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 Post subject: Namco 163 audio levels
PostPosted: Sat Sep 09, 2017 10:34 am 
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Posts: 311
The Wiki page on Namco 163 audio lists some very approximate relative volumes for several games. A different page lists the mixing resistors used in the various games. I know that APU<->expansion audio balance is a hopeless affair, since it differs between Famicom revisions. But surely it would be possible to calculate the Namco 163 sound volume at least for the 10kΩ/15kΩ/22kΩ mixing resistors relative to 4.7kΩ mixing resistor configuration with precision. Unfortunately, I cannot. Can someone else? :)


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PostPosted: Sat Sep 09, 2017 10:49 am 
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Joined: Sun Apr 13, 2008 11:12 am
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The topology on the 163-using boards looks like this:
Code:
famicom        :  cart  :  famicom
   +--100k--+  :    163 :
   |        |  :     |  :
C--+--|>o---+--:--R--+--:--RF modulator
            |  :        :
          DA15
(edit: added location of Famicom expansion connector sound)

It should be the case that any given size of resistor should make the NES audio quieter proportionate to its conductance (1/resistance).

Unfortunately, the resistor values we've observed don't correlate with the reported loudnesses. So either the reported resistors are incorrect, or something even weirder is happening.


Last edited by lidnariq on Sun Sep 10, 2017 12:08 am, edited 1 time in total.

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PostPosted: Sat Sep 09, 2017 11:12 am 
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I thought that one could identify the resistor values from looking at high-resolution images, but no. The people on that archived nifty forum page linked to in the wiki seemed to just have held an Ohmmeter to the cartridges' audio pins ([MEMO 45-46の抵抗をテスターで計った結果] ).


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PostPosted: Sat Sep 09, 2017 5:23 pm 
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Joined: Sun Apr 13, 2008 11:12 am
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One could, but the backs in NesCartDB don't match 1:1. The resistor is literally the only differnce between the different backs.


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