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Old 16th December 2014, 02:59 PM   #1
diyAudio Member
Join Date: Oct 2005
Default Input/output transformer question

I've read Bill Whitlock's excellent guide on the Jensen website ( and understand the different design requirements for input and output transformers.

My questions is: if the total cabling distance between a source (e.g. DAC with 100ohm output impedance) and load (e.g. amp with 50Kohm input impedance) is around 1m, would it generally be the case that either an output or input transformer would be suitable for providing galvanic isolation between the two devices?

I'm thinking of the situation where a balanced output voltage DAC is driving an unbalanced amp input over a typical short interconnect. It would seem that this scenario satisfies the requirements for both input and output transformers to enable them to work well.

Thanks in advance for any advice shared.
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Old 18th December 2014, 12:33 PM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
an input transformer is usually a better solution than an output transformer.

One of the jensen apnotes or "asxxx" sch that I posted elsewhere shows how to get a bal to unbal with galvanic isolation using an input transformer.
regards Andrew T.
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Old 18th December 2014, 01:48 PM   #3
diyAudio Member
Join Date: Apr 2003
Location: Eastern Pennsylvania
Make certain that the input transformer features a Faraday shield so to maximize wideband CMRR. Not all transformers advertised for input duty have them.
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