Seimens tube amp mod

The channel switching mod to the old Siemens 6 S Ela 2427c installed. The optocouplers circuit board found a place.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c guts

Another view, on the left is the input jack, switch for channels and a remote jack for channels.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c guts

I removed the guts from the pilot lamp and installed the channel indicating leds in it. We can see the two new pots installed, a clean volume pot and a mids pot.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c front

Another view where you can see the new wiring to the old pilot lamp now acting as channel indicator.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c top


Laney Klipp100 modified

Laney Klipp100 amplifier after modification. The master volume pot was a mod already made. It now holds a switch for channel selection, a 6,3mm jack for remote channel switching and indicating leds for each channel.

Laney Klipp100 front panel
Laney klipp100 front

Back of the amplifier. Bias pot, bias measuring points , effects loop with send level pot and a gain switch.

Laney Klipp100 back panel
Laney Klipp100 back

Here’s an image with the channel switching circuit board installed using optocouplers .

Laney Klipp100 channel switching
Laney channel switching

A closer look at the gain switch mod and the effects loop.

Laney Klipp100 Gain switch
Laney gain switch

Here’s an image of the bias pot with measuring outlets and the transformer for the channel switching circuit,

Laney Klipp100 channel switching transformer
Laney klipp100 power


Laney Klipp100 channel mod.

Adding some optocouplers and making the klipp and the normal input selectable. Using either the switch on the front panel or remotable with a foot switch,

Laney Klipp100 channel switching
New circuit board with optocouplers added

The front panel of the amp with the new hardware added. switching with the remote input.

Channel switching


Boss DS-1 OD mod

Turning the Boss DS-1 into something more of an overdrive, giving it a more dynamic response. Changes are made to the transistor booster stage, OP-amp gain stage and the overall frequency respons. Check Thomas Ziden as he gives an somewhat unusual pedal demo.


Boss bypass mod

Got a dead Boss DS-1 on the bench for repair and modification. I just had to replace the fried opamp and it was up and running. I was also told to mod the pedal in anyway I liked. Ever since I made the T-rex Mudhoney 2:nd stage mod the idea has been there to try something similar on a Boss or Ibanez pedal. So here it is on a Boss DS-1 pedal, the feature to choose a latching or momentary bypass.

Boss DS-1 latching or momentary bypass.

/Krister Östman

T-Rex mudhoney mod completed

I found the time to get my mod for the Mudhoney done. First a gut shot of the pedal in its original state, nice and clean.

T-Rex Mudhoney guts

First thing was to remove the HEF4013 in order to take control of the bypass circuitry.

T-rex Mudhoney bypass circuit

The new circuit board that will control the fet bypass circuitry and the boost.

Custom board for 2:nd stage mod

Here’s a caption where I’ve mounted the footswitches for bypass and boost, two toggle switches for the momentary/latching option and a third one for the clipping diodes.

Wiring up the T-Rex Mudhoney 2:nd stage mod

The clipping diodes a pair of AA144 germanium.

AA144 diodes

Time to do some wiring then. The effects circuit board has had the boost switch removed, the original clipping diodes lifted from the ground plane on the circuit board. The new pot for tuning the gain is also in place. Here’s a caption of it wired up.

The T-Rex Mudhoney 2:nd stage mod

And a short video in an earlier stage where I’m testing the switching options.

T-rex Mudhoney 2:nd stage mod

And a picture of the pedal when it’s all done.

The T-Rex Mudhoney 2:nd stage mod

Well what can you say, that turned out somewhat different compared to the original.

/Krister Östman

New T-Rex Mudhoney mod

Working on new mod for the T-Rex Mudhoney pedal. The plan is to use two stomp switches as in the mod I done before. One controlling the Boost on/off and the other one for bypass. What differs is the option to choose between latching and momentary action for the stomp switches.

Here’s the circuit board to be fitted.

/Krister Östman