One of my favourite pieces of music, let alone guitar playing, is by Ry Cooder. A track called “Feelin’ Bad Blues”. This video is an excerpt from the film Crossroads where the tune was used to great effect. For me it is the epitome of blues guitar. Sad, slow and gritty. And that thick tremolo (probably from an old Fender amp, not a Pignose) is the icing on the cake.
So that’s what this post is all about; making a pedal to give me that tremolo effect. It didn’t take long to find the defacto standard tremolo pedal; the Tremulus Lune.
Research showed that I could buy a kit, or even a pre-made one, but where’s the fun in that? I went for the layout from Guitar FX Layouts (seen here).
The novelty with this circuit for me was it used a component called a Light Dependent Resistor (LRD). Essentially one part of the circuit is a Low Frequency Oscillator (LFO), controllable with various potentiometers. The ‘low frequency’ part refers to the fact that it is creating a sine-wave in the range of 3-10hz (I haven’t actually measured it). This wave is used to drive a normal op-amp, thus varying amplitude over time, which is in fact the definition of “tremolo”. One difficulty was getting hold of the correct LDRs. They needed to have the range 5k/500k. It was easy to get hold of all kinds of LDRs, even from Radio Shack, but I had to trawl through Ebay to find the right ones. I have a bag of 20 now.
This isn’t my first veroboard build, so the build/assembly went quite quickly, in a pleasant way, and I had it operational on my prototype rig within a couple of hours. It sounded amazing! It truly is a versatile tremolo; you really don’t need anything more complex than this.
The device has three LEDs. One for the usual on/off indicator; another one to couple the LFO with the op-amp (by pointing the LED at the LDR, kind of like a vibe pedal does) and a third one to show the speed of the LFO externally. I decided to use the nice fresnel lens LED holders I bought a while ago. I just think they look really cool. The picture below shows them in their full glory, although the red LEDs look somewhat pink. To fit them I needed to get a 17/64ths drill bit. I have hundreds of drill bits, but not that one. So, a trip to Ace Hardware for that.
This one’s got 5 knobs, so I had to use a 1590BB and I chose to go for a vertical orientation. As for a design I went for the whole Crossroads theme. I combined the lyrics to the famous song, and depicted the actual crossroads by using highway signs. As far as the decal goes, I wanted it to wrap over the sides as I thought it would look cool. I printed it on transparent ink jet decal paper this time as the enclosure is bright white.
So I finished the assembly and got it all plugged into my usual rig, and recorded a swift demo. As I mentioned earlier, the reason I wanted to build this was for that archetypical blues tone. So here’s my own sloppy rendition of that kind of sound:
The setup was: Tokai Les Paul, neck pickup (a humbucker from a 1961 ES-335); my AX84 P1 Extreme into a 2×12″ speaker cab, with Celestions; my Box of Rock clone for some grit, and the Tremulus Lune of course. The reverb came from Logic, and was a ‘small church’ kind of setting.