Exposure of a fake Chinese tube amplifier Nobsound MS-10D MKII.  What do professionals think?

 

 

I disassembled a Nobsound MS-10D MKII and found it was an imitation of a tube amp. An empty box was attached on the top of the amp, that pretends to look like a real tube amp. In the box suppose to be three transformers. One is for power and two for each channel for matching tubes with speakers. 
There is only one power transformer under the box, which delivers 17V to output transistors, 7V to microchips and 6.8V to tubes. As we see there is not the high voltage for the tubes. The transformer is not high-quality, noisy. I had to repair it. 
 

The Amplifier without tubes or without at least one tube does not work.
I applied the variable signal 2B to the input of the amplifier and looked where it comes to  when the 6n1p and 6p15p lamps were removed. The signal goes to the grid 6n1p tube only!  I put the tubes back and then I found exactly the same signal after tubes got warm up on the grid and the cathode of the 6n1p tube and on the anode and cathode of the 6p15p tube. Where from the signal comes on the 6p15p tube it is not clear. 
 
It is clear that the signal is not amplified in the tubes, but somehow participates in the work. A circuit diagram is very difficult to draw, because the circuit is on both sides of the board and the details are too small. The preamplifier is made of a chip JRC4558. 

I think  the tubes form a delay time either opening or closing a transistor or chip. I'm sure that the amplifier will work with any other tubes having same pin arrangement.
Owners of the amp argue on the forums which Chinese or Russian tubes sound better. There was reported that Russian tubes sound much better, and the tubes with golden grids make the best sound. I think they are a self-hypnosis. Unfortunately, I do not have other lamps to judge the disputants. 

 

Question to the experts. 
What function do tubes perform? 
Where does the signal on the cathode 6n1p and on the cathode and anode 6p15p comes from, if the signal comes on the 6n1p grid only when tubes are removed?

Yeah, I read the post. I'm still laughing at the claim that some listeners reckon they can hear a difference between different valves.

 Best laugh of the day. So far. 

 

Still, it's early.

Edited May 14, 20188 yr by Zaphod Beeblebrox

Very aptly named amplifier

Priceless... or should that be worthless.

its got a dial uv meter on the front !

 

Unreal, the Chinese have a reputation well earned.

 

 

Make the tubes last longer.

http://members.iinet.net.au/~cool386/jaycar/jaycar.html

39 minutes ago, lusk said:

 

Unreal, the Chinese have a reputation well earned.

 

 

Those of us at the coal-face (techs, engineers, etc) have a very healthy disrespect for Chinese made products. It all started with those counterfeit semiconductors which appeared at around the same time as Chinese made valves (around 25 years ago). Although the valves have improved, the Chinese counterfeit semiconductors are still being produced. I was caught a few times. Now I only source semiconductors from ISO accredited sources. I've certainly worked on a few Chinese audio products. Some are pretty decent. Some are not.

Edited May 14, 20188 yr by Zaphod Beeblebrox

Their Electrolytic caps were pretty crap too.

I can’t understand why they would even bother to make a fake product? It looks like there is enough circuitry in the faked item to produce a real valve amp. I can understand them skimping on transformers which are costly devices, but the rest of the chassis is full of circuit boards, so why not just make a proper valve amp out of it to begin with?

 

Rubbish Chinese amps like this one are getting rarer - the majority of them now have excellent build quality and aspire to be a hi-end product. Just check out Audio Space, Cayin, Prima Luna, Consonance,  Mingda, Doge and Line Magnetic are all excellent.

Edited May 15, 20188 yr by Steve M

1 hour ago, Steve M said:

I can’t understand why they would even bother to make a fake product? It looks like there is enough circuitry in the faked item to produce a real valve amp. I can understand them skimping on transformers which are costly devices, but the rest of the chassis is full of circuit boards, so why not just make a proper valve amp out of it to begin with?

Probably because the one amp is the basis for many many amplifier types that all look different when under the bonnet it's just the same SS amp.

3 hours ago, Batty said:

Their Electrolytic caps were pretty crap too.

Why? What's wrong with them?

 

 

?

I hate fake ****.

 

**** that's just crap too. 

16 minutes ago, Steffen said:

Why? What's wrong with them?

 

 

?

At least they used Rubycons.

58 minutes ago, Zaphod Beeblebrox said:

At least they used Rubycons.

Yes, but 35 Volt ones.

After being lived in Shanghai for a year, my experiences just put me off that anything is made in china, especially Chinese brand. If anyone happen to going to Shanghai. must visit underground shops of Shanghai Science metro station. I can safely say, 100% goods sold are fake (not cheap) and they do it openly, and authority don't care. We think we are smart, think twice as they know how to dupe us.

9 minutes ago, vinilink said:

After being lived in Shanghai for a year, my experiences just put me off that anything is made in china, especially Chinese brand. If anyone happen to going to Shanghai. must visit underground shops of Shanghai Science metro station. I can safely say, 100% goods sold are fake (not cheap) and they do it openly, and authority don't care. We think we are smart, think twice as they know how to dupe us.

The locals don’t even buy locally made products....   and that goes for just about everything!   The inlaws makes a request to families in HK and then it gets taken across the boarder, just don’t get caught with quantities otherwise customs will either confiscate or make you pay import duty. 

So it is a gainclone type chip amp with valves that might do something?

I was given one of these.They sound OK .Not great but I have heard a lot worse from things costing a lot more.

4 hours ago, Zaphod Beeblebrox said:

At least they used Rubycons.

I wonder what's inside the Rubycons...

That pics been floating round the net for at least 10 years, fairly regularly posted here, and on other forums.

5 hours ago, Steffen said:

Why? What's wrong with them?

 

 

?

Now I know i I need Rubycons 2000mF 35V I can buy this one.

Is it Gibson making fake Bumble Bee caps using a 50c cap inside.

 

The Bumble Bee caps sell at a $130 odd for a pair.

http://www.mylespaul.com/threads/historic-gibson-faux-bumblebee-caps.118027/

15 minutes ago, Muon N' said:

Is it Gibson making fake Bumble Bee caps using a 50c cap inside.

 

The Bumble Bee caps sell at a $130 odd for a pair.

http://www.mylespaul.com/threads/historic-gibson-faux-bumblebee-caps.118027/

Off topic but Gibson have more to worry about right now given their financial woes...

On topic, I've also heard some excellent sounding Chinese gear like Ming-Da and Line Magnetic (have an LM dac myself) and have built gear using affordable (not cheap) Chinese line transformers, plate chokes etc. so it's not all bad if you know what to look for. "Nobsound" sets off a few alarm bells for me tho...

 

 

8 hours ago, Steve M said:

 

 

Rubbish Chinese amps like this one are getting rarer - the majority of them now have excellent build quality and aspire to be a hi-end product. Just check out Audio Space, Cayin, Prima Luna, Consonance,  Mingda, Doge and Line Magnetic are all excellent.

AM (Audio Music.... ordinary name but not as bad a Nobsound) also make some beautiful gear.

I've dealt with Fang via email and he is very serious about good sound. I have some of his copper foil and teflon capacitors and they are very good at a more than reasonable price? 

Omg, can’t believe that they can be so cheeky