Pumphouse review – Audio Damage offer side-chain compression without the need for a side-chain

Download from iTunes App StoreAs I’ve posted over the last few weeks, Audio Damage are a developer on an iOS mission, with several new releases, many of which are based upon ports of their highly-regarded desktop plugins. As well as the recent Phosphor 2 synth release, we have also seen Rough Rider 2, Grind Distortion, Eos 2, Dubstation 2, FuzzPlus 3, QuatroMod and Replicant 2, all within the last few weeks.

And there is no sign of any let up as we now have the release of a further new iOS app; Pumphouse. If the title doesn’t suggest a function to you [in old-school English, a ‘pumphouse’ was a pub, with the pumps being what was used to draw the beer out of the barrels; no, this is not an app that form a virtual bar :-) ] this is a compressor effect that’s designed specifically to get your audio ‘pumping’; that is, when you listen to the track being compressed, you can clearly hear the compressor kicking in, reducing the volume of the initial attack phase of a sound, and then quickly releasing so the volume rises again.

Pumphouse – side-chain style compression without using a side-chain.

The app is a 14MB download, universal in nature, requires iOS9.3 or later and runs as either a standalone app, IAA or via AU (the latter is the route Audio Damage obviously favour with all their apps). The launch price is just UK£2.99/US$2.99 so this is an app very much in the casual purchase category.

On the (side-)chain gang

This kind of processing has a number of applications. It can be used as a special effect and it has become a bit of an EDM cliche…. although there are plenty of other musical genres in which it can be used. However, the other way this sort of extreme compression is used is via a side-chain setup. In the world of hardware or desktop-based studios, options for side-chaining compressors (and other sorts of effects) are quite common…..  but, to be done in software, as well as the plugin effect needing to offer a ‘side-chain input’, it does require your host DAW/sequencer to support the audio routing required to route audio into such a side-chain input….  And, at present, side-chain audio routing, while commonly found in desktop music software, is still something of a rarity under iOS.

So why might side-chaining be useful? Well, let’s take an EDM-style example where you have a big kick drum and a big bass synth both competing for the same sort of frequency range. While it’s perfectly possible to mix these elements together, the danger it that, if some of their respective notes/hits happen to play at the same time (for example, on the first beat of every bar), the danger is that one with ‘mask’ the other. So, for example, your kick drum hit (which carries the beat of your track) might not be heard so clearly (or, less common perhaps, if it is the bass line you want to give prominence too, the opposite might occur). Equally, with both of these high energy sounds hitting together, if you have a compressor on your master bus (stereo output), it might make it difficult to find ideal settings for that master compressor to cope with both these regular ‘big hits’ (kick and bass together) and the rest of the track when the two don’t coincide.

As typical example of side-chain compression use might be to compress a bass sound when a kick drum hits to allow the kick drum to come through the mix more clearly….  and Pumphouse allows something similar as shown here within Cubasis.

Enter the side-chain compressor….  This allows you to apply compression to one sound(for example, the bass synth) so it’s volume is sometimes reduced based upon the volume of another sound (for example, the kick drum). So, in a hardware or desktop setup, you might insert the compressor on the bass synth track, activate it’s side-chain input, and then send a signal from the kick drum track to the compressor’s side-chain input. The compressor only then acts when it receives a signal from the kick drum track and, as a result, the level of the bass synth is compressed only when the kick drum hits.

The exact result depends upon how you configure the compressor (ratio, attack and release times, etc.) but, in broad terms, the level of the bass synth is reduced (it gets out of the way of the kick) every time the kick drum plays. In the context of your overall mix, this means that the kick drum signal is heard more consistently and is less likely to be masked by the bass synth sound.

No side-chain?

Unfortunately, as mentioned earlier, options for side-chain audio routing are relatively rare under iOS and, until all the major iOS DAW/sequencers offer the feature (I’m sure it will come in time), it is also likely to remain rare in our various iOS audio effects apps (chicken and egg time on this issue I guess). However, Pumphouse provides a suitable – and quite simple – workaround; it’s a compressor that mimics the effect of side-chain compression but without needing a side-chain audio routing system to achieve it.

The way this works becomes more obvious once you peek at the app’s UI. Pumphouse is inserted as a plugin on the track that you want to ‘side-chain’….  so, in the kind of example I’ve described here, that would be on a bass synth/guitar track. Most of the control set then looks pretty much like a standard compressor – Attack, Release, Ratio, Sensitivity (threshold), Make-Up Gain and Mix (the wet/dry balance of the effect) – and works pretty much as you would expect.

Four-on-the-floor kicks? Pumphouse can easily dodge your other sounds out of the way…..

However, the key twist is the 4 x 4 grid on the left side of the display. This represents 16th note divisions in a single bar and, providing Pumphouse is able to receive transport/tempo information from your AU host (and most can do this although Auria Pro is something of a exception currently), if you toggle any of these blocks on, the compressor will then be triggered on that 16th note step for each bar.

This is, essentially, equivalent to a kick drum send being received on a side-chain input and you can apply whatever combination of settings within the compressor to ‘duck’ your bass sound on those beat steps. The obvious ‘catch’ is that your 16th note ‘side-chain input’ pattern is the same for every bar whereas, in reality, your kick drum pattern might actually vary through your project (perhaps between song sections). That said, for most EDM applications, it often beats 1 and 3 or beats 1,2 3 and 4 (four on the floor) that require the side-chain treatment…..   so the trade off of simplicity and functionality so you can actually use this compression technique is a pretty good on in my opinion.

The other control in the feature set is the Curve knob. This is quite interesting. It’s not really the equivalent of the soft knee/hard knee setting on a standard compressor but it does do a similar kind of thing in that is ‘shapes’ the gain reduction curve when the compressor is in action. Combined with the Attack and Release controls, you can achieve some very interesting gain reduction patterns….  and if you want to recreate that classic ‘pumping’ of volume (where you get a distinct swell in volume of the compressed signal as the compression is released, then that’s easy to do.

The control set allows you to ‘shape’ the compressors response each time it is triggered…. and, as shown here, you can get quite aggressive about the ‘pumping’ effect you crate.

The other really nice feature of the app is the waveform graphic. This shows the gain reduction – including the ‘shape’ of the reduction when the compressor is triggered – in a clear fashion via a continuous pale line. However, equally useful is the fact that the waveform display is shown ‘post-compression’ so you also see exactly what the action of the compression is doing to your audio waveform. This is both interesting but also informative as you configure your settings.

Pumphouse rules?

I did most of my own testing within Cubasis (I also tried the app in AUM and it worked fine) without any problems at all. Pumphouse happily sync’ed with Cubasis playback and, used in the context of the kick drum/bass sound example I’ve discussed above, the app was a doddle to use. Yes, it’s perhaps a shame that we need an app to provide a workaround for side-chain compression in the first place but, as a workaround, Pumphouse is a neat, no-fuss, tool with a great design that’s easy to use.

Multiple instances ran fine…. as shown here within AUM.

However, while a kick/bass relationship is one application, I could just as easily see the app being useful for creating rhythmic effects in all sorts of sounds and, in this sense, it actually is something that might have creative uses whether side-chain routing was possible or not within your iOS DAW of choice. For example, applied to a pad sound, whether you attempted to match the compression pattern with a kick drum part of not, you could create all sorts of interesting rhythmic effects using the grid triggers.

Perhaps the only ‘I want more’ feature would be the option for multiple bar patterns or multiple patterns. This would allow you to create different rhythmic effects within a single track….  although I suppose you could work around this by setting up multiple AU instances on a single track and then simply automate their bypass switches in your DAW to toggle different patterns in/out of the signal chain.

Audio Damage’s collection of iOS AU effects is growing very rapidly.

In summary

That’s pretty much it. Audio Damage have done it again; this is a cool little iOS AU effects app and, while designed to overcome a technical limitation (the lack of side-chaining in most iOS audio software) can just as easily be used to create other sorts of rhythmic effects. Again, the fact that you can buy such a high quality creative audio effect plugin for such a ridiculously low price is something I’m never going to understand. Don’t worry about it just yet maybe? Just buy the app?

I’ll added a couple of demo videos below for Pumphouse. Give them a watch and then hit the  App Store download button to find out more. And, while you are there, do check out Audio Damage’s other apps (including the recent Phosphor 2 synth); this is a developer on a seriously good iOS roll….


Download from iTunes App Store

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    1. A good little app, even for peeps like me who don’t make EDM. One problem, it doesn’t work with Auria Pro. Something which is AP’s fault, and is supposed to be fixed in a future update. Annoying, as AU3 wasn’t a surprise.

      • Hi Zen…. yes, some aspect of the delivery of transport/sync data to AU plugins within Auria Pro I believe…. but hopefully something that will soon be resolved. Very best wishes, John

    2. Thanks for explaining side-chaining. I clicked the link.

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