Fosi Audio M03 200 Watt TPA3255 Subwoofer Amplifier Mini Mono Channel Audio Power Amp for Home Theater Full-Frequency and SUB Bass Switchable with 32V/5A Power Supply

I have a lot of experience with these Fosi Audio amplifiers. They never cease to amaze me. As you can see in the video, I have a subwoofer hooked up to this mono amp. I converted the subwoofer to passive because the internal amp fried. Those replacement amps are expensive while the Fosi amps Are perfect for this situation and sound amazing and caused less. Plus they're tiny, easy to hook up. Have clean sound with no distortion. They weigh basically nothing and you can put them just about anywhere. If you're an audio person or you mess with home theater or anything like that or you just want to test subwoofers this is the perfect amp for it. I keep one on my test bench as well.

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.

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.

This amp works great. I had a 10 inch Klipsch subwoofer with a blown integrated amp. I bypassed the amp and ran speaker wire directly to the subwoofer speaker and it sounds better than the original. I also used one to power an auto subwoofer speaker I built a box for and use it daily for my pc. You can dial in the frequency and volume to match your other speakers to your preference. More than enough power for my 10 inch subwoofer, but it's not going to hit like a higher powered amp. I liked the first one and purchased a second as well as a third of a different brand. The third one looks almost identical with a different name and I can't tell any difference.

I had purchased an M04 unit and returned it due to a muddy, indistinct bass sound. I upgraded to the M03, and what a difference. I love the bass sound I'm getting with this new amp! For not-much-more money, this M03 is definitely the way to go! Very pleased.

***UPDATE*** Gave it an extra star. Took a lot of tuning, letting the new sub break in... but now I can consistently use this. It is still a bit weaker than expected, because if I crank it, it will blow the (built-in) circuit breaker. It works, but I'll go with something else next time. I'll keep this thing around for playing, in the future... *** END OF UPDATE *** So, let me start with what I already had and what I bought... 1) I already had a Denon AVR-S650H which had (2) subwoofer RCA-outs 2) It was difficult to find home subwoofer amps (120v) that were not box-mounted. 3) Found this amp, saw decent reviews, seemed to be the highest wattage for its style (standalone; external) at 150w RMS / 300w max. 4) Found a subwoofer that I wanted, to fit within these specs; purchased a Rockford R1S4-12 12-Inch Single Voice Coil. 4x) Side note, that sub has two versions, an initial release and a newer version. The first was 150w RMS and the second was 200w RMS. I thought I was getting the first, but I got the 200w shipped to me. 5) Built a custom box to the optimal sealed spec from Rockford, out of birch plywood. Spent more time here than anything else. 6) Finally hooked it up to test it. TESTING ------------ I turned the crossover to the max, the volume on this amp all the way down, and the volume on the receiver down, as to get as much sound to the sub without blowing it on the first try. The Denon receiver was set to LFE, not LFE+Main. I played Lil Wayne's "A Milli" as my go-to sub tester. I thought it wasn't working at first, but when I touched the center of the sub, I could feel a slight rumble, on beat with the music. I turned the receiver up to a volume you would have a party, where people would need to speak at a slightly elevated level to overpower the music. The sub was drowned out by mids and highs of the music... so I turned this sub amp higher. I quickly reached MAX before I realized I wasn't getting the power I wanted. Let me skip to say that I pretty much maxed out all settings from both the receiver and amp, to allow the subwoofer to get as much throughput as possible. It finally blended with the music. I thought, great... I wish I didn't have to max everything out, but we're finally here. So I test a few other songs when I realize the subwoofer isn't working anymore. The red power light is on, but nothing at all. I turn it off and on... then it comes to life again. Weird. So I decide to move to a movie. Preferably a war movie with explosions and such. I go to Netflix. When I start the app, the loud "BOOM BOOMMMMmmm" sound comes on with the Netflix logo. If you don't remember it, just start the app and you will hear it. It's kind of their own Dolby Digital-style intro. I heard a loud pop. I assumed I just killed the sub or amp. I find a movie and after resetting the amp again, I hear bass. Long story short, the settings I have for music can't be played for movies. It immediately clips, a breaker is tripped, and it needs to be turned off/on to bring it back. Furthermore, I would say 150w RMS is exaggerated. I would guess 80-100w is the RMS. So for my 200w subwoofer, I feel like it's getting half the power it needs. I know it's a 200w and not 150w subwoofer, but I don't think it should preform this poorly. Lastly, I feel like there is something smarter about your typical home subwoofer's amp, compared to this little guy. I mean, look at it. It's smaller than the smallest 100w car audio amp. I feel like it's missing some volume/clipping/quality control electronic items inside. I'm no electrical engineer, but I've never had home subwoofers act like this one. It's very inconsistent. I feel if anyone is going to get this for a subwoofer, I recommend the following: if you're only going to have one sub, get a dual voice coil, with sub that needs 200w RMS. Then, hook two of these amps into each voice coil@4ohm. Maybe then you will get expected sounds. OR just get a normal plate-amp for the same amount of money.

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

Ordered and shipped up to Canada. Objective: Subwoofer amplifier for a customers 4rth order bandpass enclosure for home audio (sub is situated in adjacent utility room and ported into listening space through wall). The amp offers versatility as a sub amp with integrated variable crossover, 2nd order (-12db) low pass from 40-300 hz (not 20-300 as stated in description). I would have preferred a 4rth order or shelf filter to knock out sub quicker, customers with more time may be able to alter the circuitry, but all in good enough. Available wattage is also overstated in description as the power supply cannot exceed 160watts, even at 90% efficiency, there is only 144 watts output... max.. Though it is a potent 144-ish watts (I should measure for actual figure) that will be sufficient for most cases. Additional: no sub sonic high pass filter so careful not to distort driver. Buuut, this can also be utilized as a full range mono block which I tested on high end bookshelf speaker. Way more power then the speakers could handle, I couldn't turn past half (with full volume on source) without protective circuitry kicked in. Sound was solid and neutral. This amp is a good purchase for either need however consider the fact as your system changes with urge of continuous upgrading, this amp is adaptable. Grab a DSP and a few of these and you could make a heck of a 2.1 system on a budget. (note if using DSP, all three amps would run in full range then sound to sub would be tailored through user perimeters not amps filter) Simon

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!

todo según lo esperado

At first I was a bit sceptical but considering the price and all the positive reviews I went ahead and bought it. Well packaged and protected. Plugged it in to my passive converted JBL 550P 10” subwoofer and NAD757 home cinema amp. At first not the power I expected. After doing Audyssey (room correction) with the FOSI sub frequency fully to the right and volume set at the 1o’clock dial, it completely came to life! This small amp is much better than the original JBL 550P 500W (peak power)! Don’t fixate yourself on the Watt numbers! I highly recommended this tiny but mighty amp! Used it for over a month roughly.

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.

For the size, the sound is great :-)