PF-20T and PF-50T Bass Guitar Amplifiers Owner’s Manual
PF-20T / PF-50T Bass Guitar Amplifier IMPORTANT SAFETY INSTRUCTIONS 1. Read these instructions. 2. Keep these instructions. 3. Heed all warnings. 4. Follow all instructions. 5. Do not use this apparatus near water. 6. Clean only with a dry cloth. 7. Do not block any ventilation openings. Install in accordance with the manufacturer’s instructions. 8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat. 9.
PF-20T / PF-50T Bass Guitar Amplifier NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
PF-20T / PF-50T Bass Guitar Amplifier TABLE OF CONTENTS Important Safety Instructions...............................................2-3 Table Of Contents..................................................................4 Introduction...........................................................................4 PortaFlex Series Features.......................................................5 PortaFlex Series Front Panel Features.....................................6 PortaFlex Series Rear Panel Features........
PF-20T / PF-50T Bass Guitar Amplifier PortaFlex PF-20T / PF-50T Features: • RMS power output: 20W @ 4 or 8 ohms [PF-20T] 50W @ 4 or 8 ohms [PF-50T] • Preamp: All-tube 2 x 12AX7 • Power amp: All-tube 2 x 6V6 [PF-20T] All-tube 1 x 12AU7, 2 x 6L6 [PF-50T] • 0 dB and -15 dB inputs [PF-50T] • Tone controls: Bass, Mid, Treble • Mid-tone control: 5-position [PF-50T] • Ultra Hi/Lo boosts [PF-50T] • Input gain control • Preamp balanced line out • Pre/Post EQ • Ground lift • Transformer balanced li
PF-20T / PF-50T Bass Guitar Amplifier PortaFlex Series Front Panel Features 5 1 1. 2 3 4 6 PF-20T INPUT: The signal output from an instrument (active or passive) may be connected to this 1/4" input by means of a shielded instrument cable. 7 –15 dB INPUT: The signal output from an active instrument may be connected to this 1/4" input by means of a shielded instrument cable. [PF-50T] 3. GAIN: This control adjusts the input level of signal reaching the preamp. 4.
PF-20T / PF-50T Bass Guitar Amplifier PortaFlex Series Rear Panel Features 21 / 11 12 13 14 11. POWER SWITCH: Use this switch to turn the overall system power on or off. Press the top of the switch to turn on the power. The power switch should be engaged prior to the standby switch (as mentioned below, #12). 12. STANDBY SWITCH: Use this switch to turn the standby power on or off. Press the top of the switch to disengage the standby circuit [ON position].
PF-20T / PF-50T Bass Guitar Amplifier PortaFlex Series Rear Panel Features Continued... 21. SPEAKER OUTPUT: This mono 1/4" TS output jack supplies speaker-level power to the speaker cabinet. The rated power output is 20 watts rms [PF-20T] or 50 watts rms [PF-50T] into 4 or 8 ohms. 21 Make sure the total speaker impedance load is 4 ohms or greater. For example, you could connect: 2 16 ohm speakers in parallel = 8 ohms 2 8 ohm speakers in parallel = 4 ohms 20 20.
PF-20T / PF-50T Bass Guitar Amplifier Some Suggested Settings JAZZ: IN FUNK: IN The setting of the Gain control depends on your particular instrument. The Volume should be set to produce the appropriate output.
PF-20T / PF-50T Bass Guitar Amplifier Favorite Settings 10
PF-20T / PF-50T Bass Guitar Amplifier Changing the Tubes Tubes wear out in direct proportion to how often and how hard you play your amplifier. Power tubes should be checked at least once a year – more frequently if you use the amplifier nearly every day. When power tubes wear out, the amplifier will begin to grow weak, lack punch, fade up and down, or lose highs and lows. Power tubes work together in a push/pull configuration and should be replaced at the same time with matched or balanced tubes.
PF-20T / PF-50T Bass Guitar Amplifier Setting Tube Bias Turn the power on and allow the unit to sit in ‘Standby’ for 3-5 minutes (after following all normal setup requirements). Next, take the unit out of ‘Standby’ and do a quick check of the Bias LEDs. One LED should be lit green and the other LED off. If not, turn the Bias control until the LED is lit green. If this seems impossible, please refer to the chart on the next page for possible fault conditions.
PF-20T / PF-50T Bass Guitar Amplifier PF-20T TECHNICAL SPECIFICATIONS Preamp Power Amp All-tube 2 x 12AX7 All-tube 2 x 6V6 Output Power Rating 20 watts @ 8 ohms, 10% THD 20 watts @ 4 ohms, 10% THD Signal to Noise Ratio 60 dB (20 Hz–20 kHz, unweighted) Maximum Gain Input: 54 dB Tone Controls Bass: +8/–12 dB @ 50 Hz Midrange: +5/–15 dB @ 550 Hz Treble: +13/–20 dB @ 4 kHz Power Requirements 120 VAC, 60 Hz, 50W 100 VAC, 50-60 Hz, 50W 220-240 VAC, 50-60 Hz, 50W Size
PF-20T / PF-50T Bass Guitar Amplifier PF-50T TECHNICAL SPECIFICATIONS Preamp All-tube 2 x 12AX7 Power Amp All-tube 1 x 12AU7, 2 x 6L6 Output Power Rating 50 watts @ 8 ohms, 10% THD 50 watts @ 4 ohms, 10% THD Signal to Noise Ratio 60 dB (20 Hz–20 kHz, unweighted) Maximum Gain Input: 66 dB Tone Controls Bass: +10/–10 dB @ 60 Hz Midrange: +5/–20 dB @ 200 Hz, 400 Hz, 800 Hz +5/–15 dB @ 1.
PF-20T / PF-50T Bass Guitar Amplifier Service Information If you are having a problem with your PF-series amp, you can go to our website (www.ampeg.com) and click on Support for service information, or call Technical Support at 1-800-898-3211 Monday-Friday during normal business hours, Pacific Time, to receive assistance. If you are outside of the U.S., contact your local distributor for technical support and service.
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