Frequently Asked Questions

The sound of the Kemper Profiling Amplifier

The Kemper Profiling Amplifier offers a new paradigm for recreating the sound of a real guitar amplifier.
Here are some facts about the sound environments of guitar amplifiers you should consider:
A guitar amplifier with cabinet has two different worlds of sound:
First, there is the natural sound that you hear when you stand in front of it. This is what is sometimes called the "Amp In The Room" sound - it's the sound you hear in the rehearsal room, or on a live stage, when your amp is right in your back.
Then, there is the sound that is captured by a microphone (or two ...) close to the cabinet, that is amplified by the PA system in front of the stage to be presented to your audience. The same close-microphone technique is used in a recording studio to capture the sound of your amplifier, and you monitor it by the studio monitor speakers. It will be mixed with the voice and other instruments to compose the final sound of your song. As in the live situation, your audience will hear the sound of your playing through close microphones.
The "Amp In The Room" sound and the close-mic sound are a bit different to each other. Typically, the close-mic sound will have more character and signature. While a good amplifier will simply sound great "in the room", it takes quite a while to position the microphone to capture the best parts of the sound for a recording. This is why many sound engineers use two or more microphones (and two or more hours of time!) in the recording studio to recreate the desired character of a cabinet. The variety of microphone types, positions and mixes can create dozens of sound colors, all created by the same amp and cabinet. This might be one of the reasons why different modeling amps sound so different when modeling the same amp type.
And then there is another factor to consider: you might be accustomed to the "Amp In The Room" sound, but your audience will only ever hear the close-mic sound, either at your live gig, or on your recording.

Will the sound be OK when I play through monitors, or a PA, that I'm not used to?

The full profiles of the KPA - that is the close-microphone sound - are played through linear loudspeakers such as studio speakers or a PA. In general, we could say that most speakers are linear, except guitar speakers. However, even linear speakers do not all sound neutral, or the same. The speakers in the guitar store might sound different than yours at home. As a result, the KPA will sound different in different speaker environments. What can we do about that? Nothing! That's just the world we live in. And the different speaker environments do not only affect the sound of the Kemper Profiling Amplifier, but of other instruments, too.
Here is the best example:
When you listen to your favorite CD through different speakers, it will sound different. However, it makes no sense to judge the sound-quality of that CD production by the speakers you listen through. Instead, you can make a judgement based on your experiences of listening to various productions, played through a range of speakers of varying quality. Same story with the KPA - it does not come with its own real cabinet, so it has to rely on the quality of external linear speakers. For evaluating the quality of the profiles, it is a good idea to play the KPA along with a recording or playback that you know, through the same speakers.

Can I play different amp profiles through the same monitor cabinet?

One of the main purposes of the Kemper Profiling Amplifier is to substitute multiple amps on stage. You can run a clean Deluxe profile and a crunchy Plexi sound, just by switching the rig on the KPA. In all likelihood, you won't just use different channels of the same amp to create different sounds, but you will use several appropriate amp profiles for dedicated sounds.

Ultimately, do you recommend using a guitar cabinet on stage or in the rehearsal room?

Yes and no. Here are our pros and cons:
Pro: The guitar cabinet is a single sound-source that can be easily spotted in the rehearsal room or on stage. This way it cuts through the mix of instruments.
Con: The guitar cabinet focuses the sound in a way that cannot be found on any other loudspeaker concept: the sound is loudest, and brightest, when you stand in the axis of the speaker chassis. Unfortunately, this is not where you stand as a guitarist, but for your audience when gigging on a small stage, or for your fellow musicians in the rehearsal room, the guitar sound can seem louder than to you (standing close, but off axis, to the cabinet). This is why many guitarists tend to monitor their sound through the PA, through linear monitor speakers, or in-ear monitors. This way, they create a homogenous dispersal of the sound, and can hear the same sound that the audience hears.

So, what is the deal with the Kemper Profiling Amplifier?

The Profiler will faithfully capture and recreate the close-mic sound of your amp. It is up to you what microphone, and how many, you are going to use to capture your cabinet. You can save complex microphone configurations of your amp forever, where the positioning of the microphones took hours and seem to be irreproducible. But this doesn't mean profiling is complicated - you can achieve fantastic, professional sounds even with one basic microphone; in fact, some of the best factory profiles were done with just one mic. Once you have taken the profile, you can still modify the gain, EQ and many deeper parameters of your profile, months after you capture it. You can even choose cabinets of other profiles for your amp. As a result, you can bring to the stage a unique sound that has been created in a recording studio.
This is actually what keyboard players do all the time - they don't make a distinction between studio and stage sound. The sound you hear in the studio is the sound that you will present to your audience.

The "Amp In The Room" sound.

Still, you might want to play the KPA through a power amplifier and a guitar cabinet, for monitoring on stage or in the rehearsal room. Remember that the speaker simulation part of the profile must be switched off for these purposes, otherwise you run your signal through two speakers in a row, the real and the virtual one. This can be done by simply switching off the Cabinet in the Stack section.
For an even better solution, the dedicated Monitor Output has a switch in the Output (Master) menu that allows you to globally bypass the Cabinet, just for the Monitor Output. This gives you the ability to run the full profile sound (including the cabinet simulation) from the Main outputs to the PA (to your audience), while you monitor your sound on stage through a classic guitar speaker cabinet.
You can amplify the monitor sound by any kind of solid-state or tube amplifier. If you want to use an existing tube head for amplifying, connect the Monitor Output of the KPA to the effect return jack of the amp head. But take care: power tube amplifiers of amp heads do not necessarily sound neutral! This is not so much due to them being tube amps, but rather that they are not designed to receive an external preamp signal through their return input. The presence control still affects the sound, and often the equalizer (bass, middle, treble) is still in the signal flow, coloring the signal. For these controls, a neutral setting is not available. Also, the KPA cannot anticipate the sound of the guitar cabinet you are going to use. To compensate for any bad frequency response that may arise in this signal chain, the KPA offers a global equalizer in the Output (Master) menu. Another independent, global equalizer is available for the main output, which will help you to fit the sound to the PA.

How do different amp profiles work with the same monitor cabinet on stage?

We are aware that a significant portion of the characteristics of a profile lies in the cabinet simulation. When you switch the cabinet off, this portion is lost, and replaced by the cabinet you connect to the monitor output. Our solution is to keep the base character of the cabinet in the profile, when you switch it off, to combine it with the external cabinet. In this way, the original character shines through the real cabinet and even gives you the impression of swapping the cabinet on stage when you change to another profile.

Can I profile just my pre amp?

Yes you can! Instead of feeding the microphone signal back, simply plug the effect send output of your amp head into the Return of the KPA. When you profile just the pre-amp, the virtual cabinet is without content, so you will not hear any difference when you switch it on or off.
When you connect the Main Outputs or the Monitor Output of the KPA with the effect return jack of your amp head, you will get the same sound as you get with your real amp. If you don't want to reconnect to your original amp, then simply choose a cabinet from another profile in the Kemper Amp.

How does the profiling technique compare to classic modeling?

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.

Is the profile just a snapshot of the original amp?

In the previous section, we have seen that the Profiling Amplifier will not just take a snapshot of your tube amp, but give you the same, and often deeper, control of your sound than your original amp can provide.

Once you have stored your profile, you are free to capture more profiles of your tube amp. Try different microphone positions for different flavors, or maybe find another sweet spot of your amp's controls. If this is not enough for you, you can then step into the DNA of your profile and discover new sound possibilities, based on the amp that you are familiar with. An absolutely unique, and previously unknown, feature set is waiting to tweak the dimensions of your profile to unimaginable depths:

Amp Definition is a parameter that has been pre-adjusted by the profiling process; it tells you whether the sound leans more towards a vintage or modern direction. Increase this parameter to intensify the touch response of the virtual tubes.

Power Sagging will let the tubes breathe with your playing; damped strings will have more energy, and clean, picked notes will cut through better when you reduce the playing volume.

The Pick parameter will control the attack of your pick independently of the Gain setting, even through heavy distortion. Definitely a highlight of this feature set, this innovative parameter lets you decouple your pick sound from the natural compression of the distorting tubes and cut right through the mix. Works on clean sounds, too! Often attempted in the studio environment, this is an effect that cannot be achieved by any equalizer or compressor.

The Amp Compressor will sustain the clean guitar when you play soft, but lets the distorted sound through, unprocessed, when you revert back to normal playing volume.

The Cabinet Warp parameters will give you access to the formant frequencies and character of the cabinet sound. Change the virtual size of your cabinet, tune the bass resonance and control the character of your sound in an intuitive way.

Does this sound too scientific to you? It isn’t! With a few simple tweaks you can push your sound into as yet unknown realms of feel, touch-response and depth.

We have seen the expression of many a guitarist, when switching back to the original profile they started from - it's a look that says: "Why didn't I press Store?". (Thankfully, such regret need only be short-lived, as we also have an Undo button.)

 

How does the Profiling procedure work?

The Profiling Amplifier captures the sound of a tube amplifier and speaker cabinet via a microphone; by this method you can permanently capture either a studio or live situation for future use. The amp to be profiled is attached to the effects loop of the Profiling Amplifier. The Send jack will feed the unprocessed guitar sound and the profiling test signals to the guitar input of the reference amplifier. The microphone sound will be sent back to the Profiling Amplifier's Return input. In this configuration, the Profiler has total control over the reference amp, and an A/B comparison between the profile and the original can be made easily with the Compare function.

Does the profile contain all possible gain and tone control settings of the original amp?

Yes and no. The gain control is likely to sound the same at different positions. On some tube amplifier models we have found that the original gain control will change the tone of the guitar a bit, which is not actually an advantage. Some cut the high frequencies of the guitar when you turn it up, and some cut the low frequencies when you turn it toward a clean sound, resulting in a somewhat thin sound. We have kept our gain control neutral, so you can find the sweet spot of your amp, and run this optimal sound at any gain level. If it is demanded by our users, we can easily provide appropriate gain models or ways to capture the whole gain behavior.

In addition to all this, our gain control goes far beyond the scope of classic tube amplifiers. On the Kemper Amplifier you can control the gain of your profile within an incredible range of 80 dB from crystal clean to insanely distorted - no need for an additional booster to create your favorite lead sound!

The Profiling Amplifier will capture the momentary settings of the tone controls that represent the sound you dialled on your tube amp. We were requested by many guitarists to develop a tone stack for the Kemper Amplifier that reacts like a classic tone stack, but with more impact and range. When you profile your amp, these new tone controls will be positioned in the mid setting. We have plans to add models of original passive tone stacks of popular amps; these can be chosen for profiling the corresponding tube amp and will give you the sound of your original tone controls at any position.

If you create and store a profile of your favorite amp with all the tone controls set to the middle position, we will later have the chance to create the corresponding tone stack, so you can add it seamlessly to your profile afterwards.

Can we expect future improvements via software updates?

Absolutely! Our Virus Synthesizer range is based on a continuous development of 15 years (and counting!) - a legacy that is unique in synthesizer history. We have built our reputation on software improvements and updates that have been available free of charge on the internet since way back in 1996. We are not aware of any company providing free software improvements to their customers before we started doing so, and we feel a bit like the “inventor” of this service. We will certainly continue in that spirit with the Kemper Profiling Amplifier!

Who is Kemper?

Kemper is new to the guitar world, but an old player in the keyboard world. In 2011 we are celebrating the 15th anniversary of developing and producing the Access Virus Synthesizer, one of the most successful line of synthesizers in history, and for which we have won numerous awards.