Topic revival LOL.
I am just now finishing soldering up my first circuit which is using the whole of the components in the above schematic with the 74HCU04, and am going to try it on my NTSC revision 4 toaster NES. If it works I'll post more.
EDIT: YAHEY!! It works... only done 1 circuit so far... Now the "white noise & triangle & sample channel" is AS LOUD as the NES mono sound, I can tell by putting mono from my NES's red audio socket through 1 channel on my HHB CDR 800 CD recorder analog input (sound goes to -6dB peak max when input is at max., meter is 2 segments down from 0dB), and the above single CPU sound channel comes to the same level on it's own when it's being put into the other input on the CD recorder, from the audio out of my new PCB with the 74HCU04N on it.
Now to do the other one.
BTW my NES has the RGB mod already done, see ;-
where I show my mod and how I did it.
Here is the other topic that shows the audio circuit that I used ;-http://forums.benheck.com/viewtopic.php?f=57&t=28534&p=467312#p467312
I am using the exact schematic here (originally from Kevtris i.e. Kevin Horton) ;-viewtopic.php?p=340162&sid=f950113efd2c12115d966fffc0a7be18#p340162
I copied all the components onto a perf. board and used the same ones as the schematic including the Philips 74HCU04N that I got from http://www.quarndon.co.uk
with a precision IC socket. The Transistor that I used was the 2SC1740 in TO92 package, NPN, hFE about 550, labelled "C1740 E N" (E= Emitter, N=NPN) that I got from http://www.littlediode.com
Best of all I get NO video noise or picture interference or jail bars at all on my 14" TV or IN76 projector, even with the new audio perf. board working. So now audio and video are perfect as they can be made.
BTW there is no overmodulation distortion with this circuit, the audio sounds great through headphones.