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HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Jun 13, 2017 11:40 am
by Enviola
Hey all, This may be a stupid question but it has been bugging me and I am at a loss...

I am using the USB Soundcard setup but I cannot figure out how to have my cake and eat it too...
I was thinking the wiring layout would be:
USB Hub ---- USB Soundcard ---- Stereo Amp ---- Pot Wheel ---- 3.5mm jack ---- Speaker.

My ultimate goal is to get stereo sound through the Headphones when they are plugged in but Mono through the speaker with the Pot controlling both.

I have a Stereo Amplifier but I cannot figure out how to wire the 4 outputs (L+, L-, R+, R-) to the 2 inputs on the Pot (L/R)
Is there some kind of converter to add in between?

I've been searching online for hours and cant find a clear solution which tells me that its either not possible or the answer is so easy it shouldn't even require explanation.

Any help would be appreciated. Thanks!

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Jun 13, 2017 11:43 am
by RogerX
I've been trying to figure out the right way to do this also... with USB sound, how do you wire the pot, jack and amp so that you can have decent speaker audio and have it overridden when headphones are plugged in? I have yet to find a good guide.

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 1:46 am
by Baconbomb80
Been looking for a solution for this to and found this on how to "merge" stereo to mono.
I don't know if its the right way to do it and hoping somebody can help me out or maybe point me at the right direction

http://www.instructables.com/id/Simple- ... o-to-Mono/

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 1:51 am
by BadBert
the richt way is:
USB HUB -> USB SOUND CARD -> volume pot (stereo) -> 3.5mm jack (stereo) -> combine to mono (with resistors) -> 1 channel of your amp -> speaker

this is the way wermy does it in his gbz custom parts build, there you can find the resistor values (but 2 of them are available on the original GB board! so you can harvest them from there).

This works for me :)

On the forums here they told me that it is not simply possible to combine the channels after the amp, because of how the amp is built.

This way you have stereo on your headphones (no amp needed), and combined "stereo" over 1 channel amped to your speaker.

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 2:55 am
by Baconbomb80
Do you need an amp for the jack if you use the pi3's audio jack?

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 3:25 am
by BadBert
Baconbomb80 wrote:
Tue Aug 01, 2017 2:55 am
Do you need an amp for the jack if you use the pi3's audio jack?
No :) it is loud enough without an amp.
You only need an amp if you use a speaker :D

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 6:22 am
by 144TECH
Hi, you will need a 5 pin Pot, L in R in L out R out + gnd , idk why you want mono on speaker and stereo on the jack, but i think you should only use one channel output of the usb sound instead of 2 , and bundle them together to make something like mono but on both channels of the headphone, technically speaking in software settings, this should be impossible to have mono on speaker and stereo on headphones, unless you use one channel only on the speaker, and bundle them later into double mono/ or stereo but the jack has to break the speakers signal by plugging in.

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 6:39 am
by BadBert
144TECH wrote:
Tue Aug 01, 2017 6:22 am
Hi, you will need a 5 pin Pot, L in R in L out R out + gnd , idk why you want mono on speaker and stereo on the jack, but i think you should only use one channel output of the usb sound instead of 2 , and bundle them together to make something like mono but on both channels of the headphone, technically speaking in software settings, this should be impossible to have mono on speaker and stereo on headphones, unless you use one channel only on the speaker, and bundle them later into double mono/ or stereo but the jack has to break the speakers signal by plugging in.
If you look at my explination, and check wermy's video on the custom build, you will get:
- combined stereo to mono sound out of the speaker (not losing any sound effects)
- stereo sound on the headphone jack.

:)

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 6:48 am
by 144TECH
That's what i said kinda the same as helder did on his aio's :mrgreen:

Re: HELP with Stereo Sound to Headphone Jack (USB Method)

Posted: Tue Aug 01, 2017 6:53 am
by BadBert
144TECH wrote:
Tue Aug 01, 2017 6:48 am
That's what i said kinda the same as helder did on his aio's :mrgreen:
yeah, sorry, i misread your post :oops:

Getting the audio like that works like a charm btw :D