- The Profiler Model referred to in this thread is ...
- ☑️ Profiler Stage
1) WHAT IS THIS POST ABOUT
Since trying to create my own version of amp cloning, I have come to an understanding of how the Kemper may go about making a profile™.
My process is to do a frequency sweep of the amplifier applying a high volume signal. Then sweep again with a very low volume signal. The difference of these two sweeps will reveal the input EQ of the amplifier. This EQ is where most of the amps sound comes from. IMO, It is the critical piece of cloning an amp.
Over the years of making profiles in the Kemper, I always had better results if the amplifiers gain was set somewhere near break up. No gain sounded bassy and full gain sounded too bassy as well as undefined. After creating my cloning process, it became obvious why that was.
Creating profiles near breakup usually gives the most amount of dynamic range to the resulting INPUT EQ result.
2) HOW DOES MY CLONING PROCESS WORK
- The input EQ is the fingerprint of the amp.
- At a low input volume (gain) the resulting freq sweep shows the EQ of the entire amp (input eq, output eq, speaker, mic, etc).
- At a high input volume (gain) the resulting freq sweep shows the EQ of the entire amp minus the input EQ (output eq, speaker, mic, etc).
- Doing math on these two sweeps reveals the input EQ. The more dynamic range in this result the more accurate the cloning.
At this point, I am assuming the Kemper does something very similar when doing its profiling procedure.
3) WHAT ARE THE RESULTS
As an example, I made several sweeps of a Kemper profile at varying gain settings. I chose the Lars Luettge profile TH - Mars VM410 20 to be the sample profile.
WHY I CHOSE THIS PROFILE
- During my cloning process this amp sounded really good.
- The higher the gain the more pronounced the Input EQ is. Clean amps have flatter responses. High gain has more of a bandpass peaked response.
- This profile is in the included Rig Packs from Rig Manager.
- Everyone has this profile and can get a feel for what the perfect gain setting is by playing the profile at each gain setting.
I swept this profile from a gain of 1.0-5.5. The resulting sweeps are shown here. I stopped at 5.5 because I can only attach 10 files to this post.
Each image shows three sweeps. The highest sweep is the high volume (gain) sweep. The next lower sweep is the low volume sweep. The sweep below 0 dB is the resulting sweep that shows the input EQ derived from the upper sweeps. In this example the input sweeps have a little over 20 dB dynamic range.
From the resulting sweeps we can see that the cloning process worked well thru the whole range. However, the best results were from gain settings 2.0 to 3.5. These sweeps had the most dynamic range and therefore the most accurate results.
We can see that from the low gain sweeps 1.0 and 1.5, that the dynamic range is lower. This results in a bassy profile. More bass is present in the resulting EQ. The actual input EQ is obscured by the dynamic range noise floor of -40 dB.
The higher gain sweeps from 4.0 to 5.5 have hit the ceiling of our dynamic range. This again results in a bassy response because the higher peaks are being clipped at 0 dB. But the overall response is now being flattened as well. This results in, not only being bassy but, a wrong sounding clone. The mids and highs are flat losing the fingerprint of the amp.
The sweeps from gains of 2.5 to 3.5 have the greatest dynamic range and are more accurate at capturing the overall sound of the amp.
4) WHAT DOES THE KEMPER DO?
I have not investigated what the Kemper does. I assume it does something very similar. My cloning tests used fixed input values of 0 dB and -40 dB. This provides a maximum of 40 dB dynamic range in my clones. The Kemper may do a high volume sweep and then adjust its low volume sweep until noise becomes an issue. This means the Kemper may provide more/less dynamic range depending on the situation.
You can see from all of the above sweeps, each provides a useful clone. Some are more bassy than others and some have a flatter high freq response. The Kemper gives you a DEFINITION control in its AMPLIFIER section so the erroneous bass response can be adjusted. The DEF control adjusts the most common flaw in the process.
5) FINAL THOUGHTS
These tests show what works for a high gain amplifier. A low gain amplifier should work the same but is not presented here.
To get the best profiles, the amplifiers gain should be set to a value that sounds similar to the example profile at a gain of 2.5 to 3.5.
STEPS TO TAKE
- Set the amplfier to the gain setting your profile should sound like.
- Adjust the EQ of the amp for the best possible sound.
- Reduce the gain to a value that sounds similar to the example profile at a gain of 3.0.
- Profile the amp.
- After the profile is complete adjust the Kemper Amp gain and Definition controls to match your original amps sound.
6) DOWN THE RABBIT HOLE
How does this process work? When sweeping at a low input volume, the signal is well below the tube clipping point. As we increase the input volume, the tubes begin to clip. This clipping limits how loud the signal can get. Which means, it flattens the input EQ response out. The more volume we use, the flatter the input response gets until it eventually becomes a completely flat response. By comparing the lowest and highest input volumes you can calculate the exact input EQ response.
For best results you want the low volume sweep to never be clipped by the tubes. You want the high volume sweep to be very clipped by the tubes.