Tuesday, May 10, 2016

C64 SID Shootout part 5. - SID 6581 vs. SwinSID Ultimate (in 6581 mode)

It seemed to be a good idea to give another round to the SwinSID Ultimate because, did you know it has 6581 mode as well? Yeah, this little gem is capable of emulating both 6581 and 8581 revisions. However, its main mode is 8580 - as CodeKiller explained it to me.
Also, 6581 mode is not complete yet as there were not enough memory to emulate filter distortion and some other bits as well. Let's see (hear) how accurate is SwinSID Ultimate's (SSU from now on) 6581 emulation.

Nope, I won't normalize the recorded audio files. Yes, I know the loudness level is different on 6581 and SSU. Still, in my opinion the true comparison is WhatYouSeeIsWhatYouHearWithoutAnyModificationHearingTrueOutput. That's it. You have volume control on your audio equipment, use it to compensate loudness diferences.

The following lines needed to switch the SSU to 6581 mode:
POKE 54272+29,ASC("S")
POKE 54272+30,ASC("E")
POKE 54272+31,ASC("6")
Reset C64.

To switch back to 8580 mode just simply write "8" instead of "6" into the third line. It's quite simple, isn't it?

I used Breadbin with the most loved SID 6581, the 1485 so the expectation for SSU is VERY high. Ladies and gentlemen, make your bets. Based on previous tests, what do you think? How SSU can meet the expectation?

Ready? 3... 2... 1...

Chris Hülsbeck - Hollywood Poker Pro main - SID 6581 1485

Good ol' Hollywood Poker with the dance animation scene..! (and more but that doesn't matter right now)

Chris Hülsbeck - Hollywood Poker Pro main - SwinSID Ultimate - 6581 mode

I'm going to repeat myself: impressive! The original SID is a bit brighter and the filter seems a bit more opened but SSU is great as well. Sounds like differences between 6581 revisions.

MSK - Land Of Illusion - 6581 1485

It's a multispeed track. I didn't dig into the code to check it but it's clearly audible, especially on some arpeggiated notes. Nice track, nice sound trickery.

MSK - Land Of Illusion - SwinSID Ultimate - 6581 mode

Wow, nice. Flawless multispeed reproduction, the only noticeable difference is the filter. Again, it's a minor thing, SSU's filter doesn't have distortion and it seems a bit more closed or deeper.

Drax - Drudgery - 6581 1485

This track is something special. Not just because it's beautiful and the bassline is extraordinary, but it also has nice filter variations between bass and arpeggios.

Drax - Drudgery - SwinSID Ultimate - 6581 mode

SSU did it again, same result as before: waveforms reproduced well, filter is a bit different but has that mojo. Actually, I like the deeper filter in this track more than in the 1485 version.

Jeff - Blowing - 6581 1485

This. Is. One. Of. The. Best. C64. Tracks. Ever. (personal taste of course, don't take it too seriously) Perfect dance music, awesome sounds, great melodies.

Jeff - Blowing - SwinSID Ultimate - 6581 mode

Again, question of taste matters. Which one do you prefer? The original with a bit more opened filter or SSU that is a bit deeper-boomier?

And now, here comes my favorite 6581-breaker - that is actually a music written on a 8580 SID. Guess how SSU delivers a 8580 track in 6581 mode. Will it break as it would on a real 6581? Or will it play perfectly, because this is an emulation?

Jammer - Club Stylier - SwinSID Ultimate - 6581 mode

Aaaaawyeah, it breaks as it should! :) Honestly, I expected it would play nicely but it didn't. It makes sense, SSU is switched to 6581 mode and a real 6581 breaks this track, so SSU did it as well.


I wanted to write something nice as conclusion but I realized it's not necessary. The SwinSID Ultimate is the current best SID alternative if you want to replace your broken SID in the real C64. It doesn't matter which revision you prefer, SSU's performance is outstanding either in 6581 or 8580 mode.


  1. Very informative tests !

    It's hard to measure how much aliasing there are with those tests though, but from what i hear in high pitch notes like drudgery, there is almost none. Maybe they actually use that CPLD for sound generation at 1MHz ?

    One of the great tune out there to try is the intro of Robocop3, another one is the very beginning of the title song of Bubble Bobble (tune 8), where even a real SID shows a little bit of aliasing. I'm curious to hear how the SSU compares ! :)

    Other suggestions are Flimbo's quest tune 1 & 3 !

    1. Thanks for the suggestions, I can record those tracks through SSU to see how aliased it is. All I can say at the moment, it aliases but so far I didn't find it disturbing or annoying.

      You can contact the authors about technical questions here: https://www.facebook.com/swinsidultimate/

    2. Yes, and aliasing is not easy to quantify with words.
      Usually audio artifacts are diminished drastically when several voices are used and when listened thru speakers. Recording single voices would definitely give a much better idea on the quality of the emulation.

      Anyways, since the SID itself has aliasing which can clearly be heard in the two tunes mentioned above, it's understandable that SSU does too. The worse case of aliasing being the combined sample $50 (TRIANGLE + PULSE on both 6581 & 8580) at high pitch.

      From the examples I heard so far, it think it's already well done from the authors to have made this with such a tiny & "slow" MCU + CPLD