Fosi Audio SK01 Headphone Amplifier Equalizer Preamp User Manual

June 15, 2024
Fosi Audio

Fosi Audio SK01 Headphone Amplifier Equalizer Preamp

Fosi-Audio-SK01-Headphone-Amplifier-Equalizer-Preamp-
product

Introduction

Thank you for purchasing the SK01 headphone amplifier. The SK01 is a high- power headphone amplifier with tone controls (treble, middle and bass), high and low gain settings, bypass mode, and loudness function. The tone-control feature allows you to customize the sound to your preferences and compensate for any shortage in your headphones or audio system. The high and low gain settings are suitable for headphones with different impedance. The bypass mode provides a pure reproduction of the original sound. The loudness function allows you to immerse yourself in the world of music during quiet nights.

Packing List

Product Overview

Fosi-Audio-SK01-Headphone-Amplifier-Equalizer-Preamp-
fig-2

  1. GAIN: Initially set to high gain mode, press to switch to low gain mode
  2. TONE: Press to disable the treble, middle, and bass adjustment
  3. LOUDNESS: Enhances both treble and bass when listening at low volume
  4. Power indicator: The red light stays on during charging, and turns off when fully charged. The green light stays on during operation with sufficient voltage. Green light flashes when the battery is low
  5. TREBLE: Adjusts the high-frequency range at 10kHz (8dB)
  6. MIDDLE: Adjusts the mid-frequency range at 1kHz (#10dB)
  7. BASS: Adjusts the low-frequency range at 50Hz (#11dB)
  8. Power/Volume knob
  9. Signal Indicator: Light flashes in red and blue alternately when the output voltage reaches 2V, indicating the excessive volume
  10. 3.5mm headphone jack
  11. 6.35mm headphone jack
  12. DC 5V USB-C power input
  13. 3.5mm LINE IN
  14. 3.5mm LINE OUT

Specifications

Fosi-Audio-SK01-Headphone-Amplifier-Equalizer-Preamp-
fig-3

Operation Guide

Step 1: Connect your audio source to the Line port of the SK01 using a 3.5mm audio cable;
Step 2: Plug your headphones into the corresponding headphone jack;
Step 3: Turn the power/volume knob clockwise to turn on the device. The power indicator light will illuminate;
Step4: Adjust the volume, tone, and other settings to your desired level of comfort.

Note
Step 1: If the power indicator light does not illuminate or flashes after turning on the device, please turn it off, connect the DC 5V USB-C port using a USB-C cable for charging, and then turning it on again;
Step 2: If the signal indicator light is flashing, it indicates that the volume is relatively high. It is recommended to lower the volume before wearing headphones and then adjust it to your desired level;
Step 3: Avoid plugging or unplugging the USB cable, 3.5mm audio cable, or headphone cable while the device is turned on;
Step 4: The USB port is for power only and does not support data transfer.

Frequently Asked Questions

The tone-control knobs are not working?

Please check if the TONE button is set to PURE mode. PURE is the mode where the signal bypasses the tone circuit. Switching to TONE mode should enable the tone adjustment.

Why is the power indicator light flashing continuously after turning on?

The flashing power indicator light indicates low batteries. Please charge the device promptly.

Is the SK01 a preamplifier and a headphone amplifier?

Does the tone knob control only the 3.5mm audio output or also the headphone output The SK01 is both a preamplifier and a headphone amplifier. The tone knob controls both the 3.5mm audio output and the headphone output. When adjusting the 3.5mm audio output of the SK01, it functions as a preamplifier, connected to a power amplifier, and allows adjustment of the high, mid, and low frequencies of the audio system.

Why am I not experiencing the Loudness effect?

Loudness is an equal loudness switch designed to compensate for the frequency response of human ears at low volumes. When listening at low volumes, our perception of high and low frequencies may be reduced. Loudness compensates for this by boosting high and low frequencies, aligning perceived loudness with the actual volume.

Why is the signal indicator light not turning on?

The signal indicator light indicates the volume level. It starts flashing as the volume increases (output voltage reaches 2V). The purpose of the signal light is to let you know if the volume is too high before wearing headphones. If the signal light continues to flash and is bright, it is recommended to lower the volume before wearing headphones, and then adjust it to your desired level, ensuring the protection of your ears.

Warranty and Maintenance

Fosi Audio pledges to give a 24-month limited warranty and support from the date of purchase. If you encounter any problem when using our product, please contact our support team at support@fosiaudio.com.

About Us
Fosi Audio designs and builds innovative audio products with all your music in mind. Great sound, simple but elegant designs, high-quality components and truly useful features are what Fosi Audio pursues. We sincerely hope you can get as much enjoyment from our products as we’ve had to create them!

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www.fosiaudio.com

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support@fosiaudio.com
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