Linking Channels on Marshall and VOX AC-30 Amplifiers

Marshall --

All of the reissue Marshall amplifiers (JTM45, JTM45 Offset, 1959SLP, 1987X, 1962) can easily be identified by their appearance and the four inputs located on the right front panel. What exactly is the purpose of these four inputs? You will notice that the upper and lower left inputs are labeled “1”. The upper and lower right inputs are labeled “2”.  The “1” inputs are the high sensitivity (higher gain and somewhat brighter) inputs. The top “1” input is the higher gain of the two “1” inputs (the preferred input of most players). The “2” inputs are the low sensitivity (lower gain than the “1” inputs and somewhat bassier). The top  “2” input is a higher gain input than the lower “2” input. Each of the four inputs has its own distinct sound.

While any of these inputs can be used on their own, linking them (with a short, shielded instrument cable), will blend the high and low sensitivity channels together. The most common channel linking scenario is as follows:

Plug your guitar cable into the top “1” input.

Adjust the two channel volumes to the desired level and tone combination.

  Essentially, this allows the player to blend the brighter channel (“1”) with the bass channel (“2”) to their liking. Although, the stated example is the most common way to link channels, there are not any set rules (it really comes down to the player’s preference). 

VOX AC-30 --

The VOX AC-30 has a total of six inputs (2 per channel). Each channel (Brilliant, Normal and Vib-Trem) has a high sensitivity and a low sensitivity input.  Most players connect their instrument to the high sensitivity input (when the AC-30 is facing you, the high sensitivity inputs are the furthest from you) on the Brilliant channel. Any of the AC-30’s channels can be linked together (In fact, all three can be linked together if desired). The AC-30’s channels can be linked as follows:

  Connect your guitar cable to the high sensitivity input of the channel of your choice.

  Using a short, shielded instrument cable, connect the low sensitivity input (of the same channel that your guitar is connected to), to the high sensitivity input of the channel that you would like to link with.  (ie: Plug your guitar into the Brilliant channel high sensitivity input.  Connect a short, shielded instrument cable from the Brilliant channel low sensitivity input, to the Vib-Trem input. Voila! You have linked the Brilliant channel and the Vib-Trem channels.)

* Tip- When linking the AC-30’s channels, a cool phase cancelled sound will occur when both linked channels volume controls are set at the half way mark.