New Gear Review: SPL TDx Transient Designer

The SPL TDx packs a big punch into the compact 500 series format.

The SPL TDx packs a big punch into the compact 500 series format.

Transient processors have come to be one of the most popular dynamics tools in modern music production.

Germany’s Sound Performance Lab (SPL) has quite the pedigree in this area already, having invented the original “Transient Designer”.

Now, they have released the updated TDx: A 500 Series unit with a simple design and a lot of impact.

The TDx has only four knobs on the front panel: Attack, Sustain, Mix and Output, along with a Bypass switch.

The secret under the hood is SPL’s “Differential Envelope Technology” which, according to the company’s website, “allows level-independent dynamic processing by calculating differences in generated envelopes.”

Essentially, this unit is constantly tracking the dynamic envelope of the incoming signal, allowing you to adjust and shape the transients and sustain in real time.

Features and Use

The obvious use for such a tool is on drums, and the TDx does not disappoint there. It is great on snare, whether you’re using it to increase the “crack” of the attack, or to shorten the decay if it is dominating the mix.

On kick drum, it can really bring out the “smack” of the beater, or extend the decay of an 808 without simply squashing the track. The addition of the Mix knob is great for inline parallel processing, but I’ve found the Output trim is even more handy, allowing me to add as much attack or sustain as I like without worry of clipping the converters of my hybrid mix rig.

I was lucky to get a pair of units for review, so I tried them on my drum buss ahead of the buss compressor. This enabled me to get a ton of impact from the kit while still controlling the dynamics.

The TDx really shone on bass tracks as well. I was able to dial in nice, round R&B tones by turning down the attack and increasing the sustain, and found that the opposite treatment can really enhance the slaps and pops of funk bass. Sonically, the TDx is clean and transparent, preserving the quality of whatever passes through it, affecting the dynamics and nothing more.

I also gave the TDx a shot on vocals, particularly on some very fast raps, which can be a notoriously unintelligible sound source (sometimes to the benefit of the less lyrically gifted!)

Adding a hint of attack did wonders here, not only lending a bit of percussive life and movement to the sound, but also some clarity to the lyrics. This is a trick that should be used subtly however, as too much can cause your plosives to get out of hand—but just a bit can be a great help.

The build quality of the unit is great. The knobs feel solid and the bypass switch is firm and has a satisfying click. I did however, bemoan the lack of detented knobs. A detent at zero on the attack and release would be helpful, as would fully detented output knobs for matching stereo pairs.

Summing It Up

The SPL TDx is not the only fish in the sea of transient processors—many DAWs even come with their own version nowadays. However, this 500 series unit sounds great and does exactly what it’s supposed to.

Whether you have a primarily analog mixing setup, or just want a quick and easy transient designer for live or tracking use, the SPL TDx is a great choice for any application.

Paul “Willie Green” Womack is a Producer/Engineer based in Brooklyn, NY. Working primarily in Hip-Hop, R&B and Gospel, his credits feature artists including Donnie McClurkin, Wiz Khalifa, Open Mike Eagle, Billy Woods and many more.

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