Mono or Stereo Jack for headphones

[therockdemon]

First let's get the basics.  For pedals going from guitar to amp, you use stereo inputs and mono outputs.  The Ring on the input is used for a 9V battery.  I got that part.  Read on...

I'm interested in using a pedal for stereo output to stereo headphones (for highly mobile plugged-in electric guitar practice) as well as stereo patch cords (to car radio with an aux port perhaps?).  I believe that involves using a stereo output jack.  I was wondering how that would be wired.  I assume you just connect the output signal to both Tip and Ring on the output jack and wallah?

Correct me if I'm wrong:

Output:  Plug Mono ST Male/"Cord" into Mono ST Female/"Jack"
Tip-to-tip, sleeve-to-sleeve.  Mono signal is passed on via tip, which is normal pedal operation in 1/4".

All pedals except certain special ones have their output set up this way.

Output:  Plug Mono ST Male/"Cord" into Stereo SRT Female/"Jack"
Tip-to-tip, sleeve-to-ring and sleeve.  The mono cord would connect the Ring and Sleeve connections in the jack, which would send any of the female's Ring connection (half the stereo) to ground.  Only the tip signal is passed on in mono, and that's all the cord is for anyway.  This is how a 9V is grounded via input jack in a circuit while preserving the battery while nothing is plugged in.

If the tip and Ring connections were connected in the jack, you would effectively send 100% of the signal to ground.  In other words, if you're sending a mono signal to both the tip and ring lugs of a female stereo output jack, such as in a guitar signal application, you can't ever use a mono plug on that jack.  It has to be stereo.  

Output:  Plug Stereo SRT Male/"Cord" into Mono ST Female/"Jack"
Tip-to-tip, Ring-to-nothing, sleeve-to-sleeve.  This would be like plugging headphones into a mono jack.  One of the headphone speakers will have the mono sound (mono) and not the other since the Ring part of the cord doesn't touch anything at all.  This probably has no desirable application.

Ø

Output:  Plug Stereo SRT Male/"Cord" into Stereo SRT Female/"Jack"
Tip-to-tip, Ring-to-ring, sleeve-to-sleeve.  Stereo.

Again, for a guitar signal application the ring and tip lugs in the female stereo output jack have to both be connected.  This splits the mono signal into stereo, but then you can only use stereo cords in this plug.  This would be what I would want to use in 3.5 mm as a "secondary" jack to hook a pedal up as a preamp to car speakers via the car's radio AUX plugin (which you'd otherwise use for an iPod or whatever).

It sounds like there'd really be no way to connect a 1/4" headphone jack to a guitar pedal and have it work on both speakers, without some kind of converter.  Lastly, I'm pretty sure that if you had both a 1/4" and 3.5mm female output jack, it should work fine as long as the 1/4" only uses mono (or stereo with some kind of adapter?) and the 3.5mm only uses stereo.  A mono plug into the 3.5mm would connect all lugs from both jacks to sleeve, effectively grounding the output signal completely - no sound.

Half baked idea:  I haven't spent that much time thinking about this yet, but I wonder about using stereo jacks for both the outputs (1/4" and 3.5mm) and using switches to make/break connections for different applications.  Just crossed my mind  Hmmm....  Yeah I think that could be done with a SPST to make/break a connection between the Tip and Ring lugs on a 1/4" female output jack.


Anybody know of a good 3.5mm stereo jack for pedal-type applications?

[davent]

Anybody know of a good 3.5mm stereo jack for pedal-type applications?

Kobiconn make a plastic bodied, (isolated from the enclosure) panel mount, 3.5mm jack with perhaps enough threaded bushing to be usable in a Hammond type enclosure.  # 161-7300-ex

http://ca.mouser.com/ProductDetail/Kobiconn/161-7300-EX/?qs=sGAEpiMZZMv0W4pxf2HiV2oxafp8PWP3uLV6puKy7fU%3d

dave

[therockdemon]

What's wrong with this?

http://www.mouser.com/catalog/specsheets/KC-301090.pdf
http://ca.mouser.com/ProductDetail/Kobiconn/161-3402-E/?qs=sGAEpiMZZMv0W4pxf2HiV4Mt5ZQSVq1hAasLUHlfK30%3d

[davent]

When using those in headphone amps i always found i had to isolate the bushing from the enclosure for things to work properly, intermitent sound etc.,  and the bushing is too short to allow this to be easily done on a diecast aluminum enclosure. Fault, was no doubt was me, but having an isolated jack from the get go made life much easier. No problems with that type when using a plastic enclosure.

[Jdansti]

Maybe I misunderstood, but I think you're saying that you want to plug headphones into guitar pedals for private practice.

Most pedals won't have enough output to drive headphones, but assuming you have a pedal or small amp that will drive phones, then your options are:

1) Just plug in your headphone jack and listen through one ear
2) Install a stereo jack on the output of the pedal/amp, and connect the signal to the tip and ring. Don't connect the ring to the sleeve!  You will short your signal as you indicated. Here's what the male plug is expecting :



3) Buy or make a mono to stereo adapter that does the same as #2, but external to the pedal/amp
4) Rewire your male headphone plug by shorting the tip and ring (you probably don't want to do this if you use your headphones for listening to a real stereo amp as it could potentially damage two amp channels, plus you might enjoy stereo more than mono ).

One other thing to watch, is not to go below the specified output impedance of a given amp. By connecting your left and right headphone speakers in parallel, you'll halve their impedance. This probably won't be a problem since most headphone speakers are 16 ohms or greater (8 ohms or greater in parallel), and most amps will handle as low as 4 ohms. It's just something to watch out for.

[slacker]

If you use a stereo output socket and connect the output of the pedal to the tip and ring through resistors, this sort of isolates the outputs and you can use a stereo or mono plug. This prevents the outputs being shorted out when using a mono plug as the one output is connected to ground through its resistor instead of directly. Values of a few K Ohms or more should work for most things, there may be some volume loss and tonal changes depending on what the original output of the pedal consists of.

[Jdansti]

^+1

Good point!  Also a good reason to use an external adapter instead of putting stereo jack inside the pedals. With the external adapter, he would only use it with stereo headphones and he could use it with multiple pedals.