Multitap delay using cheap PT2399 modules

[gcwills]

Hi all,

Have just put the finishing touches on a new delay pedal and thought I'd post the details.
Some time ago I posted this delay pedal which used a very cheap PT2399 module: https://www.diystompboxes.com/smfforum/index.php?topic=120519.msg1129218#msg1129218
Subsequently I thought about using two modules in series for a multitap delay pedal. Turned out rather well with controls for level and delay time for each echo module so that there can be a fairly wide range of dual delay effects not unlike the Keeley Halo.

Here is the finished pedal:







More to come.....

[Ripthorn]

Nice! I've done a few multi tap delays with pt2399, such as my EchoWreck design.
https://scientificguitarist.wixsite.com/home/echowreck

[gcwills]

Nice! I've done a few multi tap delays with pt2399, such as my EchoWreck design.
https://scientificguitarist.wixsite.com/home/echowreck

Nice work Brian!

[gcwills]

Here is a shot of the internals of the delay:



The two PT2399 modules can be seen with the two pots controlling each delay module mounted on the top panel.
As in the earlier pedal I removed R27 (the delay time resistor) and replaced it with a 50K pot in series with a 2.2K resistor.
I added a simple one transistor preamp/buffer on the first module to buffer the lower input impedance of the module and to provide some gain to improve the S/N ratio of the pedal. This was useful as adding two modules in series doubles the PT2399 noise particularly at longer delay settings. The output of the first module connects to the input of the second and the pedal output is taken from the output of the second.
Thanks to Rob Henry (thanks Rob!) I included his EBE delay idea of adding some modulation to the delay modules via a 1.2M and 1uF network between pins 6 and 8 of the PT2399s. Certainly adds some extra colour to simulate an old dodgy tape echo unit. Having control of delay and level for each delay module provides a lot of options in delay/echo sounds.

The pedal was housed in a diy box made from a galvanised joiner plate purchased for $1 from a hardware shop. This was bent at the ends and riveted to some aluminium angle stock.

Happy to add some more details if anyone wishes to build this pedal.

[printer2]

I bought a handful of these to stick together. Would I like to see more? Sure.

[gcwills]

Thanks printer, there is not a lot more to my delay than the two modules and an additional preamp.

Here is a rough circuit of the delay showing the arrangement of the modules and the additional preamp:



I have shown the level controls removed from the modules as that worked best for me in a pedal format but those controls can be left on the modules if required. The two time pots are connected to the S and G pads on the module and the SMD R27 is removed. The preamp uses just about any small signal NPN transistor such as a 2N5088, BC549 etc. Not shown on the circuit are the optional 1.2M resistors in series with a 1uF cap between pins 6 and 8 of the PT2399. These follow Rob Henry's EBE delay idea to add some modulation to the delays.

I have had some time to play with this unit and it is certainly worth spending time playing with different time and level settings for some great ambient effects.