Fosi Audio M04 Subwoofer Amplifier for Home Theater Mono Channel Digital Class D Integrated Power Amp for Passive Speakers Subwoofer
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Availability:
20 left in stock
Arrives
Wednesday, Apr 22
Features
- High-Performance Mono Amplifier:The Fosi Audio M04 is a mono amplifier designed for driving passive subwoofers or speakers. It features the Texas Instruments TPA3116 chip and NE5532 op-amp, providing an output power of 100 watts for a 2-ohm subwoofer or speaker.
- Enhanced Bass Response:The M04 SUB amp is designed to improve the bass response of passive subwoofers. It features a selector switch that allows the user to switch between subwoofer bass amplifier and full-frequency mono amplifier modes.
- Compact and Robust Design:This mini amp has a small and robust design with a built-in low pass filter for subwoofers and a sub frequency control, making it practical and powerful. It uses highly efficient Class D technology that remains cool under demanding loads and doesn't take up much space.
- Superior Sound Quality:The home subwoofer amplifier can produce a deep, crisp, and clean low-frequency sound effect, making it an excellent addition to dedicated home audio receivers & amplifiers. It has been designed to enhance the sound and performance of your audio system at an affordable price.
- Complete Package:What You Get: M04 subwoofer amp x1, 19V/4.74A power supply x1, user manual x1.
Item dimensions L x W x H: 5.2 x 3.5 x 1.4 inches
Voltage: 12 Volts (DC)
Manufacturer: Fosi Audio
Maximum Supply Voltage: 19 Volts (DC)
Minimum Supply Voltage: 19 Volts (DC)
Item dimensions L x W x H: 5.2 x 3.5 x 1.4 inches
Voltage: 12 Volts (DC)
Manufacturer: Fosi Audio
Maximum Supply Voltage: 19 Volts (DC)
Minimum Supply Voltage: 19 Volts (DC)
Mounting Type: Freestanding
Brand: Fosi Audio
Number of Channels: 1
Output Power: 100 Watts
Specification Met: [Inf] Thd <= 0.04% and Frequency Range 20hz - 120hz
Product Dimensions: 5.2 x 3.5 x 1.4 inches
Item Weight: 15.9 ounces
Item model number: M04
Is Discontinued By Manufacturer: No
Date First Available: January 18, 2018
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Wednesday, Apr 22
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
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.
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Reviewed in the United States on February 16, 2024 by ASGM
Used this to hook up a sub to a sound system for my workout room. Works exactly as expected and I’ve had no problems. Very powerful on a Sony xplode that is probably 10 years old. Great price and great sound for such a simple piece of tech. Hooked to a boss receiver.
Reviewed in the United States on September 2, 2025 by D Riley
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...!
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Reviewed in the United States on January 23, 2019 by B. Helms
Works well with my setup. Connected a Rockville sub to my surround receiver and works flawlessly.
Reviewed in the United States on September 14, 2025 by Ryan Ryan
Well built and easy to connect. Does a great job at a reasonable price. Clear sound with no noticble distortion. Highly recommend.
Reviewed in the United States on October 13, 2025 by Kindle Customer
I purchased this to power passive the sub woofer on a Panasonic 3-speaker system I picked up at Goodwill. Great little unit, and powers the sub just fine. It is small, inconspicuous and easy to connect. Plenty of power for my office setup, easy to use and adjust quality and output levels to go along with my listening choices. This unit meets my needs for the speakers I have, and I am not disappointed.
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Reviewed in the United States on May 25, 2025 by boboprf
Internal home theater sub amp died a while back and I didn’t want to replace the whole unit. This little guy brought the sub back to life! Sounds great and is only turned up half way. Extremely happy with the amp. I bought another Fosi stereo amp a month ago and that one works great too.
Reviewed in the United States on August 20, 2025 by Melissa Melissa
Horrible product then if you return product they will say they didn’t receive so you won’t get a refund
Reviewed in the United States on January 6, 2026 by Jamie G.