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Connecting headphones to SET amp

Posted on March 25, 2023 at 08:21:05

Posts: 1282
Location: Colorado Springs, CO
Joined: October 7, 2002
I have 2A3 monoblocks with 4, 8 and 16-ohm speaker taps. I have headphones with 22 and 35 ohm impedance. What is the effect on the amps if I connect the headphones to the 16-ohm taps? They sound fine, and I have volume control via my preamp, but I am curious how the impedance mis-match might affect the amplifiers. Is there a way to alleviate any potential problems? The only info I find is about resistor networks to protect headphones from amplifiers with too much power.

Jim D


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RE: Connecting headphones to SET amp, posted on March 25, 2023 at 08:45:49
Paul Joppa
Industry Professional

Posts: 7253
Location: Seattle, WA
Joined: April 23, 2001
With zero feedback, the main effect is reduced distortion. Speakers often have much higher impedance at certain frequencies, with no problems.


RE: Connecting headphones to SET amp, posted on March 25, 2023 at 09:21:29
Tom Bavis

Posts: 949
Location: Upstate NY
Joined: May 25, 2007
Impedance matching is for maximum power transfer (with headphones: permanent hearing damage).

Since headphones are much more sensitive than speakers, hum and noise may be a problem, and the volume control may be touchy. If these are a problem, attenuation with a pad or series resistor is a solution.

If you're concerned about output transformer damage, this would only happen if you drive it into clipping and burn out the headphones.


RE: Connecting headphones to SET amp, posted on March 25, 2023 at 10:28:33

Posts: 9806
Location: Central Texas
Joined: September 24, 2006
I would never connect headphones directly to the output of a power amp. There's just too much risk of hearing damage. Even my little 6V6 SEPs have a resistive attenuator network for this.


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