Here's something I've been working on for a while, it's a PT2399 based delay called Echo Base
. It started out with some ideas for mods for a Rebote, but after playing around for a while I thought I might as well start from scratch and design something new.
The main features are:-
1. It's got an LFO that modulates the delay time for chorus/vibe/tape flutter effects, a bit like a DMM.
2. Shock horror, it's not true bypass, that's because....
3. It can do delay tails, where you bypass it and the delays die away instead of being cut off instantly.
Here's the schematic
The bypass is done using CD4066 switches and works like this. The signal goes through the input buffer which sends the dry signal straight to the output buffer, the signal also goes through the first 4066 switch (A) and into the PT2399. This section is mostly from the appnote on the datasheet with a few values tweaked, but with the output taken from pin 14 like on the Rebote 2.5, doing this taps off just the delayed/wet signal. The wet signal then passes through another 4066 switch (B) and gets mixed with the dry signal via the Level pot.
When the effect is on both of these switches are open. When it's bypassed one of the switches closes depending on the position of the Tails/Boss switch. In Tails mode the input switch (A) is closed, cutting off the signal to the PT2399, the wet sound then dies out naturally.
In Boss mode the output switch (B) closes so the wet sound is instantly cut off, the input to the PT2399 is still open. This is how Boss pedals work, hence the name.
The modulation is a simple triangle LFO hooked up to a PNP transistor in series with the delay time pot. It took quite a bit of experimenting to get this working nicely but I think it's a neater solution than using a LED/LDR combo.
Here's some sound clips, they're just guitar >> Echo Base >> Condor >> Soundcard.Slapback
Bypassed then effectRhythmic repeats
Bypassed then effectChord stabs showing the longest delay timeChorus
Bypassed then effectHeavy vibe
Bypassed then effectSlow vibe
Bypassed then effectPitch bendingDelayed vibesExample of delay tails
This starts with some (bad) distorted lead then the distortion and the delay are turned off and you can hear the echoes dying away behind the clean playing. The switch pop is from the distortion pedal.
Here's a guts shot of the finished pedal, vero layout to follow shortly
Thanks go to R.G. and The Tone God for their electronic switching articles and Francisco Peña because if it wasn't for the Rebote I wouldn't have built this.