








🎧 Unleash deep bass and pristine sound—because your audio deserves the upgrade.
The Fosi Audio M03 is a compact yet powerful 200-watt mono subwoofer amplifier featuring the advanced Texas Instruments TPA3255 chip. It offers switchable modes for full-frequency or dedicated subwoofer use, delivering ultra-low distortion and clean sound quality. Designed for home theater and hi-fi systems, it includes a 32V/5A power supply and precise bass control, making it a versatile and easy-to-integrate audio upgrade.






















| ASIN | B07VHG2LR9 |
| Best Sellers Rank | #55,935 in Electronics ( See Top 100 in Electronics ) #332 in Audio Component Amplifiers |
| Brand | Fosi Audio |
| Customer Reviews | 4.4 4.4 out of 5 stars (760) |
| Date First Available | August 1, 2019 |
| Item Weight | 2.4 pounds |
| Item dimensions L x W x H | 5.12 x 4.13 x 1.37 inches |
| Item model number | M03 |
| Manufacturer | Fosi Audio |
| Maximum Supply Voltage | 32 Volts (DC) |
| Minimum Supply Voltage | 24 Volts (DC) |
| Mounting Type | Surface Mount |
| Number of Channels | 1 |
| Output Power | 150 Watts |
| Package Type Name | Box" or "Case |
| Product Dimensions | 5.12 x 4.13 x 1.37 inches |
| Voltage | 32 Volts |
G**S
A powerful driver for a sub woofer
UPDATE: The TAPE out hookup I mentioned below worked great for levels, but TAPE out is, by design, not controlled by the volume knob on my Pioneer receiver, so I had to constantly adjust two knobs, one under my desk at the sub, so not ideal. The solution? I just added a $25 preamp before the FOSI to have excellent subwoofer levels from the Pioneer subwoofer output, plenty of signal now at half volume or less on both the preamp and the FOSI main amp. The preamp is also a simple and excellent little device. https://www.amazon.com/dp/B0945RFJ6Z?ref=ppx_yo2ov_dt_b_fed_asin_title I went with this preamp instead of some units, like the FOSI preamp, because it does NOT do any RIAA equalization that I did not want to add to the mix. I bought this FOSI to get my 24 year old KLH subwoofer running again. I am very pleased. I was able to remove the plate amp assembly and leave the SW box sealed on the back as it has always been, by the plastic box that had housed the circuitry. I might mount the FOSI in this plastic recess, but for now it sits atop the SW cabinet and if its rubber feet keep it from walking off I will just leave it there for ease of reaching the controls. This tiny powerhouse is driving the 8" KLH speaker to make better sounds and deep vibrations, than it has for years. Gone are the occasional deep pop and rattle sounds that I had thought might mean the speaker cone itself had deteriorated. It turns out the old cone is just fine. The KLH built in amp had apparently been slowly cooking its circuit board for a long time before it gave up completely last week. It looks like a bulging cap and some burned resistors... maybe I will fix that board someday. One word of warning. I was driving the old KLH ASW 100 powered subwoofer with an RCA Y-cable from the low level sub output RCA jack of a 20 year old Pioneer home theater amp. It turns out that the signal level on that jack is too low to get more than just a faint response from this FOSI, even turned up to the max. So don't assume this will be a direct replacement if you have that kind of subwoofer hookup. I ended up driving this FOSI with a dual RCA cable from the tape record outputs of the Pioneer, and I am getting loud, clear and rumbling bass from the FOSI at only about four clicks of the volume knob. The FOSI volume and freq cutoff controls have a nice, subtle, detent feel.
C**C
Great AMP
The Fosi Audio M03 200 Watt TPA3255 Subwoofer Amplifier impresses with its compact size and powerful performance. With 200 watts of output power and the TPA3255 amplifier chip, it delivers crisp and clear audio, especially in the lower frequency range. Its mini mono-channel design makes it versatile for various audio setups, whether for home entertainment systems or car audio. Overall, it's a solid choice for those seeking high-quality audio amplification in a compact package. The base sounds great in my tv room
S**E
Keep having to buy more of these!
Great little amp. Works exactly as advertised and very easy to use. The amp has an optional adjustable low-pass filter. In PBTL mode, the amp is full-range. In SUB mode, it uses the adjustable low-pass filter. There is no high-pass outputs. If you are using this amp to add a subwoofer to your existing system, your main speakers will be full-range. If you want a true crossover, you will need either passive RCA high-pass filters on your mains amplifier or an active crossover box. For the past few subwoofers I’ve built and enjoyed with this amplifier, I’ve given them away (to great delight of the recipient). So I have to keep buying more. The last one was for a home recording studio with very demanding fidelity requirements. This is the fourth one I’ve purchased. I’ll be starting the design and construction of the accompanying subwoofer over the next few months. There’s no reason to go shopping for a different amplifier. This one has done everything I’ve needed it to do. The next subwoofer might be a stereo pair, and I'm considering a pair of these amplifiers for a matching set.
B**S
Solid sub amp for price point, but not 300W RMS.
UPDATE: After using this amp for a few months, while I still think it's a good value for what it is at this price point, I'll say that the 300W rating is misleading. Normally amps are rated for their per-channel RMS capabilities, whereas in this case 300W is the peak power possible only using a 4 ohm load (half that if you're using 8 ohms). That means 140-150W RMS at 4 ohms, which certainly produces usable bass if used with a sub, but I've had the amp shut off once or twice due to clipping when driving it hard. Admittedly for that level of bass I should be using a stronger amp, but this is worth sharing. I had a couple old car subwoofers in my closet that I hadn't used in years, and when I got my hands on a box again I went looking for a way to power one of them in my living room to complement my Klipsch RB6 bookshelf speakers. I've used this Fosi Audio amp with both an Infinity Kappa 12" and Kicker CVR 12" (swapping between) and both sound solid. The bass extension goes low enough to rattle things on my walls even with this amp's volume at probably 65% in a medium-sized living room, and it's great to have the adjustable crossover. Some folks seemed to doubt whether this amp's claims of 300W were legit and I've not used a multimeter to check or anything, but I'll say that it seems to have no trouble driving my sub to nice home theater listening levels, and it's nice that it's small and doesn't take up a lot of space alongside the receiver. I've driven the sub hard enough that it's almost uncomfortable to be in the room with it for a good hour or two straight and the amp never got more than slightly warm. That's a good sign of efficient power. Build quality seems pretty good, and I like the click feature of the volume knob -- makes it easy to turn it up or down a couple clicks and have a tactile feel for precision. One area for improvement would be if the lines on the crossover knob were labelled so you knew what specific frequency you were cutting off at. As it is you're kind of guessing, but after a little back and forth of setting, sitting on the couch and listening, then getting up to adjust, I have it dialed in pretty well. Nothing about the amp feels cheap or rattles when you handle it, and I like that there are banana plug/twist style speaker connections on the back rather than cheap spring clips. It sounds good enough that my wife said, "Maybe we should get a second one and power the other sub." Any time there's wife buy-in on audio gear in the living room, it's a plus. :-) Would definitely recommend this to anyone who already has a sub and box looking for an affordable way to power it.
N**K
Read reviews, bought the item with high expectation. But the sound output is weak. This amplifier is for active subwoofer, not for passive subwoofer. In short, this amplifier needs an amplifier. Update: After putting this amp aside for months, I recently found out that the "aux output of Aiyima A08 Pro" is the main culprit all along. I was wrong for pointing finger to this little champ. After feeding the right amount of power to its inputs, it rattles the windows. WOW... She deserves 5 Stars, not 3!
I**O
todo según lo esperado
ズ**ー
真空管アンプにサブウーファーを追加するのとテレビのAVシステムのサブウーファー用に2台購入 発熱も少なくノイズ無し、電源を奢ればパワーも出ます 市販のアクティブサブウーファーを購入するとボリュームが後ろについていることが多いので 全面にボリュームを配置できるのが気に入ってます サブウーファーですから自作のスピーカー&ボックスを使えば市販品よりずいぶん安くできます
F**B
Super ampli classe D, parfait pour alimenter un HP de graves de 30cm en caisson clos. Livré avec alimentation en 36V déjà bien assez puissante. A noter la possibilité d'évolution pour plus tard et passer sur une alimentation en 48V pour les plus exigeants.
J**D
For the size, the sound is great :-)
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