Moving right along...
Started putting together the power supply yesterday evening. Rather than freezing my a$$ off in my garage (20F outside), I wired what I could indoors without soldering and made all of the necessary preparations for the morning. Got up at the crack of dawn too excited to keep sleeping, and went out to get to work.
Well no doubt my work last night shaved off a huge chunk of time, still took me a solid four hours! But lo and behold, the power supply is working perfectly
Here is the interior post power supply implementation. I also cleaned things up a bit, I'm a bit of a perfectionist (which means making work where there really is none).
Here is a closer look at the completed rectifier socket. You can see a pair of Vishay HEXFRED diodes have been added to complete the hybrid SS-tube full-wave bridge rectifier. The red wiring is the HT or B+ AC from the mains transformer. The resistor across the terminals of the 10uF resevoir cap is a bleeder to discharge the capacitors when the amp is turned off. I knew it was going to be busy, hopefully I never need to change anything on this socket, I will cry.
Up in the corner near the IEC outlet are two pairs of wirewound resistors. These are serving a few different purposes in the power supply, but mainly they drop the ~420V B+ that is being sent to the driver tube CCS boards down to ~315V for the output tubes. The tradeoff of course is heat, but they are appropriately rated and are tucked away as far as possible from the caps. The values may need to be adjusted in the final design to dial in the output tube B+. We'll see how good my math was when the amp is complete and the final voltages are checked.
In the meantime, to ensure everything was functioning as intended I picked up a pair of 5kohm 50W resistors to act as dummy loads for the supply. They approximate the load it will see from the tubes, and they are doing it quite well!
In this photo, I have one multimeter connected to each channel, getting near perfectly matched voltages. This is with the Mullard FW4-500, 320.5V for the output tubes. With the Marconi-Osram U18/20, seeing ~315V, and with the Fivre 5Z3 ~305. Will have to keep the large voltage drop in mind when using the 5Z3 in this amp. I am aiming for 315V B+ for the output tubes which results in 250V on the plates. These resistors may have approximated my tube load better than I expected.
I also measured the B+ off the 100uF cap at ~430V, which will be sent to the driver CCS boards.
So there you have it, power supply done. Very satisfying to have done so much planning and have everything going off without a hitch.
We are rounding the corner now, this amp is very close to being done. Just need to do the signal wiring, which is relatively simple, then wait for these output transformers to arrive from Sweden the amp is getting heavier and heavier, it is going to be an absolute beast when the OPTs are in.
Started putting together the power supply yesterday evening. Rather than freezing my a$$ off in my garage (20F outside), I wired what I could indoors without soldering and made all of the necessary preparations for the morning. Got up at the crack of dawn too excited to keep sleeping, and went out to get to work.
Well no doubt my work last night shaved off a huge chunk of time, still took me a solid four hours! But lo and behold, the power supply is working perfectly
Here is the interior post power supply implementation. I also cleaned things up a bit, I'm a bit of a perfectionist (which means making work where there really is none).
Here is a closer look at the completed rectifier socket. You can see a pair of Vishay HEXFRED diodes have been added to complete the hybrid SS-tube full-wave bridge rectifier. The red wiring is the HT or B+ AC from the mains transformer. The resistor across the terminals of the 10uF resevoir cap is a bleeder to discharge the capacitors when the amp is turned off. I knew it was going to be busy, hopefully I never need to change anything on this socket, I will cry.
Up in the corner near the IEC outlet are two pairs of wirewound resistors. These are serving a few different purposes in the power supply, but mainly they drop the ~420V B+ that is being sent to the driver tube CCS boards down to ~315V for the output tubes. The tradeoff of course is heat, but they are appropriately rated and are tucked away as far as possible from the caps. The values may need to be adjusted in the final design to dial in the output tube B+. We'll see how good my math was when the amp is complete and the final voltages are checked.
In the meantime, to ensure everything was functioning as intended I picked up a pair of 5kohm 50W resistors to act as dummy loads for the supply. They approximate the load it will see from the tubes, and they are doing it quite well!
In this photo, I have one multimeter connected to each channel, getting near perfectly matched voltages. This is with the Mullard FW4-500, 320.5V for the output tubes. With the Marconi-Osram U18/20, seeing ~315V, and with the Fivre 5Z3 ~305. Will have to keep the large voltage drop in mind when using the 5Z3 in this amp. I am aiming for 315V B+ for the output tubes which results in 250V on the plates. These resistors may have approximated my tube load better than I expected.
I also measured the B+ off the 100uF cap at ~430V, which will be sent to the driver CCS boards.
So there you have it, power supply done. Very satisfying to have done so much planning and have everything going off without a hitch.
We are rounding the corner now, this amp is very close to being done. Just need to do the signal wiring, which is relatively simple, then wait for these output transformers to arrive from Sweden the amp is getting heavier and heavier, it is going to be an absolute beast when the OPTs are in.
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