Buffers: What Are They and Why Your Guitar Rig [Probably] Needs Them 

So something like a piezo pickup by itself is actually very high impedance, but if your guitar has an active preamp board inside of it (like most acoustic/electrics do) that’s what’s converts it to low impedance and boosts the output. So for example, a piezo element itself might have an output impedance of 1M, super high, but the onboard preamp of say… an LR Baggs anthem outputs a very low 650 ohms. If your guitar does not have a preamp inside of it and you’re using a passive pickup like a soundhole pickup, or just a piezo, those often have much higher output impedance. Some are better than others. That LR Baggs passive M1 output Z is only 1600ohms, which is quite low. But some have much higher, like the K&K pure mini, which more in the 500k-1MOhms range. These can generally greatly benefit from a pedal preamp of some kind, either from K&K or from other brands. The other tricky thing that I didn’t get into with impedance is that it’s not necessarily constant across all frequencies. There’s often a curve to the impedance, typically rising as the frequency gets lower. So, that K&K may have an output impedance of 1Meg at a low frequency, but at a high frequency it may only be 250k. So sometimes you have to play around with different preamps (which typically have a very high input impedance like 10-20Meg ohms so they can handle the input of a 1Meg source). Some impedance matches will sound better than others. It’d be nice if they had variable input impedance but most of them don’t. Hope that helps.

@@RecordingLounge wow, that was super helpful! I had no idea. I knew K&k recommends their preamp with their pickups, but I always thought they just wanted me to buy from them and a preamp was a preamp. I have an ultratonic pickup in my Huss and Dalton which is a transducer like the K&k but a world better sounding (and I like the K&k). Thanks again for your time and knowledge. I appreciate that.

Yeah, money grubbing aside, it does make sense for a company to design their own preamp to fit with their own transducers, just because they can match the impedance to what sounds best. Granted, that’s subjective, but you’d think they’d find the best compromise for their specific pickup.

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