Old Gear Review 1: Small Stone Phaser

Josh and I collect a lot of gear. Guitar effects pedals account for a large portion of this collection. In the next few weeks we will be posting our thoughts and curiousities on since-discarded equipment. This is a good tutorial to clue our listeners in to what specific sounds they are hearing on recordings past and present. Today is phase shifter day. This is a family portrait of Electro-Harmonix Small Stone phase shifters.

I have used the Small Stone usa version 4 (yellow box), Small Stone sovtek version 3 (green box), and the Small Stone usa nano (red box) boxes. I’ve owned each one and month later sold each one. When talking about Electro-Harmonix the first thing that comes to mind is consistency. A majority of their pedals that are sold in the market sound slightly different from their neighbor. This is the genius and the curse of the matter. The components are always different across versions and the circuit boards have consistently undergone changes.

The “sound” of a phase shifter is generated by a pretty simple idea. The audio signal is split into 2 signals. A dry signal and a “wet” signal that is processed by what’s inside the box. Inside the box of a phase shifter you will find several small components which comprise a unit called an all-pass filter. An all-pass filter lets all frequencies of the audio signal through without changing their amplitudes. However the phase of the signal is slightly off from the dry signal. A low-frequency oscillator is added to the phase shifting design in order to alter the positions of the peaks and troughs in the wave of the wet audio signal. These positions vary over time which create a sound that is constantly changing in amplitude or loudness.

Each all-pass filter unit is called a stage. The Small Stone utilizes 4 stages. The Color knob on the phaser represents a 5th stage that when activated allows feedback to trickle back to the beginning of the all-pass filter chain. The number of stages used in a phaser can vary. For example, Moog makes a phaser with 12 stages of phasing. The more stages of phasing the more organic the sound of the processed signal will sound. For most purposes 4 stages of phasing is perfectly fine. Lastly (and very importantly) the key to that Small Stone phaser sound is the use of Operational Transconductance Amplifiers (OTA’s) instead of operational amplifiers with variable resistors. This is the Small Stone in action with all-analog gear.

The Small Stone when put after a distortion effect like a RAT or Boss DS-1 distortion has a very interesting sound quality. Depending on the amount of dry signal in each pedal you can get obtain very lo-fi 70s pscydelia or a very poorly defined signal. I personally would reverse the signal chain and place the phaser before a distortion box. Turn on the color knob of the phase shifter and you’re increasing the volume of the feedback signal. The end result is a textured drone that is very interesting to listen to in the absence of other sounds. Out of all my Small Stones I’ve noticed that the Sovtek Small Stone (green rectangle) is by far the most poorly constructed. However, the feedback from flipping the Color switch is much more intese and effective than its USA counterparts. I used to use this configuration exclusively with a solid-body guitar, distortion box, and tube amp. I’d let the guitar feedback on itself and play different textures. A drum machine with individual line outs, such as my Tr-707 is extremely amenable to phase shifting plus distortion. By combining a recurring drum pattern and an effect that varies the amplitude and phase of your signal over time I’ve gotten a much more mathematically-based pscyhdelia than with my string-based instruments. The sound equivalent of the drifting of one part of the drum kit in relationship to the rest of the kit is something I continually try to improve upon with newer and more advanced gear.

-M.