3
Bi-color LED. Green indicates signal presence. Red indicates clipping distortion. To eliminate it, disengage the “gain up”
or take the tube into the “triode” mode (switch out).
4
Gain boost, gives just under 5dB boost in triode and about 9dB in pentode mode. For the Mk II, gain has 3 settings: Lo, Mid and Hi.
The Mid and Hi have the same gain as on the original 2di4.
5
Tube heater voltage indicator; it should come on with the power switch.
6
Triode/Pentode mode switch. Pentode mode has more gain (33 versus 24dB) and somewhat different tone character. Pressing this
switch
changes the biasing of the tube and therefore causes a loud “pop”. To eliminate it, please temporarily mute outputs by flipping the switch #10
to the right.
7 and 8
The low and high frequency boost level can be adjusted by these 2 trim-pots.
Use a mini slot (.098”/2.5mm Ø, .031”/0.8mm wide) or hex (.104”/2.64mm hex x .055”/1.4mm deep) screwdriver to adjust them.
The default settings are maximum: 4.5dB in triode, 9dB in pentode mode. 6dB/octave. Low boost uses a real inductor for a fat tone.
9
Output level. Does not affect tube gain or overload level, just determines how hard the output buffer, transformer, and ultimately the
load are driven. The 2di4 may drive your next unit (Compressor, EQ, Converter, Mixer) into clipping even though the red light doesn’t
indicate any distortion. In that case, reduce the output level. Its always better to start with lower output level and then increase it as much as
your audio chain allows, as distortion can occur at more than one point.
10
Attenuation/Mute switch. 12dB attenuation in mid position, muted in right.
11 and 12
Low and high frequency shelving boost starting at 300 or 500Hz, and 2kHz or 4kHz respectively. Mid position is flat. “Gain up”
switch will bypass this filter. This is a subtle tone control meant for a gentle boost, adding depth or presence to the signal.
It does not use a separate stage; rather, it utilizes the tube gain stage (only one in the signal chain).
20
(Mk II only). Aux input (mini stereo jack 3.5mm (1/8”)). Accepts an output from a phone, tablet, laptop or a music player. This will be
transferred to the headphone output to be mixed with the DI out using the output level knob. Adjust the background music level on your
phone and play along or practice. Use a shielded stereo cable with mini jacks on either side.
21
(Mk II only). Headphones out, mini stereo jack 3.5mm (1/8”). Min headphone impedance is 150Ω.
2di4’s REAR PANEL CONTROLS:
