The TweakTone Delay

From the vendor

The TweakTone Delay is a PT2399 delay project with highly filtered repeats and the possibility of very long delay times (and minimal delay line noise). There is also a tone control trimmer to adjust the high-pass cutoff frequency on the repeats.

The circuit is based on the Mad Professor Deep Blue Delay , and has been heavily modified to adjust filtering, repeat/echo volume, feedback characteristics, and increased maximum delay time. The added filter control trimmer is also a differentiator, and it could be wired as an external control, if desired.

TweakTone Project Files / Notes

Download the TweakTone PT2399 delay project file pack , which includes: Schematic image, PCB layout image, legacy PCB build guide document with notes, and Eagle CAD files. The layout is for board-mounted pots and fits in a 125B sized enclosure.

The stock values of this PT2399 delay project yield a max delay time of approximately 550ms – 600ms. With a minor modification (see file pack), max delay time can be extended to almost 900ms. Granted, at these longer delay times, the filtering is very aggressive and murky and you will lose some volume from the repeats, which can also change how much feedback there is.

Longer Delay Time

Change the Time pot to A100K and then add a 270K resistor in parallel with Time. You can add the resistor either to the pot pads on the board, or you can use the pads marked “M1” and “M2” (see below for more info on these). Adding the 270K resistor brings the Time