Chinese tube amps

[Ali Tait]

You won't be disappointed Mike.Just put some nice coupling caps in,and lowering the feedback is a good mod-I may try removing it altogether when I get the chance.If I wasn't going down the direct-coupled route,I was going to try some new output trannies.

[swampy]

I bought a Yaqin MC 100b second hand from a UK seller on ebay and I love it. It had original Chinese valves but I did a bit of rolling and ended up with Russian Electro Harmonix all round.
I run mine off a Variac variable transformer (210v) because UK mains was producing 7.4 volts across the KT88 heater pins (should be 6.3) with a bias of 600mv.
It sounds great IMHO. I for one will never go back to SS (previously had a Cyrus 7)

Cheers

You can make a simple bucking transformer a fraction the size of a needed variac or step-down tx.

http://www.forum.diyhifisupply.com/v...c.php?f=4&t=12

I made this for my old Mr Liang 845 then wrote this doc.

[alb]

http://www.forum.diyhifisupply.com/v...c.php?f=4&t=12

Neat idea Dave, not seen that before.

[Marco]

Ian made one of those for me when I had my Yaqin (MC-100B, same as al) - they work really well

Marco.

[Jason P]

I'd like more info on the bucking transformer - am I right in thinking that any 240 volt transformer that outputs between around 15-25 volts at about 1 amp will do? How can I best test the output? I'm not a complete electrical numpty and reckon I could wire one up. From the PDF linked it looks to me like a case of carrying the neutral through (bypassing the transformer) and re-attaching one side of the output, but is getting the right side a case of trial and error, or can I use my trusty multimeter for a more informed approach?

Jason

[dim_span]

been reading about these chinese amps ... found a very good site ... all about lampizator (guy is in poland and a fundi on cd players etc... he tweaks and mods them .... here is his site (have given the link for the mods he done on a chinese valve amp) ... makes for interesting reading ... may send my cdp there for some mods

http://lampizator.eu/AMPLIFIERS/CHIN...ng%20Kong.html

here is the homepage
http://www.lampizator.eu/

[anthonyTD]

I'd like more info on the bucking transformer - am I right in thinking that any 240 volt transformer that outputs between around 15-25 volts at about 1 amp will do? How can I best test the output? I'm not a complete electrical numpty and reckon I could wire one up. From the PDF linked it looks to me like a case of carrying the neutral through (bypassing the transformer) and re-attaching one side of the output, but is getting the right side a case of trial and error, or can I use my trusty multimeter for a more informed approach?

Jason

hi jason,
one way round you will get the nescesary drop in voltage, the other way you will get an increase! if you have a variac then you can wind it up gradualy and test it before putting the full mains voltage through it.
hope this helps.
please be aware that mains voltages should only be handled by competent or suitably trained individuals, if in doubt do not attempt it!
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