TFR Electronics

Sundown Artist 100 Mods

 As I mention in the section on Pignose G40V mods both these amps were designed by the well-respected Dennis Kager.  The Pignose G40 and G60 being very similiar to the distortion channel from this amp with the bells and whistles stripped out.  Among it's unique features The Sundown Artist is actually the first "true" channel switching guitar amp.  Other designs at the time layered/added additonal gain stages while this amp switches to a different signal path between the 1st gain stage and the PI.  Dennis Kager apparently even got a patent on it.  Designed for the times however the distortion channel on this amp is very 80's sounding to me.  I wanted to tone it down a bit which is what my mods aim for.  I wouldn't have changed the amp so much but I got it for $100 in rough shape; no tubes, no speaker, and some gnarly water damage + mold on the cabinet.  I cleaned it up but I plan to build an all wood cabinet at some point.

 

Jan 2022 Update: I added voltages to the schematic, moved the clean channel tonestack to after V1a,

and added a voltage divider to cut signal between V3b and V4a on the distortion channel. I also changed the speaker to an Eminence tonkerlite to save a couple pounds.

 

Mar 2021 Update:  Corrected the OEM schematic based on some differences I noticed in my amp. I also changed my mind on some of the mods I tried out and have put the amp back towards stock/standard Bassman/JCM800 ish type values.  Schematic and list below are updated.

 

 


 

Here’s a list of modifications I’ve settled on for my Sundown.

  1. V3a: Shared Input Stage (both channels)
    1. None
  2. V3b: "Cold Clipper"
    1. Changed 1nF gain pot bright cap to 120pF. (more treble at low volumes)
    2. Changed Output coupling cap from 20nF to 10nF (reduce bass a bit, high pass with next resistors)
    3. Added a 470k resistor with a 120pF bypass cap above V4a's 470k Grid leak resistor to create a voltage divieder and cut down on gain.
  3. V4a/b: DC Coupled Cathode Follower
    1. None
  4. Distortion Channel Tone Stack & Master Volume:
    1. Removed 1nF MV bypass cap. (brightens things up alot)
    2. Changed 1nF treble cap to 390pf.
  5. V1a: Clean channel 2nd stage
    1. Changed 270pF bright cap on gain pot to 120pF.
    2. Moved tonestack to after V1a instead of between V3a and V1a.
  6. V1b: Reverb RecoveryNone
    1. None
  7. V2a/b: Reverb Driver
    1. None
  8. V5: Phase Inverter
    1. None
  9. Speaker:
    1. Eminence tonkerlite