About This Amp

The Ampeg Portaflex PF-800 is an 800-watt Class D bass head with classic Ampeg tone in a portable package. Its flip-top design allows it to be stored inside compatible Portaflex cabinets for easy transport.

No Sound? Check These First

Basic Connections

  • Is the power light on?
  • Is the MUTE switch turned off? (MUTE button should not be illuminated)
  • Is your instrument cable securely connected to the INPUT?
  • Is your speaker cable (not instrument cable) properly connected between the amp head and cabinet?
  • Are the MASTER and GAIN knobs turned up?
  • Check if the -15dB input pad is engaged when it shouldn't be

Speaker Connections

  • Make sure you're using a proper SPEAKER cable (not instrument cable)
  • Verify cabinet is connected to correct SPEAKER OUTPUT jack based on impedance
  • For multiple cabinets, ensure proper impedance matching:
    • Two 8-ohm cabinets = use 4-ohm output
    • Single 8-ohm cabinet = use 8-ohm output
    • Single 4-ohm cabinet = use 4-ohm output

Still No Sound?

  • Try a different instrument cable
  • Check if headphones are plugged in (this mutes speaker outputs)
  • Verify your bass's volume is turned up
  • Check if the PROTECTION light is illuminated (indicates a problem)

Sound Problems

Weak or Thin Sound

  • Check the 5-band EQ settings (especially BASS and ULTRA LO)
  • Make sure the -15dB pad isn't engaged if you need more gain
  • Verify ULTRA HI and ULTRA LO switches for your preference
  • Check if COMPRESSION is set too high (reducing dynamics)
  • For active basses, check your instrument's battery

Distorted or Fuzzy (When Not Wanted)

  • Reduce INPUT GAIN (watch the peak/clip light)
  • Turn down MASTER if the amp is clipping
  • For active basses with hot output, try engaging the -15dB pad
  • Check if FX loop connections are causing issues
  • If using pedals, bypass them to isolate the problem

Noise, Humming or Buzzing

  • Try a different power outlet
  • Move away from lighting dimmers and electronic equipment
  • Check all cables for damage
  • See if noise changes when touching the strings (could be grounding issue)
  • Try engaging the GROUND LIFT switch on the DI output

Portaflex Cabinet Issues

Weak Sound from Cabinet

  • Check speaker cable connections
  • Verify proper impedance matching
  • Make sure cabinet is properly closed (poor seal affects bass response)
  • Check that all speakers in the cabinet are working

Rattle or Buzz from Cabinet

  • Check for loose hardware on cabinet (handles, corners, feet)
  • Ensure head unit is securely mounted to cabinet
  • Check that flip-top mechanism is fully latched
  • Verify nothing is touching the speakers

Flip-Top Mechanism Problems

  • Ensure latches are properly engaged
  • Check that the amp head is correctly positioned
  • Don't force the mechanism - align properly before closing

Special Features Issues

Compressor Not Working

  • Ensure COMPRESSION knob is turned up (clockwise)
  • Set appropriate INPUT GAIN (compression is gain-dependent)
  • Note: Compression is subtle by design

DI Output Problems

  • Check XLR cable connection
  • Try switching between PRE and POST EQ settings
  • Engage GROUND LIFT if experiencing hum
  • Verify receiving equipment is functioning (mixer, interface)

Headphone Issues

  • Check if headphones are fully plugged in
  • Ensure MASTER volume is turned up
  • Headphone output mimics speaker output - all EQ settings apply

Power Issues

Won't Turn On

  • Check power cable connection
  • Try a different power outlet
  • Verify power switch is fully engaged
  • Check fuse (on back panel)

Protection Light Comes On

  • Power off immediately
  • Check speaker connections for shorts
  • Verify correct speaker impedance matching
  • Ensure adequate ventilation
  • Let amp cool down if it's been running hot
  • Power on again after addressing potential issues

When to Get Professional Help

  • If the PROTECTION light comes on repeatedly
  • If it won't power on after checking the basics
  • If it makes unusual noises through the speaker
  • If there's burning smell or visible smoke
  • If you hear significant hiss or noise that won't go away

Portaflex PF-800 Settings Cheat Sheet

For Classic Ampeg Tone

  • INPUT GAIN: Set so peak light flashes occasionally on hardest notes
  • ULTRA LO: Engaged (pushed in)
  • ULTRA HI: Off (out position)
  • BASS: 1-2 o'clock
  • MIDRANGE: 10-11 o'clock
  • TREBLE: 12 o'clock
  • MASTER: To taste for volume
  • COMPRESSION: 9-10 o'clock for subtle control

For Modern Aggressive Tone

  • INPUT GAIN: 1-2 o'clock
  • ULTRA LO: Engaged (pushed in)
  • ULTRA HI: Engaged (pushed in)
  • BASS: 12 o'clock
  • MIDRANGE: 9-10 o'clock (scooped)
  • FREQUENCY: 800Hz
  • TREBLE: 2-3 o'clock
  • COMPRESSION: 12-2 o'clock
  • MASTER: To taste for volume

For Vintage Warm Tone

  • INPUT GAIN: 2-3 o'clock (push it a bit for warmth)
  • ULTRA LO: Off (out position)
  • ULTRA HI: Off (out position)
  • BASS: 2 o'clock
  • MIDRANGE: 1-2 o'clock
  • FREQUENCY: 400Hz
  • TREBLE: 10-11 o'clock
  • COMPRESSION: 2-3 o'clock
  • MASTER: To taste for volume

For Recording Direct

  • Connect XLR DI OUTPUT to recording interface
  • Try both PRE and POST positions based on preference
  • Engage GROUND LIFT if you hear hum
  • INPUT GAIN: Set carefully watching peak light
  • EQ: Set flat initially (all at 12 o'clock) and adjust to taste
  • COMPRESSION: Consider 12-3 o'clock for recording consistency

For Slap Technique

  • -15dB PAD: May need to engage for high-output basses
  • INPUT GAIN: 9-11 o'clock
  • ULTRA LO: Optional based on preference
  • ULTRA HI: Engaged (pushed in)
  • BASS: 12-1 o'clock
  • MIDRANGE: 9-10 o'clock
  • FREQUENCY: 800Hz-1kHz
  • TREBLE: 2-3 o'clock
  • COMPRESSION: 1-3 o'clock (more compression)
  • MASTER: Set for desired volume


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