Tapco 4400a Impulse Response Library

The Tapco 4400a is a dual-channel spring reverb from the late 1970's. It was not a high-end piece of gear for its time, but those who know it well tend to love it.

The Tapco 4400a is not a subtle spring reverb, and I did my best to capture that in this library. When you drop the low end and carefully EQ and apply the highs, you can get some beautiful space creating "air"...but usually this is a box you reach for when you don't want reverb, you want SPRING REVERB.

The Tapco 4400a is my favorite spring reverb for synths, and it also sounds really good with percussion. For better or for worse, it kind of makes everything sound like it's from a recording session for a spaghetti western or an early 1980's animated movie about computer sorting algorithms. In my books this is very high praise.

Here's a demo:

This library of impulse responses was recorded in true stereo using a 60-second a sinewave sweep. I tried to capture a variety of sounds from the 4400a - even though the only parameters on the unit are two 4-band graphic equalizers, they can sculpt a surprising variety of sounds out of the twin spring tanks.

The sounds are organized in two sets of folders:

Bands (4 impulse responses) - Each IR represents a single band of the EQ, soloed and flat.

Curves (18 impulse responses) - a collection of various EQ settings, named for the settings of each band (e.g. 0_-3_-6_9 or 6_0_-3_9)

Also included in this library is an effect rack for Ableton Live. This is meant to be placed after an instance of a convolution reverb on an effect send, and it models the EQ of the Tapco 4400a while also providing tools for levelling and stereo field adjustments.

The service manual of the Tapco 4400a lists an RT60 time of 1.9 seconds, but in practice I found the springs will sometimes ring far longer. The average length of these IR's is therefore around 6 seconds - none of the abrupt endings you sometimes get with IR libraries, just smooth springs fading into the background.