How to Spec Headphone output transformers

eeyore · 30th January 2010, 10:42 AM

Can I ask a dumb question, is specifying an output transformer for a headphone really just the same as for a speaker, instead of having 8R or whatever as the secondary, it would be 600R or whatever, to match your headphone's impedance? For argument's sake, say I wanted to do a 45 Headphone amp, would I just use a 5k:600R for my Senn HD650?

Is it also true that the output stage should be designed more for power gain, rather than voltage gain?

Tom Bavis · 30th January 2010, 03:41 PM

You REALLY don't have to worry about maximum power transfer when driving headphones, as they can deliver as much as 100 dB SPL with one milliwatt... use a 600 Ohm transformer and you'll be able to drive a WATT into them... they won't take it, and your ears certainly can't... and it will be tough to get the signal-to-noise low enough

If you're using 45s anyway, why not use a transformer with 8 ohm output and attenuate the output for the headphones? Most headphones aren't sensitive to source impedance and will sound just as good with a series resistor.

30th January 2010, 10:42 AM	#1
eeyore diyAudio Member Join Date: Aug 2005	How to Spec Headphone output transformers Can I ask a dumb question, is specifying an output transformer for a headphone really just the same as for a speaker, instead of having 8R or whatever as the secondary, it would be 600R or whatever, to match your headphone's impedance? For argument's sake, say I wanted to do a 45 Headphone amp, would I just use a 5k:600R for my Senn HD650? Is it also true that the output stage should be designed more for power gain, rather than voltage gain? __________________ DF http://diy-audio-blog.blogspot.com

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30th January 2010, 03:41 PM	#2
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	You REALLY don't have to worry about maximum power transfer when driving headphones, as they can deliver as much as 100 dB SPL with one milliwatt... use a 600 Ohm transformer and you'll be able to drive a WATT into them... they won't take it, and your ears certainly can't... and it will be tough to get the signal-to-noise low enough If you're using 45s anyway, why not use a transformer with 8 ohm output and attenuate the output for the headphones? Most headphones aren't sensitive to source impedance and will sound just as good with a series resistor.

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