Treble detail in profiles woes

    So while I was sitting waiting for a compile to finish I thought to myself - what if I were an engineer at Kemper, looking at this, I'd probably think "that's a bloody useless bug report, I need data", so I decided to do a loopback of the mic through my apollo to capture profiling session data itself.


    I know this isn't yesterdays stuff and I've been futzing around with the settings a little on the Mesa one so it won't exactly match up with yesterdays settings, but regardless I figured it might be useful info.


    So here you go ckemper & team :


    http://peranders.com/music/dem…per_profilingsessions.zip

    The resulting two profiles from the session are attached. You will want to disable the effects section on the Mesa one as before I saved it I enabled a studio EQ and touch of verb.

    Quote from bshaw92

    Is there a possibility you got an unlucky bad cable?

    I don't think so as the same cables and mics are used to make the re-amp tracks (I use the Kemper in profiling mode to send the signal to the amp), and you get all the treble in those.


    I did a new quick session today while waiting for a compile, see the post just before this one, you can hear what the profiler is outputting and how the amps are responding, maybe the Kemper team is able to better identify either what I'm doing wrong or if there's the slight possibility of a bug.

    Per,


    It seems that the sound in question is pretty much clean, so no distortion or compression takes place.

    Therefore I doubt that there should be any error in the profile basically.


    However, the reference amp is pretty noisy.

    There might be a known psycho-acoustic effect happening: A noisy audio source or recording appears with more treble - even in the payload - than the noise-free derivate. Denoising software suffers from this effect, too.


    We have identified this effect a decade ago during the development of the profiler and took action against it.

    Whenever you take a profile and A/B it without leaving the Profiling Mode or saving the profile in advance, you will automatically have played back the same noise even with the profile, to make the A/B comparison appropriate. The noise is later discarded, while keeping the profile unchanged.


    Please try the A/B comparison again directly after the profiling, with the noise.

    Hey Christoph, thank you so much for checking it out. That’s fascinating about the noise effect.


    Actually the samples were recorded during A/B compare immediately after profiling. I know the Kemper records a loop of background noise for then but those examples are what it came up with and the treble difference is clearly noticeable.


    Speaking of it being clean (it’s not really they’re both at edge of break-up), when it tried a merged profile the Kemper really thought the source was much cleaner and gave it a completely different distortion sound to the actual amp sound (much less crunchy), I wasn’t able to match at all (more or less sounded nothing like the source amp). The DI profile was taken from a THD load box I plugged in for the purpose which I know isn’t the best but the line out signal shouldn’t be dramatically different to what it sends to the speaker, just much attenuated. I should find and share that data too. But it’s only for the Mesa, the Marshall doesn’t have an accessible speaker cable (closed back little bugger).

    Per, the THD is a simple resistor load so it won't behave in the way a speaker does in terms of impedance curve which will have some effect on the sound compared to having a real speaker attached. Even a reactive load is only an approximation of one particular speaker and cab so if the cab you would use is different from the reactive load that will also affect the sound to some extent.


    I have a THD BiValve here with a buit in HotPlate attenuator. so I will try and make two profiles of the same amp with a load and a real speaker to see what impact the THD load actually has.

    I have made 3 very quick profiles of the THD BiVale More Input with the volume on 4 so it is quite crunchy (probably too crunchy :)).


    I took a single profile of each method and did absolutely no refining so that differences in my playing during the refining process wouldn't have any effect on the resulting profiles.


    These were as follows:


    1 AD-THD Bi Valve Per Cab : this is the amp into a Mesa Thiele EVM12L cab. The Hot Plate Attenuator is bypassed in the amp. I have connected a speaker via a cheap ART passive DI Box.


    2 - AD-THD Bi Valve Per HP Hi : This is the speaker out going into the DI Box but with the Hot Plate Attenuator engaged with just a little shaved off the volume.


    3 - AD-THD Bi Valve Per HP Line : This has no speaker attached and a signal being taken straight from the Hot Plate. However, I didn't level match while profiling so this profile was a bit quieter than the others. I raised the Rig Volume to get it in the same ball park but it isn't exactly the same level.


    4 - AD-THD Bi Valve Per2Notes : This profile is taken by sending the amp's speaker out straight to a Two Notes Torpedo Relaod loadbox (reactive load) with no speaker attached.


    They are all uploaded to Rig Exchange if you want to try comparing the effect of different loads.

    ckemper - I know but honestly that's what it was, I made those on Gearslutz specifically that way right after profiling before saving the profile because I wanted to keep the background noise loop as I know how important it is when trying to do that comparison especially with cleaner tones. I have no idea what happened to the noise, but as you can hear the Kemper actually does have more amp "hum" noise, just the background noise went AWOL.


    Wheresthedug - Thanks. Yeah the hotplate definitely does affect the tone. But my THD Hotplate was attached all the way through that session so I'd still expect the merged profile to sound in the same ballpark as the "studio" profile, or even the original amp, it just doesn't. I'll make a new profile later on today and see what happens, I'll do a studio profile at the same time so there's a direct A/B with the Hotplate in the signal chain the whole time.

    Per, you mention on your Gearslutz post that you have cared of keeping the volumes of the comparison the same.


    You know, that with the straight A/B comparison after profiling, you do not have to care about the same volume, because they are perfectly matched in this moment, and have the same noise floor. I would need "more data" :)


    Or do I understand that this is a pure DI-Profile session, where equal volume is not given automatically?


    Btw: for slightly edgy amps and slight compression the refining can be very usefull.

    Hey Christoph - I found the levels to be quite different here after profiling. Like I said I had to adjust them in logic. The session wasn't DI for the gearslutz profiles. Before profiling during setup I only adjusted mostly by ear and eye (on the master output LED) while switching the A/B on the first page of the Profiling Mode, but once the profile was done and after I'd recorded both re-amped signals (Kemper and real amp) by sending via SPDIF to the Kemper then switching A/B I found that that I had to adjust the relative volumes in the DAW's mixer (logic X) to get them to match.


    Wouldn't it be normal for the two volumes to be radically different though? One is line level the other mic?


    Anyhow I did some more profiling. I think one thing I'm learning is that there's a big improvement if you use a preamp... but not the way you'd expect. It's in order to make it quieter! If you make the amp too loud then the Kemper can't handle it, so up till now i've only had the amp low enough that the Kemper doesn't complain. However if you use a preamp in the Apollo and use it to turn the volume down then you can crank the amp and the result seems to be much better... so far of course I may just have cloth ears. At any rate louder amp means lower background noise floor.


    I've just done another two profiles - a merged and a studio one. I'm getting pretty fatigued at this point so I don't know how far or close these are (what do you guys think?), but I did notice that with the DI profile the source has a little more "hair" to it than the Kemper result, however this time the merged was I think slightly better than the studio version.

    Here's the audio files, apologies for having them in a zip rather than separate, but hopefully you'll give them a try out. I couldn't capture the profiling session for the DI though. so it's just re-amped signals.

    http://peranders.com/music/dem…/KemperStudioVsMerged.zip

    And the two profiles (one merged, the other the studio, both with the same cab) are attached. With the recordings I took time to try and get a closer verb in the Kemper, I wish I could capture a short IR and use a convolution verb with the Kemper on this too because I feel sure that this accounts for the larger portion of the remaining difference, it's surprising how much difference it makes.


    permesacrunchmands.zip

    Anyhow guys, please let me know if I'm getting closer, as I said my ears are tired.

    Edited once, last by Per ().

    Hi Per,

    Just heard from DonPetersen that you should not use plugins while profiling.


    You said you were using UAD preamps? That's what I was using, but the results were always strange.


    One other thing that might be material information: what mic are you using?

    Quote from Per

    The trouble is it's driving me up the wall. I've tried profiling a dozen different ways, re-routing the mic through a UAD preamp and back out to the Kemper, adding verb to the Kemper source in cause it's a room thing (it really doesn't seem to be, although I couldn't quite nail the room sound with the inbuilt verbs). Changing definition and clarity settings, adding EQ's, these gave a very glossy high end but didn't bring back the detail there (if you know what I mean).

    Hey nightlight, I'm using two cheap and terrible mic's (but they're what I've got). An SM58 and an e609 silver.


    Initially I was using no pre-amp at all. So I don't think the preamps are a problem, especially given that the pro's run the mic through a desk with expensive pre's as part of their signal chain while profiling.


    Perhaps if I used the preamp to add compression or distortion it could be an issue as DonPetersen said but I've avoided that, most of the time without even using software preamps, just the vanilla line-in's on the interface (so it's just going through the audio cards pre's). I found it improved things when I started routing this way because I could reduce the volume to a level the Kemper would accept after pushing the amp a bit louder. But please do listen for yourself to the latest set of tracks in my last post, I could be hearing things in which case I need to find some other way to attenuate mic volume.

    Quote from Per

    Hey nightlight, I'm using two cheap and terrible mic's (but they're what I've got). An SM58 and an e609 silver.


    Initially I was using no pre-amp at all. So I don't think the preamps are a problem, especially given that the pro's run the mic through a desk with expensive pre's as part of their signal chain while profiling.


    Perhaps if I used the preamp to add compression or distortion it could be an issue as DonPetersen said but I've avoided that, most of the time without even using software preamps, just the vanilla line-in's on the interface (so it's just going through the audio cards pre's). I found it improved things when I started routing this way because I could reduce the volume to a level the Kemper would accept after pushing the amp a bit louder. But please do listen for yourself to the latest set of tracks in my last post, I could be hearing things in which case I need to find some other way to attenuate mic volume.


    Gotcha, so not using a plugin. Have you tried connecting directly to the profiler, i.e. mic cable into the back of the Kemper? Those mics don't need phantom power, so something to try.

    Quote from nightlight

    Gotcha, so not using a plugin. Have you tried connecting directly to the profiler, i.e. mic cable into the back of the Kemper? Those mics don't need phantom power, so something to try.

    Yes, that’s how they are in the initial session on Gearslutz.

    ckemper - with that last post for both profiles it was Guitar -> Kemper -> Amp Input (with THD Hotplate attached).


    Then the merged (DI) profile was made with the line out of the Hotplate going straight into the Kemper.


    The Studio profile was made with a e609 silver going in to the UAD Apollo, where I then had the channel do a direct send to a free output which then in turn was plugged direct back into the Kemper. This is so I could reduce the volume on the Mic (using the console app’s channel fader) as the Amp volume was too loud for the Kemper when the mic went directly into the Kemper.


    The mic was pretty much touching the grill on the amp and was just slightly off center. The room is untreated.

    Oh, and the Kemper is connected to the interface via SPDIF, which is what I then used to send the reamp signal back to the Kemper. The reamping is done in profiling mode immediately after the profile has been made with the exception this time of the ,edged profile where I had to exit profiling mode to do the merge as the studio profile didn’t show up in the available cabs till I did that.


    When I recorded the original dry signal I used the split left dry, right master mono (and set to monitor the mic/amp (b) on the Kemper in order that I could play with the original amp and it’s feel and tone. After that I reset the output to master left/right and changed the input source to spdif for all reamping.

    In case you’re wondering why I didn’t route the line out of the THD through the audio interface like the mic - simply laziness, I didn’t have a long enough cable for the job and don’t want to rearrange the amp and everything to a new closer plug socket,

    So with either the DI profile or the studio profile you could record a clip of a straight A/B comparison, with noise.


    For checking the quality of your profiling, we do not need a merged profile and all that at the moment.

    And yes, this is a "bad data" syndrom :):):)