Boz Digital Labs Transgressor Review


Transgressor is a transient shaper with a difference, developed by Boz Digital Labs. It offers the ability to separately EQ the transient and sustain portions of an audio track.

What is transient shaping? Now there is a frustrating google search indeed, and one I was first faced with when I started using the technique. The simplest and most unscientific explanation is that a transient is the initial build-up of energy at the beginning of a sound. The pick on the guitar string, the beater smacking the bass drum head, the bow scraping the violin string. By contrast, the sustain portion of the sound might be the guitar note ringing out, the boom inside the bass drum or the violin string vibrating.

Early transient shapers were a kind of compressor that was able to separately detect and treat the transient portion of the sound, perhaps to bring out the pick attack of an acoustic guitar, or ‘bring out the beater’ of a kick. The better ones could also treat the sustain of the sound. The most useful are those that offer multi-band capability. A favourite technique of mine is to reduce the sustain of the low end of a kick drum. By doing so, I haven’t made the beater or ‘clickiness’ any louder, I’ve just reduced the boomy sound, making it sit better in the mix and feel punchier, without cranking it.

Boz Digital Labs have now come along with Transgressor, with a fresh approach to transient shaping. In short, Transgressor allows you to separately EQ your transient and your sustain in completely different manners.


I’m always a fan of GUIs that look like they could be a physical hardware unit, and Transgressor doesn’t disappoint visually. The whole point of Transgressor is separate manipulation of the transient and sustain, and the GUI reflects this with large red and blue sections respectively. This may seem obvious, but it goes a long way to making it possible to just dive in and start using Transgressor.

The grey section on the left contains the threshold control, which is how Transgressor detects the transient coming in. This can be set to hard or soft, and the best way to use this is to disable ‘Sustain’ so you can accurately hear the section of your sound being sent to the ‘Transient’ section. It’s pretty easy to get used to listening for just the transient, and the visual meter gives you a bit more of a clue as to how much audio is getting trough. Next is a retrigger control, which sets the speed at which the transient detector resets

Below this is a high and low cut filter. This is an internal sidechain filter, so it does not affect the output. Instead, it affects what frequencies Transgressor will hear and therefore react to. It can be set to high and low-pass, band-pass, or bypassed altogether.

Along the bottom of the plugin is a hold and release control, along with the output gain parameter. Hold determines how long the transient will remain at full volume after being triggered, whereas Release controls the speed of the fade out after the Hold. Setting these by ear takes a little practice, but it is possible to really shape the attack of a kick drum with these controls alone if necessary. With these set and out of the way, it’s time to begin looking at the transient and sustain sections.

The bright blue section is the transient control. Although it contains a dedicated preset section, I could find only one preset within it. Of course, the option to save and recall your own is included, meaning that you can expand the plugin with custom presets. The transient level can be boosted or attenuated, which is the basic function of any transient shaper. For context, if I was shaping a dubstep kick, I might boost the transient to get a real smack from the beater. If I was producing a soft jazz track, however, I might want to tame that transient and attenuate it slightly to smooth out the sound. The entire section can be switched on or off, which is a nice touch as it allows you to then zero in on the sustain section, and vice versa.

With the level set, we get to what this plugin is really about. The transient section features a 3-band EQ, which by default is set to a high and low shelf and a bell, although the high and low can be set to a bell or a cut if needed. There are gain and Q controls, familiar from any EQ plugin. It’s quite surprising how far these controls can be pushed without sounding too extreme. It’s important to remember here that the EQ is only applied to the very tiny transient portion of the sound, which means your EQ here can be wildly different from the EQ of the source audio as a whole, allowing a wide range of experimentation.

At the top-right of the GUI are options to side-chain an external source to the plugin. This is something I hadn’t considered doing before with a transient shaper. A problem I’ve had in the past is, having used a transient shaper to sculpt a great kick sound, other sound sources featuring the original kick, such as overheads or room mics, now sound foreign and strange compared to the close-mic’d kick. Because of that, they can be much harder to zero-in on the kick to alter.

To combat this, you can, for example, have an instance of Transgressor on your overhead mics, and side-chain the kick drum. This will make Transgressor act like a dynamic EQ, allowing you to slightly duck the transient or sustain of the overheads each time the kick hits. EDM producers will be more familiar with traditional side-chaining, where the whole track or bassline is ducked against the kick for that well-known pumping effect. However, using a dynamic EQ is a great way of creating a tight low-end without killing the bass. This is just a more precise application.


I am hugely impressed with the capabilities of this plugin, although with one rather major caveat, and it’s a biggie…

In theory, it should be possible to use Transgressor to shape your drum sounds in any way you like. However, although I could get a decent smoothed-out drum sound with a little bit of tinkering, it really excels at producing a punchy, aggressive kick drum, and this is what I would use it for 99% of the time. Even the presets seem to lean this way. This does kind of make it a bit of a one-trick pony, but one that you can rely on. If you’re producing a genre that relies on a forceful kick drum, you will not be displeased with the result. Dubstep, trap, any metal or hard rock genre will benefit greatly here.

That said, tastes change quite dramatically in music, as do production techniques, and the amount of control this plugin gives you over your transient shaping means that Transgressor may end up spanning a few more genres as its usefulness becomes more apparent.

I have focussed mainly on drums in this review, however other applications for Transgressor should also be considered. I briefly experimented with an acoustic guitar sound that was quite dull and had very little string attack. The result wasn’t too dissimilar from a typical transient shaper, although I found the EQ controls in this application to be far less musical. I don’t know if EQ-ing the transient on a guitar separates it too much from the sustained note, but this plugin was obviously built for percussion and seems to excel there.

The very shallow bank of presets does lead me to believe that Transgressor is limited to doing a few jobs very well. Thankfully for me, and I would imagine for many similar bedroom producers, these jobs are staples of my production process. I do have to consider a broader spectrum of uses than my own, therefore I would advise to check out Boz Digital Labs’ very helpful tutorial videos before deciding if Transgressor will benefit your style of music.

In my opinion, being able to turn the transient and sustain up or down is superior to just being able to turn the transient up or down. Being able to EQ transients separately is superior to both. Therefore, Transgressor is a step in the right direction in the ongoing development of transient shapers.

More info: Transgressor ($99)

Transgressor Review


Being able to turn the transient and sustain up or down is superior to just being able to turn the transient up or down. Being able to EQ transients separately is superior to both. Therefore, Transgressor is a step in the right direction in the ongoing development of transient shapers.

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About The Author

Johnny Marsh is guitarist and drummer from Stourbridge, England. He produces electronic-infused progressive metal under the moniker T3TRA, with a particular penchant for blending downtuned guitars with synthesizers. He also drinks far too much coffee.

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