how much DC through phones is okay?

cuibono · 19th April 2008, 03:56 AM

I built Carlos' AD815 preamp, and am trying to use it with headphones - it can output 400mA/channel! It should work, but the chip inherently has DC on the output - .281V to be specific. I want to use them with 50 and 60 ohm headphones. Can I drive them directly - there will be 5.6mA DC moving through the headphones, or around 1mW. The etymotic er6i headphones I have are rated for over 1W continuous power handling, although that is an AC rating...

I'd like to not use 600+uF of electrolytic coupling caps. Is it possible, or will I hurt something?

cuibono · 20th April 2008, 12:04 AM

correction: the ER6i are rated for about .13W continuous AC power handling...

No one is for/against doing direct DC coupling with DC offset?

TheMG · 20th April 2008, 12:22 AM

I don't think you'd need 600uF of capacitance for capacitor coupling.

If my math is correct, that would have an f1 of about 5.3Hz with 50 ohm headphones.

220uF would be a much more reasonable value if you really want to preserve the deep bass sounds. 220uF 10V electrolytics are quite small, if size is what you're concerned about. I don't see any value in going sub-sonic with headphones.

Anyway, 1mW won't harm the headphones. The question you have to ask is will it have any impact on the sound quality?

19th April 2008, 03:56 AM	#1
cuibono diyAudio Member Join Date: May 2006 Location: City of Angles	how much DC through phones is okay? I built Carlos' AD815 preamp, and am trying to use it with headphones - it can output 400mA/channel! It should work, but the chip inherently has DC on the output - .281V to be specific. I want to use them with 50 and 60 ohm headphones. Can I drive them directly - there will be 5.6mA DC moving through the headphones, or around 1mW. The etymotic er6i headphones I have are rated for over 1W continuous power handling, although that is an AC rating... I'd like to not use 600+uF of electrolytic coupling caps. Is it possible, or will I hurt something? __________________ double complete rainbow all the way!!

20th April 2008, 12:04 AM	#2
cuibono diyAudio Member Join Date: May 2006 Location: City of Angles	correction: the ER6i are rated for about .13W continuous AC power handling... No one is for/against doing direct DC coupling with DC offset? __________________ double complete rainbow all the way!!

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20th April 2008, 12:22 AM	#3
TheMG diyAudio Member Join Date: Jan 2008	I don't think you'd need 600uF of capacitance for capacitor coupling. If my math is correct, that would have an f1 of about 5.3Hz with 50 ohm headphones. 220uF would be a much more reasonable value if you really want to preserve the deep bass sounds. 220uF 10V electrolytics are quite small, if size is what you're concerned about. I don't see any value in going sub-sonic with headphones. Anyway, 1mW won't harm the headphones. The question you have to ask is will it have any impact on the sound quality?

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