Sound output stereo / mono
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The mono adapter you linked looks interesting, but I've read reports that a lot of those adapters can have issues if you don't use resistors to impedance match the L and R signals.
Digging deeper, since Tron gives me half sound with mame2003-plus due to my single speaker setup. I decided to test Tron in mame2003. I get half sound there too. So this rolls out the emulator. The troubled games all seem to be Bally midway games...I guess it could be an issue in both emulators though with these specific games.
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So I hooked up a left and right speaker, tested every game I have, about 120. Fixes all the issues. Except now I find that having two speakers causes an issue with rampage in Mame2003-plus. The Left speaker plays static and all the game sound comes from the right speaker. This wasn't an issue before as I only had the right speaker hooked up.
rampage audio fix
I think this game needs right audio out copied to the left and right speakers to fix it. Left speaker should mirror what plays on the right. Then there would be no static.
I re-installed my single speaker setup for now. My testings find that Bally midway titles divide the game sounds between left and right speaker. So you need both to get the full sound. The only exception i found to this was rampage which plays the full sound from the right side only and left speaker only plays static if connected. This could probably be patched for Bally Midway titles.
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https://retropie.org.uk/forum/topic/17828/rampage-sound-issue-retropie-4-4/4?_=1587243274184 this only happens with the audio jack btw hdmi is fine
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Thanks. Just tested this out on my other hdmi pi setup and you're right, audio is fine for rampage. I'll test this audio fix on my cabinet for rampage using the audio jack. -- update fixed rampage
There's still the audio issue for all other bally midway titles, that I have at least. Tron, tapper, timber, satan's hollow. These games divide the sound up between both speakers. So only using one speaker I'm only getting half the game sounds. I tested this out by adding the other speaker and it fixes the issue. There's got to be a way in software to combine these...combine them then send the combined audio to left and right out so both speakers play the full sound for these titles.
Looking at the mono adapter you listed above, I wonder if I could use a jumper wire at the amplifier to get the same results?
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I know some old arcades had mono speakers and twin mono speakers as well that doesnt mean the sound is mono. It just the way it was wired up.
I know old arcade jamma boards would require in line adapter (probably 2 10k resistors) to bring the levels down to something reasonable if you wanted to go through an amp since the jamma boards are ready to plug into a speaker already. Im not sure what amp your using but I would guess the pi wont be outputting anything that would damage an amp. The only reason you would want there resistors is if you get clipping. Again it would all come down to the amp in use
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All I know is Bally midway titles play some sound effects from the left speaker and some from the right, together you get all the games sounds. I own an original Tron cabinet and verified this.
A good game to test is Tapper. The first level plays "oh susanna". So having only the right speaker hooked up it plays a choppy half sound of this tune, missing every other beat or so.
Is there any way to combine these in software before sending them out to left or right? So one speaker would play the full sound?
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Well Yes I can show you how to do this. All you need to do is tell the mame mixer not to use stereo but this will make all games mono.
change this to
is_stereo = 0;use the previous compile guide i have you and you should be good to go
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Could that be set to toggle option within mame2003-plus menu? Could be pretty useful, the default being stereo. Maybe a "general" and "this game" option ?
Use stereo.........y/n
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To be honest most people would bridge there 3.5mm jack. You could post an issue on the libretto github about it and ask them to add it. It would really be up to the maintainers at the end of the day though cant hurt to ask
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Ok I'll post there
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Found a simple way to do this at the amplifier:
https://www.google.com/amp/s/www.wikihow.com/Bridge-an-Amplifier%3famp=1
Tested and works :)
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@mahoneyt944 it usually easier to do it at hardware level to be honest. It also is dependent on what amp you are using how you go about it. Not all amps can be bridged though most home stereo amps cant do this but you can couple the input to both channels for them anyway.
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I don't really understand it fully but with my specific amp. It works. and that's enough for me. Thank you for the support.
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glad you got it sorted all roads lead to rome the easiest solution always works best!
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