Hello, I recently got a cheap Chinese tube preamp, just to mess around. It says that it need 12v AC to work. Searching the web I ve seen many tube heaters working on DC, sometimes I read that you can use the two interchangeably. So I wanted to clear any misinformation.
What would happen if I where to power my 12 vAC pre Amp with DC ( 12 volt I guess shouldn't be enough). Will the answer depend on whether it's are using a bridge/tube rectifier or not?
What would happen if I where to power my 12 vAC pre Amp with DC ( 12 volt I guess shouldn't be enough). Will the answer depend on whether it's are using a bridge/tube rectifier or not?
the chinese preamps use a voltage quadrupler to produce the high voltage.
If it has an input rectifier you can feed it with DC in any polarity (it's a rectifier, remember), but you'd need indeed a bit more voltage.
12VAC, when rectified, would give something like 1.4*12=16.8, but you lose a bit in the rectifiers, so a DC of 15 or 16V would do it.
But check that there is a rectifier that is not followed by some switching thing that increases the input voltage.
Best would be to measure the internal supply voltage.
Edit: only now see your 2nd post. That makes it unsuitable for DC unless you feed the DC after the quadrupler.
Jan
12VAC, when rectified, would give something like 1.4*12=16.8, but you lose a bit in the rectifiers, so a DC of 15 or 16V would do it.
But check that there is a rectifier that is not followed by some switching thing that increases the input voltage.
Best would be to measure the internal supply voltage.
Edit: only now see your 2nd post. That makes it unsuitable for DC unless you feed the DC after the quadrupler.
Jan
You are not only feeding the filaments. so in principle the answer is no.
Besides, my usual rant: you are not providing a single bit of information: neither schematic nor picture not even a direct link.
Actually we are only guessing, we haven´t the foggiest idea about what are you talking about.
I used the foggiest word out of politeness.
Indeed I am not providing a lot of information, that's because I was more interested in general answers regarding tubes.
So thank you.
Indeed it has a quadrupler :
Attachments
Hi Kyrk, it is possible to use DC for the filaments but first you will need to cut traces of the PCB to split the power supply.
The simplest way seems to cut the traces close to the tubes and wire them out to the DC power supply you are planning to use.
The high voltage part can remain the same or you can even improve it.
The simplest way seems to cut the traces close to the tubes and wire them out to the DC power supply you are planning to use.
The high voltage part can remain the same or you can even improve it.