Berlusconi I agree with you, but according to Russian forums, printed circuit boards are different. I have a Chinese clone of this amplifier, and it plays well, but I am looking for a good bare board to assemble from good parts. https://aliexpress.ru/item/32821886...88#3325#1_668#2846#8110#390_668#2717#7566#815
Whom should we believe? Just search this thread to find the opposite info about that Quensway pcb. Just take the board and compare it to the schematics if in doubt. And BTW: the only difference between the real clone and QUEENSWAY version is that QUEENSWAY version involves DC servo well known as the crap feature. On that web site there is a BOM that explicitly indicates that their "1:1" version involves that Servo which is not in the original NHB-108. Don't waste your money on crap.
Think.
PS: In your post there is a link to the Weiliang NHB-108. There is also a photo of the board which I also have and I know it is good. That board has just one single capacitor between R13 and R14. That board is also good. The only difference from real clone is that extra capacitor.
Think before you buy. And don't t be naive to believe that QUEENSWAY version is a real stuff. They added a crap feature to it.
I must go to sleep now, but tomorrow I will upload a photo of both sides of the PCB so you may compare it to yours and QUENWAYs.
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Did a PCB design for a friend a few months back, not that hard. Was planning maybe to build one for me, using original parts. I would like a protection circuit similar to the original though. Pretty sure the original high capacitance power supply was part of the sound, but I'll certainly won,t plug that amp to my speaker with a good protection circuit. That huge caps bank can generate an awfull large current, frightning!
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I think you could be right about that. Normally I hate the Dale resistor sound - they are steril sounding. I think PRP is worse. But maybe for this amp it is ok to use them.
Queensway was cheapest 43 $ but they answered slowly so I ordered another place 60 $
So did i. Unlike some people complaining about ch crooks but still buying their wares 🙂
As for the the protection, look at the triac protection of the Revox A740/A68. Something tells me it served for HD's inspiration as well 🙂 The opamp part is probably better served by one of the popular protection IC's like the upc1237.
😕
CH=Switzerland ?
😉
But these other ch are real crooks.
Just look at THIS.
And they convinced our friend from Russia that the same product is THE ONLY real 1:1 clone because:
1. someone at the Russion forun said so
2. they sell the same product at higher (Premium) price
Yes I will still buy from ch crooks because they are cheap enough even if their stuff doesn't work at all. Because I know them and they are cheap crooks.😀
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Thanks for the tip, will look at it... Analog_sa So no need to match the input transistor, so I can buy just 10-25 of each and that's enough?
SB
SB
Berlusconi Вы против такой печатной платы? https://aliexpress.ru/item/32815061845.html?spm=a2g0o.detail.1000023.11.64c5152171bjC1 Queenstore intermediary - manufacturer Wyleng, I bought an amplifier in 2017. The capacitor must be removed if you select the input transistors.
Вы против такой печатной платы?=>(Google translate)=>Are you against such a circuit board?
If you like the sound, keep that board and make a beautiful chassis and get some good speakers for it. It is worthy.
I have exactly the same board and it works well. I wish I was an expert but I ain't that clever as our friend analog_sa, but he remains silent on crucial questions.
What I've heard here is that Weiliang store was present here at Diyaudio.com and that they have earned good reputation.
But, what I know for sure is that I have phisycally compared it to the bare board sold on ebay and is exactly the same as that board from Weiliang store, except some slight differences at holes for 2N5401 & 2N5551 transistors. The only "real" difference is that "extra" capacitor on Weiliang board bwtween R13 and R14, but the ebay board is identical to the published schematics. Also, all other boards do not have that "extra" feature.
Below is a photo of the ebay bare board.
As I said, I am not an expert in this field but I have lots of experience and I know how to judge situations and people based on scarse information. I know that the famous "1:1 clone" board is a bluff, an ordinary scam. Ask yourself: "Why the Hell would Chinese market that super board exclusively in Russia?" My answer is: they assume that the Russians are naive and ignorant enough to swallow that crap and afterwards be grateful for that exceptional "privilege". That's what I think.
С уважением (Ang: Kind Regards)🙂
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Berlusconi Thanks for the answer, we do not argue but discuss, with respect to all participants. For some reason, this circuit board is considered unsuccessful. Even my good friends from Germany and Canada. Unfortunately, I am also not a specialist in printed circuit boards, but I have a KSA -5 Chinese clone, and another made by me. PSB boards are different and the sound is great everywhere.
On the dartzel website there is information that the first amplifier was without a capacitor, the second version is already with an ionistor, the Chinese made for every taste. I wanted to put a smiley, I don’t know where to click)))
I think we are speaking about two different capacitors. I am not talking about that "ionistor" but about that capacitor between R9 and R10 which is present just on one of the clones I have seen. Are you talking perhaps about SCNP?
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Yes, we are talking about the same thing, according to the scheme that is available, the Chinese put both capacitor and an ionistor, as I suppose it consists of two capacitors and connects these 2 resistors through themselves to the ground, or I'm wrong. If you look at everything that is in China, the most expensive ones, as close as possible to the original, have an ionistor, which helps to have zero in the output, in the very first version it is not in the original, but since the dartzel was unstable and made an upgrade. It would be nice to compare all versions of Chinese boards but it is probably time consuming.
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More than enough.
The VA part of the circuit adds an insignificant contribution to the total distortion.
But the SCNP is not a part of the board. It can be added to the board if you decide to do so.
Let us hear analog_sa:
So, for time being I have decided to adjust offset manually to avoid additional complications, especially that servo board that distorts sound.
😎
PS: But if you decide to use SCNP buy it from reputable supplier, not in a kit.
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Полностью согласен ))) =Google translate= I completely agree
All what I wanted is to share information with you and not confront you, quite the contrary. I just wanted to tell you what I have learned about that subject, respectfully and friendly. And I am not pretending, I do really appreciate all of members here at this forum and want to be helpful as much as I can.
Have a pleasant weekend, We have wonderful May weather ond I intend to relax after very intense work during the past week.
🙂
Just for giggles ran some simulations with the input circuit. A 75% mismatch in the model BF (beta) of the input transistors led to a thd change from 0.0005% to 0.0006%. 10v pk into 10k.
Below is the circuit which i incidentally like to use on its own as a preamp.
EDIT. Only now i notice the reduced gain of this circuit as it was meant for a line stage, but this does not change the conclusions
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