Date: Mon, 17 Aug 1998 12:35:00 -0700
From: "Brigman, Corley" <corley.brigman@intel.com>
To: analogue@hyperreal.org
Subject: info: digitech rds-1900 rackmount digital delay

     ok, it's not analog, hopefully this one will slide by without anyone 
     noticing :) actually, there IS some analog in there...in a moment...
     
     digitech rds-1900
     
     what it is: It's a digital delay, with some interesting features. Part 
     of a line of Digitech gear (according to the manual). this is the 
     lowest end. The rds-1900 has 1900 ms of delay max, with 15Khz 
     bandwidth. There's also an rds 3.6, with 3.6s=3600ms of delay (but 
     only 7.5Khz sampling, basically the same box with sampling rate cut in 
     half?), an RDS2001 (an RDS-1900 that can sample), and an RDS 7.6, a 
     7.6 second box with sampling (both of those are 15Khz bandwidth).
     
     They all come with pretty much the following: There are 4 delay 
     ranges, labeled Flange, Chorus, Double, and Echo. There's a delay time 
     knob (which goes between .25-1.0 of the time labeled for each button), 
     a mod width and a mod rate. The rate goes high, but not crazily high. 
     In the echo range, there's a repeat hold button that just repeats 
     whatever's in the buffer and takes no new input.
     
     Feedback is 0-100% and can be inverted (reversed? can't tell for 
     sure). Then there are the standard mix out/dry out levels/input level 
     knobs. 
     
     In the back: Input, mix out, dry out (for daisy chaining), phase out 
     (for pseudo-stereo). There are footswitches for bypass, repeat hold, 
     and something else (can't remember) and an expression pedal input for 
     VCO control (modulation). unfortunately no pedal direct for delay 
     time. 
     
     Overview: Clean sounding delay, with a reasonable length of delay. It 
     IS digital, but that's not all bad in this case....it's "bright" but 
     not necessarily "cold" to my ears. 
     
     Anyway, I've got some mods planned for mine (my first!), I have two 
     now so I have a guinea pig :) Apparently the feedback loop is NOT 
     digital, at least on the schematic there appears to be a trace for 
     feedback - I'd like to break this out and allow effects to be inserted 
     into the feedback loop, either for HF/LF damping (using EQ) or maybe a 
     slight distortion (so it gets more distorted as it fades into the 
     background....) hmm who knows. It appears there's a real VCO in there 
     as well for control of the delay time (CV control?) so I'd like to 
     yank that out as well and put an expression pedal input there. Could 
     be lots of possibilities here.... and they are cheap, I got my first 
     one for $50 (with manual, good shape, 1 knob cap missing) and the 
     other for $70. not bad for 2 seconds of delay....there's always the 
     se-70, or a wedge for finer control (with less/no knobs) if you need 
     it....
     
     corley brigman
     intel corp.
     corley.brigman@intel.com
     
     speaking for me, not for intel.