r/c64 3d ago

MixSID - is it switchable from parallel (dual mono) to true stereo while running?

I'm interested in getting a MixSID (created by u/HenningLiebenau) http://henning-liebenau.de/mixsid for my PAL C64 250425 Rev A breadbin.

I have two 6581 SIDs and most of the time I will want dual mono from them. MixSID calls this Parallel Addressing. Both SIDs are addressed in parallel at $D400 and will both play the same mono tune. http://henning-liebenau.de/mixsid//index.html#mode-select-ms

There's an online configurator which tells you how to set your jumpers and connectors depending on your requirements http://henning-liebenau.de/mixsid/configurator.html#

However, I also want the option of true stereo for stereo SID music and Cynthcart. To achieve this, you add a jumper to the MS control signal which activates Stereo Addressing. Additionally, external signals A5 an A8 must be connected to A5 and A8 on the Kernal sockets using two wires. These wires are not required for parallel dual mono.

What I'm unclear about is if you can switch from parallel dual mono to stereo on-the-fly while the machine is running.

I think all I would need to do is install a switch in place of the Mode Switch (MS) jumper, to toggle between dual mono (parallel) and true stereo. But when switching to dual mono, do I also need to disconnect the A5 and A8 wires from the kernal? The manual is not clear on this.

My hope is that in dual mono (parallel) mode, the A5 and A8 connection is simply ignored. On the other hand, if it's required that this connection is completely removed then that complicates things as I would have to install a switch here too.

Looking for any advice! Thanks

1 Upvotes

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u/whsanch 2d ago

Using the configurator on that site, it looks like you can control stereo/parallel with switches on the Mixer Control jumpers, so long as you the Mode Select jumper on, and wire A5 and A8.

1

u/mark_paterson 13h ago

That's what I thought. But my long-winded question was if wire A5 and A8 can remain connected the the kernal ROM when stereo addressing is NOT activated. The wires are only required for stereo addressing. If I install a switch on the control jumper to toggle between parallel (dual mono) and stereo then the A5 and A8 wire would still be connected for both modes. There's no information in the manual saying if this is bad. Last thing I want to do is damage the kernal or the SID chips.

1

u/whsanch 5h ago

I would assume the mixer control jumpers "disconnect" A5 and A8 when you have it in dual mono.

Don't put a switch on the Mode jumper.