How do I play back one channel into both ears of my headphones?

[Jack Clark]

I've tried searching for this, but no luck.

All I want to do is play back the right channel (only) into both ears of my headphones.

My situation: I'm using iTunes (or Audiolobe) on a Macbook to play back play-alongs into headphones. The Macbook headphone jack is stereo. My headphone plug is stereo. I tried buying a stereo-to-mono adapter from Radio Shack: It has a male stereo plug and a female mono jack. I set the balance control to output right channel only. I know the balance control works because, with no adapter, I hear only the right channel in the right ear of my stereo headphones. Then I put the adapter I bought between my Macbook and my headphones, but I still hear the right channel in my right ear only. [CORRECTION: With the adapter in place, I hear both channels in my left ear only. -Jack 8/25/09]

Have I got this backwards? Do I need an adapter with a male mono plug and a female stereo jack instead?

Anybody know how to do this?

Thanks!

[T-Bird]

Hi.

This may help. (I do know about the lameness of wiki quotes, haters, live with it)

http://en.wikipedia.org/wiki/TRS_connector

As You can see, right channel is the ring, so no normal adapter will work.

DIY is the approach I'd take.

Regards
Sam

[Jack Clark]

Yeah, Sam, I now see the problem with the help of the diagram at the website you referenced.

So, now I'm thinking of just getting out the soldering gun and making a small box with two jacks so I can cross-connect the L and R channels. Then when I connect a double-male stereo cord between my MacBook's earphone output and one box jack, and my stereo headphones into the other box jack, I'll get the right channel in both ears. Is that the type of DYI you had in mind?

I can't hurt the MacBook by doing this can I? (Not worried about the headphones too much.)

[kumde]

VLC media player can do this, and is available for Mac. See www.videolan.org.

Edit. if you really, really want a hardware solution, the straighforward solution would be to buy one 3.5mm stereo plug, one 3.5mm stereo jack
and some microphone cable; then wire the sleeve of the plug to the sleeve of the jack and the ring of the plug to both ring and tip of the jack.

Edit2. actually, this is just what you outline in your post above. I should take the time to read all the posts :-)

[ggunn]

Originally Posted by nimbleswitch

Have I got this backwards? Do I need an adaptor with a male mono plug and a female stereo jack instead?

Yes and yes. Look on the rack at the Shack; you should be able to find a mono to stereo 'phone adapter.

[Jack Clark]

Originally Posted by kumde

Edit. if you really, really want a hardware solution, the straighforward solution would be to buy one 3.5mm stereo plug, one 3.5mm stereo jack
and some microphone cable; then wire the sleeve of the plug to the sleeve of the jack and the ring of the plug to both ring and tip of the jack.

Edit2. actually, this is just what you outline in your post above. I should take the time to read all the posts :-)

Yes, but you pointed out that I don't need to fool with a box. I can do it within the jack and plug themselves. Thanks much.

[Jack Clark]

Originally Posted by ggunn

Yes and yes. Look on the rack at the Shack; you should be able to find a mono to stereo 'phone adapter.

Well, I'm certainly no electronics expert, but I've been thinking about this mono plug with stereo jack--which is just the opposite of the adapter I tried. But wouldn't such an adapter just throw the left channel into my left ear if I plugged it into my MacBook's stereo jack? I mean, wouldn't the right signal coming from my MacBook just be in direct contact with the ground sleeve when I plug the mono plug into the MacBook's stereo jack?

I'm thinking that the purpose of a mono plug to stereo jack adapter must be to transfer a mono signal from a mono source to both ears of your stereo headphones. But that's not going to help me solve my problem since the jack in my MacBook is a stereo source.

[Jack Clark]

Originally Posted by kumde

VLC media player can do this, and is available for Mac. See www.videolan.org.

Well, the VLC media player, if it does this, would be better than iTunes for play back. But I really want to play these play-alongs back through Audiolobe, since it's a slow-downer, a speed-upper, and at the same time can change pitch to all 12 sounding keys--and do loops. So, I'm looking for a hardware solution, I think. Just making the home-made adaptor you describe above seems the best way. But there's no danger of damage to my MacBook from that, is there?

[T-Bird]

Hi.

Well, You can insert the mono-stereo adapter to the first notch only (ring, R), leaving the tip contacts (tip, L) in the jack shorted.

That's the age old trick to make splitter point out of an insert point on certain mixing consoles. That have the ring as the send and tip as the return obviously.

The only thing to be concerned about with Your laptop, is the same thing that you'll worry about when connecting any adapters to the often crappy plastic parts. The weight of the adapter will put some stress to the jack itself. IIRC MacBooks are a bit sturdier than most of the PC clones in that regard.

Regards
Sam

[ggunn]

Originally Posted by nimbleswitch

Well, I'm certainly no electronics expert, but I've been thinking about this mono plug with stereo jack--which is just the opposite of the adapter I tried. But wouldn't such an adapter just throw the left channel into my left ear if I plugged it into my MacBook's stereo jack? I mean, wouldn't the right signal coming from my MacBook just be in direct contact with the ground sleeve when I plug the mono plug into the MacBook's stereo jack?

I'm thinking that the purpose of a mono plug to stereo jack adapter must be to transfer a mono signal from a mono source to both ears of your stereo headphones. But that's not my problem since the jack in my MacBook is a stereo source.

Then I guess I'm having trouble visualizing what you want to hear and where. If you want to hear one channel in both ears, then a mono to stereo adapter will do that no matter whether the output jack is stereo or mono as long as the signal you want to listen to is routed to the tip connector of the jack. If the channel you want to listen to is on the ring, then pan it the other way.

If you have the playback on one channel and your play-along on the other and you want to hear it all in both ears, you could use a stereo to mono adapter and a mono to stereo adapter in series to do that.

[Jack Clark]

Thanks, Gordon, for your continued input. The problem is that the channel I want to hear in both ears is the right channel, which you recognize is in the ring rather than the tip. I don't understand what you mean by "pan it the other way," though.

Im not trying to hear my recorded sound over the play along's recorded sound. In more detail, what I'm trying to do is pretty simple:

I use Aebersold and Leonard play alongs playing them through Audiolobe on my MacBook using on-the-ear headphones that do not keep out other sounds in the room. (Audiolobe is a slow-down, pitch-change software.) Typically, the bass is recorded in the left channel; piano and drums in the right. When I get a tune down good enough, I want to cut out the bass channel and play that part myself. With my stereo headphones plugged into my MacBook's stereo jack, when I move the balance control over to the right, it cuts out the bass alright, but then I hear the piano and drums only in my right ear--which is very unnatural and weak sounding. It would be much better to hear the piano and drums in both ears, and then lower the volume as needed to hear myself play with them.

Again, I see where you say that I should "pan it the other way" in this situation, but I don't understand what that means.

Seems to me that I'm going to have to make my own short adapter cable, with a stereo plug at one end and a stereo jack at the other. Only, I want to solder one cable wire between the sleeves of both plug and jack (for ground) and the other cable wire between the the ring of the plug and the ring and tip of the jack, for right channel in both ears when I plug my stereo headphones into that jack. Isn't that right?

[ggunn]

Originally Posted by nimbleswitch

Thanks, Gordon, for your continued input. The problem is that the channel I want to hear in both ears is the right channel, which you recognize is in the ring rather than the tip. I don't understand what you mean by "pan it the other way," though.

Im not trying to hear my sound over the play along's sound. In more detail, what I'm trying to do is pretty simple:

I use Aebersold and Leonard play alongs playing them through Audiolobe on my MacBook using on-the-ear headphones that do not keep out other sounds in the room. (Audiolobe is a slow-down, pitch-change software.) Typically, the bass is recorded in the left channel; piano and drums in the right, especially, in the Aebersolds. When I get a tune down good enough, I want to cut out the bass channel and play that part myself. With my stereo headphones plugged into my MacBook's stereo jack, when I move the balance control over to the right, it cuts out the bass alright, but then I hear the piano and drums only in my right ear--which is very unnatural and weak sounding. It would be much better to hear them in both ears, and then lower the volume as needed to hear myself play with them.

Again, I see where you say that I should "pan it the other way" in this situation, but I don't understand what that means.

I mean make what you want to hear be in the left channel rather than the right so that it's on the tip rather than the ring. Do you not have that option in your software (Audiolobe?)? If you don't, then making your own adapter may indeed be your only option.

Or if you can port the material into Audacity (free Mac software), you might be able to wipe the left channel and copy the right channel onto the left and listen to it with no adapter.

[Jack Clark]

Originally Posted by ggunn

I mean make what you want to hear be in the left channel rather than the right so that it's on the tip rather than the ring. Do you not have that option in your software (Audiolobe?)? If you don't, then making your own adapter may indeed be your only option.

Or if you can port the material into Audacity (free Mac software), you might be able to wipe the left channel and copy the right channel onto the left and listen to it with no adapter.

Ah, that was the problem, Gordon. No, Audiolobe, can't do that. It isn't a sound processor program, just a playback program. I'm going to take a good look at Audacity, though, as you suggest. I've heard about that program, but haven't checked it out. Thanks for the tips!

[Jack Clark]

I want to thank all you BG guys for helping me out with this electronics question. Although I know that a standard guitarrón is a type of acoustic bass guitar, I generally identify with the DB guys because of the ways I've modified my guitarrón and the way I play it. Also, I have a passion for the particular DB sound, even though I don't play one, so I don't generally spend much time on this side of the board.

But I figured that DB guys weren't as likely to know about an electronics question, so I posted it twice: under Double Bass Miscellaneous and under Bass Guitar Miscellaneous. Sure enough, I got zero comments on the DB side, while you BG guys came through big time over here.

So, thank you all again.

[Jack Clark]

Hey, guys-

I just rigged up both of these adapters--a "right" one that plays the right channel into both ears for accompanying play-alongs, and a "left" one that plays the left channel into both ears for transcribing bass from the left channel. They both work great. You still need to move the balance lever all the way right (or left) because of slight cross-over between the channels, but that's no problem.

Having drums and piano in both ears is far more natural and listenable, sounds like I'm accompanying real people now.

Here's a pic of the final products.

Thanks for your help!