MarkV power amp only modeling

j20056

j20056

Member
My use case is a W/D/W studio rig. Main config is AF3 and a Boogie MarkV:25 head connected via 4CM.
The MarkV power amp is connected to a cab as the center Dry channel.
My room being too small and reverby ; I cannot mike the cab to feed into the AF3 so I need ro emulate the power amp cab to feed into AF3 to add wet FX for the W-W speakers. With the 4CM method; all I want to do is take the MarkV preamp output (in 2C+ mode) into the AF3 then emulate only the power amp section of the MarkV and the cab:
From what I read; Fractal doesn’t allow to bypass the preamp so I try a combination of amp and settled with the MarkV amp and set the preamp gain really low and messed around with the power amp EQ (in Mark 5 band mode) to match the tone. What surprised me is that the closest match was to use a MarkV amp in 2C+ mode as I am already feeding a signal which is the output of a MsrkV preamp in very high gain 2C+ mode. I would have thought a very neutral power amp like Freyette or even the MarkV in low gain clean green channel would have been more adequate but it wasn’t.
I obviously had to set the preamp gain on the MarkV to very low levels.
So I was wondering if others have gone through the same type of situation and if where I landed is the best way. Ultimately it sounds good and my benchmark was to match the tone out of the MarkV CabClone, so at the end of the day I am done but curious. I cannot use the CabClone with my AF3 as I ran out of inputs that are more important thence the need to model it.
 
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There are several ways to do this, and I'm going to list them in increasing complexity:

  1. Abandon the real amp. Abandon true W/D/W. Use a Stero L and R powered speaker, where you output the dry amp signal panned center, and L/R affects signals panned respectively. You only have 2 real speakers, but you also only have 2 ears so sonically this can still create those sounds.
  2. Abandon the real amp, but stil with W/D/W: Use Out 1 for your L/R wet signals, and Output 2 for a Dry signal into three powered speakers.
  3. Do the above, but use a poweramp into a guitar cab for the dry signal instead. A SD Power Stage for portable option, a Matrix for larger solid state option, a rack tube power amp like a Carvin TS100 if you insist on tubes for it, or just the power section of your MarkV:25 to use things you already own.
If you insist on using the 4CM and retaining the use of your exsisting amp preamp:

  1. You could use your real amp as Dry, but instead of trying to feed the preamp signal into the Axe just use an amp model for the wet signals. You might find that adjusting your tone/gain/etc separately on the wet channels actually works nicely to make the Dry and Wet signals sit well with each other.
  2. You could consider using the Cab Clone instead of the tranditional effects loop in a 3 Cable Method. Guitar -> Axe Input 1 -> Out 3 -> MarkV Input -> CabClone out to Axe input 3, and Speaker out to speaker for Dry signal -> Wet chain in Axe leading to Out1 for wet outputs, amp feeds the dry speaker cab directly.

    This way your amp is doing the full amp and cab job (assuming you like the CabClone) and the Axe is just doing the Wet effects. Some people gribe about the CabClone tone, but you're going to be running affects on it anyway which will make that less important anyway.
  3. You could do your 4CM as now, but feed the CabClone signal back in after as part of a 5CM. You say you've run out of inputs but Input 1 for guitar, input 3 for 4CM, Input 4 for CabClone still leaves you with another set of unused inputs.

I think the 3 Cable method of using the cab clone instead of the effects loop would be easiest if you want true W/D/W using your real amp. You run the Axe before your amp for pre-effects, then your amp connects to the dry cab normally. Then the cab clone feeds your Wet effects chain on a second input which feeds your Wet speakers.

Doing it all inside the Axe is actually easiest if you're willing to leave your amp turned off.
 
I am always careful before buying gear to see how vibrant and responsive the user forums are. This forum is just something else and the quality and speed of responses has no equal!!! Thank you.
@IronSean: Thank you for a very detailed and thoughtful answer. I actually really like having the real cab in the center, as it is a small Orange 1x8 that sits on my desk. I use Genelec studio monitors for the stereo W/W. What I like about a real small cab on the desk is that it sounds much more 3D than stereo modeling the dry channel. In fact, what I am trying to do is really a W/D1/D2/W setup where Dry1 is the amp+real cab, and Dry2 is dry modeling of the amp + cab (to which the FX would be applied and sent L-R to W/W). I want to assign an expression pedal to do a cross fade between D1 and D2 to modulate how focused the dry is. It is hard to describe in words, but let's just say that the real center cab and the ability to modulate its blend is really great as a modeled dry signal panned center with stereo speakers doesn't sound as focused as a real cab in the center (same a center channel in a surround home theater setup, in fact A/V guys call systems without a center channel a "phantom" center channel). In addition, it provides for an infinite and noiseless sustainer even at very moderate volumes as it sits right in front of my guitar.
Now, with the MarkV, the CabClone is always at the same volume as the external speaker, so there would be no way to separately modulate the volume of the CabClone and the real cab, thence the need to replicate the cabClone, which I do indeed like the sound of.
As far as inputs, I am maxed out because I also have an Eventide H9000 connected to Input 2 and the piezo pickup of my guitar connected to input 4. I wish the AxeFx-III had 8 inputs instead of 4 but I understand it's a small use case.

Sorry about the length but your careful answer needed some clarification from me. My primary question was more about the fact that using a clean AF3 amp (with real MarkV in 2C+ high gain mode preamp input) to model the CabClone wound up being less accurate than using an amp block with a MarkV in 2C+ mode but with the input gain trimmed a lot. Would have thought this would double load the preamp, but my ears don't lie.
 
That does help clarify some things. Regarding the amp model in question, it's hard to say. The Clean channel may have some inherent EQ and voicing which is skewing things more than the lead channel does.

And in that case, Are you using the L and R of all 4 (3.5?) inputs? If not, perhaps you could make use of the inherently mono nature of the Effects loop and cabclone signals by sending them to L and R of Input 3, and use blocks on the grid to split the L and R signals into separate rows?
 
Splitting is a good idea, didn't know that was possible. Buys me one mono input.
Thing is that I have to model the CabClone (or to your point any good sounding dry tone) from the real MarkV preamp if I want the ability to modulate between my real D1 center dry versus the modeled D2 one. So in many ways, I don't really need the CabClone any more, especially now that I was able to replicate it pretty closely. I think I'm good now. This AF3 unit is really powerful and this forum makes it even better, so thank you.
 
I run the wet signal out left and right outputs 1 to two channels to FOH and use the (pre-out set-up form the Ax) out channel 3 of the Ax to the front input of my mark V for my dry signal. Than mic the mark V and send it to FOH. My preset sends the signal out the Ax before the amp and cab directly out to output 3 of the Ax. Sounds very thick and wide out FOH. And still have that blended sound on stage. It allows me to use the compressor, gates and pre effect I want to the Mesa. Than I have the expression volume pedal controlling both Ax and Amp.
 
j20056 said:
Splitting is a good idea, didn't know that was possible. Buys me one mono input.
Thing is that I have to model the CabClone (or to your point any good sounding dry tone) from the real MarkV preamp if I want the ability to modulate between my real D1 center dry versus the modeled D2 one. So in many ways, I don't really need the CabClone any more, especially now that I was able to replicate it pretty closely. I think I'm good now. This AF3 unit is really powerful and this forum makes it even better, so thank you.
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Restating your original question then, you're looking for which amp models work best for modelling a power amp when fed with a high gain preamp signal. Off the top of my head I'm not sure, but that should be something you can search for some threads on.

Normally for high gain poweramps run relatively clean too, so you could try just putting an IR after the amp signal without a power amp. Tube preamp setting inside the cab block could help too.

Otherwise, changing the input EQ to something which defauilts to flat (maybe one of the active EQ models) might make some simpler clean amps color things less as well.
 
Also try turning down the power tube bias and hardness and the preamp tube harness. That's what I did to the SLO Clean model when I ran my Carvin VLD1 preamp into the FM3, until I remembered that my old Amplifire pedal had EL34, 84, 6L6 and KT88 power amp models,
 
Sounds to me you could simply do this:
  1. Guitar -> Axe-Fx 3 front input
  2. IN 1 -> Pre-fx -> OUT 3 -> MK V:25 input -> Real cab
  3. IN1 -> Pre-fx -> Mark V model -> Cab sim -> Post-fx -> OUT 1
Doing 4CM seems unnecessary when you have great Mark series models in the Axe-Fx.

There's IMO no point in making things complicated by building a complex W/D/W system inside the Axe-Fx as well when you can just mix and pan your fx to your studio monitors. You could also just set #3 to completely wet fx if you want to build a "real dry amp, wet stereo fx to studio monitors" setup.

Another thing you could try is forgetting the real preamp on the MKV completely. Add Amp 2, copy the settings from Amp 1 and set Amp 2 poweramp modeling off, then run that into the poweramp of the real MKV.
 
laxu said:
Sounds to me you could simply do this:
  1. Guitar -> Axe-Fx 3 front input
  2. IN 1 -> Pre-fx -> OUT 3 -> MK V:25 input -> Real cab
  3. IN1 -> Pre-fx -> Mark V model -> Cab sim -> Post-fx -> OUT 1
Doing 4CM seems unnecessary when you have great Mark series models in the Axe-Fx.

There's IMO no point in making things complicated by building a complex W/D/W system inside the Axe-Fx as well when you can just mix and pan your fx to your studio monitors. You could also just set #3 to completely wet fx if you want to build a "real dry amp, wet stereo fx to studio monitors" setup.

Another thing you could try is forgetting the real preamp on the MKV completely. Add Amp 2, copy the settings from Amp 1 and set Amp 2 poweramp modeling off, then run that into the poweramp of the real MKV.
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Fair analysis EXCEPT... I like to have an expression pedal to do cross-fades between real cab and simulated cab for the dry channel. So my setup is really W/D1/D2/W and I cross-fade D1 and D2 (this is also so that I can use the same config for playing live in the studio versus through headphones at night). I can only do that by assigning a Volume modifier to the signal going in the FX return of the Mark V, therefore I need 4CM to do that.
 
Here is a dumb question though: When getting the preamp signal from the MarkV, do I even need a Power amp, i.e. an AMP blocxk in the AxeFX? Why can't I go from preamp to Cab directly and EQ to match the tone? I mean I only want the pure power amp section, which is not supposed to color that much, so why not removing it altogether?
 
j20056 said:
Here is a dumb question though: When getting the preamp signal from the MarkV, do I even need a Power amp, i.e. an AMP blocxk in the AxeFX? Why can't I go from preamp to Cab directly and EQ to match the tone? I mean I only want the pure power amp section, which is not supposed to color that much, so why not removing it altogether?
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I actually suggested that just a couple posts up. @sprint is right that it still contibutes something, but it's also relatively mild on a high gain amp like the Mark series where they tend to sound best with a clean power amp instead of a pushed one. Plus the el84 based power section in the 25 is not quite the same as the full 90w in the model anyway.

So although it may still contribute something, no reason not to test it out and see if it works for you. I used to do recording with a tube preamp plugged directly into my interface with an IR after it and it still got good results.
 
j20056 said:
Fair analysis EXCEPT... I like to have an expression pedal to do cross-fades between real cab and simulated cab for the dry channel. So my setup is really W/D1/D2/W and I cross-fade D1 and D2 (this is also so that I can use the same config for playing live in the studio versus through headphones at night). I can only do that by assigning a Volume modifier to the signal going in the FX return of the Mark V, therefore I need 4CM to do that.
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You could probably use a Mixer block after the Amp block and expression on that, don't remember if it supports modifiers or not.

In this scenario you just use the Mark V model on the Axe-Fx and then run that into "wet only", "dry only" and "dry into real poweramp return and cab" paths.

Since there's no separate poweramp sim on the Axe-Fx 3, the best way to go is IMO flipping the scenario where you feed an amp model into the real Mark poweramp. Using two Amp blocks lets you tailor the sound better for the real amp and cab vs fully digital.
 
laxu said:
You could probably use a Mixer block after the Amp block and expression on that, don't remember if it supports modifiers or not.

In this scenario you just use the Mark V model on the Axe-Fx and then run that into "wet only", "dry only" and "dry into real poweramp return and cab" paths.

Since there's no separate poweramp sim on the Axe-Fx 3, the best way to go is IMO flipping the scenario where you feed an amp model into the real Mark poweramp. Using two Amp blocks lets you tailor the sound better for the real amp and cab vs fully digital.
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That's more or less what I did. I have a volume/pan in the path of my FX return loop of the MarkV and another in the path of the modeled amp. I setup a cross-fade on the two volume controls connected to the same expression pedal. Works well.
Modifiers work equally well on Volume/Pan modifiers as well as Mixer and I am using both as my setup already consumes all 4 Volume/Pan blocks
 
laxu said:
You could probably use a Mixer block after the Amp block and expression on that, don't remember if it supports modifiers or not.

In this scenario you just use the Mark V model on the Axe-Fx and then run that into "wet only", "dry only" and "dry into real poweramp return and cab" paths.

Since there's no separate poweramp sim on the Axe-Fx 3, the best way to go is IMO flipping the scenario where you feed an amp model into the real Mark poweramp. Using two Amp blocks lets you tailor the sound better for the real amp and cab vs fully digital.
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That would still leave one of the two paths either without power amp coloration, or the other with double the power amp coloration. IF you use the AMP block with power amp modelling on, then the Axe dry path would be normal but the amp power amp would add a second set of tube power amp coloring. If you use power amp modelling off so that the amp itself doesn't double the power amp modelling, then the dry path inside the axe won't have power amp modelling.

Having a transparent power amp into a real cab instead would let you use the AMP block with power amp modelling on both for the dry output from the Axe and for the real guitar cab output.
 
IronSean said:
That would still leave one of the two paths either without power amp coloration, or the other with double the power amp coloration. IF you use the AMP block with power amp modelling on, then the Axe dry path would be normal but the amp power amp would add a second set of tube power amp coloring. If you use power amp modelling off so that the amp itself doesn't double the power amp modelling, then the dry path inside the axe won't have power amp modelling.

Having a transparent power amp into a real cab instead would let you use the AMP block with power amp modelling on both for the dry output from the Axe and for the real guitar cab output.
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You would just have Amp 1 w/ poweramp modeling on for the dry and wet paths going to studio monitors and Amp 2 w/ poweramp modeling off for dry into real poweramp and cab.

Yes, a more neutral poweramp would be better but honestly for moderate volumes the full amp model into a clean guitar poweramp works just fine. Use settings to compensate.
 
laxu said:
You would just have Amp 1 w/ poweramp modeling on for the dry and wet paths going to studio monitors and Amp 2 w/ poweramp modeling off for dry into real poweramp and cab.

Yes, a more neutral poweramp would be better but honestly for moderate volumes the full amp model into a clean guitar poweramp works just fine. Use settings to compensate.
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I forgot you fancy Axe FX III users have two AMP blocks, this makes perfect sense now.:sweatsmile:
 
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