Universal Audio Ampex ATR-102 Manual page 132

The EP-3 is the favored unit by guitarists, and EP-4 is the last unit that was re-
leased and has an improved feature set over its predecessors such as meter-
ing and tone controls making it even more useful as a mix tool. Some didn't
like the EP-4 because of a noise reduction circuit that was added that was not
implemented correctly. Unfortunately in a production mistake, the circuit was
placed in across both the direct signal and the tape playback causing the dry
source signal sustain to be cut off prematurely. Most modded their units to re-
move the noise compressor, and Maestro quickly removed the compressor de-
sign from the design.
The Echoplex EP-3 hardware unit
*EP-34 Tape Echo is not affiliated with, sponsored nor endorsed by any companies currently using
the Echoplex name. The EP-34 Tape Echo name, as well as the EP-3 and EP-4 model names, are
used solely to identify the classic effects emulated by Universal Audio's product.
UAD Powered Plug-Ins Manual - 132 - Chapter 11: EP-34 Classic Tape Echo