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

/Krister

Tube amp channel switch

A new channel switching circuit board prepared for an old tube amp.

Tube amp channel switching
Tube amp channel switching

The plan is to fit it in this one.

Siemens Tube Amp
Siemens 6 S Ela 2427c

/Krister

SubZero TUBE-H5 repair

Got this one in for repair, would not make a sound.

SubZero TUBE-H5 repair
SubZero TUBE-H5

Sometimes it’s an easy fix, when opening the back I found the 12AX7 preamptube at the bottom of the chassie. Just put it back in place and it was ready o rock.

I opened it up and took a look at the circuit. Besides from the single 12AX7 preamptube and the EL84 power tube there’s two JRC4558 opamps on the circuit board, so what we got is a hybrid of solid state and tubes.

SubZero TUBE-H5 repair
SubZero TUBE-H5 circuit board

/Krister