The Morley ABC Pro Selector is an amp selector pedal: it takes one input, your guitar or the end of your pedalboard, and routes it to three outputs labeled A, B and C. You can run one amp at a time, or any combination of the three at once, which makes it a tool for players who build a live sound from multiple amps or who want a spare output for the front of house board1.
It is a Pro version of the original Morley ABC Switcher, announced in January 2019 alongside the Morley ABY Pro, and it carries a set of upgrades aimed at the problems that come with running several amps: hum from ground loops, phasing between amps, and signal bleed when switching2.
What it does and how you control it
The core function is routing. Morley describes it as "the ultimate amp selector. Route 1 input into 3 outputs. Choose A, B, or C individually or in any combo"3. In practice that means three footswitches, one per output, so you can bring amps in and out of the mix while you play. Morley also points to a live sound use: with three outputs available, one can feed an amp while another goes to the board1.
Around the switching sit two problem solving controls:
| Control | What it does |
|---|---|
| Ground lift switch | Disconnects the ground between connected gear to break ground loop hum4 |
| High frequency filter | Activates automatically when ground lift is engaged, to eliminate unwanted frequencies3 |
| Reverse polarity switch | Flips signal polarity to prevent phasing issues between amps3 |
The phasing issue is worth a word for anyone new to multi amp rigs. When two amps receive the same signal, slight differences in how each one reproduces it can make the combined sound cancel out in places, thinning your tone. The reverse polarity switch inverts one side of the signal, which is the standard fix3.
Isolation and switching
Inside, the ABC Pro uses a custom built Morley 1:1 isolation transformer, which Morley says delivers "absolute transparency and level output"3. In Morley's own buying guide explanation, the transformers in the ABC Pro "act like a Buffer in preserving tone"5. Isolation also means the connected amps are electrically separated from each other, which is part of what keeps ground loop noise down when several amps share a source.
Switching is done by relays rather than mechanical switch contacts. Morley says the relay switching is there "to minimize switch noise and prevent bleed"3, so an amp that is switched out stays silent rather than leaking quietly in the background.
Power and build
The pedal runs on one 9V battery behind a quick clip battery door, or on an optional Morley 9V adapter, and Morley says it is compatible with most 9V adapters3. The press release highlighted the easy access battery door as one of the Pro upgrades over the original2.
The enclosure is rugged cold rolled steel, and the Pro version sits higher than the original ABC Switcher so the switches are easier to reach on a crowded board3. It measures 6.63 x 4.38 x 2.75 inches and carries a one year warranty3.
Do not use the ABC Pro on powered speaker lines. Morley's warning is blunt: "DO NOT use on powered speaker lines. You WILL damage your amp, speakers or both!"3. It belongs between your instrument and your amps' inputs, never between a head and its speaker cabinets.
Where it came from
The ABC Pro is based on the original Morley ABC Switcher3. Morley announced the Pro versions of its ABY and ABC switchers in January 2019, around NAMM, with Bill Wenzloff describing them as "specifically designed to be used as selectors for multiple amps"2. Premier Guitar reported the launch the same month, noting the new versions were built off the original ABY and ABC switchers6, and guitar.com listed the ABC Pro Selector at a $279 retail price4.
The new features over the original, per Morley, are the higher enclosure, the custom 1:1 isolation transformer, relay switching, the reverse polarity switch and the ground lift switch3.
The ABC Pro belongs to the wider family of switching pedals, and Morley describes it as "the ultimate amp selector," routing one input into three outputs3. Its rugged cold-rolled steel enclosure sits higher than a standard box for easier access to the switches, at 6.63 by 4.38 by 2.75 inches, and it carries a one-year warranty3. At $279, it is positioned as Morley's premium amp selector4.
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Questions
Can the Morley ABC Pro Selector run two or three amps at once?
Yes. It routes one input into three outputs, and you can choose A, B or C individually or in any combination, so two or all three amps can run at the same time. Morley also notes this is useful in live sound, since an additional output can be sent to the front of house board.
What does the ground lift switch do on the Morley ABC Pro?
The ground lift switch disconnects the ground connection between the connected amps, which is a common fix for the hum caused by ground loops when several amps share one signal source. On the ABC Pro, engaging ground lift also activates a high frequency filter that Morley says eliminates unwanted frequencies.
What does the reverse polarity switch do?
The reverse polarity switch flips the signal's polarity to prevent phasing issues. When two or more amps are running at once, small timing differences between them can cause the combined sound to thin out, and reversing polarity on one output is the standard way to address it.
Does the Morley ABC Pro Selector run on a battery?
Yes. It runs on one 9V battery behind a quick clip battery door, or on an optional Morley 9V adapter. Morley says it is compatible with most 9V adapters, so a standard pedalboard power supply works too.
Can the Morley ABC Pro be used on speaker lines?
No. Morley's warning is explicit: do not use it on powered speaker lines, because doing so will damage your amp, your speakers, or both. It is an instrument level line selector, placed between your guitar and your amps' inputs, not between an amp head and its speakers.
How is the ABC Pro different from the original Morley ABC Switcher?
The ABC Pro is based on the original Morley ABC Switcher but adds a taller cold rolled steel enclosure for easier access, a custom Morley 1:1 isolation transformer, relay switching to minimize switch noise and prevent bleed, a reverse polarity switch and a ground lift switch. It launched in January 2019 at a $279 retail price.
Sources (6)
- Gold Series ABC, Morley
- ABY PRO & ABC PRO PRESS RELEASE, Morley, 2019-01
- Gold Series ABC Pro Selector, Morley
- NAMM 2019: Morley introduces ABY, ABC Pro Selectors, guitar.com, 2019-01-14
- BUFFERS VS. TRUE BYPASS, Morley
- Morley Unveils the ABY Pro and ABC Pro Selectors, Premier Guitar, 2019-01-11
