Introduction
Welcome to the user manual for the Ampeg PF-500 500-watt Portaflex Bass Head. This compact and powerful bass amplifier head delivers 500W of power, offering the classic Ampeg tone in a highly portable design. It features precise tone controls and versatile input/output options for various applications.
Important Safety Information
Please read and understand all instructions before operating your PF-500 bass head. Keep these instructions for future reference.
- Power Source: Connect the unit only to the specified power supply voltage. Ensure the power cord is not pinched or walked on.
- Ventilation: Do not block any ventilation openings. Install in accordance with the manufacturer's instructions.
- Water and Moisture: Do not use this apparatus near water or expose it to dripping or splashing.
- Cleaning: Clean only with a dry cloth.
- Servicing: Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way.
Warning: To reduce the risk of fire or electric shock, do not expose this apparatus to rain or moisture.
Key Features
- Compact 500W Bass Amplifier Head
- Mid-tone Presets for versatile sound shaping
- Lo/Hi Boosts for enhanced low and high frequencies
- Built-in Compressor for dynamic control
- 3-band EQ for precise tonal adjustments
- Input Pad (-15dB) for active basses
- Mute function
- FX Loop (Send/Return)
- XLR Line Out (Pre/Post EQ, Ground Lift)
- Headphone Output
- Tuner Output
- Footswitch Input
Setup Guide
Unpacking
Carefully remove the PF-500 from its packaging. Retain the packaging for future transport or storage.
Connections
Follow these steps to connect your PF-500 bass head:
- Power Connection: Connect the supplied AC power cord to the PF-500's AC input and then to a grounded AC outlet. Ensure the power switch is in the OFF position before connecting.
- Speaker Connection: Connect the speaker output (Speakon or 1/4" jack) to your bass cabinet. The PF-500 supports a minimum load of 4 ohms. For optimal performance, use a cabinet rated for 500W or more.
- Instrument Input: Plug your bass guitar into the
Inputjack on the front panel. If using an active bass with high output, engage the-15dBpad switch. - Optional Connections:
- FX Loop: Connect external effects pedals to the
FX Loop SendandReturnjacks. - XLR Line Out: For direct connection to a mixing console or recording interface, use the
XLR Line Out. ThePre/Post EQswitch determines if the EQ affects the output signal. TheGND LIFTswitch can help eliminate hum. - Tuner Out: Connect an external tuner to the
Tuner Outjack. This output is always active. - Headphones: For silent practice, connect headphones to the
Headphonesjack. - Footswitch: Connect an optional footswitch to control Mute and FX Loop functions.
- FX Loop: Connect external effects pedals to the

Figure 1: Front Panel Controls and Inputs. This image displays the front panel of the Ampeg PF-500 bass head, showing the input jack, -15dB pad, mute switch, compression, gain, Ultra Lo, Ultra Hi, Bass, Midrange, Frequency, Treble, FX Mix, Volume controls, and headphone/auxiliary inputs.

Figure 2: Rear Panel Connections. This image shows the rear panel of the Ampeg PF-500 bass head, including the AC power input, power switch, cooling fan, speaker outputs (Speakon and 1/4"), XLR line out with pre/post EQ and ground lift switches, and the FX loop send/return jacks.
Operating Instructions
Powering On
After all connections are made, turn the Volume control to minimum. Flip the Power switch to the ON position. The power indicator will illuminate.
Basic Operation
- Gain Control: Adjust the
Gainknob to set the input level. ThePeakLED will flash briefly on loud notes. If it stays lit, reduce the gain or engage the-15dBpad. - EQ Section:
- Bass: Adjusts the low-frequency response.
- Midrange: Controls the mid-frequency response. Use the
Frequencyknob to select the center frequency for the Midrange control (200 Hz, 400 Hz, 800 Hz, 1.6 kHz, 3.2 kHz). - Treble: Adjusts the high-frequency response.
- Ultra Lo/Hi Boosts: Engage
Ultra Lofor a deep bass boost andUltra Hifor a crisp treble boost. - Compression: The
Compressionknob controls the amount of dynamic range reduction. Turn clockwise for more compression. TheThresholdLED indicates when compression is active. - FX Mix: If using the FX Loop, this knob blends the wet (effected) signal with the dry (unaffected) signal.
- Volume: Adjust the
Volumeknob to set the overall output level of the amplifier. - Mute: Press the
Mutebutton to silence the amplifier output without affecting the Tuner Out.
Optimizing Your Tone
Experiment with the EQ controls and Ultra Lo/Hi boosts to find your desired sound. The Midrange Frequency selector is crucial for shaping the character of your bass tone. Start with all EQ knobs at 12 o'clock (flat) and make small adjustments.
Maintenance
Cleaning
Disconnect the power cord before cleaning. Use a soft, dry cloth to wipe the exterior of the amplifier. Do not use liquid cleaners or solvents.
Storage
When not in use for extended periods, store the PF-500 in a dry, cool environment, away from direct sunlight and extreme temperatures.
Service
The PF-500 contains no user-serviceable parts. Refer all servicing to qualified Ampeg service personnel. Unauthorized modifications may void your warranty.
Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No Sound | Power off; Volume low; Mute engaged; Speaker cable disconnected; Faulty instrument cable. | Check power, increase volume, disengage mute, check speaker/instrument cables. |
| Low Output Volume | Gain too low; Speaker impedance mismatch; Faulty speaker. | Increase gain, ensure correct speaker impedance (min 4 ohms), test with another speaker. |
| Hum or Noise | Ground loop; Faulty cables; Nearby interference; Dirty power. | Engage GND LIFT on XLR out, try different cables, move away from electronic devices, use a power conditioner. |
| Overheating | Blocked ventilation; Incorrect speaker impedance. | Ensure clear ventilation, check speaker impedance. |
If the problem persists after attempting these solutions, please contact Ampeg customer support or an authorized service center.
Technical Specifications
| Feature | Detail |
|---|---|
| Model | PF-500 |
| Output Wattage | 500 Watts RMS at 4 ohms |
| Amplifier Type | Hybrid (Solid-state preamp, Class D power amp) |
| EQ | 3-band with 5-position Midrange Frequency selector |
| Controls | Gain, Bass, Midrange, Frequency, Treble, FX Mix, Volume, Compression |
| Inputs | 1/4" Instrument Input (-15dB pad), FX Return |
| Outputs | Speakon, 1/4" Speaker Out, XLR Line Out (Pre/Post EQ, Ground Lift), FX Send, Tuner Out, Headphone Out |
| Dimensions (H x W x D) | 36.83 x 20.32 x 45.72 cm (approx. 14.5 x 8 x 18 inches) |
| Weight | 5.9 kg (13 lbs) |
| Power Source | Corded Electric |
| Compatible Devices | Bass Guitar |
Note: Specifications are subject to change without notice.
Warranty and Support
For warranty information and technical support, please visit the official Ampeg website or contact your local authorized Ampeg dealer. Keep your proof of purchase for warranty claims.
Online Resources:
Ampeg Official Website: https://www.ampeg.com
Contact Support: Refer to the Ampeg website for regional contact information and service center locations.







