Marshall JVM410HJS - real amp versus Axe3

Orvillain

Orvillain

Power User
So I and @MirrorProfiles were talking recently. We both feel like the Axe's Satriani JVM doesn't really sound like the real thing. Does anyone else feel this way??

I'm comparing them back and forth, and the Axe version is both fuzzier, seems to have more emphasis on the pick-attack (but in the low frequency region) and isn't as bright as the real amp is, at reasonably stock settings.

For example, here are my real amp settings:
1691579119660.jpeg

And here are my Axe 3 settings:
1691579416137.png
They're pretty comparable. Please ignore the 7dB boost on the amp block - I'm just compensating for level differences there, and it doesn't affect the tone of the amp and nothing is clipping anywhere in my chain.


This is what I get when I run pink noise through the real amp and the Axe3:
1691579467078.png

Now this is obviously just an initial test to try and confirm what I'm hearing when I compare them. The pink line is the real amp, and the white line is the Axe3 JS.


And here are the clips:

Real amp:


Axe3:



I should clarify, I have an IR on each of these. The exact same one. There are no differences in mic position here.

Thoughts??
 
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Karl Houseknecht said:
Assuming you’re running the real amp through a load. What speaker impedance curve is selected on the model and I wonder what curve is applied in the load? Perhaps the difference could account for what you see and hear?
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For the real amp, the load is my real Egnater 4x12 Tourmaster cab, with Chinese V30's.

On the Axe3 it is all default:
1691580576433.png
 
You could try disabling any poweramp sim on the Axe-Fx, then running that signal through the real JVM poweramp via fx return. Maybe that results in better match to the real amp. This would confirm that the preamp behavior is right.

Then you can start looking at impedance curves and poweramp behavior.
 
Karl Houseknecht said:
Where are you getting the direct feed into the Axe? And are you sure the impedance curve of that Egnater cab matches what is selected in the modeler amp? It will affect the sound even without a cab block.

412 Brit 800 curve isn’t using V30’s, I’d think.
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I've got a DI I recorded through my Neve DI box. That is being routed out into the amp via my Signal Arts Reamp Box, and into the Axe3 via SPDIF. I've lowered my SPDIF level to -18dB to account for the level differences in accordance with this thread: https://forum.fractalaudio.com/threads/unity-gain.194836/page-2#post-2434935

I know the Brit 800 doesn't use V30's. But to be honest, I've tried a whole bunch of them and none of them really get the amp closer in terms of brightness (which some call fizziness I suppose) and punch.
 
laxu said:
You could try disabling any poweramp sim on the Axe-Fx, then running that signal through the real JVM poweramp via fx return. Maybe that results in better match to the real amp. This would confirm that the preamp behavior is right.

Then you can start looking at impedance curves and poweramp behavior.
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I actually did this a few months ago, and yes the preamp part of the amp does seem to be quite close. A/B'ing the real preamp with the Axe3's preamp (with power modelling turned off) does give a closer result.
 
Those Egnater cabs are sleepers, I had a 2x12 version and wished I never sold it. This sounds like a difference in mic placement to me, of coarse impedance curve, amp pot(s) tolerance could be the cause.
If you can run two of the same GTR DIs out to each at once, try using Dyna cab and moving the mic around in the fractal to match the eq curve.
😁
 
Bioloop said:
Those Egnater cabs are sleepers, I had a 2x12 version and wished I never sold it. This sounds like a difference in mic placement to me, of coarse impedance curve, amp pot(s) tolerance could be the cause.
If you can run two of the same GTR DIs out to each at once, try using Dyna cab and moving around in the fractal to match the eq curve.
😁
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Nah. Same IR on both signals. It aint to do with mic placement.
 
I’ve always struggled with this model, and couldn’t tell if it’s something I was doing or something in the model. That’s why I reached out to @Orvillain to try and work out what’s going on.

I’ve tried all kinds of impedance curves, removing the LPF, dropping bias, lowering the master right down (and up) trying to get that top end sizzle of the real amp.

To get them close would take getting my hands dirty with EQ and deeper parameters which isn’t the case for me with most Fractal models.

Just for comparison, I was sent some NAM models and I can match those much closer with Amplitube without any fuss. Some small differences that can mostly be dialled out with the amp controls but the top end sizzle is there.

No matter what, I can’t get that 10kHz ish sizzle from the Fractal model (which can sound good in its own right, but it’s always too rolled off).
 
When reading such comparisons, I tend to think that in order to really accurately compare any amp+cab, end to end with Axfx, one would first need to shoot an accurate IR of the real cab, measure the real cab's IC and have those values present in the Axfx model. Then with that, A/B audition both with the preamps set equally, and the power amp sections being pushed equally (and not just using knob positions to confirm that equalness since knob tolerances vary), and listening to the real amp+cab mic'd (with the same mic in the same room as was used to shoot the IR) through the same monitors as Axfx. Of all the real amp to Axfx comparison threads I've read here over the years I don't recall any that ever went through that kind of process to ensure no apples to oranges effect, which makes sense because it's a lot of work and requires some specialized gear (IC measurement). Comparing Axfx to real preamps is easy to do (and probably best done as a prerequisite to an end to end pre+p.a.+cab comparison, to ensure the preamps are equal in isolation to start), while comparing Axfx to real pre+p.a.+cab is a pretty tough go - and that's just to compare one static sound, never mind comparing Axfx vs real end to end in terms of response to controls variations or feel.
 
sprint said:
When reading such comparisons, I tend to think that in order to really accurately compare any amp+cab, end to end with Axfx, one would first need to shoot an accurate IR of the real cab, measure the real cab's IC and have those values present in the Axfx model. Then with that, A/B audition both with the preamps set equally, and the power amp sections being pushed equally (and not just using knob positions to confirm that equalness since knob tolerances vary), and listening to the real amp+cab mic'd (with the same mic in the same room as was used to shoot the IR) through the same monitors as Axfx. Of all the real amp to Axfx comparison threads I've read here over the years I don't recall any that ever went through that kind of process to ensure no apples to oranges effect, which makes sense because it's a lot of work and requires some specialized gear (IC measurement). Comparing Axfx to real preamps is easy to do (and probably best done as a prerequisite to an end to end pre+p.a.+cab comparison, to ensure the preamps are equal in isolation to start), while comparing Axfx to real pre+p.a.+cab is a pretty tough go - and that's just to compare one static sound, never mind comparing Axfx vs real end to end in terms of response to controls variations or feel.
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if you want the absolute closest, then yes, this would be preferable. Whether or not the added benefits are noticeable is another matter, I’ve done countless comparisons and blind tests and most of the time they can be dialled to match just adjusting the front panel controls by ear. Occasionally i’ll need to tweak impedance curves, bias, valve types, NFB, but it’s very amp dependent. The Egnater with V30’s impedance curve won’t be drastically different from any other V30 impedance curve in Fractal, I’d be amazed if anyone could hear a difference. Other factors like parts tolerances, wall voltages, bias etc will have a far bigger influence.

In this case, it’s just about trying to get them close enough, which IMO, isn’t easily possible.

I can’t adjust impedance curves or 90% of the stuff you can on Amplitube, but with amp settings alone it’s much closer. Enough so that it doesn’t matter, and enough that if Fractal was equally close, I’d be happy with the model.

I am sure the problem here is nothing to do with impedance curves being too different.
 
I own 2 jvm410hjs heads and fm9 and i ve been able to obtain the same sound from both.. Basically satriani settings also on fm9... Everything at 11:00 or near that with a boost in front.. In my case or bb preamp or klon both with gain at zero or 0.5..the cab i use is evh 4x12 so with the 5153 speaker impedance curve.
 
Fab8040 said:
I own 2 jvm410hjs heads and fm9 and i ve been able to obtain the same sound from both.. Basically satriani settings also on fm9... Everything at 11:00 or near that with a boost in front.. In my case or bb preamp or klon both with gain at zero or 0.5..the cab i use is evh 4x12 so with the 5153 speaker impedance curve.
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would be keen to hear both! and preferably without pedals first, just so the JVM410HJS amp modelling is isolated.
 
Orvillain said:
I actually did this a few months ago, and yes the preamp part of the amp does seem to be quite close. A/B'ing the real preamp with the Axe3's preamp (with power modelling turned off) does give a closer result.
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In that case poweramp sim settings and impedance curve would be where I'd look.

When I was comparing my real amps vs Axe-Fx 3 through a Fryette PS-100 into a few cabs, the impedance curve was the last thing that took them from "pretty similar" to "really close". I tried figuring out the impedance curve with the settings but it was just impossible to tune by ear, so for me the best solution was to just roll through the options until you find the closest match.

So maybe you can repeat the experiment with a few different 4x12 impedance curves and see if that shifts the frequencies up?
 
laxu said:
In that case poweramp sim settings and impedance curve would be where I'd look.
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it does seem to be poweramp related, but it doesnt seem to relate to pot tapers, valve types, bias, impedance curve etc, because they don't bring it closer. Myself and @Orvillain have both had lots of experience tweaking amps to get them sounding the same as real amps, and this model simply behaves differently to the real amp than other ones do. Its also not an amp that underwent different revisions or circuit tweaks.

I think it would be really helpful if anyone who owns the real amp, or has owned it and compared it can chime in (either saying they noticed the same, or saying how they addressed this).
 
Do you have the bright switch on in the Axe? At a gain of 5, it would make a difference. The capacitor value on the schematic is 470p, but it is in series with a 470k resistor, so it's effect would be lessened on the real amp.
 
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