Hello all. I built a Chinese PP tube amp I have had laying around for a few months. As we know there are no instructions aside from the schematic they send with it, which isn't great.
I followed as best as I could here: https://www.diyaudio.com/community/threads/problems-with-chinese-pp-kit.353111/
I have the transformer marked as 110v, same or similar to the one in post #98 in the above link. I am still not sure how to wire the primaries or the 2 yellow and one black (Yel-Blk-Yel). They show going to the 6.3v/0 and I assume the black go to chassis ground. And the primaries? Red-Blk/Red/Blk. I see only 6+ volts on one of those primaries. Are they marked incorrectly, perhaps?
I followed as best as I could here: https://www.diyaudio.com/community/threads/problems-with-chinese-pp-kit.353111/
I have the transformer marked as 110v, same or similar to the one in post #98 in the above link. I am still not sure how to wire the primaries or the 2 yellow and one black (Yel-Blk-Yel). They show going to the 6.3v/0 and I assume the black go to chassis ground. And the primaries? Red-Blk/Red/Blk. I see only 6+ volts on one of those primaries. Are they marked incorrectly, perhaps?
Hi Robert, I have attached some photos. Red and black leads are currently disconnected. Thank you.
Attachments
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Hello,
Connect one red lead with one black lead.
The mains has to be connected to the remaining 'free' black and red lead, but with the fuse and the on/off switch between the mains and one of these leads (it does not matter which lead).
In this way the two primary windings of each 110 V will be connected in series, resulting in one primary winding of 220 V.
Edit:
I just realized that according to the flag you use, you are likely living in the US, so your mains is likely 110/115 Vac.
If this is the case, you should connect the red leads to each other, and the black leads to each other.
The mains has to be connected to each of these joints, but with the fuse and the on/off switch between the mains and one of these joints (it does not matter which of the joints).
In this way the two primary windings of each 110 V will be connected in parallel, resulting in one primary winding of 110 V.
Connect one red lead with one black lead.
The mains has to be connected to the remaining 'free' black and red lead, but with the fuse and the on/off switch between the mains and one of these leads (it does not matter which lead).
In this way the two primary windings of each 110 V will be connected in series, resulting in one primary winding of 220 V.
Edit:
I just realized that according to the flag you use, you are likely living in the US, so your mains is likely 110/115 Vac.
If this is the case, you should connect the red leads to each other, and the black leads to each other.
The mains has to be connected to each of these joints, but with the fuse and the on/off switch between the mains and one of these joints (it does not matter which of the joints).
In this way the two primary windings of each 110 V will be connected in parallel, resulting in one primary winding of 110 V.
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Probably 120v +. You quite often see people using a bucking transformer (to reduce primary AC) for amps originating in China.
jeff
Robert, you are correct. My mains sits at around 117 to 121 at the wall. Thanks for the edit.
Jeff, yes, I was considering a buck transformer to get the voltage down a bit so as not to stress the main transformer over time. I will build one. In the meantime I'll temporarily use a 25w 8ohm or so resistor during testing.
Jeff, yes, I was considering a buck transformer to get the voltage down a bit so as not to stress the main transformer over time. I will build one. In the meantime I'll temporarily use a 25w 8ohm or so resistor during testing.
All good now! Amp is running and actually sounds pretty good with the included tubes and a pre I had laying around. I have some other tubes I may swap in once I am satisfied this thing is stable. So far, so good. 🙂
Thank you all for the help.
Thank you all for the help.
Just a small report. I found an old bedside radio transformer (120v in/9v out) and wired it in as a buck power supply. It took my wall power down to exactly 110 volts feeding into the amp's main transformer. It also was small enough to fit into the cabinet to be hidden nicely. Heater volts are hovering at around 6.29v.
All voltages are looking pretty good and the amp sounds way better than expected. I ran it for a day or so with the Chinese tubes and then swapped in some NOS Svetlana 6P1P-EV tubes along with some Telefunken 6GH8A to replace the 6F2 tubes. Not a huge change, but the bass tightened up a bit and a little more detail, as well. I have a Luxkit A3400 all tube pre-amp feeding into it now and it is quite the combo.
All voltages are looking pretty good and the amp sounds way better than expected. I ran it for a day or so with the Chinese tubes and then swapped in some NOS Svetlana 6P1P-EV tubes along with some Telefunken 6GH8A to replace the 6F2 tubes. Not a huge change, but the bass tightened up a bit and a little more detail, as well. I have a Luxkit A3400 all tube pre-amp feeding into it now and it is quite the combo.