Sunday, December 27, 2015

C64 SID shootout

Page has been updated with a nice music player, shouldn't any playback issue appear anymore \o/

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Have you heard about Stone Oakvalley? He is the man behind http://www.6581-8580.com aka. SOASC aka. Stone Oakvalley's Authentic SID collection:

"The SOASC= project is an automated recording technique invented by me (Stone Oakvalley) in order to mass-record music from the legendary Commodore 64 and its original SID sound chips (6581 and 8580), including variations of 6581, such as R2,R3 and R4!"

He gave me the inspiration to make a SID shootout and record 1 (one) music with different SID revisions. I was lucky enough to have my hands on 5 different SID, basically I have one SID from each available revision.

Why did I do it?
Because there is a difference in each SID revision's sound - sometimes it's just a slight difference but it's there - and I was curious how one of my favorite music would sound on each.

Brief SID history, copied from Wikipedia:
  • 6581 R1 - Prototype, only appeared on the CES machines and development prototypes, has a datecode of 4981 to 0882 or so. Has the full 12 bit filter cutoff range. An unknown number were produced, probably between 50 and 100 chips. All are ceramic packages.
  • 6581 R2 - Will say "6581" only on the package. Filter cutoff range was reduced to 11 bits and the MSB bit disconnected/forced permanently on, but is still on the die.The filter is leaky at some ranges and they tend to run hotter than other sid revisions. Made from 1182 until at least 1483. First 10 weeks or so of chips have ceramic packages (these usually appear on engineering prototypes but a few are on sold machines), the rest have plastic packages.
  • 6581 R3 - Will say "6581" only, "6581 R3" or "6581 CBM" on the package. Had a minor change to the protection/buffering of the input pins. No changes were made to the filter section. Made from before 2083 until 1386 or so. The 6581R3 since around the week 47 of 1985 made in the Philliphines use the HMOS HC-30 degree silicon though the manufacturing process remained NMOS.
  • 6581 R4 - Will say "6581 R4" on the package. Silicon grade changed to HMOS-II "HC-30" grade, though the manufacturing process for the chip remained NMOS. Produced from 4985 until at least 2590.
  • 6581 R4 AR - Will say "6581 R4 AR" on the package. Minor adjustment to the silicon grade, no die change from R4. Produced from around 1986 (week 22) until at least the year 1992.
  • 6582 - Will say "6582" on the package. Typically produced around the year 1986 in Hong Kong.
  • 6582 A - Will say "6582A" (or "6582 A") on the package. Typically produced around the years 1989, 1990 and 1992 in the Philippines.
  • 8580 R5 - Will say "8580R5" on the package. Produced from the years 1986 to 1993 in the Philippines, Hong Kong and in the US.

Are you still with me? I hope so because we shall jump into the most interesting part now.

So, based on the WIKI article and the fact that different revisions have different properties, the different SID revisions must sound different. And they do, of course :)

Let the competition begin! The music is "Jeff - Anal'ouge" (HVSC/MUSICIANS/J/Jeff/Anal_ogue.sid), which was composed on a 6581 - as Jeff confirmed he used a C64 with 6581 SID for most of his music.

The computers are Breadbin, Aussie and Blue:


The SIDs are:

01. 6581 R2 - 1485 (Breadbin's original SID)



02. 6581 R3 - 1585 (Aussie's original SID)



03. 6581 R4 - 3387 14 (put into Breadbin)



04. 6581 R4 AR - 4486 14 (put into Breadbin)



05. 8580 R5 - 3991 25 (Blue's original SID)








Conclusion:
This track sounds different on each SID revision :) Even the C64's own noise is different and not equally loud.

My favorite is the 6581 R2, it's rough and dirty and the bass is awesome. However, I like the 8580 R5 as well, it's clean (just listen to the flute-alike instrument at the start) and the bass is softer but somehow this makes the music more ear-friendly to me.

The other revisions sound like they have glitches, the snare-clap is a bit muffled (filtered?), bass is different but not bad at all. The most interesting difference is the already mentioned flute-alike instrument which is kinda distorted/modulated/filtered in a different way on each SID revision.

Which revision is better? Can't tell as it's a question of taste. Pick your favorite.

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