We recently had a request from a double bass player to modify his Effectrode ‘Glass-A’ buffer pedal to give it a higher impedance as his bass was fitted with piezo pickups. Piezos sound at their best when connected to a high impedance buffer/preamp in the range of 5 to 10MΩ with a very short cable. This reduces ‘quack’ (an unpleasant sounding mid-range hump in the frequency response) and loss of clarity (high frequency content).
Being so tiny, it was possible to install the ‘Glass-A’ in-situ on the body of the bass and therefore ensure the cable length was kept to a minimum. Further, the tube electronics of the ‘Glass-A’ effortlessly handle transients of ±50V—much higher levels than any solid-state buffer could ever hope to cope with. But the ‘Glass-A’ isn’t just limited to guitars and bass: this miniaturised tube buffer is also the perfect tool for interfacing other ‘difficult’ instruments, such as hammered dulcimer, harpsichord and all kinds of bizarre esoteric ethnic instruments to amplifiers, mixing desks or computer. If you’re looking for a natural sounding buffer to bring out the absolute best in your instrument then the you should definitely look into the ‘Glass-A’, but do let us know before placing an order, so one of our techs can modify it before shipping—5MΩ and 10MΩ options are available.
For further information on how to use a buffer pedals in effects pedal-board setups check out our in-depth article and if you’re a real anorak this paper on Steampunk Technology: The Inner Workings of Vacuum Tube Buffers.