Why don't headphone amplifiers have an option partially to blend left and right?

[Arkless Electronics]

I didn't just overhaul a Sansui AU-717 to not use the headphone amp!

But it doesn't have a headphone amp! Like most amps with a headphone socket (not all) it merely sticks resistors after the main amplifier.... In your case 220R and it would be fine to do it after the headphone socket. Just wire a log pot of about 5K as a variable resistor with the log back to front so there is mono at fully anti clockwise, with a switch if you want to be able to switch it out, and connect this between the two channels using a 1/4" jack plug to 1/4" jack socket.

 

[booja30]

But it doesn't have a headphone amp! Like most amps with a headphone socket (not all) it merely sticks resistors after the main amplifier.... In your case 220R and it would be fine to do it after the headphone socket. Just wire a log pot of about 5K as a variable resistor with the log back to front so there is mono at fully anti clockwise, with a switch if you want to be able to switch it out, and connect this between the two channels using a 1/4" jack plug to 1/4" jack socket.

Ooh, interesting! That's the kind of solution I was hoping for. Thanks!

 

[davidsrsb]

I always think that it is a pity that amplifier and headphone amplifier designers never think about selectable output impedance.
There is a huge difference in balance with some headphones between what amounts to current drive from a typical amplifier and an Ohm or two from some headphone amps.

The old IEC 61938 standard is surprisingly high, 120 Ohm source impedance

 

[gustav_errata]

This seems like something that could be achieved relatively cheaply with a small project box, a female headphone jack, a male jack on a pigtail, and a few resistors. Sort of like how you make an inline attenuator but with cross linking instead of grounding the signals. Would it be safe for the headphone amp or power amp?

Maybe @Arkless Electronics can suggest a simple design with (I'm guessing) 4 resistors. I'd try it!

It needs to be properly designed achieve proper stereo crossfeed. Just blending the channels a bit won't cut it. You also need time delay and band filtering/boosting.

Read this: http://bs2b.sourceforge.net/#r1
From that page you can link to actual circuit designs:
http://www.linkwitzlab.com/headphone-xfeed.htm
http://www.johncon.com/john/SSheadphoneAmp/index.html

 

[JemHayward]

I'll be listing my Audio Alchemy headphone amp in the classifieds when I get out of hospital. It has a mix button that does a really nice job.

 

[Arkless Electronics]

It needs to be properly designed achieve proper stereo crossfeed. Just blending the channels a bit won't cut it. You also need time delay and band filtering/boosting.

Read this: http://bs2b.sourceforge.net/#r1
From that page you can link to actual circuit designs:
http://www.linkwitzlab.com/headphone-xfeed.htm
http://www.johncon.com/john/SSheadphoneAmp/index.html

if people want to go to those lengths then there is ample info there

 

[suzywong]

I think it was the Linkwitz jobbie that I built several years ago. Must have been a disappointment, coz it's somewhere in the loft. Perhaps I should get it down for another trial.

 

[marshanp]

Surely devices which only provide partial channel mixing (Linkwitz? Sonneteer?) are going to be less than completely satisfactory.

Equally important (but rather harder to implement?) is the time delay of right-channel-to-left-ear and vice versa - the crucial thing that you get with speakers and which is lost via headphones.

The SPL Phonitor 2 amp appears to have all this sussed, which is why it is top of my shopping list if I am ever deprived of speaker listening.