I purchased this zh-mt21 these days. I can assure you that it works very well with 2 speakers and subwoofer, and that there is no hiss when it is not playing music. I can't guarantee how long it will last, but for now it's perfect.

@AstrosElectronicsLab

Ай бұрын

Did you put it on an oscilloscope?

I also purchased a 2.1ch amplifier that uses an IC called "CS8673E". This amp also adds a lot of noise to the music. I understand how you feel. Let's throw this thing away! !

@AstrosElectronicsLab

Ай бұрын

At least I'm not the only one experiencing problems with this thing.

Even at 1 ohm nominal load it drives my 2600w quad 6 inch subwoofer to its absolute limit indefinitely all drivers and the twin ten inch passives reach full excursion. The only heat is the power leads running to the 12.6v batteries. For mids and tops I use 4 150w jbls running at a nominal impedance of 2 ohms... phenomenal little amp. Because of its analogue gain it is substantially louder than its big brother the 760w SY-S350H requires twice the voltage.. I wouldn't do what I do with it at any higher voltage tbh.

@AstrosElectronicsLab

Ай бұрын

I might have just got one with a bad batch of the fake output ICs.

@deepaknanda1113

9 күн бұрын

Mine is also running great.

In the reference circuit diagram of datasheet, I can see an inductor in the speaker output line, but I can't find an inductor in that product pcb. Is it possible to output from the Class DMP without an inductor?

Thank you You saved me from DS

I downloaded a ZK-TB21 manual (same controls, same claims) that shows large square type ferrite output inductors and not the tiny smd chip inductors that are on your board. The ZK-TB21 board uses TPA3116 chips, who knows what chip type is on your board ??. Also YOUR board defaults to BT operation when the 3.5mm input is unplugged and you may need to fit a solder bridge to connect the pcb BT antenna or fit an external antenna across the ANT pads on the pcb as shown in the ZK-MT21 manual.

I just got the mt21 as well... Hooked it up to an oscilloscope. And switching noise is really there. The way they implemented the filters is truly inadequate... I got it somewhat looking good by adding my own filters. But it sill looks quite horrible

I saw some kits says it has the tpa3116 d2 but when you remove the heatsink and you will see that same ic. It does not look like the real tpa3116 d2, but instead they mark the ic with tpa3116.

@AstrosElectronicsLab

7 ай бұрын

They're pretty much rubbish, to be honest...

Any idea how to repair not turning on? Cooling fans heat up fast but no power

@AstrosElectronicsLab

2 ай бұрын

On what amplifier? This one? It doesn't have fans.

@KAOSshortyrip

2 ай бұрын

@@AstrosElectronicsLab cooling fins* yes this exact model

@AstrosElectronicsLab

2 ай бұрын

@@KAOSshortyrip ah, right. In that case, it's most likely the chips themselves. I don't think these modules are even tested before they're sold! You could try replacing the chips, as they're getting hot indicates an internal short, or just request your money back.

Is the speaker or a dummy load connected during the scope testing ?......a load is required to load the output reconstruction filters, elsewise you can expect high levels of pulse noise. "Class AB amplifiers can run without load. Class D amplifiers should not run without load because the load is used to damp the LC output filter and prevent the filter-chokes from generating excessive voltages. Some class D amplifiers may survive running without a load, in particular if they are protected with catch-diodes."

@AstrosElectronicsLab

7 ай бұрын

Yes

@Amplified208

7 ай бұрын

I did see some surface mount Inductors on the outputs buy the ic but I don't think there adequate. Definitely need some improvement. And I agree when testing any classes of amplifier a outputs should be properly loaded.

@ericmc6482

7 ай бұрын

@@AstrosElectronicsLab You need this - www.ti.com/lit/an/sloa107/sloa107.pdf

@ericmc6482

7 ай бұрын

@@Amplified208 Do some searching on "measuring class d amplifiers" and you will find info you need. The takeaway is that the spikes on the output are normal and the loudspeaker inductance integrates the spikes so you don't get to hear them. Also you should be using scope in two probes differential mode to see what is actually across the loudspeaker.

@Amplified208

7 ай бұрын

@@ericmc6482 I have studied many designs on class d and proper scope techniques.but a bad design is a bad design now matter how you measure. Im also not a fan of cheap class d design for that reason. Now the Fosi audio Class d amps is done beautifully.

These little amps sound awesome, but I'm not so sure about your connections and testing methods.

@AstrosElectronicsLab

4 ай бұрын

It's connected correctly, as per the silk screen on top

Class D tpa3116 d2 Please tell me if this IC is good when available

@AstrosElectronicsLab

7 ай бұрын

It is, when it's not faked. This is the problem with so many components being manufactured in China (especially obsolete ones), %90 of them are fake/junk.

Get tb 21 it has the real ic

You probably bought one with a fake chip. These chips are notoriously copied. And since lot of noobs building audio systems can't distinguish between 60W and 100W subwoofer, it's easy to sell it to them. And to be honest, it will sound and play reasonably good for that price. Just for the next time, please use different scope. These "build your own scopes" are maybe even worse than the amplifier you are testing. If you want something cheap and reliable you can try something similar to ADS1013D. Simple reliable and surprisingly good Chinese oscilloscope.

They are selling this module with original chips u took fake chips in auction

@AstrosElectronicsLab

7 ай бұрын

Well, this wasn't from an auction, just a regular sale. But, it wouldn't surprise me if the ICs are fake.

hi sir i live in india this has arrived in india now tell me can i buy this or not i don't understand your technical

@NoneYaBiz200

5 ай бұрын

Not good according the review.

Looks like a noise loop

tb21 is way better..

@faristvtechtips8043

6 ай бұрын

I just bought it has really tpa 3116 d2 ic

@laszlo_d

6 ай бұрын

@@faristvtechtips8043 well i got scammed... my has the chinese mosfets but with nice inductors on the output... and has some power issues.... after on third of volume the satelites distort like hell... and im using a 20v 4.5A powersupply....

Wow, a poor design. 😂 which is a shame a proper LC is definitely needed lol

@AstrosElectronicsLab

7 ай бұрын

Yep. He offered me 3 bucks reimbursement if I changed my review from neutral to positive

@Amplified208

7 ай бұрын

@AstrosElectronicsLab lol well tell him to send proper schematics with components for proper RD, lol, but I don't blame them for wanting a good review. But in this day and age, you get what you pay for, unfortunately. It is not like your 15watt×2 project RD IS CRUCIAL

@Amplified208

7 ай бұрын

kzread.inforecRM7ue6ds?si=cXv56PT5RyP-L0lu

@Amplified208

7 ай бұрын

This is one of my old projects on my old youtube page. I did this class AB Amplifier. Great kit from LJM L10 kit from Amazon. I simulated this circuit on a android program called proto spent along time matching components but well worth the effort. The sound was outstanding.

Not worth the $2

an absolute dog

@AstrosElectronicsLab

7 ай бұрын

What, the amp? Yeah, it's pretty much junk.

@wizardx4187

7 ай бұрын

yeah it's a dumpster fire@@AstrosElectronicsLab