ZK-TB21 Bluetooth 5.0 50W+50W+100W 2.1 Channel Subwoofer Amplifier Board TPA3116D2 HiFi Treble and Bass Control Stereo Digital Audio Amp Board for Home Theater DIY Speakers

I am an avid audio addict. I have a massive collection of audio gear from high end vintage stuff like luxman, b&k, marantz, hk and many more as well as 20+ pairs of great speakers, mostly vintage "Heritage" Klipsch. I bought one of these on a whim because I wanted to out some speakers and small subwoofer I to one of my old cars but I wanted to keep the factory stereo head unit in it for the look and hide a small Bluetooth, 12v amp in the glove box. I hooked this up to 2 blaupunkt 6x9's and a 6.5 inch Boston subwoofer and holy crap it sounds fantastic! I have several vintage vehicles and I will be ordering 10 more of these to keep for future conversions. It punches way above its weight class, sounds clean, and clear. I highly recommend!

Design quality is surprisingly decent. It is not fully enclosed and the sides of the box are open just like the pictures, but the PCB, solder quality, silk screen, etc are all pretty good. Components are obviously not name-brand, but off-brand resistors/capacitors/etc are OK now days it seems like (not sure about long-life though). Bluetooth connection range is OK, reaches through 2 walls in a house at least, but there was a random clicking noise in the bluetooth audio mode even when up close. That's fine for me since I'll be using the 3.5mm jack which doesn't seem to have any audio distortion that my ears can pick up. But I'd be cautions buying this if you plan to use it and use the bluetooth. Power output seems sufficient. They always lie about the "max output" on pretty much all audio equipment, but the same is true for speaker input wattage. I'm running this with about "2x40w rms" car speakers on each channel, 4 total speakers, and it is more than loud enough without clipping, powered through a 20a relay the car battery 13.5v source.

using for a van office build ... 2.1 computer setup this thing blasts loud and clean on house battery bank: 13V takes only 0.25 Amps at 75% volume. Definitely more sound than my ears can handle. CON: no Aux filter .. laptop is giving out noisy signal, this thing has NO signal cleaning (for ex: prior Logitech 2.1 setups clean Aux incoming audio nicely) .. so only works well over bluetooth .. so pray the connection is stable.

I bought this product like 2 weeks back, this product was excellent it blown my mind. I giving this a power supply of 12v 3a still working perfect with my 30w woofer+20w tweeter 4ohm bookshelf speakers and 100w 4ohm Sony subwoofer. It has good sound quality and nice power handling. This security mechanisms works excellent. Like the auto power cut off, or else the short circuit protection and over voltage and under voltage. Everything works perfect. Ease of use, easy setup. Nice and fast Bluetooth connectivity. Great durability, I dropped it from my table still it good doesn't have a scratch on the body. Small in size fits perfect on my desk.

I got this ZK-TB21 for just under $20. It's wild something so cheap sounds this good. I hooked it up to some older NHT speakers (A450 bookshelf pair and SW2Si subwoofer) and it's great. Don't expect it to match $5,000+ tier amplifiers, but as long as you get some good speakers, it will treat you well.

Bought this as a stereo amp for my campervan, to power the built in speakers from the original TV sound system it came with since I updated to a newer TV, and also had the idea it would power a small home entertainment subwoofer as well. It does that just fine, ant having a subwoofer frequency adjustment is REALLY nice, so I can turn it down low enough to not sound too boomy at certain frequencies and only comer the low end stuff that the speakers can’t. I’m sure the ratings are a bit exaggerated (or are only peak ratings at best), but it’s nice, small, clear sound, and I like it. With my particular kit, assembly was required, but not too difficult. All around pretty nice!

Sounds great. The subwoofer channel seems a little underpowered, but still sounds good. I've had similar models where the high channel and the sub channel each had a volume control, and then a master volume. You could get more out of the sub channel with that setup. But again, this amp sounds great

Worked ok for 2 months, then stopped working. While it was working it did emit a low buzz. Seems to be very low quality item. Not sure what warranty or recourse the buyer of this item might have. Suggest avoiding purchasing this.

Ficou mais barato montar o som.

This is one of the best 2.1 channel amp. I had oneplus q2 pro 65 inch tv and the tv stopped working after a year but the tv had best sound system ever,i never saw a tv with such sound system. So basically i wanted to reuse that sound system with my new lg c4 so i took out the speakers subwoofer and the tweeters from oneplus tv but the sound system was passive and needed an external amp to drive them. I ordered couple of amps before but they were giving good sound quality. Finally i ordered this amp with seperate channel for subwoofer and it works amazing. For now I’m using it via Bluetooth and the sound quality + bass levels from subwoofer are 8.5/10. I imagine how good the quality will be via wired connection,so i have ordered DAC,digital optical audio cable,aux and i know it will sound much better via wired connection. I have checked all the 2.1 amps on amazon some good brands are above 8k and the ones under 8k aren’t good. Don’t judge this amp considering its cheap price,just buy right away. Only thing i am concerned about is its logetivity since it has no warranty. Rest i can assure you that its the best amp.

EXCELLENT PRODUCT. IT CHANGE THE QUALITY OF SOUND... :-)

I bought this on an impulse when I found an unused passive sub, so that I could get better desktop sound. There are no instructions/manual/documentation but fortunately this product is globally popular so there was enough help going around. It was an easy setup, and when i first played it, I nearly fell off my chair - my cheap setup sounded like something 4-5 times this price. I am using the amp with 2 basic Micca bookshelf speakers and a Tribit passive sub from a cheap soundbar. If you shut your eyes, the setup has the sound of much bigger and far more 'evolved' speakers. I paired it a decent power supply that I had bought for an old Topping class D amp. The bluetooth works well and pairs fast - a little too fast sometimes since it aggressively connects with previously connected devices as soon as they are in range. The sub crossover is a little difficult to get right since there are no frequency markings. A curious thing that I found on the amp board is that it has expansion ports for mics (I think) and for some other functionality. There is no mention of this online. I would have bought this much earlier if it hasn't looked so ugly :) but after hearing it perform, you can forgive that easily at this price. So good!

Quality is good but The 2.1 amplifier arrived without the screws and pillers ​Could you please assist me in obtaining the missing parts?