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Review wuzhi zk-1002 (mostly subjektiv)

tomtoo

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#1
I was intersted in this thing just out of curiosity. Had a 24v/3amp powersupply useless hanging around. So 17€? Why not?
Ok order at amazon.de 2 days later arrived.

https://www.amazon.de/gp/aw/d/B086R..._1?ie=UTF8&psc=1#immersive-view_1595664120952

Nice little package. Screwed it together, nice even one more screw than needet.
Ok lets test two tpa3116 in bridge mode.
Blue tooth works flawles with androide and win10 realy fast connection without distourbing voices. Even at full gain no noise. Power for this little thing even with only 24v/3amp is realy not bad. So estimated clean 2*20w at 4ohms makes it easy.
So you could say nice product for the money? NO! There is the aux-in and this is horrible. Highs are gone! I found this on inet
http://www.hifi-forum.de/viewthread-331-3-24.html#1152

I cant measure but the measurements fit well to what i can hear.

So overall it is a nice unit if you dont need the aux-in. If you need aux-in i would not recommend, at least not if you cant eq the source.
 
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tomtoo

tomtoo

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Thread Starter #2
Update: Whuzi zk-1002T

So i got now a zk-1002T nearly the same like the zk-1002 but change5d preamp. Has now bass and treble adjustment. And that unlinear aux in is MUCH better. Overal this is now a very nice little cheap amp. No complains for 25€ this is a nice build. So i would recomend the zk-1002t. Dont buy the 1002 buy the 1002t. With the right power Adapter this little thing can make a lot of fun.
 
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tomtoo

tomtoo

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Thread Starter #4
Hi @tomtoo, can you tell us if zk-1002T has completely fixed the high/low frequency losses, or just improvements. Somebody on Amazon posted a comparison graph between the old zk-1002 and another board based on TDA7498E, and the difference is significant. https://www.amazon.com/gp/customer-...ef=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B081SXYSFW (also do you have the frequency graph for the new board?)
Iam sry but i cant measure. I can only tell that i cant recognize any high loos
Hi @tomtoo, can you tell us if zk-1002T has completely fixed the high/low frequency losses, or just improvements. Somebody on Amazon posted a comparison graph between the old zk-1002 and another board based on TDA7498E, and the difference is significant. https://www.amazon.com/gp/customer-...ef=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B081SXYSFW (also do you have the frequency graph for the new board?)
Iam sry but i cant measure. I can only say that there is no hearable high loos on aux-in any more. With the old you could hear easy the problem, thats no more. Iam happy with the new one, works very well for the price.
 
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#6
I purchased this amp and just received it today. As described, lovely little package and the Bluetooth audio is superb... But oh no... The Aux in :( it's almost like you are running your audio through some kind of audio encoder at 96k mp3. It's dull and lifeless.

Is there any known mods that I can do to fix this? I bought it off Ali so sending back isn't much of an option.

@tomtoo Is the Whuzi zk-1002T that much of an upgrade?
What about the 50w versions like ZK-502L or ZK-502C ? Might these be better?

I just need a mini amplifier to drive a set of HiFi speakers. I don't want to build anything custom. Just something off the Aliexpress shelf that doesn't cost me a fortune. If the Aux-In had worked as well as Bluetooth, this would have been perfect. Hence if it can be modified, I'm up for that....

I've also been reading about TDA7498
https://a.aliexpress.com/_B1IGLh

Which seems a little more hobby craft in design but apparently a better sounding amplifier? Although it's a direct competitor to tpa3116.

Anyone fancy helping a total noob?
 
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tomtoo

tomtoo

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Thread Starter #7
Like i told if you need the aux in buy the 1002T. The 1002 aux in is NOT useablle. With the 1002T this problem is gone. About the 50W versions i cant tell anything.
 
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#8
Like i told if you need the aux in buy the 1002T. The 1002 aux in is NOT useablle. With the 1002T this problem is gone. About the 50W versions i cant tell anything.
I only saw your message today after googling "wuzhi aux in" :( it's too late for me. Turns out, you and others already had posted about it but I didn't look before buying.

Is my best option another TPA3116 in the form of the 1002T or TDA7498 which you also mentioned?

This is a 50w TPA3116:

https://www.ebay.co.uk/itm/TPA3116D...-/284092233641?_trksid=p2349624.m46890.l49292

It's a shame there's no modifications to fix it. The audio is so crisp on the Bluetooth input :(
 
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tomtoo

tomtoo

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Thread Starter #9
I only saw your message today after googling "wuzhi aux in" :( it's too late for me. Turns out, you and others already had posted about it but I didn't look before buying.

Is my best option another TPA3116 in the form of the 1002T or TDA7498 which you also mentioned?

This is a 50w TPA3116:

https://www.ebay.co.uk/itm/TPA3116D...-/284092233641?_trksid=p2349624.m46890.l49292

It's a shame there's no modifications to fix it. The audio is so crisp on the Bluetooth input :(
Someone mentioned a fix, but i cant find it any more. It was just cutting out two capacitis. Maybe you can find it? About tda boards, i cant say anything. The 1002t does what it should, i play a dab+ radio over aux and the smartphone over BT. Nice littel amp that works flawless. I prever that wuzhi amps, couse they have nearly a case. I mean they are ok for the workbench in the basement or a garage.

Edit says: The problem with this chipamps is that the chips are good but the implementation can suck. So its more having good luck with the implementation.
 
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#10
Someone mentioned a fix, but i cant find it any more. It was just cutting out two capacitis. Maybe you can find it? About tda boards, i cant say anything. The 1002t does what it should, i play a dab+ radio over aux and the smartphone over BT. Nice littel amp that works flawless. I prever that wuzhi amps, couse they have nearly a case. I mean they are ok for the workbench in the basement or a garage.

Edit says: The problem with this chipamps is that the chips are good but the implementation can suck. So its more having good luck with the implementation.
Was the fix posted on this forum? I'll have a good look. It's worth trying to fix before I chuck. I have it hooked up to a good power supply.

Yes, I also like the design. They're a nice balance between minimalist and actually usable. The circuit board with cover and proper power etc. These ones that don't even have proper power sockets are too hobby craft for me.
 
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tomtoo

tomtoo

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Thread Starter #11
Was the fix posted on this forum? I'll have a good look. It's worth trying to fix before I chuck. I have it hooked up to a good power supply.

Yes, I also like the design. They're a nice balance between minimalist and actually usable. The circuit board with cover and proper power etc. These ones that don't even have proper power sockets are too hobby craft for me.
I think it was in a comment on amazon.com. But iam not 100% shure.
 
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#12
I think it was in a comment on amazon.com. But iam not 100% shure.
I found it:

Hi Davide, regarding WUZHI AUDIO ZK-1002 board I have notice exactly the same issue on the line In input. yesterday I have analysed the circuit and found that the problem is due capacitor C41 and C42 that are connecting que input signal after pass through a resistor to a ground before connect to the bluetooth IC. I have just removed these capacitors and surprise, now the sound is full of bright.

I'm going to attempt this mod. Returning on AliExpress from UK is futile lol. Disputes are even more pointless :D
 
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tomtoo

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Thread Starter #12
I found it:

Hi Davide, regarding WUZHI AUDIO ZK-1002 board I have notice exactly the same issue on the line In input. yesterday I have analysed the circuit and found that the problem is due capacitor C41 and C42 that are connecting que input signal after pass through a resistor to a ground before connect to the bluetooth IC. I have just removed these capacitors and surprise, now the sound is full of bright.

I'm going to attempt this mod. Returning on AliExpress from UK is futile lol. Disputes are even more pointless :D
Cool! If you try it, and it works, i would be happy if you could tell. I know its not the money that couse that little anger, it's more hey this little thing could be great if the aux-in is fixed. ;)

Edit says:Btw this little tpa3116 amp that you linked is interesting with the line out and usb in. Maybe i test it just for fun.
 
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#13
Cool! If you try it, and it works, i would be happy if you could tell. I know its not the money that couse that little anger, it's more hey this little thing could be great if the aux-in is fixed. ;)

Edit says:Btw this little tpa3116 amp that you linked is interesting with the line out and usb in. Maybe i test it just for fun.
I'll do a video of Bluetooth, Aux-In Before mod then Aux-In after mod although probably my phone camera won't be able to pickup the quality differences through the little microphone :( I could try recording through a condenser mic ?

Totally agree it's not the money issue. This only cost around £11 delivered to my house. That's about two pints of lager :D I suppose the only other issue is that there's no easy answer of which to buy. Some are obviously better than others but the review thread is like 1000 pages long and some are hobby craft, some are finished... I found nothing on the above one I linked from eBay which is also only 6 quid on AliExpress. It becomes a lottery to if it works :(

If this works though I'll post back and then people can be aware of the improvements by this product.
 
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#14
I'll attempt this mod today (it's slightly early at the moment ;) ). Just setup a mini sort of, test rig to record bluetooth, before, after. Going to use a Condensor mic which is fine although I sometimes have problems with it being too sensitive so I'll have to knock the gain right down.

Having looked at the board, it'll need a steady hand and probably a set of tweezers if you have any. You might be able to just push it off the board though. I don't think a hot air gun is necessary and might even be harder. I'll see if any of my tips for my air gun are small enough though.
 
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#15
It's actually worse than I thought. Using an Aux cable from my phone which is low input, I think the amp is able to boost some of the frequencies more which gave a bit of warmth to the sound. When I went from my PC which is a very hot input, the audio quality is actually laughably bad. I even tried a second cable because I was convinced it was that bad. I will put up my evidence soon. I am about to perform this mod in the next few mins.
 
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#16
Well great news, I can report back that this mod has made a big difference to my little Wuzhi amp and I have the evidence to prove it.

Now I'd be lying if I said this was anything other than unscientific. It's surprisingly hard to match the output volume of Bluetooth and Line-In and even different Line-In's which seems crazy but is true and I've struggled with. Of course, once the caps are gone, they're gone. :)

Bluetooth from my phone seems quite hot. Aux-In from my phone seems really quiet. Aux-In from my PC seems very hot. I also realized the audio output might not be the same from all sources, but you can only try your best, which I have :)

I recorded using a Condenser Mic which isn't designed for this job and isn't going to pickup the best sound. Even so, I think you can hear the difference, before and after. The speakers are Kenwood LS-VH7 which are your typical HiFi speakers. Not overly cheap but nothing spectacular either, good mid-rangers.

I need to work out a way to upload the audio now as even compressed, the uploaded files are too large. Could try YouTube or just banging them onto my web server.

As for the actual desoldering, not as challenging as expected (although I do quite a lot of funky soldering so I'm reasonably experienced)... I opted for an iron with a thin pointy tip + flux. I think the components are a bit too close to each other for air gun. I used tweezers to help prize them off the board but really, it doesn't need an expert. Fairly novice stuff.

These are what need removing:
IMG_20210118_084847.jpg



After removing caps and yes, I did desolder them on top of the HiFi speakers... which is where they still are :D :
IMG_20210118_122823.jpg


Recording:

IMG_20210118_102614_1.jpg
 

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tomtoo

tomtoo

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Thread Starter #17
Absolutly Cool! Toghether we are strong!! I try to use a cutter knife. But hey its cool that it works!
 
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#18
I think a cutter knife would probably work yes. Just be extra careful when doing it :) I still plan to upload video but just not had an opportunity yet as I have to download Windows Movie Maker which is stupidly hard to get in 2020 :D
 
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#19
I've uploaded the video. I have some additional clips that can also be uploaded if you're curious. Interestingly, some of the volume differences have now disappeared after removing these two caps. I wonder if the aggressive curve sucked some of the volume out as well?

I also recorded a step after removing the C42 Cap (this is the easier of the two to remove, so I did first). You can hear the difference instantly. I think removing both is best though. Unfortunately, there was a little bit of clipping on the first Bluetooth sound recording which is why it's pushing the edges slightly at the beginning. Nothing to do with the amp. My fault. Had the gain up too high on the mic.

Hope you like Hot for Teacher by Van Halen lol :p

If you haven't worked out.... I'm dreadful at video making :)

Don't get me wrong, this little amp isn't perfect. I'm confused at why Bluetooth is still on, when the amp is switched off (which is also mentioned in other forums) but this mod takes it from being junk to being very much usable :)
 
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tomtoo

tomtoo

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I've uploaded the video. I have some additional clips that can also be uploaded if you're curious. Interestingly, some of the volume differences have now disappeared after removing these two caps. I wonder if the aggressive curve sucked some of the volume out as well?

I also recorded a step after removing the C42 Cap (this is the easier of the two to remove, so I did first). You can hear the difference instantly. I think removing both is best though. Unfortunately, there was a little bit of clipping on the first Bluetooth sound recording which is why it's pushing the edges slightly at the beginning. Nothing to do with the amp. My fault. Had the gain up too high on the mic.

Hope you like Hot for Teacher by Van Halen lol :p

If you haven't worked out.... I'm dreadful at video making :)

Don't get me wrong, this little amp isn't perfect. I'm confused at why Bluetooth is still on, when the amp is switched off (which is also mentioned in other forums) but this mod takes it from being junk to being very much usable :)
Very cool! No its not perfect. But also its not junk. A littel bit of a big mouth, but hey ;). As a oldie, iam amazed what comes out of this thiny bit of a "I want to be a big amp“. ;)
 

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