ZK-ST21 TPA3221 Bluetooth Power Amplifier Board with Subwoofer 2.1 Channel 100W×2+200W, 12V-30V Audio Power Amplifier Module with Treble and Bass Control

This is probably the 10th "Class D" amplifier card I've bought on Amazon. Being a 3rd generation woodworker, I like to install them into hardwood cigar boxes and put them up For Sale when complete. I even installed one into one of those junky little "Bass Cannon" 15-watt-glorified-toilet-paper-tubes. It isn't junky anymore. IT CRANKS, just like the others. I find that each one is a new "puzzle" in and of itself.I've got a very nice cigar box and a 200 watt unit hooked to this laptop, driving 2 SONY SS-ZX66i BIG bookshelf speakers, and a BOSS 10" DVC subwoofer wired down to 2 ohms, and mounted passively in a downfiring Klipsch box. Some may scream "BLASPHEMY", but the Klipsch speaker was wrecked, and the amp plate was blackened...UPDATE: The two pictures above are the cigar box I mentioned, after removing the 200W board, and modifying the faceplate to fit the new 500W board... I designed the labels myself, printed them on my laser printer, cut them out with a sharp scissors (14 attempts to satisfy my OCD), and glued them in place... It was tough, as this board is bigger than the old one in every direction... I had to modify all my previous wiring to make it fit the back side... It was another GREAT puzzle...So......a few weeks ago, "540 Watts" jumped off the Amazon page and bit me. Could it be true?? I thought about it, did some homework, and finally bought one to try it out. Lemme tell all of you: "They" got it RIGHT when "they" designed this little beast of an amplifier, whoever "they" are. This thing is SOOPER LOUD!!! I'm talkin' BLOW THE ROOF OFF loud. And that was using a 24VDC 2A power brick. My 36V 9A MeanWell power supply is on the way.-------------------------UPDATE: Getting the MeanWell 36VDC power supply from Amazon was like getting a shark to hold still while pulling it's teeth out... But it finally arrived... Lemme tell you about !! W-O-W !! What a ride!! I think I broke a different kind of sound barrier than planes. This amplifier is insanely LOUD, and clear sounding, when you get it dialed in to your taste. I listen to Hard Rock/Metal, and this thing will melt your eardrums. I can't pinpoint what 500 watts actually sounds like, But, it's gotta be close. It's infinitely louder than all the other 200 watt boards I've bought in the past.-------------------------When I opened the box, it was very well packed in plastic bags and bubble wrap. You have to mount the top and bottom panels onto the amp card, using stand-offs. That's all the assembly there is. I hot-glued the 2 capacitors down, 'cuz they were, well, just not glued down. And I removed the fan/heatsink and repasted the 2 main chips with Arctic MX-4 thermal compound, instead of Chinese toothpaste.It's rather clear sounding, but not the best I've ever heard. But there's ALOT of variables that define "clear" sound. It's not all about the amp itself. The speakers, the subwoofer, the wiring, and the room shape & furniture all play a role in that definition. Hook up junky speakers to it, and you'll get a junky sound. Drive it with 2 amperes, and it'll be cutting out every time you hit the volume or bass. Just like anything else, what you put into it will determine what you get out of it. This new amp may very well replace my first 200 watt amp, described above. UPDATE: IT HAS...160 watts X 2 (L & R) + 220 watts (Subwoofer) = 540 watts. Now, I know those are PEAK numbers, not RMS. But I'll bet this amp will do every bit of 350 watts solid with the right hardware hooked to it. I found a PEAK->RMS formula that said "...multiply the PEAK wattage by 0.707 to get an approximate RMS wattage..." I don't know how accurate the formula is, but I came up with 380 watts. It's hooked to a pair of large SONY 4 ohm bookshelf speakers, and a BOSS 10" DVC 4 ohm subwoofer, wired down to 2 ohms or less. I can work with the 380 watt estimate. It is SO loud, my dogs got up and walked out of the room. My subwoofer "dances" across the floor. My neighbor called me asking if they opened the Club downstairs early. A friend asked me what I was gonna use it for. I said, "1) disturbing the peace, 2) rattling my windows, 3) melting my eardrums, and 4) taking over the world... MUAHUAHAHAHAHA".For those of you who like it LOUD, and already have or will buy a MEANWELL 36VDC power supply, GET YOU ONE OF THESE BAD BOYS, and CRANK IT UP. For mobile use, a DeWalt 20VMAX 3Ah or 5Ah battery works GREAT, although you won't get the 500 watts out of it. You should definetly use a multi-meter to test the voltage proposed. Anything over 36 volts may cause problems, up to and including failure.BUY ONE, YOU WON'T REGRET IT, UNLESS YOU CAUSE YOURSELF PERMANENT DEAFNESS...AND YET, ANOTHER UPDATE, 1 YEAR LATER:Well, it took me a year, but I did it now... I can only make a presumption about the cause, but I've BLOWN IT OUT... I blew out the subwoofer chip - see the 3rd pic above... Oh well, snot happens... EZ-COME-EZ-GO [Tesla]... My presumption is that having a big 10" dual voice coil subwoofer wired down to 2 ohms (or less) is the most-likely culprit... So, I'm gonna buy another one... And if it lasts me a year, it'll be all good... I'm not really bothered by it, because it has rattled my eardrums and my windows very nicely for the last year, and I know another one will do the same... No harm, No foul...Good Day!!!

Low volume, bass control seems to be a boost not a low pass filter, at 36 volts I never got over 2 watts out of it....

I used this with a 36v battery in a portable audio enclosure and it works awesome. However beware if you are running speakers that are 4ohm it is NOT the same power. The max wattage output is for 2ohm. Theres nothing that tells you that other than on the bottom of the amp

Let me first start off by saying that I'm an audio guy. I've installed aftermarket stereos in my cars, I have expensive home theater setups, and my office desk is held up by solid wood speakers from the 70s. I know good sound when I hear it.When I first got this, there didn't seem to be much to it. No huge coils on the circuit board, like you would expect from an amplifier that puts out this much power. The largest things are two capacitors; one on each side.The instructions are very basic and there weren't any instructions on how to put the pieces together, but it's not hard. Screw on the bottom > bottom cover > short standoff > circuit board > long standoff > top cover > top screw. Easy!I bought a 36V DC power supply for this, so that I could get the most power out of it (lookup: Aclorol 36V 10A 360W Switching Convert Power Supply Universal Regulated AC Adapter for LED Strip Pixel Lights CCTV Camera Security System Radio Computer Project).When powering it on, it's best to already have the power plug inserted into the circuit board. Otherwise, it will arc a little. 36 volts, after all...The Bluetooth pairing isn't exactly as the instructions said. I have a Pixel and maybe the Android is different than an iPhone, but I only saw two entries that were exactly the same - Wuzhi Audio. But one had a Bluetooth logo and the other had a headset. Pair the headset one. Oh, and you have to turn the unit on via the volume control, before it will start the Bluetooth.After I paired my phone, I connected two EV C8.2 speakers and a Rockford Fosgate 10" sub. The speaker terminals could be a little larger. They are TINY. But I got them screwed in.Once I started playing a song, I was blown away with the amount of volume that this thing can put out. The sub was shaking the walls!The instructions don't give you ANY clue as to what the crossover frequency knob settings are, so I kept mine at the lowest setting, thinking that would keep the crossover frequency low.As for the Bluetooth volume, I didn't use the tiny little control arm on the right side, I just turned it up on my phone and that worked. I'lll also never switch between Bluetooth, USB, and AUX, so that switch really doesn't matter to me.The fan turns off and on while it's playing but it's not loud at all. You can't even really hear it.This thing is like the Bluetooth speaker I wish I've always had! Would definitely buy it again!

When it comes to powering 6-1/2” components speakers and a 8” sub with a “300-600” watt max handling this amp provides. You have to have the 36v power supply or you will not get its full potential. All the bad reviews on every single amp like this one is from people that don’t understand watts/voltage and ohms. With the correct power and speakers this amp will get loud and all the quality you need, if you do it right.

took too long to try it out, but Dead out of the box junk. don't waste your money on this cheap quality amp.

Cons: Don't use the bluetooth features, you need an app and the functionality is absolutely limited. It's barely usable to control volume.Pros: Ignoring the lackluster BT connectivity capability, this amp packs some serious power. I'm using a pair of JVC 20W bookshelf monitors, and a pair of 400w JBL 10" subwoofers. Coupled with a 36V 30A power supply, this little amp has had absolutely no problem making my walls shake. I don't need to turn it up more than a few clicks, and it's loud enough to hear across the whole apartment. It's so small that all of my other electronics in the same cabinet dwarf it by far, with the humble Wii being about 3-4x bigger and it's the smallest console in the cabinet.That lacking BT connectivity knocks off a star. Otherwise it is a decent product.