My electric utility is awful, the line voltage has been swinging between 116V and 122V. And as such, the cheapo 12V DC transformer for my turntable can’t keep up and I’m hearing the pitch swings as the platter slows down when the voltage sags.

Instead of buying the stupid expensive audiophile transformer, I picked up a ‘60s era HP bench power supply with pos/neg/gnd terminals.

The actual question: I just ignore the ground terminal, right, and connect a DC barrel to the + and - sides?

  • \$\begingroup\$ A cheap modern 12 V switching power supply (note that "transformer" refers to a very specific thing, which always outputs AC; your "DC transformer" is not a transformer, though it probably contains one as a component) could also work--no need for the antiques. It's likely you have an unregulated power supply (common in the 80s and 90s); modern ones are going to be regulated and will ignore such small line fluctuations. \$\endgroup\$
    – Hearth
    Jan 11 at 16:18
  • \$\begingroup\$ Assuming your nominal supply is 120V, then the range of 116 to 122 is within ANSI tolerances of ±5%. If a DC supply is sagging with that little variation in the mains voltage, there's probably a failure of its regulator. \$\endgroup\$
    – Theodore
    Jan 11 at 16:18

1 Answer 1


Sounds right. Make sure to get + and - the right way around, and make sure the voltage is 12V before you plug in the turntable! You don't want to accidentally bump the dial and fry the turntable with 36V or whatever your supply goes up to.

These kinds of supplies are isolated - otherwise they wouldn't have separate ground terminals. You may choose to connect the ground terminal to a convenient grounding point on the turntable, but it's also quite normal for low-voltage DC equipment to not be grounded. Probably, your other adapter was not grounded either.


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