within the Kemper itself.
It has a resonance pot on the rear to dial in how much bass you want in the power amp.
It has an extra valve gain stage and second gain control pot on the rear that allows you to dial in how much gain you would like on the extra stage.The 4th gain stage is footswitchable via a relay.This pot also doubles up as a push pull to engage the “Fat” boost, which as you can guess increases the bass in the pre amp.
It has two post phase inverter master volumes on the front which can operator as a footswitchable solo boost or just a way to tame the amps volume while being able to crank the master volume to distort the phase invertor making it easier to get “power valve” saturation at manageable volumes.
It has a valve FX loop added with an effects return pot.
Finally it also has a push pull pot also on the rear (this is also the variable negative feedback pot) which when pulled out enables zener diode clipping, think the Friedman SAT Switch or some Jose Arrendondo or Cameron mods.When enabled, two 24 volt zener diodes clip the peak to peak signal going into the tone stack by 25%.This gives a more compressed feel, a little more distortion and hair without colouring the tone like an overdrive in the front would.It also has a high pass filter wired to it to keep the lows tight with the extra distortion and compression.
Although the profiles are fully tagged with as much info as I can fit, here is what the naming convention means anyway. JMP 2203 followed by:
3GS = 3 Gain Stages
4GS = 4 Gain Sages
TS9 = Boosted with a Ibanez TS9DX
Zener = Zener diode clipping enabled
Pre Amp = Pre Amp only, no power section, profiles from the FX Loop Send
L = Low Input was used
+ = Cranked Master Volume
The distorted profile settings were:
Presence =2
Bass = 8
Mids = 6
Treble = 6
Master Volume = 3
Gain 1 = 8
Gain 2 – 10
Variable Negative Feedback = 0 Tight
Resonance = 6
Clean profile settings were:
Low Input
Presence =7
Bass = 10
Mids = 6
Treble = 6
Master Volume = 3
Gain 1 = 2
Gain 2 – 10
Variable Negative Feedback = 0 Tight
Resonance = 8
The cab used was my Mesa Boogie Dual Rectifier horizontal 2X12 with V30’s, miced around 2” from the cap edge with a SM57 on the speaker and a MD421 on the other, both on axis, blended about 60/40 in favour of the SM57 with a low pass filter applied around 10kHZ on the distorted profiles only.
I’ve uploaded them all to the rig exchange just search for Liam Thompson and they’ll appear.
Hope you enjoy them!
Cheers.