Low audio on the Coleco(vision)

[Jess Ragan]

I just did a composite mod on my ColecoVision, using the technique described here on AtariAge. I was worried that it didn't work properly when I connected it to my Vizio, but when I connected the CV to a better television, the picture improved substantially. It's not astonishingly crisp, but it's clean, and for a system this old, it's good enough.

 

There's still a problem, though. The audio is very low, to the point where I have to crank the volume up to 80 (out of 100) to clearly hear sound. I connected the audio jack to the video board, that small metal covered square at the top of the system. Should I be taking it straight from the SN7 sound chip instead? What else can I do to give the sound a boost?

 

It's probably worth mentioning that I only have Super Game Module games at the moment. Does that make a difference? I know the SGM has an extra sound chip along with the SN7... where on the board can I retrieve the sound from that chip?

[Jess Ragan]

I'm told that capacitor 88 is the best place to get an audio signal from the ColecoVision, so I guess that's where the wire will go.

[+-^CrossBow^-]

2 hours ago, Jess Ragan said:

I'm told that capacitor 88 is the best place to get an audio signal from the ColecoVision, so I guess that's where the wire will go.

This is correct...kinda. See one side of C88 comes from the audio off the CV itself, while the other side of C88 comes from the expansion bus audio that would be coming from the SGM. There isn't much from the main sound chip other than a resistor and capacitor. There is nothing from the expansion bus side at all. So this is what I've been doing although the volume output is still rather low as compared to other consoles.

 

I actually remove C88 completely. I then run a wire from each side of where C88 was. I add another 10µf cap from the audio off the CV side, but just run the wire from the expansion bus side directly to the audio jack. So basically the extra capacitor is only for the CV audio side if that makes sense? If I run the SGM or expansion audio through the capacitor along with the CV it resulted in the expansion audio being even lower output and still getting drowned out by the CV audio. I've messed a bit with trying to use a cheap external amp to help with this, but ended up with even lower volume output or the output being quite distorted. So yeah... the CV like the Jaguar and PC Engine / TG-16 is one of those consoles with low audio output.

 

[Jess Ragan]

I suppose it does. I know the ColecoVision does have issues with peripherals... anything connected to the expansion port won't necessarily send its audio signal to the television set, if it's not wired in the right spot. This seems to be a big problem with the 2600 adapter.

 

So the extra capacitor lowers the volume of the SN7 to better balance it with peripherals like the SGM, is that what I'm hearing? Or am I misunderstanding? (I need to get some stock CV games. All mine are stuck in MI, regrettably.)

[+-^CrossBow^-]

13 hours ago, Jess Ragan said:

I suppose it does. I know the ColecoVision does have issues with peripherals... anything connected to the expansion port won't necessarily send its audio signal to the television set, if it's not wired in the right spot. This seems to be a big problem with the 2600 adapter.

 

So the extra capacitor lowers the volume of the SN7 to better balance it with peripherals like the SGM, is that what I'm hearing? Or am I misunderstanding? (I need to get some stock CV games. All mine are stuck in MI, regrettably.)

Can't say for sure as I would think that the resistor on the CV side is for better balancing the audio between the two. Just know that the initial resistor off the sound chip is still needed to balance and mix in the two. You could try adjusting it to see if you can get the expansion audio to come out better by increasing the resistance from the CV audio side, but it isn't going to make anything louder in the process.

 

One of my clients with this exact issue sent their CV to me at least twice to look into and try and correct for this. I wasn't able to do much more than what I've listed above. They stated that it now sounds louder on one of their TVs vs another so it could also be how the TV or whatever you have handling the audio is able to do with the signal. In my AV setup, the CV is lower but I only have to increase my volume by about 10dB to get it more in line with how my Atari systems sound. Although in the case of the Jaguar I actually have to go even louder and also have my Extron set to further boost the audio another 6dB on the jaguar input.