Many guitarists transitioning to digital amp modelers like the Kemper Profiler often have questions about frequency response, especially when going direct to a PA system. A common point of confusion arises from the traditional understanding of guitar speaker frequency ranges and how they relate to the full spectrum audio capabilities of modern sound systems. Let’s clarify these points to help you optimize your guitar tones for both live and studio environments.
Guitar speakers are indeed designed to operate within a specific frequency range, typically from around 80Hz up to 5-6kHz. This range is tailored to reproduce the core frequencies of a guitar, ensuring clarity and punch without unnecessary information outside of this spectrum. However, when you see frequency charts of guitar recordings, or when you’re working with a digital profiler like the Kemper, you’ll notice frequencies extending far beyond this 5-6kHz limit, reaching up to 20kHz and beyond. This begs the question: where do these higher frequencies come from if guitar speakers are limited?
The answer lies in the microphone and the profiling process itself. When creating a profile of a guitar amplifier and cabinet, microphones are placed strategically to capture the sound. High-quality microphones are capable of picking up a much broader frequency range than the guitar speaker itself. They capture not only the direct sound from the speaker but also the nuances of the cabinet resonance, room reflections, and importantly, the high-frequency information produced by the amplifier circuitry. Elements like preamp tubes, power tubes, and even certain components in the amp can generate harmonics and subtle high-frequency content that extends beyond the speaker’s primary range. The microphone faithfully captures these details.
Therefore, the Kemper, when profiling an amp, isn’t just capturing the speaker’s output; it’s capturing the entire sonic signature of the amplifier and cabinet as presented to the microphone. This includes frequencies beyond the limitations of the guitar speaker alone. This is why Kemper profiles and other amp modelers can sound so detailed and realistic – they reproduce a wider frequency spectrum than you might initially expect from a guitar speaker.
When using your Kemper live through a PA system, it’s wise to consider using a low-pass filter (LPF). You mentioned using an LPF around 6-7kHz for live performances and around 10.5kHz for studio work. This practice is rooted in several factors. Firstly, the Fletcher-Munson curves illustrate that human hearing perceives frequencies differently at varying volumes. At louder volumes, like in a live setting, our ears become more sensitive to high frequencies. Cutting some of the very high frequencies with an LPF can prevent harshness and ear fatigue, especially when amplified through a PA system designed for full-range audio.
Secondly, PA systems and full-range speakers are designed to reproduce frequencies across the entire audible spectrum, unlike guitar cabinets which inherently roll off higher frequencies. Therefore, without an LPF, the full high-frequency content from your Kemper profile could potentially sound overly bright or fizzy through a PA. A gentle LPF helps to emulate the natural high-frequency roll-off of a traditional guitar cabinet in a live setting.
For studio use, a less aggressive LPF or even no LPF at all might be preferable. In a studio environment, you often aim for capturing the full detail of the guitar tone, and you have more control over the final mix. The higher frequencies, even if subtle, can contribute to the overall character and clarity of the guitar sound and can be shaped further in the mixing process.
Regarding whether to strictly adhere to the guitar speaker frequency range when setting your LPF and HPF: it’s not a rigid rule. While understanding the guitar speaker’s frequency range is helpful context, your ears should be your primary guide. Experiment with different LPF settings in both live and studio scenarios. Start with a conservative LPF around 6-7kHz for live and perhaps 10kHz or higher for studio, and then adjust to taste. There’s no single “correct” setting as it depends on the specific profile, the PA system, the room acoustics, and your personal preference.
In conclusion, the extended frequency range you’re hearing from your Kemper profiles is a result of the microphone capturing the full sonic spectrum of the profiled amp and cabinet, beyond just the limitations of the guitar speaker itself. Using an LPF, especially in live settings with PA systems, is a practical way to manage the high frequencies and create a guitar tone that sits well in the mix and is comfortable for listeners. Don’t be afraid to experiment and trust your ears to find the sweet spot for your “Guitar To Speaker” setup.
