ESE Echomatic VI as supplied

The ESE Echomatic VI tape-loop based delay echo unit is capable of providing some pretty complex echo effects by virtue of the ability to select any combination of the six replay heads for playback and regeneration. However, it seemed capable of a lot more, but is limited by the circuit design that provides an emulation of the Meazzi Echomatic model 2 effect. This echo effect is based on the first three replay heads as a group with variable level control - see control labeled FX 123 in above photo; the contributing level of each head is preset (by series resistors), within the group. Consequently the first step was to allow the full output from the first three heads to contribute (directly) to the output echo effect. This was achieved by adding very low value resistors (10 ohms) in parallel with the series resistors of replay heads 1, 2 & 3, for both replay and regen selection.

The result of the above change was so encouraging that further modification was embarked upon. This (step II ) involved a simple replacement of the push-button switches for selecting which replay heads are used for the echo effect inc the regen, or persistence of the echoes. Variable resistors were substituted for the switches to allow control of the level of contribution to the echo effect from all the heads, individually.

An example - APACHE

The original echo effect used by Hank Marvin for Apache has been previously attempted using the ESE Echomatic but without much success. It is a somewhat unusual effect in that it sounds more of a reverberation bolstering each note with little indication of longer delay echoes, throughout the number. Somewhat surprisingly, the closest yet was found by complete accident. Have a listen.

Modified unit set-up for the above recording

Note the type of variable resistors used feature 'push to lock' hence those standing proud are the ones used to control the echo effect i.e. replay: heads 1, 2, 3, & 5; regen: head 3 only. An unfortunate quirk of the design is that the obvious way to mount the pots resulted in the pointer on the knobs being upside down e.g. heads 4 & 6 controls are at minimum, and only head 3 is employed in the regen, in the above photo.  Also note that the FX 123 control has been re-employed to vary the EQ of the regen signal. Here's a visual representation of the resultant echo effect.

The greatest contribution to the effect is from heads 3 (204mS delay) and 5 (340mS delay). However heads 1 & 2 contribute a (short-delay) reverb type effect that compliments the principal echoes. The above visualisation of the echoes fails to truly represent the effect, considering how it actually sounds - listen to the echo. The input signal to the echo unit was one cycle of a 500Hz sine-wave, analogous to the musical note A. The moral here is trust ears not eyes!

Sensitivity of controls

By way of illustrating how sensitive the settings are, the same head selection was used with increased echo level (a small amount) and regen (quite a bit) as shown in the following photo, for a recording of Find Me a Golden Street.

 I've separated the number into constituent parts for ease in appreciating the overall effect. Listen to part 1 , part 2 and part 3.

Update: 14th Sept 2012

The opportunity has been taken to revised the head positions courtesy of the additional tapped holes in the head mounting plate, of the Echomatic VI, as shown in the following photo.

The record head has been moved to the left-most position, and heads 1, 2 and 3 moved to positions that give a decreasing inter-head time interval. The range of (head) delays for slow, medium and fast motor speeds is given in the following graph.

Sample output waveform

Update: 21st Sept 2013

Assessment of the modifications continues, somewhat erratically due to other interests and activities getting in the way.