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Solid Power to Your Home Theater System
Fosi Audio M04 Subwoofer Amplifier
- SNR: ≥ 102dB; THD: ≤ 0.02% (1KHz, 1W)
- Max Power Output: 100watt @2Ω
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Drive Your Bookshlef Speaker
Fill your device with the throbbing bass beats you want.
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Drive Your Subwoofer Speaker
Play low frequencies without distortion, and provide enough clean power.
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Sub Freq & Volume Control
Fine tunes the volume level signal you wish to control.
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Fit Almost Anywhere
Improving the bass and the power of your music.
Texas Instruments TPA3116 Chip
Wide voltage input range and high efficiency.
Switching Between Modes
There is a switch for changing modes on the subwoofer amplifier M03. PBTL defines it as a Full-Frequency Mono amp for driving passive speakers. To SUB, it's a subwoofer amplifier used with passive subwoofers.
DIY Your Audio System
Creating a professional sound system is easy with this mono amplifier. You can use this amp to drive most bookshelf speakers or subwoofers in your home.
Subwoofer/Mono Amp M04
Fosi Audio Subwoofer Amp
100W | MAX Power Output | 220W |
RCA | Input | Bluetooth + RCA |
≤ 0.02% | THD | ≤ 0.05% |
≥ 102dB | SNR | ≥ 102dB |
19V/4.74A | Power Adapter | 24V/4.5A |
Bluetooth | |
100W | MAX Power Output | 200W |
RCA | Input | RCA |
≤ 0.02% | THD | ≤0.03% |
≥ 102dB | SNR | ≥106dB |
19V/4.74A | Power Adapter | 32V/5A |
Bluetooth |
100W | MAX Power Output | 220W |
RCA | Input | RCA |
≤ 0.02% | THD | ≤ 0.04% |
≥ 102dB | SNR | ≥ 98dB |
19V/4.74A | Power Adapter | 24V/4.5A |
Bluetooth |
- Subwoofer/Mono Amp M01-BT
- Subwoofer/Mono Amp M03
- Subwoofer Amp TP-02
David_Jr
Reviewed in the United States on March 5, 2025
I needed an amplifier for a passive subwoofer that came with a Kenwood HTIB and the receiver died. I was skeptical that this would work, but for the price thought I would try it. I didn't expect it to be so small, but it feels like a quality product. Using this in a bedroom system with an older Denon receiver. I connected the amp using a Y cable from the Denon Subwoofer output and turned the frequency knob all the way up. I ran Audyssey setup and it works great. Bass sounds good and not boomy. Very pleased so far great product.
RY
Reviewed in the United States on January 25, 2025
Purchased this to use with an old passive subwoofer from a stereo system that went bad. It was easy to set up and works perfectly, sounds great and brought new life to an otherwise perfectly good subwoofer!
Steve-O
Reviewed in Australia on January 2, 2025
Purchased to replace the blown up plate amp of my sub.Disconnect the old amp and wire in this little bad boy and my old KEF woofer is thumping again.Sure, it's a class D (all you need for a woofer anyway) and the power brick is external (a good thing in my eyes for heat dissipation) and newer designed circuits mean it will probably last a lot longer.Easier and cheaper than repairing the old amp!
パパ
Reviewed in Japan on January 18, 2025
低音調整が簡単に、自分の好きな音に合わせれます。
Gerardo Segura Lira
Reviewed in Mexico on March 23, 2024
Muy bien con una buena instalación, hizo lo que esperaba, así es que estoy satisfecho 👌
ASGM
Reviewed in the United States on February 16, 2024
Got this subwoofer amp to bypass the amp component of my active subwoofer which died months ago due to a peak in voltage. My amp was those that work in "stand-by" mode, so they are always powered up somehow. Replacing the board with a new one (original) was too expensive, even more expensive than what the sub costed me in the first place, so in order to not throw the box and the woofer cone to the trash, I decided to just rewire things up in order to bypass the sub's integrated amp, so I got this GREAT little FOSI amp to power my "now passive" sub.Things worked great and my sub is now back to life, shining again.The M04 Fosi Amp is a great choice as it is POWERFUL, noiseless (at least to my ear), very small and does not generate any important heat. It comes with a power adapter, so you only need the cables to connect the input signal and the output signal to the passive subwoofer. I used the convenient "bare wire connection" to hook the modified sub to the speaker output of the Fosi Amp. Worked NICELY.Quality of the M04 Fosi AMP is VERY GOOD, in a very neat, compact and ellegant BLACK enclosure. It is definitely worth the money, which is NOT AT ALL expensive, but quality exceeds by far the amount paid for this amp.Until now, i'm really loving it.
Stephen Young
Reviewed in Canada on November 5, 2024
It works well with a passive sub-woofer and with the cut-off frequency adjusted right it compliments the sound of the rest of the system (high-end speakers which just lack deep bass).
p2
Reviewed in Japan on December 27, 2023
2.1chの中華アンプでパッシブサブウーファー鳴らしてましたが、やっぱり2ch+1chSW構成（SW端子ではなくパラで繋いでます）のほうが全然調整しやすいですね。SWだけ鳴らして低音具合確認できないとまともに調整できないです。また、2.1chのSW出力だと出力足りなかったということもよくわかりました。もっと早くこうしてればよかった・・・こんなにいい低音で鳴らせたんだ・・と時間を無駄にしたことを後悔。
B. Helms
Reviewed in the United States on January 23, 2019
I recently upgraded a low-budget A/V system located in a technically challenging environment - an attached greenhouse with hot tub. The previous system's receiver had a built-in amp. for the passive sub. The "new" (relocated) receiver has only line-level sub outputs, so this amp. was an obvious choice to close the "gap". I can make all the speaker and sub. adjustments including level and cross-over frequency in firmware, but it's quite convenient to have the sub volume easily adjustable on the unit itself as various sources need to be tweaked. As far as I can tell, the input jack is mono only so the mono 3.5mm plug to RCA adapter cable I bought works fine. (The photo the supplier provides in the product description shows a stereo 3.5mm plug at the input and the related consumer questions/answers on this topic are unclear.) When I first connected the system I had no sound out, but the issue was quickly traced to the speaker settings in firmware where I had declared the front L/R speakers as "Large". They need to be set to "Small" to get audio to the sub. I set the sub level in firmware to +5dB and the crossover freq. to 90Hz, but that latter will need some additional tweaking. At first experience the audio is great! Good, thunderous bass without overdriving the sub...more than I expected from this cheap system!. The unit runs cool to the touch and shows no evidence of being stressed in any way. I expect it to last a long time!.A couple of suggestions for the manufacturer: 1) consider using a less bright LED as the power on indicator - the current one is almost blinding in a darkened environment, as others have reported (the LED is dim when the volume control is switched to the OFF position then becomes very bright when switched ON) - and; 2) consider providing a standby mode when no audio signal is sensed (system power-down) like powered subs provide. I guess this latter is moot since the attached power supply would always be active and pulling some minimal power any time it's plugged-in. Otherwise, so far this seems to be a great product that will serve me well for many years...!
Mickey B
Reviewed in the United States on August 29, 2018
I'm using this amp to power a 1990 Bose Acoustimass 3 passive sub, 5-1/4" driver. The driver has dual 8-ohm coils, so I jumpered the inputs in parallel to give the amp a 4 ohm load.I'm in shock at how well this setup works. In the adjacent corner of my living room, I have a Sony 15", 200 watt sub, and down to 40 Hz, this little beast keeps up with the Sony. Very good transient response. It can make the room resonate with the Sony sub turned off, and this listening area is probably 3 times the cubic feet recommended for such a small sub. I have no idea what the RMS output is, I'll bet it's 50W or less, but it's plenty of power for the tiny Bose sub at my listening levels, which rarely go above 85 dB.Class D is nice. Stays cool, doesn't eat a lot of power.I experienced a few negatives as other reviewers mentioned.When I hooked it up stacked on top of a Kinter K2020A+ amp, there was 60 Hz hum feeding to the sub. Didn't matter if it was near the Kinter or not. Then I noticed the hum disappeared when I grabbed hold of both amps with my hand. A jumper wire between chassis screws on the amps fixed it.The power LED is ridiculously bright. It took 4 layers of 1st aid tape to tame it.It would be nice if it had a power switch separate from the volume control, so you don't have to fiddle with the volume setting every time you turn it on (with my 2-sub setup, it doesn't sound right unless both subs are at exactly the same level). But that's a minor complaint. Plugging it into a switched power strip with some of my other stuff takes care of that.We'll see how long it lasts. If it outlasts the 18-month warranty by a few years, good deal.
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