Review wuzhi zk-1002 (mostly subjektiv)

[tsakaji]

Hi guys, i have a ZK-1002T and i think it's a bit harsh on the upper range. I can hear noise if i put my ear near the tweeters of my 2.0 two-way stereo speakers. Also, i have ear fatigue from prolongued listening.

I read about putting a Bootstrap snubber in diyaudio, but i am not sure where should i solder the components (10ohm resistor and 330pf cap).

I'm a bit electrical and repair stuff from time to time, but this Class D amplifiers are new to me.

Main Volume pot is 10k.
Bass and Treble pots are 50k each.

If i put the treble pot to the right (increasing), the noise is much more apparent.

If there's another mod that would make this little amp more pleasant to hear, i'm open to your ideas.

Thanks in advance.

 

[tomtoo]

Hi guys, i have a ZK-1002T and i think it's a bit harsh on the upper range. I can hear noise if i put my ear near the tweeters of my 2.0 two-way stereo speakers. Also, i have ear fatigue from prolongued listening.

I read about putting a Bootstrap snubber in diyaudio, but i am not sure where should i solder the components (10ohm resistor and 330pf cap).

I'm a bit electrical and repair stuff from time to time, but this Class D amplifiers are new to me.

Main Volume pot is 10k.
Bass and Treble pots are 50k each.

If i put the treble pot to the right (increasing), the noise is much more apparent.

View attachment 151726
If there's another mod that would make this little amp more pleasant to hear, i'm open to your ideas.

Thanks in advance.

Hi! So you have no input source, means no cabel in aux in, and you have some noise?
At which volume?

 

[tsakaji]

Hi! So you have no input source, means no cabel in aux in, and you have some noise?
At which volume?

Thanks for your response. I just tested and when i remove the aux in cable, the speakers are silent, no noise.

Perhaps it's my source (computer motherboard audio), because when music isn't playing, i can hear the noise. At all volumes, but at medium and high volume i can definitely hear it sitting next to it.

Maybe i just need a DAC.

Edit: Just tested using my smartphone as source. Noise is still present, but is less apparent in volume than PC, and i still think music is a bit harsh.

 

[tomtoo]

Thanks for your response. I just tested and when i remove the aux in cable, the speakers are silent, no noise.

Perhaps it's my source (computer motherboard audio), because when music isn't playing, i can hear the noise. At all volumes, but at medium and high volume i can definitely hear it sitting next to it.

Maybe i just need a DAC.

Ok, at least we have learned its not amp self noise. And now the shit starts, where does it come from?
If your computer is connected, but switched off, whats with the noise?

 

[tomtoo]

Ok, if your smartphone is not connected to usb, and you go out of headphonejack.
My feeling is strong, your aux cable is shiit.

 

[tomtoo]

Harsh? Ok, a problem could be to find the middle of that treble poti?

 

[tsakaji]

Ok, at least we have learned its not amp self noise. And now the shit starts, where does it come from?
If your computer is connected, but switched off, whats with the noise?

Noise is still present in that case.

 

[tsakaji]

Ok, if your smartphone is not connected to usb, and you go out of headphonejack.
My feeling is strong, your aux cable is shiit.

It might be. My aux cable is Serve Shield and doesn't have too much copper wire around the conductors (L and R).

I'll buy a foil shielded cable and try. I'll post a response of that matter in a couple of weeks when i get the cable. I'm looking at a ecosurvivor 3.5 mm aux cable dual shielded at Amazon and seems good. But i'm open to suggestions, any brand you recommend?

 

[tsakaji]

Harsh? Ok, a problem could be to find the middle of that treble poti?

I don't know what do you mean. Could you please explain?

What i mean with harshness is that after a couple of minutes i feel my ears fatigued, at low and medium level of volume, near and far from the speakers. Treble is dull.

 

[tomtoo]

I don't know what do you mean. Could you please explain?

The mid is the 0 position and its not marked. So you have to find the mid by ear. Or estimation.

 

[tomtoo]

It might be. My aux cable is Serve Shield and doesn't have too much copper wire around the conductors (L and R).

I'll buy a foil shielded cable and try. I'll post a response of that matter in a couple of weeks when i get the cable. I'm looking at a ecosurvivor 3.5 mm aux cable dual shielded at Amazon and seems good. But i'm open to suggestions, any brand you recommend?

Sry dont like to recomend a brand. I just can say there is a difference between ultracheap and some proper cable you can find lets say at thomann.de

 

[tsakaji]

The mid is the 0 position and its not marked. So you have to find the mid by ear. Or estimation.

I always listen music with the treble pot at 1/3 turn. Apparent middle is too scandalous.
Perhaps the harshness is the EMI noise induced in the poor shielded cable that is amplified along with the music.

 

[tomtoo]

I always listen music with the treble pot at 1/3 turn. Apparent middle is too scandalous.
Perhaps the harshness is the EMI noise induced in the poor shielded cable that is amplified along with the music.

Dont know hard to say over distance. I can only say from comparing and hearing at near mid treble position FR sounds linear to me.
But if you have realy much noise from cable a lot is possible.

 

[tomtoo]

I always listen music with the treble pot at 1/3 turn. Apparent middle is too scandalous.
Perhaps the harshness is the EMI noise induced in the poor shielded cable that is amplified along with the music.

Btw, what happens when you use BT?

 

[DilshanM]

Hi folks, I just received my ZK-1002 amplifier and its works perfect. But when it comes to AUX its worse than I thought. Highs are gone but it not a problem. (It can be fixed). When I connect the aux cable, its getting noise from the line in even its not connected to any source. I think its coming from the cable.(Maybe I'm wrong). Is there any way to eliminate the noise without changing the cable?

 

[tomtoo]

I think this is the same https://fosiaudio.com/products/fosi...o-stereo-bass-amp?_pos=2&_sid=b2abac960&_ss=r

I think so too. The difference is that Fosi is printed on. And i not understand why there is a "subwoofer-amplifier-board-" in the description, Couse it is not, maybe you could ask fosi? See after your first posts i have the impression you like to advertise fossi. So you have maybe better connections to fossi, and with that connections you can maybe help to change this missleading description?

 

[ogonex]

Hello. I have also found this version:

2.99US $ 69% OFF|Kompatybilny z Bluetooth 2*50W 2*100W AUX TPA3116 karta do cyfrowego wzmacniacza mocy 2.0 CH Stereo do domu z motywem muzycznym moduł bezprzewodowy Audio AMP|Wzmacniacz| - AliExpress

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pl.aliexpress.com

Version name C100H

This works as a USB sound card

 

[ogonex]

Użyłem 3 sztuki równolegle 0,1uF X7R_50V_10% _0603 na każdy kanał - były pod moją poduszką) Możesz użyć 0,47uF X7R_50V_10% _0603, będzie jeszcze lepiej. Oczywiście, jeśli jesteś audiofilem, możesz użyć kondensatorów foliowych, ale na tej płytce jest bardzo mało miejsca. W każdym razie wynik będzie dobry dla tej płyty.

0603 i a small one oryginally there is size of this capacitors 100nF 0402. You can barely see it

I will try to do it with 0805 470nF/50. My problem is that i use old non Pb free Sn ;-) is a place there for 0805 in Your opinion?

 

[ogonex]

@All

@All: Is it possible to connect the zk 1002 to a computer via bluetooth? My Win7 didn't see it.
Regards
ps. I just removed the C41 / 42 and now AUX doesn't cut the higher frequencies

The ZK-1002 shows that the output filters are of good quality. Good inductors and film capacitors. The ZK-1002T is clearly inferior.
If someone is looking for a good digital amplifier with a good D/A converter and bluetooth 5.0 supporting lossless formats, you can buy one for 10 liters of beer and in a nice aluminum housing This amplifier is of very good quality and high power TPA3255 from TI

76.61US $ |Tpa3255 Bluetooth Amplifier Audio Amp 325wx2 Stereo Class D Bluetooth 5.0 Sound Amplifiers Dac Pcm5102 Decoding - Home Theater Amplifiers - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

example how to fix input filters in ZK-1002. Input circuit diagram here you will also find:

 

[Bogibig]

Hello, I removed the capacitors C41 and C42 - high frequencies are clearer.
I have a question if anyone tried to remove the C37 and C39 capacitors and not add others.
I understand that capacitors are responsible for filtering high and low frequencies at the input, which cuts the characteristics.