How much overvoltage can I use?

Question

I have a pre-amp (Presonus TubePRE) which needs 16 Vac @1000 mA. I have a 22 Vac power supply. It can produce 6.6 VA. Can I use it safely to power the Sonus, which uses one ECC83/12AX7 valve? If not, what overvoltage would be safe, if any?

From the FAQ: Can I use a higher/lower/alternate voltage power supply that was not supplied with my TubePRE? Use of any power supply that was not included with the unit voids the warranty of the TubePRE and may cause damage to the unit or the user. From specs: 16VAC/1000mA (factory configured) - configured?! — greybeard, Oct 17 '23 at 11:09
Does this answer your question? Choosing power supply, how to get the voltage and current ratings? — winny, Oct 17 '23 at 12:58

score 2 · Answer 1 · answered Oct 17 '23 at 11:06

No, it's not OK to use a 22 Vac power adapter for a device that is designed to work with a 16 Vac. It may temporarily work, but don't assume it will be reliable or safe. For instance, you may be close of above the voltage rating of the input capacitors. That will result in a much lower lifetime and/or explosion of the caps...

Or, it could be that the device is fine. But without the schematics and some calculations, it's impossible to tell. Thus, you should consider it's not safe to do so.

Moreover, 22V is 6V more than 16V. It's not just a little more. Thus, it's more likely that it will damage your device.

Please have a look at: Choosing power supply, how to get the voltage and current ratings?

How much overvoltage can I use?

1 Answers1