“Profiling” is what we have named our proprietary technology that captures the sound and feel of a specific tube amplifier. In other words, the Kemper Profiler doesn’t simply give you a list of static digital amplifier reproductions. Instead, profiling creates a vivid, living, dynamic and multi-dimensional image of your existing tube amp.
Profiling is as simple as plugging your tube amp into the Kemper Profiler and pressing ‘record.’ Just insert the Kemper Profiling amplifier into the recording chain and it will do its magic. Test signals will be sent from the Kemper Profiler Amplifier into your tube amp and recorded by the microphone in front of your cabinet.
You don’t even have to play your guitar. After less than a minute the Kemper Profiler acquires the sonic DNA of your tube amp and offers you the resulting custom profile. You can then use the A/B comparison mode to compare original tube amp sound with the profiled sound.This gives you a fast and convenient way to make final tweaks to the profile to get it exactly right.
It took us several years of research and development to have the Profiling algorithm up and running. This chapter might be of interest for the more technically-minded amongst you.
Initially, we focussed our attention on existing and well-documented techniques, most of which fall under the heading “Dynamic Convolution”. Even though these approaches seemed very promising at first glance, and certainly useful for recreating simple, soft distortion circuits, they were by no means adequate for complex guitar amplifiers with heavy distortion. Reality has shown that no other company has managed to create a profiling amp by these methods so far.
Other well-known modeling methods, such as a distortion devices framed by a pre- and post-equalizer, have been used in modeling amps of the first generation. They deliver reasonable results, but the sound still lacks complexity, depth and feel; furthermore, these methods don’t qualify for an automated profiling procedure.
So, we had to go much deeper and, in the process, developed our own technology. A tube amp has dozens of dimensions in sound; consequently, the equation of the profiling algorithm needed dozens of variables to exactly recreate the sound and feel of the original amp.
We spent considerable time researching the dynamic behavior of the tube. It was also necessary to study the interactions between the tube and surrounding circuits, which become very complex when the tube starts to distort. We were lucky to find a way to extract this exact tube behavior by analyzing the intermodulation products of crossing sine sweeps. The relation between the intermodulations and the unprocessed sine sweeps tell us the full story about the distortion shape and dynamic of the tube and the behavior of the surrounding circuit. It can even deliver the information about several distortion stages in a row, so long as there is only one stage significantly distorting. This measurement is independent of the frequency response of the amplifier. Once the distorting part has been analyzed, it can be separated from the transfer function. The frequency response of the cabinet is then easy to determine and separate.
Aside from the ease of profiling the whole amp, there is another good reason not to analyze the amp part by part: we capture the sound of every component at the place where it belongs, including all interactions between the components.
The Kemper Profiler includes the standard Gain, Bass, Middle, Treble and Presence controls that you would expect from an guitar amplifier. However, in contrast to many vintage amps, we have kept the gain control neutral, so you are able to find the sweet spot of your amp, and run this optimal sound at any gain level.
The gain control ranges over 80dB and features an automatic volume compensation for clean settings.
Now, imagine if you could change the sonic character of a profile way beyond what’s possible with the amp itself...What if you could change the sonic age of the amp, or the bite of the pick? What if you could modify the power supply of your profiled amp in order to benefit from power sagging or be larger than life? With the Kemper Profiler, you can! We allow you to dynamically adjust key aspects of your favorite amps which would otherwise be impossible or require hardware modifications. You can do anything from minor tweaks, such as making your Marshall Bluesbreaker profile sound a bit more vintage, to more radical changes such as adding some modern high gain chunk to your vintage Fender Bassman.