Hi,
I'm here with a question that could be pretty idiot, but I'm a newbie in power supply for tubes, so please be patience.
I'm going to design/build my first power supply for a pre-phono stage and I've seen that usually people use linear power supply but it's not clear to me if switching power supply has any relevant side effects.
Now, I've on my desk a notebook AC adapter that I don't use (the notebook no longer works): DC output is 18,5V (3,5A).
Is it possible to use it to feed the heaters of the tubes in my pre-phono, where a stable voltage is important? Obviously I have to put a couple of resistances to have 12,6V.
If the answer is NO, could you please explain me why (with easy words 😀)?
I'm here with a question that could be pretty idiot, but I'm a newbie in power supply for tubes, so please be patience.
I'm going to design/build my first power supply for a pre-phono stage and I've seen that usually people use linear power supply but it's not clear to me if switching power supply has any relevant side effects.
Now, I've on my desk a notebook AC adapter that I don't use (the notebook no longer works): DC output is 18,5V (3,5A).
Is it possible to use it to feed the heaters of the tubes in my pre-phono, where a stable voltage is important? Obviously I have to put a couple of resistances to have 12,6V.
If the answer is NO, could you please explain me why (with easy words 😀)?
It is probably possible but not very practical. You didn’t mention the tubes that you plan to use for your preamp, but if you use tubes such as a 12AX7, 12AU7 or similar, the 12.6 VDC heaters are two 6.3 VDC heaters in series. Three 6.3 Volt sections =18.9VDC. If you wire these heaters as Marantz did with their 7c preamp, then your 18.5 DC voltage will work well.
RE: marantz 7c preamp Rect #2 - Tre' - Tube DIY Asylum
Unless you understand the operation of switching power supplies, I wouldn’t recommend that you try to modify it to produce 12.6VDC output. Be aware that when out of the insulated case, switching power supplies are hazardous to power up.
You can build your own new heater supply for about $20 (US Dollars) that will have stable and adjustable voltage.
Unique Tube Heater Supply
RE: marantz 7c preamp Rect #2 - Tre' - Tube DIY Asylum
Unless you understand the operation of switching power supplies, I wouldn’t recommend that you try to modify it to produce 12.6VDC output. Be aware that when out of the insulated case, switching power supplies are hazardous to power up.
You can build your own new heater supply for about $20 (US Dollars) that will have stable and adjustable voltage.
Unique Tube Heater Supply
Just add a regulator to make it 12.6V. That's what those mini tube (pre/headphone)amps are doing anyway. Power brick outside and LM317 inside.
Right.
I'm going to use a couple of 6DJ8 and a couple of 12AX7.
Also I need to bias one 6DJ8 and one 12AX7, due to the chosen configuration.
If I use two different power supplies, is it possible to bias one of them connecting it to the anode voltage (through a voltage divider) in the same way I'd do in case of a linear power supply 😕
I believe when you mention “bias” that you mean that you need to need to raise the heater supply above ground potential, so not to exceed the heater/cathode voltage limit.
The circuit I showed has been tested to +100 VDC, and I assume that it could be elevated higher. Using any other heater power supply; I don’t know. I would depend upon the exact configuration of the supply, and the specific application. I would be cautious.
The circuit I showed has been tested to +100 VDC, and I assume that it could be elevated higher. Using any other heater power supply; I don’t know. I would depend upon the exact configuration of the supply, and the specific application. I would be cautious.
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