I thought it would be something like a 6V6.....
But that Chinese PCB shows 2x 6SN7 like the Sun Audio design, which Stephe has shown to be pretty useless. Unfortunately if you use
a PCB like the one shown it makes it hard to modify and improve. Better to start again point to point and use a proper driver tube.
I am trying to understand if that PCB has merit or not. Because I have not seen 1/2 of a 6SN7 AC coupled into the other half using some kind of slingshot method before. It may sound terrible, but I doubt it's entirely nonfunctional.
It's easy to dismiss Chinese products, but they have plenty of smart people, and being underestimated has allowed them to retire most manufacturing jobs in the rest of the world.
It's easy to dismiss Chinese products, but they have plenty of smart people, and being underestimated has allowed them to retire most manufacturing jobs in the rest of the world.
<<<It's easy to dismiss Chinese products, but they have plenty of smart people
Chinese are plenty smart, and a lot of high end audio is made in China.
What we call "chi-fi" is the bottom end of the market, which is pretty basic and just made to "work" and sell in quantities.
Chinese are plenty smart, and a lot of high end audio is made in China.
What we call "chi-fi" is the bottom end of the market, which is pretty basic and just made to "work" and sell in quantities.
A friend here built 300b monoblocks based on the 6SN7 AC coupled design years ago. They don't sound terrible.
jeff
https://www.aliexpress.com/i/2251832743141221.html?gatewayAdapt=4itemAdapt
Perhaps this one is more appropriate
Perhaps this one is more appropriate
Is this the original (if even you can talk about "original" in the case of Chinese production)?
http://www.haodiy.net/m/view.php?aid=3393
http://www.haodiy.net/m/view.php?aid=3393
I figured in China they call this 6SN7/300B arrangement, the J configuration. It appears to be the dominant and preferred arrangement in their DIY audio community.
But in the schematic I posted, the first half of a 6SN7 is AC coupled to the second half, most likely to provide more drive for the 300B, without another stage and tube.
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If you're talking about the schematic in your first post, there is no "second half" of the 6SN7, it's a 6V6. This is all becoming very confused.
@andyjevans Confusing indeed, there are like 3 different schematics, and PCB pictures that are not clear to which schematic they conform to.
PS I think #27 is the right schematic, but not 100% sure. Tried to follow PCB routes, but no clear photos of both sides.
PS I think #27 is the right schematic, but not 100% sure. Tried to follow PCB routes, but no clear photos of both sides.
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Yes, based on the images, post #27 indeed is the correct schematic, you can clearly see 6SN7 pin 1 directly linked to pin 5, and pin 3 go to 300B grid via a 0.22uF capacitor.
My BS meter just went off. 😉 Here's a schem. form this Japanese site: http://www.single-ended.com/we300bjames.htm
Do you mean an SRPP driving a 300B? Cary, Wavelength and other 300B amps use (or used) an SRPP to drive a 300B. Gordon Rankin's Bugle is an SRPP design, so is the Baby Ongaku. It's a very common circuit.
That's it exactly. Recycled a zillion times in all kinds of amps by Chinese designers, both single ended and push pull.
jeff
jeff
This may be of interest: https://www.diyaudio.com/community/threads/diy-300b-monoblock.403801/post-7465849