Virtual Synths on dedicated hardware

Hi guys.
Quite a while ago I mooted this idea and have gotten around to testing it.
Basically using a micro form factor PC as a ‘hardware’ synth. (Which synths are anyway).
The first test is using a Macmini as the master - in this case an old 2012 running Maverics.
The testing was done with Cubase on that machine…
The ‘Slave’ machine was another old clunker, an old HP200 all-in-one from 2010 running Windows 7.
The midi was sent from the mac using the Apple network midi system. The PC received it using rptMidi (from Tobias Erichsen. ) The Midi latency was less than 1ms, likely much less than that. The returned audio was sent to a USB desk (Roland 24 channel VS-700) and from there back to the mac and Cubase.

The vsts on the PC were hosted on vstboard or Cantible. The PC is set to auto login and start the vst host.
The host and midi settings are automatic on startup for all machines.

The test was measured by sending midi from Cubase and recording the returned audio.
The time difference between the two was on average 3ms. The longest was Arminator 2 vst at 5ms.
Diva at full quality playing a triad on ‘Space Diva’ and using 20 - 68% CPU on the HP came in at <3ms round trip.
Midi custom controls on VMPK on the mac were used to adjust Diva remotely via midii or change vst or racks etc on the PC.
RDP ( Remote Desktop Protocol) from the mac (master) was used when required to really fiddle the PC.
I drove 2 PCs and another Macmini to different tracks in one session.

So what you end up with is a little box(s) with Diva, Legend (say) that is controlled by midi with only Ethernet, audio and power cables in the same manner as my hardware synths.
Mac to Mac, PC to PC, or any mixture works absolutely fabulously!!!
I used texta to write Diva / Legend on one mac mini and ‘master’ on another.


I forgot to mention that my keyboards plugged into the master, and programmable buttons would switch ‘synths’ machines from a fully loaded diva rack on one machine to a massive piano library on another machine to some other setup on another. Or two keyboards each controlling a different ‘slave’ through the master.

Indeed, I think quite a few of us are doing just about the same thing (although not all going totally headless and using RDP). Certainly building a dedicated synth box with a micro form factor PC is the way to go!

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Cantabile on my NUC PC (Neil’s recommendation) has the horse power to run many VTSs, backing tracks, etc. All in one small box inside my gig rack. Have also used RTP MIDI for triggering a video laptop (using Show Cue Systems 11) from Cantabile transport bindings. RTP MIDI is good in this use case as a small network hub is all you need (not two more MIDI interfaces) to connect the computers. I did try connecting direct port to port, but making the connection was not 100% reliable.


I only use one port on each ‘slave’. The Mac as the master handles however many slaved units on the network through 1gig switch. It passes on the midi from the USB Keyboards(s) to the selected unit.
The central 24 ch mixer (VS-700R) key as well.

My test and setup bench.

Interesting. The price is right on them as well.

But the Mac is growing on me though. Free OS(s), very few plugs that don’t come in MAC these days. And a proper Unix platform that’s not a science project.
Roll on Cantabile for Mac!!

My main computer is a MAC, but have stuck with PCs for audio computing as some of my older VSTs are PC only. Mac is much more pleasant to use, although I think Apple have lost their way somewhat in the past few years - certain things to do with OS X and iOS sync now irritate the heck out of me, especially on a slow broadband connection. On the plus side, the MAC has lasted me seven years (a lifetime in the computing world) and never crashed in that time period, only occasional OS updates needed…

This is a bit off topic but related to this discussion. I started another thread where I outlined what I might now call a 2U Cantabile case on a stage stand with all the ports on a custom panel in the back - the USB hub power adapters mounted inside and USB interface front panel exposed in the front - laptop mounted on top.

I’m still going to build that but in the meantime I had a simpler idea for the open mic’s I’m going to. The goal is to fool the participants into thinking I’m playing a stage piano when it’s actually a controller and laptop. Why, because the open laptop is a bit of distraction in these sessions. For this design I’m going to use a slide out keyboard drawer that has a 2U back plate with all the audio and power connectors. In the keyboard drawer is the powered USB hub, a 12 Dell XPS notebook, power adapters and the USB interface mounted so its front is just under the keyboard. This will hang with 4 metal straps from the tubes of the X stand that hold the keyboard. I’ve been working in Cantabile creating bindings to states in a song that solo True Pianos or VB3 II or Lounge Lizard. These and program next and last will be assigned with bindings to the 8 pads on the keyboard. For VB3 the Axiom sliders, rotary knobs and buttons give me the same controls a B3 player has. Setup is walk on stage open X stand, hang the above described unit in place, put the keyboard on top - plug one IEC power, mono or stereo out and USB from back plate (which goes from keyboard into powered hub). That’s about as quick as setting up a Nord C2 and looks the same when done. The notebook runs closed underneath and instrument changes are done from the pads. The laptop has 16GB RAM and an SSD.

Brad, don’t worry - Cantabile large sticker is on the Axiom :grinning:

My goal would be to fool participants into just thinking. That would be quite a task in itself. :grin:


I want to fool them into drinking, so the stingy owners are happy to payup.

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Sounds cool.
My Oxygen88 has heaps of sliders, switches and knobs
My aim is to finish up with a box with eight XLR outputs and an ethernet and power socket. Four macminis, fan and switch inside. A working hibernate thing would be nice.

I used to be a Microsoft MVP LOL.
I love the Mac Minis and iMacs.
I’m using Mavericks because the VS-700 mixer wouldn’t work with High Sierra, BUT, I had an epiphany about old unsigned drivers and turned off the OSX SIP. Yaaay I was so effing happy!! And with my linked slave PC I run the Windows vsts I missed. My next adventure is to see how bad the latency is in a virtual box.

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I didn’t do it in 2U, but 4U, as I wanted a home for my Nord G2 Engine and IEMs. but my Gig Rack Guide on my case can be found on the first link on the Page below

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Veeeery nice.
Now if only someone would invent say a 10gig wireless midi / ethernet / USB & audio doodad.

Hi Derek,

Your posts in the “Show me Your Cantabile Rig” inspired my project - thanks.

Mine will really be 3U because the laptop mounted on top has a 1U cover.


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I’m using a Skull Canyon i7 inside the lower manual of my old XK3 System to run the B5/AmpliTube Leslie combination (amongst other things, all controlled from the XK3 presets). For the front end I use my Surface Pro 4 via NoMachine software over ethernet so that I can see the NUC/Cantabile when changes are needed. This means I can use the SP4 for the music sheets. In addition I’m using Chameleon and Elephant (for Surface Dial) via rtpMidi. The whole thing runs very well and using the NUC has rid me of the dropouts and glitches that occurred trying to run the whole system on the SP4 alone.

Hooking it all up took some figuring but I got there in the end! My XK3-system has a new lease of life, too!



Good to inspire somebody in the same way that the advice from Neil and others inspired me. :slight_smile:

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