I purchased from Aliexpress this kit cuz I have NOS 6V6 and 5654 tubes. I use what I got. The version I'm getting was designed for 5654's, not the 6J1 in the schematic. Your comments on this circuit and how it could improved are welcome. https://www.aliexpress.com/i/3256802488665450.html?gatewayAdapt=4itemAdapt
It is a very simple circuit that will work. The output power will be quite low though, check that your speakers are up to the task.
The coupling cap should be 400V, not 250. B+ could go up quite a bit depending on who warms-up faster, the rectifier or the 6P6/6J1.
Connect the centre tap of the 6.3V heater supply to the ground.
The coupling cap should be 400V, not 250. B+ could go up quite a bit depending on who warms-up faster, the rectifier or the 6P6/6J1.
Connect the centre tap of the 6.3V heater supply to the ground.
Thanks that makes sense OldHector. Like rongon said I will check the board first but that will be a while since it's coming on a slow boat from China.
I would also buy better quality caps for the power supply. The one's provided will most likely be junk.
jeff
jeff
Just noted this in the description:
"Circuit structure reference drawing (component parameters are subject to the actual product, the drawing is for reference only):"
That's encouraging.
"Circuit structure reference drawing (component parameters are subject to the actual product, the drawing is for reference only):"
That's encouraging.
That's China. 😉
Also, you'll want to either change C1, or the rectifier tube. 5Z4P data sheet says 4uf for input capacitor, not 33uf.
jeff
Good catch thanks!!
This is true. I have a couple of circuit boards coming for a linear power supply for a Pass ACA amp and I wanted to know if the mounting holes are attached to the common ground trace. Seller replied he wasn't a professional just a small business operator and I will have to see for myself. Well at least he answered and I don't fault these poor folks for trying to make a buck or a yen.
That type of note is almost in any consumer product out there, usually stating that "the manufacturer reserves the right to modify parts of the product without changing functionality bla bla bla".
Yes, there are a number of Chinese kits and amps that use the 5Z4P. I replaced one that failed with a ‘winged’ 5ц4С and the (even larger!) input cap with a decent Nichicon 4uF. I’ve heard some say that it’s probably safe to use 22uF and that may be the case, but I feel better going by the data sheet in this case.
I think the fear is that using such a low value will result in excessive hum, but I did not notice a change. Then again, my speakers sensitivity was low-ish around 92dB. Maybe it could be an issue with more sensitive speakers.
If you do go higher than 4uF, then absolutely avoid rapid-cycling the power or the rectifier may be toast. (Good advice in any event, I know).
Board came in. The grid stopper is in the wrong place but that's an easy fix. The filter capacitor following the rectifier is 33 mfd. Too large? All the voltage ratings on the capacitors are at least 450 volts so no problem.
I would like to make this a triode amp. So I suppose I just need to connect the plate to the screen grid with a 200 ohm 3 watt resistor and cut the trace delivering high voltage to the grid. Anything else? What about the feedback loop?
I would like to make this a triode amp. So I suppose I just need to connect the plate to the screen grid with a 200 ohm 3 watt resistor and cut the trace delivering high voltage to the grid. Anything else? What about the feedback loop?
My view is that you should build it exactly as designed, get it to work. then look for modifications. If you plan surgery of the board it is a good idea to draw the circuit so you have a route to get support if you have problems later. I use LTSpice for drawing the circuits, and the bonus is that the circuit can be simulated if other changes are planned.