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Old 6th November 2017, 10:01 AM
John Caswell John Caswell is offline
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Join Date: Dec 2005
Location: Wokingham, Berkshire
Posts: 1,450
Default Re: Balanced circuits for Pre/phono/psu 2and3

Now the fun begins!!
1) If you use the Pre3 as a balanced output, the screen of the twin screened cable should be earthed somewhere either at the send or receive end, helps reduce unwanted spurious noise ppickup
2) Ideally the input of the amplifier should be balanced either electronically or with a transformer (My personal choice)
3) Will it remove the hum? Haven't got the faintest, but using an input coupling transformer I would suggest yes. If you go fully balanced it will remove any earth/hum loop as the pre/power are only earthed via the power lines and not power/signal lines
4) No the input transformer is not required to be large as it is dealing only with audio not DC and audio as in Pre2/3. I would look at Sowter, Hammond, eBay, and any other quality manufacturer for a 1:1 - 10K:10K or 20K:20K transformer. Usually they are 10K, do not go any higher or lower. be prepared to pay for them! The output impedance of Pre3 is very low ca 10R and will drive pretty well anything including headphones.
Any further questions or comments ask here.

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