Bark Filter review – VirSyn add a powerful multi-band compressor to their iOS music app catalogue

Download from iTunes App StoreVirSyn will be well known to the majority of computer-based musicians whether you work on the desktop or a mobile platform such as iOS. The company have an extensive portfolio of iOS music apps covering a number of different synths, audio effects and a dedicated arpeggiator app.

Many of these apps are iOS-sized ports of VirSyn’s desktop virtual instruments and effects and I’ve reviewed a good number of them here on the blog over the last few years or so. VirSyn newest addition to this impressive catalogue is Bark Filter and, yes, it’s a weird name and, yes, it’s another port of one of their desktop plugins. So, what’s a Bark Filter when it’s at home and what might you use it for?

Bark Filter – up to 27 bands of compression in an app.

Woof, woof

Let’s start with some basics. Bark Filter is a universal app and, for a limited time only, is available at an introductory price of just UK£6.99/US$6.99. It is also worth noting that the desktop plugin upon which the app is based, is priced at €169. As far as I can tell, the feature set and audio processing algorithms are identical, although I’ve no documentation to go on to confirm that (and a PDF manual would be a useful addition at some stage despite the in-app help system).

The app requires iOS8.0 or later but, as it can run as an AU plugin as well as via IAA or Audiobus, you would need a suitable AU host and iOS 9.0 or later. The app is a 16MB download and ought to run quite happily on an iPhone 5s/iPad Air or newer.

In essence, Bark Filter offers multi-band compression. However, while many of us might be used to the concept of a multiband compressor and perhaps have used a typical 3, 4 or 5 band compressor as part of a DIY mastering signal chain (apps such as Final Touch and Audio Mastering offer this), in Bark Filter you get an impressive choice of up to 27 bands. This is flexibly though; you can link bands to reduce this number so the app could operate as a single band compressor or a more typical 3 or 4 band unit if you wished.

Bark Filter runs stand-alone and, as shown here, as an AU plugin.

The ‘Bark’ element of the name apparently derives from the Bark scale that divides the frequency spectrum up based upon the way sound is perceived (presumably by the human ear?) rather than some single mathematical approach. Each filter/EQ band/compressor is carefully designed with steep transitions and to match the way the ear responds to sound and, I assume, the intention is to create a tool that can manipulate sound in a fashion that seem ‘natural’ to our ears.

Barking orders

As shown in the various screenshots, whether used stand-alone or as a plugin, you get a standard set of compression controls for each of the frequency bands. You can, therefore, set the Threshold, Ratio, Attack, Release and Make-up Gain either globally (via the Master tab) or independently for each of the (up to) 27 bands, via the various individual tabs for each control.

The Master tab includes an on/off (bypass) switch, a global compressor on/off switch, master compression controls (these are overridden if you make any band-specific settings elsewhere), and Auto Gain switch and, if you want to engage it, a Limiter that sits across the main output.

The app includes VirSyn’s usual ‘in app’ help options to guide you though the controls.

Five of the other screens – Threshold, Ratio, Attack, Release and Make-up – provide the compressor controls for your various bands. These are presented as vertical sliders for each band and are adjusted via the touchscreen.

However, it’s also worth noting that, by touching at the base of each of these screens you can toggle on/off a ‘link’ between adjacent bands. This allows you to control how many bands you actually have available and the frequency range over which each operates. This is very neatly done and, once you have ‘linked’ a few bands into one wider one, that wider one then offers just a single set of controls. Again, the screenshots show some examples of where this has been done….

Each tab provides a set of blue sliders for parameter adjustment within each band.

The other tab takes you to the Filter screen. This essentially offers you a gain control for each band and, while the compressor does its thing in terms of dynamics, the filter gain controls provide something akin to a graphic EQ. And, if you set a band’s gain to zero, well, you can’t hear it. If you want to create some dramatic EQ shapes, this is where to come. Equally, if you simply make some modest tweaks, you can change the tonal character of your audio in quite subtle ways much as you would with a graphic EQ.

The spectral display shows you exactly what your processing is doing to the sound including gain reduction for each band…. although don’t copy these settings; they are extreme simply for illustration purposes :-)

While it is displayed slightly differently between stand-alone and plugin formats, the graphical display of what’s going on is very useful. You see a real-time EQ spectrum for your audio with the blue curve showing the original signal and the yellow curve the compressed one. In addition, red bars indicate the gain reduction being applied for each band in real-time. This is all kind of cool… but also incredibly useful if you want to see just how hard you are pushing things or spot a frequency that perhaps needs a bit of a cut/boost within your mix.

Take the dog a walk

I tried Bark Filter as a stand-alone app, within Audiobus and as an AU plugin. From a technical front, I has no issues and, while I suspect there might be quite a bit of processing going on under the hood, sliding the app in and out of my Cubasis project (for example) didn’t seem to generate too much of a CPU hit on my large format iPad Pro.

The obvious spot for Bark Filter is applied on your stereo output bus….

That said, while I could imagine using the app on something like a drum mix or ‘stem’ for guitars or bass tracks (perhaps within AUM or Auria Pro, for example), I would think that the most obvious use for Bark Filter is sat on your master buss/stereo output channel within your DAW/sequencer. In that role, it offers the same sort of ‘bus mastering’ element that something like NoLimits or PressIt might…. but with up to 27 bands of control.

And, applied to a few different projects, I have to say that Bark Filter does a pretty good job in that role. Do you need 27 bands of compression to control the dynamics of your stereo mix? Well, I’m not sure I’m qualified to answer that question, but the results certainly sounded pretty good.

If I had to offer any advice for initial use, I think it might be the same as for any DIY ‘mastering’ style processing; take it very easy. With Bark Filter that perhaps means starting with the ‘All Band Compression’ preset and just tweaking the Master tab controls to start with. I might then move on to the Filter section if I wanted to make very fine adjustments to the EQ of the mix….

Note the ‘link’ icons at the base of the screen where some of the individual bands have been joined…. and that you get a display of the exact settings as you adjust a control. Again, settings used here for illustration purposes only :-)

The other obvious approach is to combine the various frequency bands and go from 27 down to, for example, 3 or 4. I might feel a little braver to then tweak each band individually as I might with some of the other apps mentioned earlier.

However, unless you are deliberately going after an extreme processing effect of some sort, or you really feel you know what you are doing, avoiding making dramatic changes to individual narrow bands is probably a good thing. While the design if the filter crossovers does seem to be very good, this kind of adjustment is much less likely to leave you with a ‘natural’ sound; the human ear is a sensitive thing and could easily perceive drastic inter-band setting differences as something just a bit ‘odd’.

Linking bands means you can use Bark Filter in more conventional 3, 4 or 5 band configurations also.

I suppose the final question is whether 27 bands better than 3 or 4 for stereo bus compression? All other things being equal, you might imagine that the ability of the compressor to respond to narrower ranges of frequencies would, in principle, mean that it creates a ‘smoother’, more controlled, result. I’m not sure I’ve done enough side-by-side testing with Bark Filter up against some of the other apps I mentioned earlier, but I was certainly very pleased with what Bark Filter was able to do in terms of control and punch with the projects I used.

The app ships with a selection of useful presets to get you started.

That said, I was (as best as I could), following my own advice and keeping things pretty gentle and maybe for such ‘gentle’ mastering tasks the differences are likely to be subtle? However, where Bark Filter might have a clear advantage is when you have been given a less-than stellar stereo mix and are attempting to ‘rescue’ its overall EQ/dynamics without the option to go back to the original mix and put it right at source. Providing you know what you are doing, maybe 27 bands of EQ adjustment and compression might then be a life-saver?

In summary

Given the commentary above, while it can obviously be used in other roles, Bark Filter is perhaps most likely to appeal to those iOS music makers who like to indulge in a bit of DIY mastering. Whether that occurs on your DAW’s master output (as part of the mixing process) or as a separate ‘post mix’ process, I’m sure Bark Filter could be put to good use…. and, if the great power is used with great responsibility (that is, go KISS on the settings), then the app will undoubtedly let you fine-tune the dynamics of your overall mix in a very effective fashion.

The other thing to say is that, while a deep app in terms of what it lets you do to your audio, the control set itself is pretty easy to use; learn how to use one compressor and you have learned how to use all 27 :-)

And, of course, at the launch price of just UK£6.99/US$6.99, it is unlikely to leave you with too big a hole in your pocket even if you acquire it for just occasional use. iOS has a number of multi-band dynamics apps already available but, as an example of ‘most flexible in class’, I think VirSyn has just claimed the crown…. Well worth the price of entry so check out the demo video below and then hit the App Store download button to find out more.

Bark Filter

Download from iTunes App Store


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    1. A 9 years old specialist psychoacoustical multiband compressor ‘claims the crown’? How do you like using, say, Pro-MB, on iOS?

      • Hi Kurz….. well, I did state that Bark Filter “claims the crown” for “most flexible in class”…. and, with up to 27 bands on offer, that’s perhaps a case that’s easy enough to make. I think Pro-MB is up to a maximum of six bands? Still very flexible I’m sure, although under iOS, only available to Auria users, so Bark Filter is also ‘flexible on that front as it will work with any AU host….. I’m sure both are capable of impressive results though and you can, of course, think of ‘flexible’ in a very different context (range of applications for example rather than the number of bands or some other feature count)…. very best wishes, John

    2. I wondered if Bark Filter (used as an AU insert effect in AUM) could be used as an alternative to Audiomaster Pro, for adding a bit of polish to on-device mixes of my iPhone demos?

      I usually mix (and after a fashion, master) recordings in Logic on our Mac. However, a lot of the time I record songs mostly on iPhone, and sometimes I might want to do a rough mix on the device itself. As Audio Mastering is iPad-only, I’ve currently got a three-month subscription to AMP (renewing early in September, and I wondered whether Bark Filter might be a more useful target for the cash?

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