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Ease of use​


  • Automatic SID model detection, any combination of 6581 and 8580 (aka 6582) is supported

  • Manual on-the-fly switching between 6581 (old SID) and 8580 (new SID) while the tune/games/demos are playing!

  • SIDFX support has been built into SIDplay64 and the player of 1541U and 1541U+ by the respective developers

  • Open API for full software control

  • Stereo SID capable with second SID located at either address $D420, $D500**, $DE00 or $DF00***

  • Also works with one SID if you just want to use old SID in new C64 or new SID in old C64

    ** $D500 is unavailable on C128, please refer to the FAQ.
    *** Please refer to the FAQ for instructions and limitations.

Optional accessories

  • SIDFX adapter for C64 Reloaded MK1; our custom adapter that enables SIDFX to fit the ZIF sockets of a C64 Reloaded MK1 motherboard while being mounted in a C64C chassis

  • SIDFX adapter for C64 Reloaded MK2; our custom adapter that enables SIDFX to function with the C64 Reloaded MK2 motherboard

  • Additional accessories are available in our online shop

Sound quality

  • Precision filter capacitors located on the SIDFX module replace those on the motherboard

  • Replaces incorrect filter capacitors found in SX-64 and early C64 models

  • Stereo capable mini phone jack for dedicated high-fidelity output (available in all operating modes)

  • Sample playback fix for 8580 with configurable boost level and manual-/automatic operating modes

  • Reduced audible noise due to individual voltage filtering and regulation for each SID

  • Configurable external audio input mute function for reduced noise

Voltage control​

  • Generates safe and accurate operating voltages for each individual SID

  • Protects SID input and output against over-/under voltage and short-circuit


  • 4 detachable cables for easier installation and less clutter

  • Two cable lengths, you select the length when ordering. Fits all variants of Commodore 64 and 128


Frequently Asked Questions

Can I switch between SIDs while listening?

Yes, SIDFX comes with 4 cables, including switch 1 which allows you to select SID chip while the music is playing.

Can I use any SID model on C64/SX-64/C128?

Yes, SIDFX is designed to detect the SID model in each socket and set voltage and filter-capacitors accordingly. So putting a 6581 into a C64C or two 8580 into a C64 bread-bin or a 6581 and a 8580 into a C128 - any combination you wish - is possible.

Does SIDFX have a cleaner audio output?

Yes, SIDFX filters the power supply voltages and thereby reduces the audible noise by up to 40 dB
(depending on operating conditions).

Are all of the 4 included cables required?

No they are not all required for SIDFX to work but for the full feature-list you must connect them all.. It depends on your needs but we provide you with as many options as possible.

Are the cables long enough for e.g. my C128D?

The standard cable length has been tailored to fit all regular C64/C64C/C128 cases but longer cables are available for use with SX-64, C128D and C128DCR.

Can the cables be installed without drilling?

It is strongly recommend to permanently install the cables in order to avoid damage. We do however understand the wish to avoid drilling holes in your computer. Consider e.g. a 3D printed blanking panel covering the user/cassette port and mount the cables there. Hardware accessories allowing switching using the keyboard also exist (e.g. Keyman64) but may require some soldering and use of our SIDFX DIY cable accessories.

No soldering required, okay...
- but am I required to assemble anything?

SIDFX ships as a complete unit but you do need to open your computer, extract your SID chip and install SIDFX in it's place. We have written an extensive manual with many photos in order to guide you through the entire process.

Please consult our online manual for further details.

Can I use $D500 for SID2 on C128 models?

No, unfortunately the C128 memory map is not fully backward compatible with the C64. In C128 mode the MMU resides at $D500. Although the MMU is inaccessible in C64 mode the $D500 address space is not mapped to the SID socket.

Does SIDFX work with MSSIAH/Prophet64?


Yes, several customers confirm that MSSIAH works with SIDFX.

Does SIDFX work with Cynthcart?

Yes, we have several customers confirming that Cynthcart works with SIDFX. Please see the related FAQ section if you require SID2 to be located at $DF00.

Does SIDFX work with C64 Reloaded MK1?

Yes, but if your C64 Reloaded motherboard has ZIF sockets and is installed in a C64C chassis then our special  adapter is required in order to allow fitting SIDFX below the keyboard. If C64 Reloaded is installed in a bread-bin chassis or doesn’t have ZIF sockets then the adapter is not required.

Does SIDFX work with C64 Reloaded MK2?

Yes, but our new adapter is required in order to allow the motherboard to detect SIDFX as an 6581 SID and provide 12V to the SID 1 socket of the motherboard. Otherwise the motherboard is unable to supply sufficient power to SIDFX.

Does SIDFX work with SwinSID/ARMxSiD?


Yes, SwinSID Nano, SwinSID Ultimate, ARMSiD and ARM2SiD have all been confirmed to work with SIDFX. But you need to install our advanced SIDFX firmware which allows manual configuration of the SID types because SwinSID and ARMSiD are not compatible with the detection method used by SIDFX.

Where does the 2nd SID appear in memory?

SIDFX can be configured to map SID 2 at either $D420, $D500 or $DE00. These are the typical address spaces used for stereo SID tunes. While in mono mode SID 2 resides at $D400.

Can I map SID2 to address $DF00?

SIDFX does not natively support use of $DF00 but there is an easy workaround. If you install the yellow grabber on pin 10 of the expansion port connector (instead of pin 7) then $DF00 is used when you select $DE00 in the SIDFX configuration tool. However with the yellow grabber in the new location you will no longer be able to use address $DE00.

Can I map SID2 to both $DE00 and $DF00?


By installing the yellow grabber on either pin 7 (for $DE00) pin 10 (for $DF00) of the expansion port connector you can select at which address SID2 is mapped when you select $DE00 in the SIDFX configuration tool. If you frequently wish to change between $DE00 and $DF00 it is also possible to install a switch (SW3, similar to the ones provided with SIDFX) to toggle which pin is used as the chip select line. To do so connect the grabber to the center SW3 pin (or cut off the grabber and solder it). Then wire pin 7 to the left SW3 pin and pin 10 to the right SW3 pin of the switch. Using SW3 you can then easily select $DE00 (left position) or $DF00 (right position).

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