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

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.

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.

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.

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 is a very nice, compact amp that delivers the perfect punch for a Sonos sub that I converted to a passive speaker after its power & amplifier board failed. The switches and knobs have good feel. The unit feels well built. After driving my sub at nearly full power for a couple hours the case was only slightly warm, so it does a good job of keeping itself cool and should have a good lifespan.

Replaced the amp stage of a burned active Subwoofer with this. Great solution. So far it does the job and makes a great companion to my receiver. Both connectors and knobs feel sturdy enough, especially for the price tag.

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

I bought the Fosi to drive a 4 ohm 10" subwoofer in a 1 cubic foot sealed enclosure in a small office. It couldn't do it. It barely produced an audible signal past the halfway mark on the gain knob and a few more clicks caused it to shutdown. So the Fosi can't drive a lightly driven bog standard subwoofer. Returned it within hours of receipt.

Parfait pour mon bass shaker de 300w

Excedió mis espectativas, lo vi muy pequeño, tengo un subwoofer de hace 20 años el cual no quería deshacerme de el por ser mi primer sub que sonaba espectacular, un jbl 10" de los frontales, tiene un sub bajo exquisito comp el de un sonos sub pero con mucha más potecia, este se le daño el amplificador integrado, lo mande con muchos técnicos, solo duraba unos minutos y tronaba la fase, con este Amp fosi, alcanzó un 80% de su capacidad, pero se sigue sintiendo su bajo presencial y profundo, acompañado con unas buenas bocinas pfff exquisito, una excelente compra este fosi

Un amplificador muy bueno y a buen precio.

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.

Great little amp. It's not 150rms into 4 ohms thats for sure, might be about 100rms, but for the money it is great value. I built a custom shallow sub to fit under a tv unit, using a 10" Soundstream shallow sub (sealed) rated for 250rms, and it drives it great. I probably wouldnt want to drive anything bigger to drive it well. It makes amazing sound and easily keeps up with my B&W 606s playing loud, and I am only running this amp at just over half, with my receiver sub out at -3db. If your priority is sound quality and need something small and convenient, this is well worth a buy. And I think if you arent running it hard, which I certainly dont need to, longevity wont be an issue. Love this little amp and glad I found it.