Although setting up OX with a separate amplifier head and speaker cabinet is relatively straight forward, making the required connections with an all-in-one combo amp (amp and speaker in the same cabinet) can be a little more confusing at first. This guide will help you through the steps required to set up OX with a combo amp.
Locating the Speaker Output
The first step is locating the combo amp's internal connection between its speaker output and its speaker. The specific location and style of this connection will vary from amp to amp, but it is usually found on either the back or bottom panel of the amp.
If the connection is found on the back panel (as it is, for example, on a Fender '65 Princeton Reverb), it will be visible by looking at the rear of the combo amp without having to remove anything, as shown below.
'65 Princeton Reverb back panel connections with main speaker output highlighted
If you don't see a main speaker output on the exposed back panel, you will need to remove the back panel cover to access the speaker output. One common example of a combo amp that needs to have its back panel cover removed is the Fender Hot Rod Deluxe. Once the panel is removed, you will see the speaker output on the bottom panel, as shown below.
Hot Rod Deluxe bottom panel connections with main speaker output highlighted
Note that some combo amps have a hard-wired speaker connection and do not have a speaker output jack at all (for example, a vintage 1972 Fender Vibro Champ). For an amp of this type, you'll need to have custom wiring work done by a qualified technician.
Additionally, be sure not to use any Preamp output or Send / Return jacks for speaker connections!
Connecting to OX
Once you have located the speaker output on your combo amp, the next step is to remove the speaker cable that is plugged into it (highlighted in both of the above images). Using a separate speaker cable, connect from the high-power speaker output on the combo amp to the red "FROM AMPLIFIER" jack on OX's rear panel.
Connecting to Speaker
The final step is to connect the combo amp's internal speaker to the "TO SPEAKER" jack on OX's rear panel. Since the cable connected to the combo amp's speaker is typically very short, you will likely need a speaker extension cable to reach OX's "TO SPEAKER" jack. Here is one example of the type of extension cable you could use.
Connect this speaker extension cable to the "TO SPEAKER" jack on OX's back panel, set OX's impedance selector to the appropriate value, then power up your amp and OX and start playing!
Combo Amp Wiring Diagram
OX high-power connections with a combo amp
(speaker and amp in the same cabinet)
Combo Amp Wiring Notes
When connecting a combo amp to OX, the amp's internal speaker cable might not be long enough to reach OX. The methods below can be used to extend the length of the internal speaker cable so it can reach OX's "TO SPEAKER" output jack.
- Speaker cable extension – A speaker extension cable has a 1⁄4” female jack at one end (which connects to the internal speaker's 1⁄4” plug), and a 1⁄4” male plug at the other end (which connects to OX's "TO SPEAKER" output jack).
- Female/Female coupler plus speaker cable – The barrel coupler has a 1⁄4” female jack at both ends. In this case, plug the internal speaker into one side of the coupler, and an additional 1⁄4” speaker cable (male/male) into the other side of the coupler. Plug the other end of the additional speaker cable into OX's "TO SPEAKER" output jack.
- No speaker jacks or plugs? – Speakers in older combo amps might be wired directly to the internal amplifier, without removable connectors. In this case, a qualified amp technician can modify the amp to accommodate 1⁄4” connections.