Nobsound M-504C 5 Band EQ Equalizer Stereo Valve Tube Balance XLR/RCA Preamp Headphone Amplifier User Manual
- June 16, 2024
- Nobsound
Table of Contents
Nobsound M-504C 5 Band EQ Equalizer Stereo Valve Tube Balance XLR/RCA
Preamp Headphone Amplifier
Product Information
Specifications
- Frequency response: 16300
- THD: Not specified
- SNR: Not specified
- Working voltage: Not specified
- Headphone output power: Not specified
- Earphone impedance range: Not specified
- RCA Input sensitivity: 0.775Vrms
- BAL Input sensitivity: 1.5Vrms
- RCA output Level: 1.2Vrms
- BAL output Level: 2.4Vrms
- Packing weight: 1.03kg
- Packing size: L310 W240H70 mm
Front and Rear Panel Description
The manual does not provide explicit information about the front and rear panel description.
Operation Steps
- Install the matching electronic tube into the electronic tube base according to the direction (the electronic tube is not divided into left and right, and pay attention to check whether the pin is deformed).
Product Usage Instructions
Step 1: Installing the Electronic Tube
To install the electronic tube:
- Ensure the machine is powered off.
- Locate the electronic tube base on the product.
- Insert the matching electronic tube into the electronic tube base, following the correct direction.
- Check that the pins of the electronic tube are not deformed.
FAQ
Q: All my wires are connected. Why is there no sound?
A: To troubleshoot this issue, follow these steps:
- Check whether the machine is powered on and switched to the corresponding input channel.
- Ensure the back-end connection is correct and the volume is not set to the minimum.
- If the above steps are normal, check whether the input playback device is muted, paused, or set to the minimum volume.
Q: Why is the sound distorted?
A: The sound may be distorted due to excessive input level. To resolve this
issue:
- Reduce the volume of the input device.
- Lower the volume of the machine.
Q: Why is there a lot of electrical noise from the loudspeaker?
A: If you are not using the original standard power supply, try replacing it
with a different power supply to test again. Many power sources in the market
have a large disturbance coefficient, which can cause significant electrical
noise.
Q: Why does the speaker make a loud buzzing sound when I plug in the input
cord and don’t connect the audio source?
A: When using a signal line without shielding, interference signals can enter
the power amplifier for amplification. It is recommended to replace the signal
line with shielding or unplug the signal line to eliminate the buzzing sound.
Q: Can I replace the tube without turning off the power?
A: No, replacing the tube without turning off the power is not recommended.
The inside of the machine operates at high pressure, and hot-plug vacuum tubes
can potentially damage the machine.
Warnings
- Please do not open the machine shell. Improper operation may cause electric shock.
- Use only the regular manufacturer’s switching power supply to avoid the risk of damage to the machine.
- Do not change the vacuum tube without proper guidance, as it may burn out your vacuum tube or the machine.
- Avoid placing the machine in high-temperature or humid environments.
Thank you very much for choosing our products! Please read this manual carefully before using the product
Front and rear panel description
- Power key / Channel select
- 3.5 headphone output (synchronous output with RCA)
- 64Hz adjustment knob
- 256Hz adjustment knob
- 1KHz adjustment knob
- 4KHz adjustment knob
- 16KHz adjustment knob
- Left and right channel balance adjustment
- Main volume adjustment knob
- Balanced input
- RCA input (white/left channel, red/right channel)
- RCA output (white/left channel, red/right channel)
- Balanced output
- Power interface (DC voltage shall not be higher than 12V)
Operation steps
- Install the matching electronic tube into the electronic tube base according to the direction (the electronic tube is not divided into left and right, and pay attention to check whether the pin is deformed).
- Connect the sound source to RCA and balance input interface.
- Connect the rear stage equipment to RCA and balance output interface.
- Connect the headphones to be used to the 3.5 headphone output connector.
- Finally, connect the power supply (the DC voltage shall not exceed 12V).
- Move the switch upward to start and switch to the corresponding input channel.
- Turn the main volume knob to the right to adjust to the appropriate volume.
- Adjust each frequency knob to achieve the appropriate sound effect.
- When not in use, turn it off and unplug the power.
Specification parameters
| Frequency response | 20Hz～20KHz(±1dB) | RCA Input sensitivity | 0.775Vrms |
|---|---|---|---|
| THD | 0.01% | BAL Input sensitivity | 1.5Vrms |
| SNR | ≥98dB | RCA output Level | 1.2Vrms |
| Working voltage | DC12V | BAL output Level | 2.4Vrms |
| Headphone output power | 125mW | Packing weight | 1.03kg |
| Earphone impedance range | 16～300Ω | Packing size | L310 W 240 H 70 mm |
FAQS
Q: All my wires are connected. Why is there no sound?
- Check whether the machine is powered on and switch to the corresponding input channel.
- Check whether the back-end connection is correct and whether the volume is in the minimum state.
- If all the above are normal, please check whether the input playback device is muted, paused, or the volume is at the minimum value.
why is the sound distorted?
the input level may be too large. If the volume of the input device is turned on very large and the volume of the machine is also turned on very large, it is easy to be distorted. Just turn down the volume of the sound source input device or the machine.
Why is there a lot of electrical noise from the loudspeaker?
If you are not using the original standard power supply, please replace the power supply and test again. Many power sources in the market have a large disturbance coefficient, which will cause a large current sound.
Why does the speaker make a loud buzzing sound when I plug in the input cord and don't connect the audio source?
When the signal line without shielding is used, there will be interference signals entering the power amplifier for amplification. It is recommended that you replace the signal line with shielding or unplug the signal line.
Can I replace the tube without turning off the power?
No, because the inside of the machine is working at high pressure, the hot plug vacuum tube burnt out may damage the machine
Warning！
- Please do not open the machine shell. Improper operation may cause electric shock.
- please use the regular manufacturer of switching power supply, otherwise there will be the risk of damage to the machine.
- Please do not change the vacuum tube at will, or it will burn out your vacuum tube or machine.
- Do not put the machine in a high temperature or humid environment.
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