Balanced Input for Phono-Pre with SUT and INA134

[reins]

Hi,

recently I read about balanced input for phono pre.

I have a Denon 103R cartridge, a cinemag SUT and an Elliott phono pre.

Now my question: would it work to connect the cinemag SUT in balanced configuration like here: http://cinemag.biz/mic_input/CMQEE-3...oving-Coil.pdf
to a differential line receiver like INA137 or THAT 1200 before going into the Elliott pre?

Is there advantage expected in regards of noise, with a balanced cable to the cartridge? Other advantages?

Thanx
Stephan

[SY]

Originally Posted by reins

Now my question: would it work to connect the cinemag SUT in balanced configuration like here: http://cinemag.biz/mic_input/CMQEE-3...oving-Coil.pdf
to a differential line receiver like INA137 or THAT 1200 before going into the Elliott pre?

The best way to do this is to put the SUT right at the input to the preamp (which does not have to be balanced). Float the primary and use a balanced input connector (I use a DIN plug, but an XLR would probably work just as well). Now replace your phono cable with a shielded twisted pair for each channel. Connect the shield at the turntable end only. The twisted pairs go to the SUT primaries. I've found this to work extremely well with a Technics MC; likewise, Morgan Jones uses this connection for his Ortofon. With some very oddball exceptions, nearly all cartridges are inherently balanced, so why not take advantage? The only downside is compatibility with other people's systems.

See also "His Master's Noise" in the articles section of diyAudio.

[reins]

Do things still get better, if input stage is a differential OP-Amp like INA134?

[SY]

If you're using a balanced input transformer, running the electronics balanced won't gain you much.

[kevinkr]

I suspect running it as shown is going to make it at least several dB noisier overall than if the INA134 was not there. Think of the added noise from those 25K input resistors in series with the source and the input voltage and current noise of the INA134 as well.