Connecting headphones to amp speaker terminals - Project Amphones

Hi all,

For a long time I wanted to use my 2x20 Watt Class A Musical Fidelity Amp for driving my headphones.  Because of oxidation of all switches/volumepot I desoldered these a long time ago.  It now only takes one input signal and is always full power (volume has been bypassed).  Then I saw this article by Rod Elliott of Elliott Sound Products, bless his heart.  It explains how to lower the amps output wattage using 3 resistors per channel, making it usable for headphones.  I would use my T-box headphone-amp as pre-amplifier for volume control.

I have my amp, and I have a Stax SRD-4 which includes a very handy switch to select between Earspeaker (Stax SR-30 Old But Good Earphones) and Loudspeaker (Which I shall use for my "Amphones")

I want to clarify that you don't need the Stax SRD-4.  I just use it as a housing and because the switch turns the headphone-output on and off.  You could just as easily directly connect the amps loudspeaker output to the resistors ( left and right positive signals) and jackplug (left and right negative signals), and put this in a housing of your choice.

So ...  I got myself 2 X (47, 120 an 180 Ohm) resistors and a 6.3mm jackplug.  I needed 47 and 180 Ohm resistors because the amp outputs 2 X 20 Watts of Pure Heaven.  Then I got soldering.

This is how it looks like when soldered onto the jackplug

and from another angle

This needed to get connected inside the SRD-4.  I used the loudspeaker-wiring to feed into the jackplug.  I desoldered these leads from the 4 terminals in the back.

I then removed the now unused terminals and used one of the holes to insert the jackplug.

This is everything connected

And then the final result

I do admit, I have crazy amounts of hummmmm on low volume... But I can live with it  Long live my Amphones !

I didn't invest in expensive parts because I wanted to test this configuration first.  And the hum is coming from the amp, not from the resistors.