neogeo / jamma stereo safe switch

Someone posted a diagram of a safe way to handle stereo audio and mono audio in a shared jamma / neogeo setup - I'll be buggered if I can find the post it was in, I spent ages looking for it last night.

Please help to point me at the correct thread / diagram.

Thanks,
Mark.

 

Sorry for the Bump - but anyone have a clue where that diagram could be?

Also, while I'm here if I'm making a wiring harness for neogeo mvs / jamma board swapping, it would make sense to wire button 4 to a switch that can toggle between neogeo button D or the 4th button from a kick harness as 1,2 and 3 are on the jamma edge for most boards and when I want to use 4,5 and 6 for 6 button games they'll be on a kick harness. AFAIK neogeo button D isn't recognised by jamma games expecting a 4th button unless it's presented on a kick harness configuration.

For the sake of a simple spdt toggle switch I can have much greater compatibility and flexibility.

 

Well, in my experience, you can just wire buttons 4 and 5 straight to the edge connector and you don't need toggles to disconnect. If a board doesn't have those buttons on the JAMMA edge connector then they are Not Connected, to anything. Also, I've heard with Capcom games sometimes you need to connect both button 4 on the edge and to the kick harness.

Anyway, don't worry about the buttons. For Stereo with the MVS you could goto hardmvs.com to look for info.

For flexibility I was going to have toggle switches to allow remapping certain buttons on my supergun but I never got around to it. The main reason I'd need remapping was for Mortal Kombat. Anyway, I think a switch will handle your stereo situation.

 

Perfect! Thanks Eric :dance: :clap:

 

How is this safe? Its still going to send a negative signal to the positive terminal of a speaker with a standard jamma board if the switch is set to stereo, is it not?

 

Can you post a diagram to illustrate this point please.

 

You need a 4 pole 2 throw switch wired like this:



Note: based on http://www.antsarcade.net/pinouts.html

 

Is Calpis's diagram more along the lines of what you were thinking of? (thanks for the diagram Calpis)

 

It still suffers from the same problem. I can't think of any way to avoid this from happening.

Of course its not a big deal if you have your supergun hooked up to a cheap speaker or amp, I have a good quality receiver which is why I've chosen to avoid any potential damage from happening and go with a mono neo board (which unfortunately means I only get 1 slot).

 

The whole point is to connect the amplified speaker output directly to a speaker. If you're going to use a receiver, you should take line audio somewhere or at least attenuate the speaker output, but that's sloppy since by nature the level will change depending on the volume setting.

I don't understand what you mean by "if the switch is set to stereo", the Neo Geo's? The diagram I posted assumes that there's always stereo audio from the Neo since it's always there on the edge connector. If you don't mean the Neo, what are you talking about since Jamma is mono?

In diagram I drew the left speaker is either properly switched onto + and - of the mono Jamma output and the right speaker is disconnected, or both left and right are properly switched to how they should be on the Neo. It doesn't switch to dual mono though but random Jamma game's amplified output won't necessarily be able to drive two 8 ohm speakers (= 4 ohm).

 

Calpis my point is if you are using a MVS board and then plug a JAMMA one in (or vice versa) and forget to flick the switch you're likely to do some damage.

Thats a risk I (and many other people) don't want to take. I don't mean to sound critical, I think you did a good job on the circuit, I'm just pointing out a potential problem with it.

Edit: Regarding this, is there any way of making an MVS output GND to pin L?

 

Sure but pin L is speaker Left+ on a MVS, so I don't follow...

 

In order to make the sound mono, hence jamma compatible.

 

If that's all you want:

 

If you still need to employ a switch as Calpis's latest diagram has indicated to have totally compatible mono, then I'd rather have a switch and an extra speaker so I can enjoy stereo sound when available.

To add a further level of complication, I'd actually like dual mono and stereo, but I've held back from asking for that as doubling the load will probably complicate it further (well, maybe a resistor or two).

 

Dual mono for Jamma/stereo for MVS (this is the best design):



The only issue is that the amplifier must supply twice as much current as it would with one speaker. I think cabs often have two speakers though, so this may not be an issue.. Keep the in-game volume down low!

 

Thanks Soldier!

 

Calpis thanks for the diagram but the possibility of damage by forgetting to flick the switch still exists, which is why I don't think these switches are such a good idea. A fingerboard could be used to merge L+R however I'm not sure if that'd cause distortion due to excessive volume, what do you think? In either case, I'm wondering if theres a simple mod that can be done to the board.

 

With the mono setup, there is no way you can damage anything by forgetting to flick the switch. Also there's no need to merge L & R yourself since mono is provided for you from the Neo's connector.