Fosi Audio V3 Stereo Power Amplifier 300W *2 TPA3255 Class D Mini Amp 2 Channel Audio Amplifier for Subwoofer Passive Bookshelf
SPECIFICATIONS
Brand Name: Fosi Audio
Certification: CE
Channels: 2 (2.0)
Control Method: Push button
Dynamic Range: ≥110dB
Feature: audio amplifier
High-concerned chemical: none
Highlight: Home Theater Amplifier
Input: RCA
Input Voltage Range: DC 24V~48V
MAX Power Output: 300w x2
Material: aluminum
Maximum Power Per Channel: Above 200W
Model Number: V3
Origin: Mainland China
Output: Speaker Output+3.5mm Pre-out
Output Power: 300W
Package: Yes
Power Amplifier Chip: TI TPA3255
SINAD: 88dB
SNR: ≥110dB
Surround sound channel configuration: Others
THD: <0.003%
Terminal Impedance: 2~8Ω
Type: Stereo Audio amplifier
feature: HIFI amplifier

Fosi Audio V3 Stereo Power Amplifier 300W x2 TPA3255 Class D Mini Speaker Amp 2 Channel Audio Amplifier for Passive Bookshelf
Feature
Compact Yet Powerful: The V3 mini power amplifier combines a minimalist design with exceptional performance. With a power output of up to 600W, it can effortlessly drive 2-8Ω speakers, delivering impressive sound quality. Its compact size makes it suitable for various applications, from bookshelves and desktop setups to home theaters
Audiophile-Grade Components: It features the TPA3255 high-end digital class D amp chip and utilizes premium Japanese NCC, ELNA, and German WIMA capacitors, and Japanese Sumida inductors for exceptional audio quality. With a SINAD rating of up to 88dB, an SNR of up to 110dB, and a low noise floor of only 140uV, it delivers exceptional clarity and low distortion
Innovative Cooling: The V3 stands out with its groundbreaking heat dissipation design. Equipped with vents on the casing's top and bottom, and a whole-body heatsink design, it efficiently dissipates heat, preventing damage to components and ensuring optimal performance
Scalable and Fun: Tailor your sound experience by swapping the stock NE5532 op-amps. V3 is compatible with a variety of 8-pin dual op-amps like Sparkos SS3602, MUSES02, OPA2604, OPA2134PA, OP249, AD827, RM4559, LM4562, LME49720HA, etc. When replacing the op-amp, please make sure the chip is oriented correctly and the procedure is done accurately
Enhanced Pre-out Functionality: The V3 features an optimized "Pre-out" design. The level is now controlled by the volume control, allowing for adjustable sound levels when connected to the "Pre-out." This enhancement offers greater flexibility and convenience for users who prefer to fine-tune their audio experience
Highlight:
1. Replaceable Op-Amp Chips: MUSES02, OPA2134PA, OPA2604AP
2. Passive Speakers + Pre-out
3. Replaceable Knobs: ORANGE KNOB
Note: The "Pre-out" level is NOT controlled by the volume control as the V3 is not an integrated amplifier, so the sound is NOT adjustable when you are connected to the "Pre-out".
Specifications:
Max Power Output: 300Wx2 @4Ω
SINAD: 88dB
SNR: ≥110dB
Terminating Impedance: 2-8Ω
THD: 0.001%
Power Amp Chip: TI TPA3255
Op-Amp: TI NE5532 x2
Power Supply: 32V/5A, 48V/5A
Input Range: DC 24V-48V
Frequency Response Range: 20Hz-20kHz(±1.2dB)
QA
Q1: Is it normal for the V3 amplifier to get very hot during use?
It is normal for the device to generate heat, as the vents on the top and bottom, along with the whole-body heatsink design, enhance air circulation and heat dissipation.
Q2: What is the difference between the 32V version and the 48V version?
The higher the voltage, the greater the amplifier's output power. Therefore, we recommend purchasing the 48V version.
Q3:Which operational amplifiers does V3 support?

FAQ
Q: The screws on the bottom are so tight it is impossible to remove with a normal hex wrench.Any tips how to get them loose?
A:The H2.0mm Allen Wrenchis able to loosen it.
https://www.youtube.com/watch?v=feH5_22hQCA 07:43 Rolling Op-Amps
Q: Low volume on new V3
A: Please ensure that you set the volume level of your audio source to 50% or higher, and adjust the V3 amplifier's volume to maximum. The V3 amplifier is equipped with a built-in logarithmic taper A Pot, which means the volume control becomes more responsive at higher levels (see the below diagram). If you encounter low volume issues, you can also consider using a preamp to address this.

Q: How can I connect an active subwoofer and control the volume if it s constant output?
A: Connect a single 3.5mm cable from the preout to the audio input port on the active subwoofer. You can refer to the tutorial video at this link: https://youtu.be/WhYpHkovCWs (go to 2:44 for the PRE OUT demonstration).
The "pre-out" is a fixed output, you could control the volume by the input device connected to the V3.
Q: I was just wondering what the differences were by using the different op amps?
A: Different op-amps can produce varying sound qualities. You can refer to this video showing different dual op-amps for comparison:https://www.youtube.com/watch?v=nrqVYE4_v1M
You can consider replacing it with op-amps like the SS3602, MUSES02, available on our official website, or options like ORACLE II-02 and LME49720, for different sound.
Q: I intend to use the V3 as a power amp and control the volume with the preamplifier. Is the volume on the V3 a passive attenuator or an active gain circuit?
AThe volume on the V3 is an active gain circuit, you can set the V3 amp at the 3:00 position, then turn up the preamp controls to your comfortable listening level.