Half Wave fuzz = Depletor Fuzz

After updating the design a bit, the Half Wave Fuzz is now, wait for it…Depletor Fuzz. The main changes were the addition of a second knob for Output Volume, which will allow the effect to integrate better with other stompboxes. I recently compared its sound with the popular Dunlop Fuzz Face pedal and found the Depletor Fuzz has a lot more variation in harmonic content as well as more sustain than the other. I’ll be posting demos soon using different equipment to really show it off, but right now here are some pictures of the recent updates.

Isolation-spring reverb box with active preamp for acoustic instruments

I’ve written before about spring reverb and contact microphones, but here is a special project where I applied them both. I’ve always liked the simplicity of cigar box instruments, so that is likely the inspiration for making a spring reverb tank using wooden housing. I’ve taken the wooden dowel plugs from my acoustic guitar spring reverb kit to stretch the spring from both ends within the box. Luckily the box was the perfect size for the spring, I only had to shorten the plugs slightly to make the spring stretch across the box far enough to get a good sound. As pictured below, the contact mic I used is fixed under a thick foil layer that acts as a shield for interference.


Using the Alex Rice phantom-powered preamplifier design was important to amplify the subtle vibrations created by the spring while the box resonates. My idea was to implement an auxiliary microphone for larger acoustic instruments such as the piano, or complex percussion with the spring reverb tank creating a distant or hallowed effect. Being that the spring is a metal object and produces an inharmonic spectrum, the span of sound it resonates with is wide, but the tank does have a tendency to emphasize the lower frequencies. The fact that the box itself is wood will allow it to vibrate nicely alongside acoustic instruments; placed atop or beside should do the trick to capture the sound and produce a very evocative treatment of its original source.

If you are interested in having a spring reverb tank made for you, I’d love to be in touch. You can use this contact form for all inquiries.

Half Wave Fuzz released

I’m excited to share news about my stompbox design, Half Wave Fuzz. It is a similar design to the Depletor standalone effect, using a discrete transistor for shaping the sound. I also decided to include a preamplifier stage using the TL062 JFET input opamp, to boost and preserve tone before any further treatments in the circuit. The effect produces a very classic sounding fuzz across the entire range of the electric guitar that definitely stands on its own without any compression or further boosting. It has a single potentiometer for drive control, affecting the initial gain stage. This adds more or less grit to the overall tone. IMG_4328.JPG

Amplification of a nylon string guitar

IMG_5265The subject of amplification is surely complex and highly personal when it comes to the guitar. However, when choosing a method of amplifying an acoustic instrument, it is often desirable to pursue a sound that closely reflects the original, non-amplified version. For example, a recording engineer will often place microphones around the guitar to best reflect this. The live performer rarely has as much control as what is offered in the studio, and must use alternatives. Most commonly with instruments having nylon strings, the piezo microphone is used, often under the soundboard of a guitar with the signal sent to a preamplifier for the first step of gain staging.

Since there were many electrical considerations with choosing a transducer and matching its impedance with the preamp, I decided to follow the design of Alex Rice’s piezo preamplifier. It had very good reviews and I understood the basic theory of why it works so well. The piezo transducer is unbalanced and it connects to a balanced preamplifier that is wired as a differential amplifier. This allows the ability for vibrations represented by positive and negative half cycles to get louder, while signals that are common (like hum) get rejected and are sent through a separate ground via the XLR cable.

I wanted the ability for the guitar to remain fairly portable, so I terminated the piezo directly to a 3.5 mm socket, with the wires being fed to the outside through a pre-drilled hole I created from another project. I realize there is some connector loss in signal power by doing this but figured it was worth it. I also use an additional unbalanced cable from the guitar to the preamp, so that is again less than ideal, but…an outstanding sound was achieved that I am extremely pleased with.


I highly recommend using this circuit for amplifying acoustic instruments. The only drawback I can see is I need to connect a balanced XLR connection to a mixing desk with phantom power (48 V). I planned on using this in my setup anyway, so it worked out ok, but others may want to follow instructions in the design for powering the circuit using 9V batteries. Since I know everything works, I plan to fix the electronics to a small chassis box that I will drill holes to mount the jacks – plug in and just play.

I would exercise some caution with your levels though, a feedback loop could be easily created with the amount of signal gain achieved and the piezo is definitely not immune.