Wasabi Sound: Headphone Adapter for Your VCR, or TV

posted: 2011-03-20 | updated: 2020-08-06

wasabi can project box

wasabi can project box

I’ve always wished my old CRT TV had a headphone jack. There are times when I want to veg out and watch some tube without disturbing anyone else. Alas, the only connection my TV has is an input for a coax cable. I recently received a hand-me-down VCR, which has a line-level, stereo output. Hmm, me thinks, a possibility?

Not being sure about connecting headphones directly to a VCR’s audio output, I did a little searching online. One person was using an adapter cable consisting of two RCA plugs on one end, and a stereo jack on the other. I whipped up a cable and gave it a try using inexpensive headphones. Encouraged by the lack of smoke, I tried plugging in my Sony MDR-7506 headphones. The headphones didn’t complain, but my ears certainly did. While this is a simple and inexpensive solution, the volume was way too loud for comfort and the VCR has no volume control. I’m assuming the volume will vary with different VCR and headphone combinations, but I needed a volume control.

a few simple components inside wasabi can

a few simple components with room to spare

There are some great examples of do-it-yourself audio preamps on the web such as the CMoy Pocket Amplifier tutorial. A preamp would solve the volume control problem, but I was looking for something quick and dirty. The solution is an ultra-simple circuit with passive volume control—take a look at the schematic and photos.

RCA jacks on bottom of wasabi can

RCA jacks on bottom of can

The hardest part was drilling the extremely thin wasabi can. I marked the hole locations with a centre punch, drilled pilot holes, and then gingerly drilled the correct size holes for the jacks and potentiometer shaft using a scrap of wood as a backing plate. I’m really glad I securely mounted the wasabi can in a vise, otherwise I’d be typing this blog entry with bandages decorating my hands.

wasabi sound schematic: a very simple circuit

wasabi sound schematic: a very simple circuit

The success of this project is completely reliant on the electro-acoustic properties of the project enclosure. After weeks of exhaustive testing of every conceivable shape of enclosure built from all manner of exotic materials—some including titanium and yttrium compounds—as fate would have it, the empty wasabi can sitting on my kitchen counter produced the most mellifluous results. The reward for my efforts? I can now listen to the tube in stereo with sonic clarity that soundly thrashes that which dribbles from the speaker of a 20 year old television. And I’m not disturbing anyone.

Garfield enjoying wasabi sound with headphones

Garfield enjoying wasabi sound

Parts list:

  • Wasabi can (or other suitable enclosure)
  • Panel-mount RCA phono jack (2 required)
  • Dual 10 K ohm log potentiometer
  • 3.5mm stereo mini jack
  • 22 gauge insulated solid wire (24 gauge is fine)
  • RCA plug to RCA plug stereo cable

Update: 2020-08-06

While the VCR and cathode-ray tube TV are ancient history, Wasabi Sound Headphone Adapter lives on. When I watch movies or TV using headphones, I crank the volume to compensate for actors that whisper and mumble, and turn it way down to protect my ears from the sonic booms produced by sound effects and thematic music. Twisting the audio pot on Wasabi Sound is faster and easier than thumbing the volume buttons on a remote control. I also use it on my computer. Same reason.

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