My DS1 Mod

I was introduced to the DS1 Keeley mod by a local friend/work acquaintance that sold parts to the company I worked for. He offered to loan it to me, and I was very intrugued.

When I got the pedal, it was pretty obvious that the clamping diodes had been replaced by a higher-breakover voltage LED. All diodes exhibit a forward voltage drop, where they will simply hold a drop of .3V ( germanium ), .6V ( Silicon, as in the stock DS1) and higher, with 1.6V being 'textbook typical' of most LEDs. Again, I say typical, but not written in stone. I've seen higher. I did experiments on things like this back in high school Vo-tech electronics class, we called them clamping circuits. Clipping was a description best left to actual amplifiers.

The Keeley shop had also added several 'sonic' components to increase clarity. I cannot confirm nor deny that these upgrades sound better. I believe in the theory of their component selection, but I personally do not hear it. However, I continue to salute and respect them for creating an industry within and industry, and am proud to follow in their footsteps, along a slightly different path.

One thing that was missing in the Keeley DS1 was the 'big Marshall tone' that I kept reading about on the 'net. There wasn't enough bottom end for that kind of sound, so that's where I went to work. After I had changed out the clamping diodes with LEDs, I placed the LEDs on a switch, so you could run the op-amp output either with the clamp circuit, or wide open when the diodes were effectively removed by the switch. Then came time for the big change. I started experimenting with the tone section of the DS1. This is very similar to the tone of some of the EH/Muff devices of the 1970s. When I had the bottom end sound I was looking for, I knew I had my mod.

Here's a video showing the screen capture of my multi-track software playing and recording the intro to 'Working Man' thru my old POD, and three variations of the DS1. Stock; My mod clamped; and my mod un-clamped. Note: I selected 'Working Man' simply because it uses alot of different techniques; Open strings, power chords, and single notes, ( and it's easy )

the set up for the audio file was as follows:

Recording Setup for WORKING MAN INTRO

all DS1 knobs 1/8th turn to the right of 12.00

POD: Amp- Modern Class A; Drive- 9 oclock; Bass, Mid, Treb- 12 oclock
Channel volume- 3 oclock
Effect- Delay; Effect tweak- a hair above 9 oclock; Reverb ZERO
all straight into my highly refined $20 cheapo soundcard.

Additionally, I labeled the DS switch for clamp/boost on the side of the unit. I've sold a few dozen here and there, and had one customer ask me to put in a switch for the bottom end boost as well. I use this in my regular church gig as a lead guitar player. I'll turn it on for solos, because the extra distortion will give me just a little more 'cut through the room' in the same manner the BBE enhancers add distortion to the higher frequencies to increase brightness without adding noise. Not only does it add brightness, it adds a nice full bottom end. You can judge for yourself.

If you think you need one, you can contact me by email coxster@yahoo.com

Jim