Strat piezo pickup7/26/2023 It worked so well for modeling acoustic environments that other people tried applying it to other things we commonly try to mimic, like guitar amplifiers and speaker cabinets, and eventually, a methodology for capturing the impulse response of acoustic instruments themselves was developed. This "impulse response", more or less an acoustic fingerprint of the space's reverb time across the frequency spectrum, can be analyzed and applied to any other sound, making that sound appear to have been played in that resonant space. The Fishman Aura Spectrum and others like it use a technology originally developed for digital reverbs an "impulse", a short burst of white or pink noise, is played into a resonant space, while a reference microphone captures the space's reverberation of that impulse sound. Preamp-based solutions can only do so much they can help, but they can't add the parts of the waveform that you're not getting because of how the piezo senses the instrument, and so you just can't EQ that plastic tone out completely.Įnter the second major solution these boxes bring to the party digital modeling. Well, the piezo is sensing the vibrations in the worst possible place in terms of brassy, nasal tone. Every guitar player knows that the closer to the bridge that you strum or pluck, the harsher the tone gets, and that pickups get brighter but more nasal the closer to the bridge saddles you place them, as the fundamental tone is reduced in favor of higher overtones. One critical problem with piezos is that they capture the vibrations of the string at an anchor point. What it was actually designed to do is disappear into the traditional styling and construction of the acoustic guitar, changing its native acoustic characteristics as little as possible. You'll hear a lot about how the piezo was designed to capture the total instrument, responding to vibrations throughout the instrument body, not just the strings. Now, while these units can help, a lot of the problem is that a piezo really isn't the wonder pickup its touted as. Now, feed the device pink noise, and compare the output spectrum of the noise (should be a straight line at the output level on a logarithmic frequency chart) with the input spectrum of the unit to see how the unit colors the input signal with the controls in any configuration you like. Set up the DI in a "loopback" configuration, where the output of the interface feeds the input of the DI and the output of the DI feeds back to the interface. ![]() The exact native EQ curves of these are proprietary, but you can explore what the units do with an external soundcard and some frequency-analysis software (available free in a variety of flavors, personally I'd try Room EQ Wizard, built to assist in "ringing out" performance and recording spaces). That's a combination of the preamp's and transformer's natural "coloration" of the piezo tone, and your ability to dial in more or less of that color by tweaking the EQ. The preamp solution is 100% about using EQ to smooth out the harsh plastic tone. ![]() The Fishman Aura Spectrum is an example of the second and much more extreme solution, digital modelling, specifically "acoustic impulse response" modelling. The unit is basically a combination of a preamplifier stage like you'd find on a combo amp, running through a DI transformer to produce the balanced lo-Z output. ![]() Baggs Para Acoustic DI is a good example of the first one, straight up tone shaping. Piezo processors come in two primary flavors.
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