My Hell Dice Pedal Board Design

November 24, 2018December 28, 2020 raycharlesring Audio Electronics, Compressors, delay, PT2399, Vibrato

I have been performing way more than I use to! I play club gigs twice a week or more these days…and as a result, my relationship with my rig has really changed. Which is to say, my perspective on what I actually use and what features matter most, has evolved. My conclusions are these: I want small, light weight rugged equipment…I don’t want too many knobs or complexity. I like to use a few basic settings and sounds and that is it. So I have designed a compact amplifier and set of small 1590a form factor pedals to create a complete amplifier/pedal board rig that weighs a couple of pounds and is about 12 inches long and 4 inches wide. It includes: My 100 watt stomp amp with an auxiliary 9 volt output, a high performance PT2399 type delay, a simple but really nice sounding LDR based envelope filter, A very pleasing two stage LDR phase shift Vibrato and a hex inverter based overdrive with slightly different approach than the typical design.

My New Compact Pedal Board

pedal board2

As an aside all of these pedals are made with machined(not die cast) Hammond sized aluminum enclosures from Ebay (alpinetech), which I etched and anodized. You cannot properly anodize die cast enclosures because of other ingredients that are mixed with the aluminum…so you have to get CNC milled enclosures if you want to anodize the enclosures. I discussed my home anodizing process here: Anodizing discussion

More Pictures: funkyfilt

vibrato board

delay board

Links to Schematics and Design Notes:

A few notes: Many of the part choices are not critical..like transistors, op amps and voltage regulators I use.. The LDR based effects will need tweaking based on the output efficiency of the LED/photo-resistor combo or if you use a commercial opto-coupler instead. The vibrato uses my pic based LFO…but it can easily be replaced with other LFO circuits. The delay uses a 8 pole switch cap filter IC but if desired, this can be replaced by using the unused op amp on the PT2399 IC as a low pass filter.

Hell Dice Funky Filter:

Pedal Board Demos From Live Show:

Demo of Delay and Vibrato:

Demo of Envelope Filter(two minutes in):

The Kool-Verb

October 19, 2014August 20, 2015 raycharlesring Audio Electronics, delay

This is a simple but nice sounding reverb based on the FV-1 dsp chip. Lots of low pass filtering gives a nice washy sound. You can adjust from a small room to a large hall. The unit provides about a 75/25(dry) max reverb. Anything more than that is useless. Check out the stomp amp demo for how it sounds…same reverb, but just with just one fixed room setting.

The switch mode power supply keeps the current down to 30mA so you can use a battery if desired. You can use a linear regulator and it will work great, but then the current consumption doubles.

The schematic:

built into a 1590b case:

PT2399 Delay is Complete

September 20, 2012July 26, 2015 raycharlesring Audio Electronics, delay, PT2399

Yes its ugly – but it works great!

Check out the videos below. I have pooped out a slap back demo. You can get a really great 50’s tape echo sound

slap back

How to Significantly Improve a Simple PT2399 Delay Circuit

September 4, 2012July 26, 2015 raycharlesring Audio Electronics, delay, PT2399

Lots of great PT2399 designs out there….. I have tried a number different variations and have built what I consider a best performance design, using a compander, elaborate filters, etc. I have been frustrated as many builders out there are – that the PT2399 is so easy to use but that it just goes to crap with longer delay times! So I decided to work and experiment with different approaches to converge on a simple, yet well performing design. I am really happy with what I have come up with.

The design uses a discrete FET input buffer and uses one of the on board op amps as the wet/dry mixer. The dry signal always passes through and the effect is defeated by just opening the connection of the signal input to the delay chip. This allows “tails” or the echos to naturally decay even when the delay is bypassed. There are two features that make this circuit perform really well. One, the cap between pins 9,10 is made much larger than typical in other designs and the data sheet reference design and two, I use a 8 pole switch cap filter IC for the post delay aliasing filter. The larger cap provide significant increase in the delay output but the noise remains at the same level. I then attenuate the output in the wet dry mixer to the normal level this also downward expands the noise. The switch cap filter is really simple, requiring only one capacitor to set the corner freq from 1Hz to 5KHz. It is very easy to implement and has excellent performance. The total circuit rivals the simplest bare bones designs but approaches the performance of the more advanced circuits such as the PT80 delay.

Below are the schematic, a picture of a breadboarded prototype and some example audio of the prototype below, in use.

Updated Version in pedal form