• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Tube Amp Questions

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I own the Musical Fidelity X-Can v2 headphone amp. My question is about the AC Power Transformer that is needed to power it up.

It is supplied with a 12 VAC-500ma wall transformer. Now, a lot of other owners of this amp claim that a transformer with a much higher amperage rating is better to use. So, here's what I tried:

First, I tried a 12 VAC- 1A transformer. It worked fine, but the amp got much warmer. Sound-wise, I couldn't hear any significant difference.

Then, I rigged up a bigger power transformer rated at 2 Amps; and Yes, it did sound way better. The only problem is that the amp was getting much hotter. So, I'm concened about using this transformer because I don't want to shorten the life of the amp, and/or Tubes.

So, I guess my main question is: Is it safe to run the amp hotter for the better sound? or safer to go back to the original transformer? Thanks for any advice.
diyAudio Senior Member
Joined 2002


From what I could find:

Total powerconsumption of the circuit is 490mA/12V when idle.

Running this from a 500mA/12V AC adaptor may give you trouble in the long run and starve the circuit for current.

IMO running it from a higher rated transformer will not hurt neither the tubes nor the transformer itself and I would certainly recommend it.
You even build your own PSU unit and include mains filtering.

Best regards,:)
One explanation for the behavior is regulation. A 12V @ 500mA xfo is probably putting out pretty close to 12V at 490mA, but a 2A one might be putting out 13-14V+. Depending on what is inside your black box it could be getting a lot warmer than the 17% additional voltage would seem to indicate. Try measuring this?

Additional amperage alone shouldn't have any effect on the temp.
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