VC-1 review – Numerical Audio add chorus to their popular iOS AU effects range

Download from iTunes App StoreI reviewed the excellent RP-1  and RF-1 apps from Numerical Audio developer Kai Aras here on the Music App Blog when when both first launched. They provides compact, but well-featured delay and reverb effects respectively and both are capable of conventional and more creative treatments. And, as I mentioned yesterday, both of these effects are now also available as desktop plugins….

For the iOS musician, both RF-1 and RP-1 are universal apps, requires iOS9.0 or later, are approximately 30MB downloads and are individually priced at just UK£5.99/US$5.99. However, on a technical front, perhaps the best bit is that both apps include Ableton Link and Audio Units (AU). The latter means that you can, of course, run multiple instances of the app within a suitable AU host such as MultitrackStudioCubasis, Modstep, Auria Pro or AUM.

VC-1 …. Numerical Audio add a sophisticated chorus effect to the iOS app lineup.

Today, however, Numerical have released a new app in the series; VC-1. This is described as a ‘vintage voiced multi-stage chorus’ so, if modulation effects are your thing, then read on….  The UI design, technical features, download size and pricing are pretty much identical to RF-1 and RP-1…..   and as this includes stand-alone, AU, IAA, Audiobus 3, Ableton Link and MIDI control, this is an effect app that is easy to slot into almost any iOS workflow.

All mod(ulation) cons

A quick look at the control set from the screenshots shows that VC-1 offers something more than just a stomp-box style chorus/modulation pedal. Yes, within the Modulation section (in the central strip of the control set) there is a Mod Frequency and Mod Amount knobs but the rest of the control set offers much more control/flexibility than a conventional chorus stomp box. This includes the option to switch between Sine LFO (a conventional option for chorus) or a ‘Noise’ option to shape the modulation effect. I’m not entirely sure I know what this latter option does but it does change the character of the effect in a perfectly useable fashion so just press it and enjoy :-)

For example, on input (on the left) you get a three band EQ to change the tonal character of the sound. On the far right in the Output section, you also get a Chorus Mix control where you can blend the balance between the dry and processed (wet) signals as well as additional high and low shelf EQ controls. What this combination of Input and Output section controls mean is that you can – if you want to – control the frequency range within you audio to which the chorus effect is applied (your dry signal always passes through VC-1 unprocessed). If (like me) you prefer your modulation effects on the subtle side, this frequency-selective chorus is another way in which you can achieve that other than just keeping the wet/dry balance turned down.

In AU mode, the UI is more compact as the input/output meters are removed and those features are handled by your AU host.

In stand-alone and IAA modes, you also get in/out meters and Level controls located at the base of the screen. This includes a Mono switch and Mute switch and the latter is ‘mute’ rather than bypass; the dry signal is cut also. At the top of the screen in stand-alone/IAA mode you also get access to the settings for Ableton Link, MIDI control and Tempo (when tempo is not controlled by a host or Link). These are all very straightforward to use and I had no problems using the Ableton Link support to sync the tempo of the chorus effect to whatever else was going on in my workflow.

Configuration stage

So far, so good….  but where things get really interesting is within the the different ‘modes’ and the Configuration section of the control set. VC-1 operates in three different emulated ‘modes’; Analog, Digital and Vintage Digital and you can switch between them using the + and – buttons located centre-top of the UI. These model different types of ‘classic’ chorus effects and each uses a different processing algorithm to produce a very different style of effect.

The app ships with a number of presets that demonstrate the different ‘modes’ of operation.

Analog is a nice warm and fairly full sound while Digital is somewhat brighter (full bandwidth) sound. The Vintage Digital is based on just 12-bit processing and has a more limited bandwidth….  it gives a darker and less pristine end result. The various presets include examples that make use of each of these modes to show them off but each has a useful character of its own.

In the Configuration section to get further control over the way the chorus is created. First you can switch between 1, 2 or 3 stages of processing. As you might expect, the more stages you apply, the richer the modulation becomes. You can also modify the resulting effect by adjusting the Min Delay setting, with longer delay times between the various modulated elements of the sound making for a more obvious effect. Finally, you can switch between serial or parallel processing between the various stages. Again, the end result is different with each setting.

Numerical Audio’s iOS AU effects catalogue is expanding nicely…. :-)

Spread your things

The final set of controls come under the Stereo section and, as you might expect, these influence the stereo width of the chorus effect. Spread does pretty much what you would expect and can either focus the effect in the centre of the stereo field or push it to the edges for a big ‘stereo’ effect. Again, this is great if, at times, you prefer to keep things a little more subtle.

The Animate knob applies as much (or as little) of an automated pan to the chorus effect so that part of the signal moves back and forth between your speakers. I think this is tempo-sync’ed….  and it is certainly effective if you want a sound to get obviously noticed. I’m less sure I understand exactly what the Shape control does although it does seem to interact with the Animate control so I suspect it influences how the automated panning is applied….   Feel free to correct me if you know better with a comment below :-)

The app worked very smoothly within Cubasis when used as an AU plugin.

Chorus of approval?

From a technical perspective, I had no issues at all running VC-1. I think Kai has pretty much got is act well and truly together when it comes to the various IOS between-app communication specs and VC-1 was a pleasure to use. Multiple instances under AU worked a treat and the preset system also seemed fully functional.

I tried VC-1 on a range of source material – guitars, bass/bass synths, pads (an obvious candidate and it sounded great), vocals and even some drums – and the results were consistently good. Used subtly – and the app offers enough controls to make that possible in a number of different ways – it made for a very nice ‘vocal thickener’ effect (not quite an automated double track but along similar lines). Equally, if you wanted a synth sound to really go ‘notice me!’ in a mix, then a dollop of VC-1 could easily achieve that also. In short, if VC-1 was the only chorus effect I had at my disposal, then I’d be more than happy.

Multiple AU instances of VC-1 also worked very well…. as shown here within AUM.

Of course, it is not….  and we have had two other chorus/modulation app releases with AU support recently that are perhaps in the same general ballpark as VC-1; QuatroMod and FAC Chorus. The latter is focussed on chorus treatments and perhaps has slightly fewer control options than VC-1. It is also even cheaper. QuatroMod does a broader range of modulation treatments than VC-1 but offers a somewhat less sophisticated control set. It’s very slightly cheaper than VC-1. All three, however, sound great and, in terms of features, are probably a step up from something that is design to be more of a stomp-box style effect (and some folks prefer the simplicity of that approach) such as Catcus Chorus.

Do you need all of these apps in your collection? Well, I guess that depends upon how much you like to use modulation effects in your music making. They all support AU though and they all sound good. They are all competitively priced also so owning all of them is not that much of a stretch….  I’d be happy with any of the more feature-rich options mentioned above as my ‘only’ chorus app but, of the three, specifically for chorus style effects, VC-1 is perhaps the most flexible.

In summary

Like RP-1 or RF-1 under iOS, there really is a lot to like about VC-1 and it is great to see Numerical Audio expanding their product line. At just UK£5.99/US$5.99,VC-1 can be seen as a pocket money purchase. No fuss to use, these apps all sound great and are very affordable. You can read the previous RF-1 and RP-1 reviews here if you need to catch up….   Like both of the earlier releases however, VC-1 come highly recommended. Check out the audio demos embedded below and then hit the App Store download button to find out more…


Download from iTunes App Store


Download from iTunes App Store


Download from iTunes App Store


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