Fosi Audio Bluetooth Subwoofer Amplifier 2.1, BT30D Pro Subwoofer Amp with TPA3255 Chips 165W x2+350W & Bass Treble Control, 2.1 Channel Sub Amplifier for Desktop/Outdoor/Bookshelf Speakers

Having just built a new home, I’d installed an in-wall subwoofer and a few decent ceiling speakers in one room. I needed a small, adjustable amp capable of taking care of the 3 channels, with a built-in crossover for the sub. Enter this little beauty - it has huge power for such a tiny box, and with a good source is a remarkably good sounding amplifier. I’ve built amplifiers for decades, from simple transistor amps, to vast Hexfet ones, to hybrid ones with very high end standards. I couldn’t come close to this kind of value, and the quality is really very impressive too.Easy to set up, plenty of power, clean sounding, bonus of Bluetooth connectivity for the times that might be handy.Bottom line - excellent value!

My goal was to setup excellent sounding backyard garden speakers. First a quick story about what led me to this incredible Fosi amp. I found a terrific "all in one" setup from OSD Audio that was a Bluetooth capable powered outdoor subwoofer with 2 channel satellite powered outputs (can power up to 4 satellites total). I purchased 4 of the OSD Forza 4" satellites, which are AMAZING commercial grade outdoor speakers with separate woofer and tweeter in each speaker. The system sounded great until the speakers and sub started crackling and popping, even when nothing was connected. It turned out water penetrated the sub enclosure, the amp inside the enclosure was shorting out, and the OSD folks were fantastic about sending me a replacement. I setup the replacement and thoroughly enjoyed listening to the setup for over 5 hours the day I installed the replacement. The next morning I heard the same crackling and popping, AGAIN! This time I broke open the sub enclosure to figure out what went wrong, and the OSD plastic logo on the very top of the sub enclose is not sealed with silicone like the rest of the sub enclosure is sealed up. My sprinkler system, or almost daily rain we get here in New Orleans penetrated that weakness (water will ALWAYS find a way), and the amplifier sits immediately under the nameplate inside the enclosure and got really wet. Amazingly, the OSD folks were REALLY kind enough to send me another replacement, but this time I shared with them the cause of the malfunction, and hopefully they will seal that part up if you order from them. I received the new OSD replacement setup, put lots of silicone on top of that OSD nameplate on top of the sub enclosure, and put that setup by my pool, and no problems yet!I shared all of this because that 2nd replacement OSD sub that I broke open I repurposed by clipping off the internal wires of the amplifier, satellite speaker outputs, etc. and converted the OSD sub into a passive sub now needing power from another source, and naturally sealed it up really good with lots of silicone. I searched long and hard for "outdoor" 2.1 or 4.1 amplifiers and this Fosi seemed to check all of the boxes, except that it wasn't waterproof. I wanted to put a quality amplifier in an outdoor weatherproof box to avoid the issues I had with the OSD sub setup. After getting it all hooked up, and tuning the amp (adjusting bass, treble, sub crossover to blend w/ the satellites, sub volume, and amp volume I leave in the same position sealed up in the weatherproof box to use my phone's volume when connected via Bluetooth), this Fosi 30D Pro amp sounds every bit as good, if not better, than my home theater setup with $1,000 Yamaha receiver, Paradigm speakers, and $2,000 SVS subwoofer. I actually go sit in my backyard now to listen to my garden speaker setup over my home theater setup it sounds so well balanced and that good. I play music (piano and trumpet), and definitely have an "ear" for music, and this Fosi amp is the real deal, especially when connected to the right kind of high quality speakers. One shortfall about the amp when sealed up in the weatherproof box is that the amp only has a manual lever switch on the unit itself to turn it on or off. Obviously it's not a good idea to leave the amp "on" at all times, and it's very inconvenient to open the weatherproof box every time you want to turn the amp on or off. My solution was to connect the power supply cord of the Fosi amp to an extension cord (bought an outdoor cable cover to protect that connection), and plugged the end of the extension cord into a short extension cord that has an outdoor "on/off" switch, which is then plugged into an outdoor electrical outlet box. Now, whenever I listen to the garden speakers with the Fosi amp, I just walk over to the easily accessible electrical outlet and flip the switch to "on," and my Bluetooth on my phone finds the Fosi amp in no time to connect, and I'm enjoying beautiful, full, rich music...easy peasy! And when I'm finished listening, I just walk over to the switch by the outdoor outlet and flip it to "off." This way the Fosi amp is only "on" when I'm actively listening to it. Hopefully that trick will give it plenty of life! I'll put a link for all of these things below.Here is the box I purchased to house the amp and power supply outdoors: https://www.amazon.com/gp/product/B0CP5RL1PZ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1Here are the OSD Forza 4" satellite speakers I used for the system: https://www.amazon.com/OSD-Landscape-Mountable-Commercial-Resistant/dp/B0916DWXB5/ref=sr_1_2?crid=11056H4LSDN72&dib=eyJ2IjoiMSJ9.gXdDGu8oqU6XiOzDj8u_3rcA2hslL7UTIJmBiwG7-2hbrwNmy7k6LoCGQX15P6aautXVnUXHOW8BoAb_JmqIEb2bFIvZpUJ8T1ZWOvLHuwd3LDQPvNp6VHNJ-9AQlrunzEQWPpHtbrz0H-eBII_sl0FIgOVJnWu6vg6xTF7A6VKLvuDrKV8pffWRfNN1eoGQYeCVYvwJdTFHPFHNTHUf3gbmiawF4akuyNX8olshjtg.SEPJM2UZxVcC-f0JL_dDnT_TxCJ0EFLeuaDYJ76bdYQ&dib_tag=se&keywords=forza%2B4%2Bspeaker&qid=1719723606&sprefix=forza%2B4%2Bspeaker%2Caps%2C115&sr=8-2&th=1Here is the passive outdoor sub I would recommend to use with the Fosi amp: https://www.amazon.com/Forza-Outdoor-Weather-Resistant-Subwoofer/dp/B07R3FCV5K/ref=sr_1_1_sspa?crid=C9VIY16QR2TA&dib=eyJ2IjoiMSJ9.-gZpe9alIyquiwEciwwy_th2Z8h9E_FxalkH-E3bEjzcdF4a1gSljKYLatMM1MxJovLfQGnJmGzyVY0k8KcsB_K5VPKrbtmKJCDpPPnrGADUW_5iXfCiSmPhH0aB1nxnLJU696Gp7y4pfE5CufG9q8rjA26q7mi03W09ruL-tgn6bejQo1-Eg7ghcqR41wmPvbJFHa5iNOSbiDJ5ZKTOzgmqbhdywOyYWyDDSnvB70g.svHb9CJqXcq5JPseVJzdJpKNc1FxKVsuKGJGk9x6V0w&dib_tag=se&keywords=OSD+outdoor+subwoofer&qid=1719723686&sprefix=osd+outdoor+subwoofe%2Caps%2C131&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1Here is the outdoor "on/off" in-line switch on short extension cord: https://www.amazon.com/gp/product/B0BP7XL3MH/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&th=1Here is the OSD "all in one" active / powered 8" subwoofer with powered satellite outputs if you're interested (remember to put silicone sealer on top of the OSD nameplate to really seal it well): https://www.amazon.com/dp/B089DTP3MX?ref=emc_p_m_5_i_atc&th=1

EXTENSIVE testing trying to figure out "why" this great little amplifier didn't punch out the power. The subwoofer amp kept clicking off at higher volumes with the stock AC/DC 32v adapter. I ended up using a 12/24v to 36v step up booster and a 24v (10a) AC/DC adapter (Output is 36v, 10-amps). I tested the max current draw at full power - about 8.6 amps! The stock adapter is rated for 5 amps. Duh? That was the problem.This amp runs at 36v all day long...and a little warm. But, if you want full power and not having the subwoofer amplifier chip kicking off all the time -- either get a 32v (10-amp) adapter or even better 36v (10-amp) adapter. The good thing, a simple turn off/turn on resets the amp (subwoofer amp will reset).The Bluetooth 5.0 is phenomenal...excellent and fast connectivity.The fidelity and sound quality is totally quiet and pure. THD ratings are probably dead on accurate. It really plays beautifully all the way up to full power.The pre-amp out 3.5mm jack is a brilliant addition -- I tested it and it works like vintage equipment. Bluetooth connectivity is not affected. Linear with mains. If you ever wanted to add an active sub via this jack, you can -- it is full range.AUX input works -- no issues with low power pre-amp section like many other of these little digital chip amps. Bluetooth 5.0 is set HIGHER than expected -- NICE job Fosi! So many are set too low.Use banana connectors for your speaker wiring -- 4-8 ohm for mains, 4-ohms plays best.BOTTOM LINE - feed this little guy 36v and 10-amps of power and it is one helluva performer. It will deliver some nice subwoofer bass if your subs are decently efficient. PA sub cabs @ 4-ohms work best. Car subs are not that efficient (low SPL per watt). For those just wanting a lower volume 2.1 home AV system (like for watching TV or on a computer), no need to upgrade the included AC/DC adapter. For me, why by a Corvette and drive it like grocery getter Camry?

I installed this amplifier in a modern pinball machine to improve upon the sound provided by the machine's built-in amplifier. Wow, it made a dramatic difference! I love that it has more than enough power to produce deep, rich bass in a JBL Stage 82 subwoofer while providing strong midrange and crisp highs in a pair of Kicker CSC5 coaxial speakers. I also like that the bluetooth functionality works reliably and seamlessly (when a bluetooth source is detected, it instantly switches from the wired input to the wireless input). Amazing for such a small amplifier!

This little amp is amazing. I use it only for bluetooth. I have 2 nice KEF bookshelf speakers attached, and it works flawlessly. The volume, bass and treble work perfectly. We had this onsite during months of house construction and it was the bomb.

Easy hookup. Excellent power.Blue tooth is easy. Great tone quality