Measuring channel balance of Cambridge Audio Duo Phono

[Chester]

Hi

I run my turntable into a Cambridge Audio Duo Phono and then into an RME ADI-2 Pro for digital conversion. One channel seems slightly louder than the other when viewing the RME’s display. Before I start tinkering with anti-skate settings etc on my turntable, I want to make sure the Duo balance is spot on. It’s an adjustable balance on the Duo, which is helpful but that’s also what leads me to wonder how accurate the centred position is on my particular unit.

Could I run a quiet analog signal into the Duo from a DAC, so I can play a test signal and see the output on the RME, thus confirming the Duo’s balance? Would this cause any damage etc?

Alternatively, is there an alternative method for approaching this?

Thanks

Chester

 

[MaxwellsEq]

Cartridges frequently have a channel imbalance (which is why the Duo has a balance control!). Ideally, you would be able to prove or disprove this only with a test LP.

You could inject tone at 1kHz at, say, -70dB into the MM input and measure the output, it will at least allow you to work out the exact position to "zero" the balance control. The MM stage has 39dB of gain, so -70db should not cause any overload. Don't forget to mute the speakers in case something goes wrong.

 

[Chester]

Thanks, yes I will definitely be calibrating the turntable/cartridge but want to make sure I’m starting from zero in terms of the other equipment in the chain.

Good tip re. muting. I won’t have the power amp on as I only need it to go as far as the ADI-2 in order to measure the balance so hopefully risk is minimal.

 

[SoNic]

I used to have a "test" LP, master cut at 1/2 speed, printed on heavy weight vinyl.
There are still some:

https://www.amazon.com/HIFI-NEWS-Test-Producers-Cut/dp/B00KMCL1PE/

 

[JP]

I'd do as @MaxwellsEq advises. Test records are not perfect - it's more common to see channel imbalance than not, and you'll have no way of knowing what error is from the record vs. the cartridge. Always adjust things with known and verified test signals if possible.