Fully functional. Needs Power Adapter (see below in Power Requirements)

SD Card Support: Slot accepts up to 2 GB SD card

(I have included this 2 GB card to make up for the missing power supply)

Line 6 JM4 Looper (also called JM-4 Looper) is a discontinued legacy guitar/bass/vocal looper pedal from Line 6, originally released around 2008–2009. It combines a full-featured looper with over 100 pro-recorded “Endless Jam” backing tracks and drum grooves, Line 6 amp modeling, effects, and multi-input recording capabilities in a rugged floor unit. It’s designed for practice, songwriting, live looping, and jamming, with hands-free footswitch control.

Physical Specs

• Dimensions: 12.5" (L) × 7.5" (W) × 3.25" (D)
• Weight: 4.1 lbs.
• Build: Rugged metal chassis with footswitches for stage/durable use.

Power Requirements

• Included Line 6 PX-2 power adapter only (9V AC, 2000 mA, 2.5 mm barrel connector).
• No battery power option.

Inputs and OutputsInputs:

• 1/4" instrument input (for guitar or bass)
• 1/4" auxiliary input
• XLR microphone input (balanced, no phantom power) with dedicated trim/gain knob
• 1/8" stereo CD/MP3 input

Outputs:

• 1/4" stereo line outputs (unbalanced dual-mono; signal appears on both left/right for amp or PA use)
• 1/4" mono guitar output (or combined with the stereo pair depending on setup)
• 1/8" stereo headphone output

Additional:

• SD card slot (on the unit for import/export)

Looper Features

• Dedicated footswitches: Record/Overdub, Play/Stop, Half Speed, Undo.
• Sound-on-sound overdubbing and layering (guitar, bass, keyboards, vocals).
• Quick-capture mode (hold Undo then Record).
• Integrated looper records from guitar input or mic/aux input (not simultaneously, but aux can be routed with either).
• Half-speed playback.
• Undo function for the last layer.
• Works standalone or layered over backing tracks.

Backing Tracks / Endless Jams

• 152 total pre-recorded tracks: 71 song loops + 81 drum grooves.
• Performed live by top LA/Nashville session players (real rhythm sections, not MIDI/robotic).
• Arranged by tempo and style (more than 10 genres).
• Can loop and overdub on top of them for practice or performance. line6.com

Presets, Amp Models, and Effects

• Presets:
• • 200+ artist-created presets
  • 150+ song-based presets
  • 36 user-programmable presets (Banks 01–09, A–D)
• Amp Models: 12 Line 6 amp models (Clean to Insane), with variations (Red/Green channels inspired by classic amps like Marshall, Fender, Vox, etc.).
• Guitar Effects: 7 Smart Control effects (Chorus/Flanger, Phaser, Tremolo, Reverb, Delay with tap tempo, Tape Echo with tap tempo, Sweep Echo with tap tempo).
• Tone Controls: Bass, Mid, Treble (plus Drive on amps).
• Mic/Aux Effects (independent): 3-band EQ, Compressor, Delay, Reverb.
• Built-in chromatic tuner.
• Master Volume knob; mic trim knob. sweetwater.com

Recording and Storage

• Internal Recording: Up to 24 minutes total CD-quality recording time (44.1 kHz); stores up to 100 individual jams/loops. premierguitar.com
• SD Card Support: Slot accepts up to 2 GB SD card (FAT16 formatted; SD card not included). Allows import/export of 16-bit mono 44.1 kHz .WAV files. Supports up to 6.5 hours of recorded jams. (Note: Early firmware required computer transfer for some functions; v2.0+ firmware improved direct SD browsing/editing.)
• Loops can be saved, exported to a computer for DAW use, or shared.

Additional Notes

• The JM4 shares many presets and tones with the older Line 6 Spider Jam amp.
• Firmware updates (up to v2.07 or later) added SD card enhancements and other refinements.
• It’s a compact all-in-one practice/performance tool rather than a simple delay-style looper like the DL4.

The unit is no longer in production, so new stock is rare