How can I tell if a 1/4" female jack is balanced or unbalanced?

Question

I purchased a used Yamaha Clavinova CVP-65 and there are two 1/4" female output jacks labeled L/L+R and R on the underside. The manual does not indicate if these are balanced to be used with two male TRS cables or unbalanced to be used with two TS cables. The manual does state that if I only plug into the L/L+R that I will get monaural audio out.

Ultimately I want to plug the output into my computer audio interface. That ends up being about a 25' cable run and is the reason that I would want to use balanced if I can.

Is there any easy way to tell, short of disassembling the piano, if they are balanced or unbalanced? Perhaps using a TRS cable and clipping a voltmeter to the tip and comparing the output between the ring and sleeve?

Any help would be greatly appreciated.

Answer 1

You could actually just 'guess' based on percentages/chance ;)

Line level is very, very rarely run over balanced line, so the safe bet is that it's not balanced.
For consumer-level equipment I'd reckon the percentage is going to be so close to 100 that you needn't worry.
In this particular instance, I can add to this 'percentage/skill & judgement' call by virtue of the fact I used to work in Yamaha R&D in the 90s & know for certain they never used balanced line on CVP outputs.

Line level ought to survive a 25' run so long as you're not in a hugely noisy [electronically] environment. Alternatively, you could perhaps run longer USB to the interface & split the difference.

Answer 2

Both outputs are unbalanced. What the manual means is that if you insert a plug into only the L/L+R output, the result is a mono mix of the left and right channels ("L+R"). If you insert a plug into the R output, the unit disconnects the mix of of the right channel to the L/L+R output, and the two outputs are now "L" and "R"—left and right.

That lets people connect to a stereo system with two cables. But if you connect to L/L+R only, you'll have a mono mix that you can plug into a mono PA system.

Keyboards, synthesizers, drum machines, and similar sound generators are nearly always unbalanced.

Answer 3

Yes, balanced outputs are scarce in digital pianos. They are typically available on advanced stage pianos (Kawai MP11SE, Roland RD2000…), but not with the Clavinova series.