PDA

View Full Version : SNES Stereo to mono



MuppeT
03-31-2015, 11:33 AM
I am working on trying to get a SNES working in my arcade cab and I have a question... snes produces stereo and I need mono for the jamma edge. What is the best way to do that in terms of sound performance?
:scratch:
Thanks

Kid Panda
03-31-2015, 11:57 AM
There's no amplifier in the Snes, so to get sound you'll need to build an amplifier in which case you can just merge the stereo audio to mono like that.

Lemony Vengeance
03-31-2015, 12:03 PM
you can't just connect both lines into one, you need to build a circuit that will merge them without overloading stuff.

And yes, unless your cabinet has an amp, You will need to put a mono amp in there.

Kid Panda
03-31-2015, 12:10 PM
you can't just connect both lines into one, you need to build a circuit that will merge them without overloading stuff.

And yes, unless your cabinet has an amp, You will need to put a mono amp in there.

What about running the audio out in series instead of parallel? That would increase the ohms and lessen the load on the output.

MuppeT
03-31-2015, 01:28 PM
So any ideas how the circuit should look or any ideas for a mono amp that would do the job ? I just got into this kind of stuff and quite noobish. thanks for the help.

bustedstr8
03-31-2015, 01:38 PM
Combined L/R>Trimpot>Amp>Jamma Mono

Jamma amps are around 18W, Class AB. You might find a mono amp or just use one channel of a stereo amp.

mikew
03-31-2015, 01:59 PM
So any ideas how the circuit should look or any ideas for a mono amp that would do the job ? I just got into this kind of stuff and quite noobish. thanks for the help.

The standard way to do this is with a summing op-amp, basically an audio mixer.

Here's an example:

http://www.electronics-tutorials.ws/opamp/opamp_4.html

pulstar
03-31-2015, 02:04 PM
Or if you want to do it on the cheap, a 4.7k resistor on both the L & R channels into a single mono output...I'd prefer the op-amp suggested above though.

MuppeT
03-31-2015, 03:58 PM
thanks for feedback guys. How about this ?

24141

as per site i found
You probably won't need this often as most games are mono anyway and games which are stereo usually have a mono option (for the JAMMA standard) but if you have a multi-slot Neo Geo motherboard here's how to stop it from sounding a bit one sided:

Parts:

Optional - JAMMA fingerboard
2 ohm resistor X 2
4 ohm resistor
"Standard" Formula for converting Stereo to Mono:

Mono = L/2 + R/2 = (L+R)/2

Dividing a signal's amplitude by 1/2 is simple -- just use a voltage divider formed with 2 equal resistors. The "adder" in your case can be just hooking the wires together.

Okay... That's the textbook answer, here's what it means! Bridge the + and - speaker wires with a 4ohm resistor and use 2ohm resistors instead of wires to connect the +ve signals. This will keep it all at 4 ohms and roughly the same volume. Add capacitors to taste for 1st order crossover (not THAT necessary).
The optional JAMMA fingerboard is to make things easier to connect, after all you don't want to have to disconnect wires inside your cab/supergun to perform the mod!!! Also, if you're making a multislot Neo Geo loom you'll also need to make the correct connections for the test button and the game select buttons as well as its NOT JAMMA like the one slots are.

I am looking for something simple that I could do myself.


Also don't they sell amps that get in stereo and output mono ? I went on ebay and found many small amps for around $10-15 ... but do't know which one will do the job... here are few :

http://www.ebay.com/itm/201207717721
http://www.ebay.com/itm/271463838799
http://www.ebay.com/itm/250530515447
http://www.ebay.com/itm/221665079882

any suggestions ?

mikejmoffitt
04-04-2015, 06:21 PM
you can't just connect both lines into one, you need to build a circuit that will merge them without overloading stuff.

And yes, unless your cabinet has an amp, You will need to put a mono amp in there.

No, you can definitely do this. Nintendo's manual even suggests it if you only have mono sound.

EDIT: Doesn't the SNES generate mono to feed to the RF encoder? You may be able to simply use that.