Scaler tempo not tracking Clock Signal from VCV Rack 2

Scaler 2 Support Bug Reports
1

Hi, my DAW is VCV Rack 2, which uses a clock module to set the tempo in my projects. I am using VCV HOST to open and use the Scaler VST inside my project. So far so good, Scaler VST loads, opens and plays chords in VCV Rack through VCV HOST.

However,…Scaler is failing to sync itself to the tempo of my project. I have created a clock input to Scaler in VCV HOST, and connected my VCV project clock (which is pulsing at the designated BPM) to VCV HOST, but Scaler is not recognizing or responding to the clock in anyway. If I press play on a set of chords, the chords do play through…but at some undisclosed tempo (sounds like it may be around 120bpm?) that has nothing to do with the clock signal being fed into Scaler through VCV host. And, when I change the clock tempo in VCV to check, nothing happens in Scaler…it just keeps playing the chords at whatever rate is is defaulting to and never changes tempo.

How do I set up Scaler in VCV Rack 2 using VCV HOST so that Scalar will recognize and follow the project tempo specified by my project clock in VCV Rack?

2

Hi @keith_g_wagner Hard to diagnose here but firstly welcome to the forum. Some more info on your setup would be good (platform, OS etc) and then maybe we can help. My initial hunch is it sounds to me like a sample rate issue.

3

Thanks for getting back on this: Platform is VCV Rack 2 Standalone (not the VST running in a traditional DAW). System/OS is Windows 11.

VCV Rack Standalone is different than a conventional DAW, because it has no “built in” tempo or BPM controls of the type Scaler 2 would usually self-detect in a DAW such as Ableton (Scaler 2 time syncs fine for me in Ableton).

In VCV Rack (which emulates modular racks), however, there is no clock until one is put into a “rack”, and then cables (virtual) must be drawn/linked from the clock to any/all other modules/devices that need to follow the clock for tempo/BPM.

VCV Rack does not host VSTs (including Scaler) natively. However, it has an add on module called “VCV-HOST” which acts as a VST “wrapper,” allowing one to use VST2s and VST3s as modules in VCV Rack.

The way VCV-HOST works is that it provides an interface with cable ports that can be assigned to the inputs/outputs of the VST (including, most importantly here, CLOCK pulses coming in to the Scaler VST from a clock running inside of VCV, so that the VST may be internally time synced with the VCV Clock which establishes the tempo for the whole project).

I have tried this syncing of VCV clock to other VSTs’ tempo rates that need clock information from VCV (specifically Stepic VST and Pigments’ sequencer) and it all works fine with both of those VSTs. Both Stepic’s and Pigments’ sequencers receive and follow the clock signal being input from VCV Rack through VCV-HOST, and adjust their tempos/playback rates correspondingly when the rate of the clock in VCV Rack is changed.

Scaler 2, though, is not responding/recognizing the incoming clock pulse from VCV Rack through VCV-HOST. Scaler does load and otherwise work fine in the VCV Rack environment. But…when I put Scaler 2 into a loop playing a series of chords, it does start playing and I can hear the loop, but Scaler 2 is playing the loop at some internal tempo of its own, and is not recognizing or following the tempo of the incoming clock pulse. And when the rate/tempo of the Clock in VCV is adjusted up or down, there is no response from Scaler 2.

(I did try turning “sync” to DAW on and off of course, but that is just for transport sync, it doesn’t seem to affect or be related to syncing to tempo.)

4

ADD ON: One possibility is that Scaler is relying on BPM information from the conventional DAWs, instead of a clock signal(?). The Clocked module in VCV rack has a separate output for a BPM CV signal that is different than clock pulses.

VCV-HOST does have the ability to feed clock pulses into VSTs. But it has no option to send in a BPM CV signal. So…if Scaler 2 is relying on direct BPM settings in traditional DAWs, rather than following clock, the solution may be that I need to go back to VCV to let them know I have a VST that needs BPM information to be fed to it (not straight clock pulse), and ask if they can add BPM as an additional input option for VCV-HOST.

If you want to see more info about the Clocked module or VCV HOST, here are a couple of links with pictures and a description):

5

Hi @keith_g_wagner thanks for the info here. Unfortunately this is a fairly obscure use case of Scaler 2 and not one we have tested so I’m not sure what to suggest I’m afraid. Personally I’m also a big fan of VCV Rack and would love to see this all working as expected, but it’s not something we’re able to address immediately. We’ll certainly try our best to look into this for a future update so keep an eye on the forum here for more info.

Thanks.

6

SOLVED: Omri Cohen, VCV guru, identified the issue for me, which is what I think Davide was saying: the clock rate pulses I was sending into Scaler from VCV rack were at a quarter note rate, and Scaler was not responding. Omri gave it a look, and said I should feed the clock in at a “x24” rate, which the VCV HOST does have an option for. Once I ramped up the clock to 24x and enabled that port on VCV HOST, Scaler 2’s bpm/tempo synced up with my project, and now Scaler follows any changes in clock rate that I make inside of VCV Rack. Thanks again, Davide, for your response (it was the right answer, once I was educated what to do by the VCV crowd).

2 Likes