Using headphones via speaker output channel 2?!?!

[admin_exported]

I've been wondering if it's possible to use a standard hi-fi amp. for headphones? The idea is that instead of using a headphone amp. you would use your headphones in the same way as you would use passive speakers (instead of using the headphone socket on the front of the amp. [that usually sound poor]). You would use banana plugs and instead of connecting speakers to the other end you would connect your headphones using either a custom 3.5mm jack or 'editing' the headphone cable.

Would this be feasible and/or sensible? I would like to do this but don't want to kill myslef or my headphones doing so. I have an old Marantz PM4001 that I would use and my Grado SR225s, as mentioned above, the headphones would be connected via the speaker outputs instead of the headphone jack. If this is a stupid idea I won't try it but if it's known to work then I'll give it a go.

Just a note - the PM4001 output is 40w @ 8 Ohms and the headphone impedance is 32 Ohms

Is this a stupid idea or does it have a chance of working? I would appreciate your advice. :wall:

 

[idc]

There are a very few headphones that can run from a normal amp, the AKG K1000 ear speakers are the only ones I can remember. But they will also run fine from my headphone amp, which is a powerful one outputting 1.3 watts into 32ohms. The FiiO portable amp outputs 0.5 watts. So normal amps are way too powerful for headphones and the destruction of the headphone is a likely consequence.

 

[eggontoast]

You can run headphones from the speaker terminals but obviously you have to be careful. The problem you have is getting a usable range on the volume control, older amps used to have -20dB attenuators in the preamp which helped with doing this. If your amp doesn't have this function you could buy some phono attenuators for the inputs of the amplifier, this will do the same job. But TBH most headphone sockets are run from the power amp anyway, they just have a couple of 330 ohm resistors in series to drop a proportion of the voltage. I'm not sure you will hear a great deal of difference without the resistors though. If you give it a try report back your findings it will be interesting, just be gentle with the volume control.

 

[dalethorn]

Most headphones are powerful enough to damage your ears on a single large pulse from a power amp. Playing with that is like Russian Roulette.

 

[eggontoast]

Most headphones are powerful enough to damage your ears on a single large pulse from a power amp. Playing with that is like Russian Roulette.

Not really, you can do this with 1.5 Watts from a headphone amp if your stupid.

 

[Anonymous]

You can certainly do this provided you attenuate the speaker outputs from the amplifier with a pair of resistors per channel. Otherwise you risk blowing the headphones and, much more importantly, possibly damaging your hearing with an unwanted transient (I mean permanent damage in the extreme).

If you are competent with basic electronics you can make your own. You'll need an L-pad for each channel - two resistors in series between the speaker output and ground. The first one should be say 150 ohms 3 watts, and the one to ground say 10 ohms 0.25 watts (or greater). You connect the headphones across the 10 ohms resistors. All modern linear class A/B amplifiers should be stable with this kind of load by the way and will also have less distortion than when driving a speaker. You can't do it safely with class D amplifiers or some valve amplifiers. No responsibility is accepted by me for anyone trying this and screwing up!

Hope this helps.

John Dawson