Description

Somewhere on your campus, perhaps in a closet in the media center, there are potentially useful resources for computer education.  Some may even date from my childhood (I’m a boomer).  They are ancient, but well made, headphone listening centers.  Unfortunately, they are equipped with GIANT 1/4″ phone jacks from the early days of telephony.  Rubbish….many say.  I say….repurpose them….put them to work with modern headphones.  The transition is easy and inexpensive.

HOW??? Using these adapters, those GIANT 1/4″ mono jacks can be safely be converted to accept modern 3.5mm stereo headphone plugs.  The 1/4″ plug on the listening centers can also be adapted to 3.5mm.  These adapters change small plugs into to large ones (little mechanical leverage).

The prime electrical consideration is the impedance of the headphones you use.  Impedance at the plug into your computer or audio source should be at least 4 ohms.  You can calculate this by dividing the impedance of the headphones being used (SchoolPHONES are 32 ohms) by the 2x number of headphones being connected to the listening center.  Each 32 ohm headphone converted to mono becomes 16 ohms (the 2x) then dividing by the number of headphones you arrive at the “load” impedance.  Thus…four 32 ohm headphones converted will equal a load of 4 ohms (32/2)/4=4.  If you’re interested in making more exotic calculations, let me suggest the following website: https://geoffthegreygeek.com/calculator-speakers-in-parallel/ .

To convert the listening center’s 1/4″ plug, I suggest a small dongle adapter 6.3mm mono / 3.5mm stereo.  The reason I suggest the dongle is a fixed adapter (converting a large plug to small one) creates a large amount of leverage against the solder joints of the small 3.5mm jack in your computer, CD, DVD or tape player.  Unless this leverage is controlled, there can be a “bad” outcome for the source device. -Ted Simons