Review wuzhi zk-1002 (mostly subjektiv)

[Skezza]

It sounds like when you first plugged in something shorted on the board, which could simply be down to a defective one off. More concerning, is it that the alternative is that it could be a sign of a defective design and this will become commonplace with this product.

I'm surprised they didn't include a USB cable for you to attach it to your PC.

Are they sending you a new one?

I'm happy to keep endorsing the Wuzhi ZK-1002 if you remove the two capacitors as per the instructions above. I've been using it the last week and the output is excellent now and cannot be faulted. I think the USB functionality would have been nice, but it's perhaps not 100% there yet.

 

[ClassicGuy]

I think it is shorted, as you said. I just started the return process, but will consider ordering another one to try. I do wonder if the USB functionality is quite there yet, because they don't emphasize that feature at all.

Glad the ZK-1002 is working out for you. It becomes a very economical and good solution for an amplifier.

 

[Skezza]

It's not just the economics, it's the size. Picking up a decent amplifier for cheap isn't that hard (although trickier during lockdown). Local car boot sales are full of old HiFi's that sell for peanuts. There's a Morphy Richards one just around the corner from me with two 40 watt speakers for just £10 all in. The attraction of these little micro amps is the size. I don't have space for a big amp and nobody cares about CD's and tapes and stuff anymore. It's Line-In, USB, and that's all we really need these days.

 

[ClassicGuy]

I just received another ZK-502H board, it worked. Here are the observations:

• USB works with Windows 10, sounds similar to AUX
• Didn't notice any issues with rolled off highs or lows in any of the input modes (I hope my ears are up to task here)
• Overall sound quality similar to ZK-1002T (my only reference)
• AUX-out is mutually exclusive with speaker out, so cannot use it to drive another active speaker etc.

Overall seems like an improved version of the ZK-502 board. It does not have treble/bass adjustment, but I don't need them.

 

[DjangoJI]

Hello good:
I am using the translator, in case there is a problem in the translation.

Seeing your reviews about the zk-1002 board and the modification of the C41 and C42 that improved the audio, I decided to buy the board for a project.

The problem is that I have received the image board, and it does not correspond to the zk-1002 that you have, and the photo of the advertisement.
From the tests that I have carried out, it is heard better by Aux than by Bluetooth. Background noise is heard over Bluetooth.

Do you know if this board is the zk-1002? Any improved version?
If I remove 103 will it sound better? I don't want to try in case I can't solder it again later.

Any recommendations for this board?

 

[Skezza]

Why not try it? See how it sounds....

 

[DjangoJI]

Why not try it? See how it sounds....

For fear that it does not sound, and having to re-solder them. I have a poor quality soldering iron and I don't know if I could solder them again.

 

[Ioannis]

Today i made the mod of C41 and C42. Surely made big difference in sound! Thanks to all good people that share the info.

I wonder if there is a way to disable BT when power up the amp. Anyone has any fix for that please?

Maybe it is better to directly feed the amp on 3116 input, but have first to find which is the input cap.

Ioannis

 

[AdamG]

Today i made the mod of C41 and C42. Surely made big difference in sound! Thanks to all good people that share the info.

I wonder if there is a way to disable BT when power up the amp. Anyone has any fix for that please?

Maybe it is better to directly feed the amp on 3116 input, but have first to find which is the input cap.

Ioannis

Welcome Aboard @Ioannis.

 

[gergreko]

Hi guys! I use a translator, so keep that in mind. Indeed, C41 and C42 affect high frequencies, but this zk-1002 board still has problems in the low frequency region - a drop of about 6 dB. To fix this, you need to replace the capacitors C37 and C39 with 300-500 nF. I only had 300 nF and this is already giving a good result - see the blue versus yellow graph (sweep tone 20-20000Hz). Ignore the high frequency region in the yellow graph - I just experimented with different inductors in the output filter, but then went back to stock inductors as they are better. So you have to remove C41 and C42, and replace C37 and C39 with 300-500 nF and you get a blue graph. Now great sound! Good luck!

 

[tomtoo]

I just received another ZK-502H board, it worked. Here are the observations:

• USB works with Windows 10, sounds similar to AUX
• Didn't notice any issues with rolled off highs or lows in any of the input modes (I hope my ears are up to task here)
• Overall sound quality similar to ZK-1002T (my only reference)
• AUX-out is mutually exclusive with speaker out, so cannot use it to drive another active speaker etc.

Overall seems like an improved version of the ZK-502 board. It does not have treble/bass adjustment, but I don't need them.

Thx for the info! Mutually exclusive makes it useless for me

 

[Ioannis]

Can the ZK-1002 start in AUX mode instead of Bluetooth? If i do not carry a bluetooth device to turn it off then it is useless...

 

[tomtoo]

Can the ZK-1002 start in AUX mode instead of Bluetooth? If i do not carry a bluetooth device to turn it off then it is useless...

Sry not shure if i get you? If BT is not connected, aux is active.

Edit says.: As long no bt device is connected aux works. If bt connected, bt works.

 

[Ioannis]

When I power on the unit (after power cycle) the BT is ON by default and tries to connect with a BT such as my mobile. I have to turn off my mobile BT and then the 1002 can work on AUX in.

It is very annoying.

 

[tomtoo]

When I power on the unit (after power cycle) the BT is ON by default and tries to connect with a BT such as my mobile. I have to turn off my mobile BT and then the 1002 can work on AUX in.

It is very annoying.

Ah ok, yes thats how it works. Was never a problem for me, bt on the phone is only on if i need to.

 

[ClassicGuy]

Thx for the info! Mutually exclusive makes it useless for me

I wish I can edit that post. Big warning, the ZK-502H board fails easily, so I do not recommend it any more.

 

[ClassicGuy]

When I power on the unit (after power cycle) the BT is ON by default and tries to connect with a BT such as my mobile. I have to turn off my mobile BT and then the 1002 can work on AUX in.

It is very annoying.

For this and other BT related reasons, I prefer amplifiers that either has a Bluetooth switch, or prioritize AUX input over BT. Those amplifiers are harder to find.

 

[Skezza]

Hi guys! I use a translator, so keep that in mind. Indeed, C41 and C42 affect high frequencies, but this zk-1002 board still has problems in the low frequency region - a drop of about 6 dB. To fix this, you need to replace the capacitors C37 and C39 with 300-500 nF. I only had 300 nF and this is already giving a good result - see the blue versus yellow graph (sweep tone 20-20000Hz). Ignore the high frequency region in the yellow graph - I just experimented with different inductors in the output filter, but then went back to stock inductors as they are better. So you have to remove C41 and C42, and replace C37 and C39 with 300-500 nF and you get a blue graph. Now great sound! Good luck!View attachment 132367

It doesn't look like a huge amount. What voltage cap?

 

[gergreko]

It doesn't look like a huge amount. What voltage cap?

I used 3 pieces in parallel 0.1uF X7R_50V_10% _0603 for each channel - they were under my pillow) You can use 0.47uF X7R_50V_10% _0603, it will be even better. Of course, if you're an audiophile, you can use film capacitors, but there is very little space on this board. In any case, the result will be good for this board.

 

[Jonny99]

Today i made the mod of C41 and C42. Surely made big difference in sound! Thanks to all good people that share the info.

I wonder if there is a way to disable BT when power up the amp. Anyone has any fix for that please?

Maybe it is better to directly feed the amp on 3116 input, but have first to find which is the input cap.

Ioannis

I got Zk-502c and wondering will it make a difference in sound if I do this mod? Or is it only for Zk-1002?