Increase Digital Volume
Project: Increase volume level of the SID's digital output
Target : C64 (new boards with 8580)
Time : 20 min.
Cost : <1 US$
Use : Make digital voice (switching volume on/off rapidly) as
loud as the other ones so that it will not be drowned out.
Connect the SID's audio input to GND via
a 330k resistor (optimal value may vary).
- 1 330kohm resistor (value not necessarily optimal for your machine)
- ~30cm of two-core cable
- 1 single-pole switch
- Select a tune containing a digital voice (e.g. Iron Maiden),
listen to it and remember the volume.
- Pull off all cables and open case.
- Solder the resistor between pin 26 (EXT IN) and pin 14 (GND)
of the IC socket carrying the SID, optionally via the switch.
If you have a potentiometer, you should try this first. When the volume of both
digital and non-digital sound is okay (is about equal), measure the resistance of
the potentiometer and solder in a resistor of that value.
- Listen to the selected tune again and check the volume. Listen to non-digital music,
too, and check if the volume is roughly as loud as the digital volume.
- If the volume seems to be okay, close the case again, otherwise
experiment with the resistor's value (or use a potentiometer).
Note! The smaller the resistor's value, the more silent is the
non-digital music, so you have to check BOTH the volume of digital and
non-digital ('normal') music when you experiment with the resistor's
- Connected resistor to wrong pins - ARGH!
Updated: January 7th, 1998
Created: March 17th, 1997
Status : Verified on September 23rd, 1997
Thanks to: Ghostrider / NoName for telling me about this trick
Site copyright © 1997 by Marc-Jano Knopp
This document is part of MJK's Commodore 64 & LCD Page
Brought back to life by Peter Schepers, Dec 10, 2005 because I really liked this site!