Posts by nejo_hh

I made them myself using a method described here. It's the cab from the factory profile MB - /13 JRT915 84 3.

Ever wondered what the High and Low Shift parameters of the Profiler Cabinet implementation actually do to the cab frequency response? See attached plots.

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Quote from Andrew_Ongley

I've just been messing around with the presets. The Bob Weir 2 is absolutely perfect for what I'm looking for, but the pedal is working in reverse (ie open sound is on the heel). Anyone know how I can reverse it round without changing the tone?

1. Manual (new) = Manual + PedalRange / 10
2. Peak (new) = Peak + PeakRange / 10
3. Pedal Range (new) = - PedalRange
4. Peak Range (new) = - PeakRange

Required limitations (as the Profiler does internally):

1. Pedal Range: [- 10 * Manual, 100 - 10 * Manual]
2. Peak Range: [- 10 * Peak, 100 - 10 * Peak]

So the Profiler internally interprets the Bob Weir 2 settings

1. Manual 5.6
2. Peak 7.7
3. Pedal Range -79%
4. Peak Range -77%

actually as (he knows we like to exaggerate, but doesn't hold it against us)

1. Manual 5.6
2. Peak 7.7
3. Pedal Range -56%
4. Peak Range -77%

which in reverse translate to

1. Manual 0.0
2. Peak 0.0
3. Pedal Range 56%
4. Peak Range 77%

Quote from nejo_hh

1. Manual = ln(f1) * 1.80034 - 7.11148
2. Peak = ln(Q1) * 2.69813 + 1.84876
3. Pedal Range = ln(f2/f1) * 18.0034
4. Peak Range = ln(Q2/Q1) * 26.9813

No calculator at hand? Just follow this link, modify the values of f1, q1, f2, q2 at end of input to your liking, hit enter and find the Profiler Wah Wah parameter settings under Result (order as above).

Curious to do the opposite, i.e. derive the resonant frequencies and the filter Qs from the Wah settings? Here:

1. f1 = exp(Manual * 0.555451) * 51.9395
2. Q1 = exp(Peak * 0.370627) * 0.503989
3. f2 = exp((Manual + PedalRange / 10) * 0.555451) * 51.9395
4. Q2 = exp((Peak + PeakRange / 10) * 0.370627) * 0.503989

Still no calculator at hand? Just follow this link, modify the values of k1 (Manual), k2 (Peak), k3 (Pedal Range), k4 (Peak Range) at end of input to your liking, hit enter and find the resonant frequencies and the filter Qs under Result (order as above). Required limitations (as the Profiler does internally):

1. Pedal Range: [- 10 * Manual, 100 - 10 * Manual]
2. Peak Range: [- 10 * Peak, 100 - 10 * Peak]

Thank you very much for your effort, Dragonsf! You've inspired me: I did an analysis similar to yours. My results (here) differ slightly, so I'd be glad if you find time to review my stuff. Best-

Hi Guys, many thanks to all the good people who have contributed and collected such helpful information!

I did an analysis similar to that of Dragonsf which he presented here. But in order to not spread related info among different threads I've decided to post my results here. Hope that's ok...

My intention was to derive formulas for the calculation of the Profiler Wah Wah parameters as functions of the resonant frequencies (f1/f2 for heel/toe) and the filter Qs (Q1/Q2 for heel/toe). In contrast to the white noise thing I followed a different approach to extract and analyse frequency responses which - in theory - should give more accurate results. All responses have been corrected for the input filter of the Profiler prior to the analysis.

Here is what I've found (all natural logarithms):

1. Manual = ln(f1) * 1.80034 - 7.11148
2. Peak = ln(Q1) * 2.69813 + 1.84876
3. Pedal Range = ln(f2/f1) * 18.0034
4. Peak Range = ln(Q2/Q1) * 26.9813

No calculator at hand? Just follow this link, modify the values of f1, q1, f2, q2 at end of input to your liking, hit enter and find the Profiler Wah Wah parameter settings under Result (order as above). Required limitations (as the Profiler does internally):

1. Pedal Range: [- 10 * Manual, 100 - 10 * Manual]
2. Peak Range: [- 10 * Peak, 100 - 10 * Peak]

For those who are interested: Attached you can find plots that show

1. an example of the many frequency responses I've extracted, corrected and analysed
2. the data points and (restricted) best fit for the Manual parameter
3. the data points and best fit for the Peak parameter

While the Peak parameter seems to be strictly linear in ln(Q) this does not hold true for the Manual parameter with regard to ln(f). The fit is fairly good only between 1.5 (~120Hz) and 8.5 (~5830Hz). But that should be good for most applications.

Cheers-

Chances are high that the tonal differences in XLR vs. S/PDIF are caused by the (mic) preamp of the interface, see post of lightbox here. If you like what the preamp is doing EQ wise you may analyse it's frequency response by two recordings of e.g. a loop (one XLR, one S/PDIF) with a Match EQ.

The reason for this particular IR to fight so hard against truncation is the steep cut-off at 33Hz. Such a curve can only be accurately reproduced by filters of extreme length.

So to drive things even further I tweaked my machinery to allow for greater deviations in the range from 1 to 32Hz. This helps the algorithm to be more precise for frequencies above 32Hz. Attached you can find the results for an IR length of 1024 samples. If frequencies below 33Hz are of no importance or get cut by a filter anyway, you may get away with such an extremely shortened IR.

Please tell us what you think. Cheers-

Good Bommel was kind enough to help me analyse the bass cab IR he presented above (Thank you so much!). I've recreated shorter versions of said IR from the frequency response of the original and compared the results to just truncated versions of equal lengths. Attached you can find comparison plots for the frequency response and the deviation from the original for IR lengths of 4096, 2048, 1536, 1024 and 768 samples.

I leave the review of the recreated IRs to Bommel himself. But I wouldn't be surprised if the differences between even the recreated 1536 sample version and the original can only be heard in direct A/B comparisons.

In conclusion I'd say that if an IR is reluctant to truncation it's worth recreating shorter versions from the frequency response.

Hope you find this analysis informative or even helpful. Cheers-

Press and hold with the remote is already occupied by the momentary on function. Wouldn't want to loose it.

Hey drbill, was also puzzled by this. But it's a feature not a bug. Cheers-

Quote from Monkey_Man

Even if they had a 20kHz bandwidth, it'd take dozens of conversions in order to become apparent where the vast majority of modern interfaces are concerned due to the accuracy of reconstruction carried out at every D/A stage.

Totally agree! But keep your interface at a cool place if you go for dozens of conversions ?

Quote from Monkey_Man

It's more-obvious in the higher frequencies, 'though.

Quote from karlic

I just find that mid-range frequencies are less critical.

Got it, silly me. Thought you were referring to the bandwidth (i.e. sampling rate) of the interface.

Quote from karlic

Being as I have always used analog with a Reamp box for real amp heads, I have continued with Kemper. Switching clocking is something I am likely to keep forgetting anyway.

That's what's so great about the Profiler: You can do it either way and it's totally fine. People who are used to the smell of hot valves can go digital without even noticing while people familiar with the digital domain can integrate the baby without hassle.

Quote from karlic

With guitar signals not covering a huge bandwidth, it doesn't bother me anyway.

Conversion losses (non-linearities, noise of different kinds) is not a matter of bandwidth BTW.

I would add: see morphed values and ability to type them in

Quote from wwittman

I always take it in analogue just like I would any guitar amp.

Yeah, but: Your amp (Profiler) is digital as is your recorder (DAW). And for reamping: Think of the Profiler as a plugin to your DAW. Would you put any double conversion via external interfaces before or after the plugin?

I didn't get it. Please help me find the counting error.

S/PDIF Recording:

1. Conversion: A/D at Profiler in

S/PDIF Reamping:

• no conversion

Analogue Recording:

1. Conversion: A/D at Profiler in
2. Conversion: D/A at Profiler out
3. Conversion: A/D at interface in

Analogue Reamping:

1. Conversion: D/A at interface out
2. Conversion: A/D at Profiler in
3. Conversion: D/A at Profiler out
4. Conversion: A/D at interface in

Is it really six more conversions for whole round of analogue reamping?

Ok, case closed I guess? Many thanks to all the good people who helped solving the problems of a fellow Profiler user. You've totally earned all the thanks and likes.

Thanks for your confirmation. No hidden mirrors in KPA profiles.

Regarding the difference in noise floor: Whatever it is, it's about 80dB below the hottest frequencies.

EDIT: Apparently the cause is your Test DI (see attached plot). The SNR of the Profiler out just seems to be superior to your amp signal chain.

Sorry for reactivating this thread, but I've enhanced my tools for analysing and recreating IRs quit a bit (see attached plots for a hint) and would appreciate them to be really challenged. I've collected quite a few bass cab IRs but never found anything like the IR presented here.

So Bommel, may I carefully ask whether it is possible to get the exceptionally long bass cab IR you've presented above? Just post it here or PM me if you like. In exchange I would send back recreated short versions (wether good or not) and present the analysis results here.

Cheers-

Quote from easstudios

I can do a test at 44.1kHz - it would be very strange if working at higher sample rates caused the kemper to work at lower ones....

My understanding: The Profiler always works @44.1kHz. If you opt for a different S/PDIF rate it does the usual thing: (higher-oder) upsampling, then downsampling. The artefacts you get are probably just the result of the imperfections of the (every) resampling algorithm.