m00dawg
Offline
Texas

I have never quite figured this one out. It seems that there are various resistor values folks are using for the PowerPak input and was curious as to what people here are using that has produced the best results? I have tried quite a few values but it seems I am always too low as the results are still distortingly loud if I don't further attenuate them using an analog mixer. I also noticed that the values used for the PowerPak differ than those used for the Japanese import cartridges with their own audio output.

I ask as I am thinking about adding a trim-pot to my NESA design so that the volume can be set to taste with the 2A03 output. Normal volume pots could be used as well, but if I use a trimpot, it would fix both the passive mixed output and allow a single volume knob to be used for the output of the separate channels.

What I am trying to figure out at this point is the values of the trimpot so I can cater to both import cartridges and the PowerPak.

Anyone have any ideas or suggestions there?

nickmaynard
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rochester, ny

what is a powerpak input? i have two powerpaks and have modded a bunch of nintendo's but haven't heard of this.

Theta_Frost
Offline
Milwaukee, WI
nickmaynard wrote:

what is a powerpak input? i have two powerpaks and have modded a bunch of nintendo's but haven't heard of this.

I think he is refferring to the expansion chip audio the powerpak injects into our NES.  What are the original resistance values on the Famicom expanded carts?  If they are all close, a fixed resistance is fine.  But if it varies for each chip, a trimpot would probably be a good idea!

m00dawg
Offline
Texas
Theta_Frost wrote:

I think he is refferring to the expansion chip audio the powerpak injects into our NES.  What are the original resistance values on the Famicom expanded carts?  If they are all close, a fixed resistance is fine.  But if it varies for each chip, a trimpot would probably be a good idea!

Actually, if the expansion audio chips all assume different resistance, a volume knob on the back (or front?) would make more sense so it can be changed externally. This can be done with the current design (simply hook up a pot before the input pin for the PowerPak) if need be.

I seem to remember the resistance value was fixed on the PowerPak as I thought it adjusts the output to be the same across all expansion chips that it supports. I want to say it is something sort of odd like 62k.