Here is my next tweak.
As I mentioned above, I pulled the 6X4 and its socket and replaced the tube with with two 1000V,3A Diodes.
But now, as suspected, because of the "instant on" diodes, the B+ now climbs at a rapid rate and hits its full value in about 5 .seconds passes and keps going to about 150% of the B+ operating voltage, Then when the tubes warm up enough to conduct, the B+ falls to about 85% its published value.
This would probably be fine but when I probe 130V, I want to see 130V and the same for the 160V testpoints.
Therefore here is what I am going to try. Itf I getthe resistance values correct, the caps should be fully charged by the time the tubes conduct, making a nice smooth transition into B+ rather than passing it and then returning:
Instead of having wires connecting my choke to the former voltage divider resistor location, I am going to use two 2K 10w resistors. Then we'll se if the B+ startup voltage is well contained.
As I mentioned above, I pulled the 6X4 and its socket and replaced the tube with with two 1000V,3A Diodes.
But now, as suspected, because of the "instant on" diodes, the B+ now climbs at a rapid rate and hits its full value in about 5 .seconds passes and keps going to about 150% of the B+ operating voltage, Then when the tubes warm up enough to conduct, the B+ falls to about 85% its published value.
This would probably be fine but when I probe 130V, I want to see 130V and the same for the 160V testpoints.
Therefore here is what I am going to try. Itf I getthe resistance values correct, the caps should be fully charged by the time the tubes conduct, making a nice smooth transition into B+ rather than passing it and then returning:
Instead of having wires connecting my choke to the former voltage divider resistor location, I am going to use two 2K 10w resistors. Then we'll se if the B+ startup voltage is well contained.
Ok thank you, however the components will arrive in one or two months unfortunately
Thanks, Hesener!
And I now, since installing today's tweak I have a fairly obvious soundstage when listening to my tranquil piano music. I wasn't expecting that! And all hum in the music and the chassis is gone! And all this on reject 12AU7s!. Cant wait to hear what 12AY7s sound like.
Of course my 12AU7s are Mullard and Amperex.
And I now, since installing today's tweak I have a fairly obvious soundstage when listening to my tranquil piano music. I wasn't expecting that! And all hum in the music and the chassis is gone! And all this on reject 12AU7s!. Cant wait to hear what 12AY7s sound like.
Of course my 12AU7s are Mullard and Amperex.
Hi Hesener, looking for the 14v zener diode but it is nowhere to be found, does it exist?
I used 13V zener in series with 1N4148, as you can see from the picture I posted - poor mans' 14V zener diode 😀
In case somebody is interested in buying a stuffed board, check this out: https://www.diyaudio.com/community/...e-pcb-stuffed-and-working.385179/post-6995249
Hello,
I used a 1N5351BRLG bought on the RS, it's a bit big but it works.
Powering with a 12.6v AC secondary I get the following values on the control points:
- with only 4 line valves on 12.8 V
- with all 8 valves on 11.8 V
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Powering with 14v AC obtain the following values:
12.8v with 4 valves.
13.8V with 8 valves.
In this case they increase the load increase the voltage, is this normal?
12.8v with 4 valves.
13.8V with 8 valves.
In this case they increase the load increase the voltage, is this normal?
In my case, I have 14V DC at the collector of the transistor and 12.8V on the heaters (I do not turn off the phono section, disabled this function in my build).
Remember you have to set the trimpot to maximum resistance so that the zener diode actually has a possibility to work.....
best greetings from the butcher 😀
Remember you have to set the trimpot to maximum resistance so that the zener diode actually has a possibility to work.....
best greetings from the butcher 😀
hello hesener.
I keep the regulation potentiometer completely closed but I tried to check what it was doing if I tried to open it and even when everything is open the voltage does not change.
Luca
Not you my friend, I'm talking about the guys who made the PCB and put the package together. They did great wrong. 🙂