Perfect emulation of the SID 6581: the C64 sound chip.

(102 Votes)
1.4 (Updated 1 month ago)
May 30, 2015
Reaktor 5 or lower


INSIDIOUS 6581: The definitive SID emulation.

This ensemble is a perfect emulation of the extraordinary Commodore 64 sound chip. Included are all features of the original hardware:
* Three channels with realistically saturated Triangle, Square/PWM, Sawtooth, Noise and combined oscillators.
* Ring modulation and hard sync.
* Polyphonic and monophonic play modes with "Live arp" mode.
* The unique SID saturating filter that is incredibly important but missing on most emulations.
* Filter cutoff curves matching various real SID chips.
* LFOs and envelopes for pulse width, pitch, amplitude and filter cutoff.
* Step table for that genuine 8-bit sound.
* Optional quantization clock to restrict modulation updates to 50Hz or 60Hz as used in most games, or 100Hz or 150Hz as used in modern SID tunes and by Martin Galway in the Wizball theme.

I have a blog about the creation of this ensemble at

No attempt is made to create a better SID. No features are enhanced or improved. This is not the usual 'SID-like' or '8-bit style' synth. This is an attempt to recreate the real thing as closely as possible with the most user-friendly interface possible. I believe it to be the most accurate-sounding emulation available (even better than the reSID library). Included are multiple presets taken directly from Commodore 64 games by dumping out the hardware registers during playback.

The SID Filter emulates the very unusual saturation and distortion present in the real hardware, which is the main feature that distinguishes most emulations from the real thing. I spent a long time using an oscilloscope to view the output from multiple real SID chips alongside INSIDIOUS 6581 to ensure that the output is as close as possible. It can really roar in a very unique way when it gets too overloaded. Also included is the ability to choose from a selection of filter curves as the curve of each 6581 chip is slightly (and sometimes extremely) different.

The first example sound is entitled "For All It's Worth" and was created by me using multiple instances of only this plugin. All of the sounds are included in the ensemble. It was created for the free "Summer of SID" album, available at

The second example sound is a recreation of the title music of the game Delta. A MIDI file is included in the download.

The third example sound is a recreation of the title music of the game R-Type. A MIDI file is included in the download.

Also, check out Fabio Marinelli's YouTube channel ( where you can see his many recreations of classic C64 music using INSIDIOUS 6581.

As of v1.2.2, this ensemble uses a component of Simple Arp by salamanderanagram.

Changes v1.4 (2018/12/01):
* Re-built the entire oscillator section in Core. The new module has perfect combined waveforms, allows the correct PWM on the combined waveforms, and accurately emulates the Pulse+Tri wave with RingMod. It also uses a good amount less CPU than the previous version.
* Remade the filter again from scratch. Because of the improved oscillators, the filter balance is much better. I would say that it is now 99% accurate.
* Re-made the LFO handler in core.
* Added some new presets.
* Due to the remade oscillator section, the R/S input and output
is now just a frequency value instead of a square wave stream.
* The MIDI Mapper was accepting program changes, which shouldn't have been the case.
* Added an audio input that will route through the filter like the real SID.

Changes v1.3 (2018/08/23):
* Added the MIDI Router. In this mode, notes from a specific MIDI channel will trigger a Preset change on the specified SID channel. This makes creating 3-channel chip tunes or setting up a single SID channel drum kit much simpler.
* After some retesting with real SIDs, I've completely retuned the filter. It's now dirtier and really roars, and is extremely accurate to the real thing.
* Removed the DC offset correction from the PWM. The new filter makes it unnecessary.
* Replaced the noise sample with a noise generator that uses the SID's actual random algorithm. Noise is much more tonal now like the real thing.
* Added some more presets.
* Flipped the internal PWM polarity so that -1 to +1 matches 0 to 4095 respectively in the real SID.
* Fixed a bug where an LFO could be the wrong one when a snapshot is recalled.

Changes v1.2.6 (2018/08/02):
* Ring mod was allowed to operate using any carrier waveform, but the SID only uses a square wave. This has been fixed.
* Loop controls were not latching properly on Channel 1.
* Reduced CPU on muted channels.

Changes v1.2.5 (2018/05/29):
* Polyphonic mode added.
* The EQ on the noise output had only been applied to channel 1.
* A bug in Reaktor stops program recall to occur correctly. I've got around it at the expense of potentially getting the wrong patch if the DAW sends out the bank change CC after the program change.
* The Square LFO graphic had an incorrect phase.
* Added new presets.
v1.25a (2018/06/01):
* MIDI channels were getting saved with the preset. Tough to decide whether this is correct behaviour or not, but I've disabled it.
* Loop points were getting reset on Channel 1 when changing to polyphonic mode or changing preset.

Changes v1.2.4 (2018/05/21):
* Added filter curves to map the filter cutoff values to various SID types.
* Removed the filter oscilloscope to allow for the filter curve graphs.
* Added a final mix oscilloscope to the logo's SID chip.
* Changed the colour of the off colour of the PWM graph warning lights to match the channel background.
* Fixed a Clock bug where the modulation values would be smooth every other clock event.
* Fixed a potential bug when the Clock was set to Off.
* Renamed "Vol" in the Wheel menu to "Amp" to match the mod section it applies to.
* Got around a Reaktor bug where Live Arp wouldn't respond to MIDI in the Reaktor standalone app.
* Added an EQ to the noise output to more closely match the real SID output.
* Increased the stability of the oscilloscope displays.
* Fixed a bug in the filter where negative cutoff values would be treated as positive.

Changes v1.2.3 (2017/12/16):
* Added a PWM position display that shows the final combined PWM value.
* Remade the LFO Fade/Delay implementation to take into the account the starting phase of the waveform, making it more flexible and seamless.

Changes v1.2.2 (2017/12/10):
* Added new play mode options: Solo, Legato, and Live arp. With live arp you can note play those 8-bit bubbly chords live.
* Added new presets from my track 'For All It's Worth'.
* Simplified the top-most channel routing.
* The whole portamento section has been replaced. Portamento is now logarithmic instead of linear using the Smooth module from 2-OSC, but does not produce gate clicks like before.
* Fixed a bug in the table looping where an incorrect waveform could be set on a zero entry.

Changes v1.2.1 (2017/11/19):
* The waveforms are now output at the correct bit depth according to the hardware specs.
* The ADSR wave is now quantised to 8-bits.
* The Filter automation parameters had the same IDs as channel 3's parameters, so were being hidden.
* Removed the full channel switch if the waveform is set to nothing. Now only pressing mute button will completely stop processing. Fixes a potential problem with program changes.

Changes v1.2 (2017/11/11):
* More accurate root waveforms. The tone and saturation now perfectly match the real hardware.
* Much improved combined waveforms, especially at higher frequencies.
* Vastly more accurate filter, tweaked by matching waveforms using an oscilloscope connected to real SID chips. It is almost indistinguishable from the real thing.
* Root pulse width value now allows the full 0-100% rage instead of 0-50%.
* Pulse width is quantised to 4096 values like the real chip.

* Table loop start and end points. Tables can be simpler and have an attack phase.
* Increased pitch range.

User Interface
* New custom graphics
* Control sensitivity adjustments
* Improved the modulation envelope graphs and added a graph to the main volume ADSR.
* Added a MIDI channel parameter to the filter to set the channel used for its LFO Key Follow and envelope triggering.

* Better CPU usage. Also, muting a channel will completely stop it from using any CPU.
* Added volume ADSR to the automatable parameters.
* Added support for Bank Select for better patch organisation.

Bug fixes
* Fade time now matches the specified value correctly.
* Fixed a clicking that could occur on triggering a note.
* Switched from using custom MIDI data parsing to using Reaktor's built-in MIDI modules for reduced complexity.


Darren Flinders
1 week ago
Excellent, you have done a fantastic job on this, loving it!!
Henrik Sundberg
2 weeks ago
This is just fantastic, everything I wanted from a SID VSTi. Thank you so much, this will be used a LOT!
Alex Retsis
1 month ago
I love INSIDIOUS 6581! It keeps getting better in every update. Highly recommended!
andre cubilo
1 month ago
Dude ... thanks for this bloody amazing non emulated SID emulation !! Love it ... great work
Mladen Katicic
1 month ago
simply amazing!
Richard Vogel
2 months ago
I love the sound of this! I have a ton of patches from several different hardware/software SID synths that contain patch information in text format. I would love to be able to write some sort of translation between my patch format(s) to the insiduous patch format. However looking at reaktor presets they're definitely not text editor friendly. Curious if you might have any ideas of how one might go about translating patch values to something reaktor / insiduous could read?
Michael Thalmann
2 months ago
This is absolutely brilliant!
Winfried Sitte
3 months ago
This thing is awesome. There is some serious creative potential in the tables alone. Thanks Mike, looking forward to put something together usign this.
fabio marinelli
4 months ago
AndreasL: Add an instrument track and select reaktor as vst, load insidious ensemble into reaktor, insert midi file into this track, select into the inspector track ( in cubase) "all" in midi channel. in this way it works :) :)
Mike Clarke
4 months ago
AndreasL: The Cubase manual says it has an option in its MIDI Import Options, "Import Dropped File as Single Part". Make sure its switched off or you'll get everything in one track like you're seeing.
4 months ago
Hi, I just started up Raktor6 for the first time and decided to load this. TLoaded it up in Cubase and tried the Delta demosong. dragging the midi in puts all the notes in one track and using the snapshot does not make it work. Am I supposed to split the notes into tracks?
4 months ago
SID2MIDI is the only prog I know for Win7. It's old from 1997. It can't convert real SIDs. In some cases helps a hex editor, mostly. Just checked it and saw channel 1,2 and 4. To play sid tunes and many other suffixes I use a java prog without midi out. I've found some with 2 ch and other with 4 channels. Oops!
Mike Clarke
5 months ago
Paule: I had a look. You've done loads of them. Are the SID2MIDI files one sound per MIDI channel? There's a new feature coming in v1.3 that will makes these much easier to use with Insidious to recreate the original tune.
5 months ago
Do you ever test my sid 2 midi files? ---
Machtigen Salas
5 months ago
Amazing! Thank you so much, such a wonderful sound.
Roman Smirnov
5 months ago
Thank you for this incarnation of my beloved synth :)
Niclas Thorsteinsson
6 months ago
This is fantastic. Thank you.
Kris Keogh
6 months ago
You've gone above and beyond. This is amazing, and even better once reading the blog for the background. That 50HZ button makes so much difference! Thanks heaps, Kris, Australia.
Jimi Grant
6 months ago
excellent. thanks
Domenico Alessi
7 months ago
This is splendid! Thank you!
Matthias Schaffner
7 months ago
great ensemble and great demo track!
Jason Moon
8 months ago
AMAZING! Thanks!
Mike Clarke
8 months ago
grandnoise: I'm afraid not. Although it's theoretically possible to do, it would require the creation of a custom music editor/tracker inside the ensemble as Insidious doesn't know what music you're playing through it. It would also mean a complete rewrite of the patch memory/storage system. It would probably take me longer to do that than it would to just rewrite Insidious in C++.
8 months ago
Is there any way to export to c64 exe?
Kenneth Henrik Olsen
8 months ago
The Sequencer is outstanding !
Kenneth Henrik Olsen
9 months ago
Brilliant !
Mike Clarke
1 year ago
jes: This ensemble is no different to any other ensemble in operation, so either you're using the Reaktor Player and not the full version or there is a problem with your Reaktor installation. Marco Muzzi: I've seen that error and I thought I'd got it to go away. The error itself is bizarre (another Reaktor bug?), so I'll shuffle some things around and see if I can kill it.
Marco Muzzi
1 year ago
Thanks Mike! Another question: when I use a Program Change plugin in Ableton, the Event Merger gives an error ( and the presets change in an very odd way. I was also wondering how to tell Reaktor whether to change snapshots of the ensemble or of the single modules.
jes Nørholm
1 year ago
keeps saying it works in demo for a ½ hour, using reaktor 6
Mike Clarke
1 year ago
Marco Muzzi: It looks like that's a bug in the standalone Reaktor app. It works fine in the VST. I've got around it though and it will be fixed in v1.2.4.
paul hesford
1 year ago
Wow, This is stunning, If you love the 8bit sound of the Commodore 64, GET THIS BEAST... the Authenticity is amazing and you can now have a SID Orchestra in your DAW of choice... 64 channel SID anyone...10/10..
Marco Muzzi
1 year ago
I love this plugin! Just one problem, I have the 1.2.3 version and I can't use the Live Arp mode with my midi keyboard, it works only with the laptop keyboard. Any ideas why?
Markus Kaarlonen
1 year ago
Absolutely loving this, thank you! I don't think there's any way to sync the table speed to host tempo, probably because it breaks the paradigm of authenticity (or if there is, sorry for missing it...)? Anyway, I couldn't resist adding it myself, so I extended the speed knob range to -32 (to keep the interface intact and not to break any existing functionality), and added some simple "code" in the AutoCounter macro. Now the negative values correspond to note lengths of 1/x.
Paul Majchrowsky
1 year ago
Is there any tutorial how to made own music via Reaktor step by step like Rebirth ? I tryed but can play live and only one channel, rest 2 channles not playing... or how can i download your demo ?? thanks and good work with demo music :)
yerry feldstein
1 year ago
Number 5 is alive! Many Thanks ! Mike Clarke
David Coffin
1 year ago
WOW, this is really great stuff, fabulous results from randomizing…and I didn't even LIKE game noises (or games, for that matter:) back in the day. But I sure like these, and twiddling knobs for funny noises, hmmm. Thanks!!
Glenn Wiorek
1 year ago
phillip bova
1 year ago
Sweet!!! Using this on current project starting tomorrow ;)
Mark Knight
1 year ago
Mike, you're the best - thank you very much!
fabio marinelli
1 year ago
this is my youtube channel... All my c64 covers are made with insidious 6581
Enrico Bruttomesso
1 year ago
Thanks a lot for this fantastic ensemble Mike!
fabio marinelli
2 years ago
great!!! I did not understand how to set PWM...
Michael Pilyavskiy
2 years ago
Johan Smolinski
2 years ago
Update to below: I found out that the MIDI channel setting is located on the panel for each SID channel. My real problem was that Ableton Live is merging all MIDI in channels to out channel 1. That seems to be how it works, unless using the plugin called External Instrument, which unfortunately is not included with the Intro version. Bummer! That really should be a core function... I mean, playing multi-timbral VST:s is among the first things I require of a DAW. Anyway, Insidious sounds fantastic! Really cool that you can do such a thing with Reaktor.
Johan Smolinski
2 years ago
How can I set the MIDI channels to SID channels as suggested in the readmes for Delta and R-Type MIDI files?
Serhat Kahveci
2 years ago
Can't wait to use this. Thanks, Mike!
Matthew Friedrichs
2 years ago
Fantastic emulation! I found a small midi bug in Reaktor 6 where the ST Gate module would not trigger the filter modulation at all. Simply moving this module into the filter modulation macro then connecting it to the LFO and ENV gate inputs directly fixed that right up. I hope to see you port the individual elements of this .ens to blocks! :)
Jorge Rodriguez
3 years ago
Love this thing. Thank you so much!
Sam Mover
3 years ago
GG.G SakabeaT
3 years ago
i come back here to say thxagain for that ens....fabulous......friggin'awesome dude!!!!
GG.G SakabeaT
3 years ago
GG.G SakabeaT
3 years ago
Josep Mª Ricou
3 years ago
Congratulations This is excellent work.
Dana Fortier
3 years ago
Had to give props for this fantastic ensemble.
David Sullivan
3 years ago
I always thought you were a clever-clogs Mike and this proves it. Genius.
Carlo Del Prato
3 years ago
Congratulations and thanx for sharing...timeless sound.
Jussi-Matti Salmela
3 years ago
You sir, are a gentleman and a scholar!
Lee Tobin
3 years ago
This is fantastic. My goto SID emulation now. Thanks!
Neil Baxter
3 years ago
Daniel Hogan
3 years ago
5 Stars for the Demo Tune. :) Now for the download ...
benjamin bassenonville
3 years ago
Excellent work for an excellent sound ! Instant fun !!!
Quinn Hanratty
3 years ago
thank you, this is great!
Peter Christiansen
3 years ago
This is excellent work. Sounds quite authentic to me.
3 years ago
.. and another 5-star vote 4U
Malte Klima
3 years ago
That is really the sound of the C64! Thanks for your great work!!!
Goran Podrugovic
3 years ago
Thank You, really sweet!
Ng Mui
3 years ago
Wow I used to love R-Type, so many hours spent on that game xD
3 years ago
thanks. C64 reloaded!
Aynsley Green
3 years ago
Dang, I can't tell the difference between the original Delta track and this emulation, very impressed.
Frank Neumann
3 years ago
Wouw!! Sounds very, very good, best emulation i ever heard!
Dieter Zobel
3 years ago
much thanks
Mark Knight
3 years ago
Can't wait to try this tomorrow. Thanks for this Mike. Need to start building a community library of well known sounds then ;)
Tim Wright
3 years ago
Top stuff! Great fun... :oD
3 years ago
Great work! Love the Koyaanisqatsi on chip!
Rick Scott
3 years ago
I owned a SID way back. Great fun. This gives me flashbacks. Well done! :-) (
3 years ago
Is this the real sound stuff for Marcus Friedrich, the choir director from Leipzig; isn't it?
Ng Mui
3 years ago
Not bad, sounds very commodore!
3 years ago
Great! Fun stuff!