My first use of effects was in the 1960's using tape echo machines. First, a VOX unit was used with my Strat, later I bought my very own Watkins Copycat (tube technology). Since then, the echo effect became an essential part of my sound. Although the old tape units were quite good, I dont miss the tape hiss and constant replacement of tape loops any longer. A Melos EM-150 that I recently got off eBay -- still looking for it's tape cartridge to use it; really a simple one-head echo, tape speed is varied by changing the motor speed. Probably on the low end of tape echos.
My first solid-state delay was a Matao analog delay that I bought in 1983. Not quite up to par with the Copycat though. After a long dry spell, got a Danelectro Reel Echo in 2006. That, I thought, was a big improvement; simple to use, but only produced a single-head echo. It is a little noisy as well. Here they are.
In mid 2007 I bought a used Zoom 508
delay pedal. This is a floor pedal-type echo effects unit that uses vintage, 16-bit signal processing. Replicates those vintage tape echo units fairly accurately. This unit has been programmed with numerous patches to emulate Hank Marvin's sound.
Recent additions to the effects loop are a collection of vintage Alesis effects processors. 1990's vintage but still very versatile and quiet; A Quadraverb plus, Quadraverb GT, and a Quadraverb 2. These units are used mainly for adding echo effects. The GT version includes an analog preamp that does a nice job of tone shaping. The "plus" and "2" need to be used with an external, high-impedance tone-shaping preamp, otherwise the guitar tone sounds too dark.
The Alesis Q2 has wider dynamic range and allows user-defined effect chains with almost unlimited possibilities. In contrast, the "plus" and GT has preset effect chains, but fortunately cover most needed echo effects. The Midiverb series are somewhat simpler architectures than the Quadraverbs.
For a summary of my personal patches for some of these effects units, here is a summary.
Effect units and amplifiers usually have too low an input impedance to preserve the higher frequencies from the guitar pickups. Ideally, one would be looking for a tube-like input impedance, something around 1Meg Ohm. Such preamps could either be onboard the guitar or contained in a floor-based unit.
Here is my FET-based preamp built to adress the impedance matching issue, also to allow a range of tone settings. The unit is very effective and quiet. The FET preamp in the effects loop. Another favorite preamp is one that I built from scratch into an old 1U rack enclosure. It features a tube (12AU7) front end, tone stack, low-impedance buffer, and power supply. Here's what it looks like:
Schematic,
160V DC power supply,
Tube preamp and support electonics,
Front panel,
Amongst the effects units.
These images are provided to help someone restore a broken Quadraverb. These files are for different vintage Quadraverbs and in binary (BIN) format for programming a 27C512 EPROM. Always save a copy of any ROM that you're about to overwrite. Beware, these are copies of what I found in my own units and not for commercial distribution, use at your own risk!
Quadraverb version 1.03
Quadraverb version 1.07
Quadraverb version 2.03
Quadraverb GT version 1.00
Midiverb 3 version 1.00
