An odd "tool" for headphone users

ALL212

Would you like to listen to headphones on an amp that has no headphone jack? One of the guys at the Bottlehead forum dreamed this up. Cheap and easy. It might not sound the greatest depending on the impedance of the amp and the headphones used. I found that it worked great for adjusting the hum pots on my Stereomour. Obviously you MUST have a volume control in the chain somewhere or you'll blow the headphones right off your head and possibly your ear drums with them.

DaveHo

Considering most headphones have a max input in the hundreds of milliwatts, seems it would be tough to control volume.

EndersShadow

@ALL212

There is actually another device you can buy called a "Can Opener" that lets you piggy back off the speaker inputs on your amp to run a set of headphones. Not 10 bucks, but also not a couple hundred.......

Same caveat, must have volume control somewhere in the chain.






If you're serious about headphones, the Can Opener is a “must have”
accessory that lets you directly connect your favorite cans to the speaker
terminals of most stereo amplifiers.

The Can Opener bypasses the sub-par active headphone jack circuitry that
is typically found in most receivers and integrated amps to ensure the best
possible headphone listening experience at home. The Can Opener may
also be used to add headphone functionality to stand-alone stereo power
amplifiers since these components do not typically have headphone jack
circuitry.

High-quality, passive components combined with a precision, all-metal
Neutrik locking ¼-inch headphone jack ensure the integrity of the audio
signal from the amplifier speaker outputs to your headphones.

Open your cans, man!

Lets you safely connect headphones directly to stereo amplifier
speaker outputs
Bypasses internal amplifier headphone jack circuitry
Uses no active components – requires no power
5-way binding posts for use with all types of speaker cable and
connectors
Designed and Manufactured in USA


Enclosure: Laser-cut 20 g steel with black texture powder coat finish
and titanium black gloss epoxy silkscreen printing
Dimensions: 5-1/8” D x 4-3/4” W x 1-3/4” H
Net Weight: 16 oz
Connectors: Banana plug 5-way speaker terminals;
Precision metal Neutrik ¼-inch locking headphone jack

ALL212

DaveHo wrote: »

Considering most headphones have a max input in the hundreds of milliwatts, seems it would be tough to control volume.

The first 1/4 turn of most volume controls only puts out a very small output. I found on my amp I could easily go past 9.

mhardy6647

The "best" way to do it is with a little resistor network in your "box"... this protects both the amplifier & the headphones (oh, and, umm, potentially the listener's ears, too).

This may also be readily DIY'd -- i.e., if you can solder, why buy a 'black box'?

http://sound.whsites.net/project100.htm



The values for R1 and R3 (and the power rating for R2) are tabulated in the link to provide an appropriate output power for input from power amps from 10* to 250 W.

Probably worth noting that the designed headphone output impedance (Zout) is nominally about 120 ohms, give or take. A little reflection on Ohm's Law allows one to adjust the value of R2 (ahem and R1 and R3, too, of course) if need be to suit headphones that might be happy with a higher or lower Zout.

_________
* Some folks have amps of less than 10wpc -- just sayin'

maingey

never crossed my mind...

Face

Since my headphones are balanced, I'm using 4 pole XLR connectors between my amp/speakers/and headphones. Makes swapping between the two pretty easy.