The SPL 500 Series TDx is a transient shaper designed to be housed in 500-series racks. Using multiple envelope generators, the device allows you to manipulate both the attack and sustain portions of an input signal.

For example, run a snare drum through the TDx, and you can amplify its initial hit (the transient) for a thwacking/smacking sound, while attenuating the sustain of the signal so it dies rather quickly. The opposite is also possible: run a drum-room mic through the unit, and you can amplify the sustain to create ambiance, roominess, and a modicum of aggression—a suitable trick indeed for hard-rock drums.

The TDx also works well on guitars, keyboards, and in post-production scenarios. In the latter example, the TDx can be particularly useful, as it can create a gating effect for dialogue, one that smoothly response to the vocals feeding its input path.

Attack Control
- With the Attack control, you can amplify/attenuate the transient portion of a given signal, by up to 15 dB. Positive Attack values emphasize attack events, while negative Attack values smooth out the attack envelopes of sound events. The Attack control circuitry uses two envelope generators. One follows the shape of the original curve and adapts to its dynamic gradient. The second generator produces an envelope with a slower attack. From the difference of both envelopes, a VCA control voltage is derived.

Release Control
- With the Sustain control, you can amplify/attenuate the latter portion of a signal, the sustain of a signal, by up to 24 dB. Positive Sustain values lengthen the apparent sustain of a signal, while negative Sustain values shorten the sustain. The Sustain control circuitry also uses two envelope generators. One follows the shape of the original curve and adapts to its dynamic gradient. The second envelope generator produces an envelope with a longer sustain. From the difference of both envelopes, a VCA control voltage is derived. The gradient of the control voltage matches the time flow of the original signal.

Mix Control
- You can continuously blend between the processed and the unprocessed signal. In the center position (1:1), the volume of the processed and the unprocessed signal is entirely balanced. Turn the Mix control to the right to reduce the unprocessed signal. When the knob is set hard-right, you can only hear the processed signal. Turn the Mix control to the right to reduce the processed signal. In the hard-left position, you'll only hear unprocessed signal.

Output Control
- The Output control allows you to reduce the output signal, ensuring that any downstream processor receives an optimized level.

This is a product designed for 500-series racks. You'll need your own 500-series rack to supply power and facilitate connections among your other pieces of outboard gear.