Real Vox AC15 vs Default Axe

A

App12

Inspired
Borrowed a Vox AC-15 to compare with the Axe AC-15 (default preset). I am splitting the signal from my guitar to both and then switching between them. I have matched the knobs on the Axe to match those on the amp and monitoring through a 12” QSC. I know that there is the amp in the room vs a mic in front of an amp but the real amp just has a harmonic richness while the Axe sounds like it is under a blanket / a little subdued / not as rich. What can I try to get some of that richness back?
 
Well, the problem is that it is impossible to find a cab IR that replicates the way an amp sounds to your ears in a particular room, especially as you move around in that space.

The only way I can think of to get a truly valid "live in the room" A/B comparison would be to turn off the Axe's cab sim and feed the signal to as linear an amp as you can find, and drive that through the same kind of speaker as in the Vox, in as similar an enclosure as possible as the Vox. In other words, don't simulate the cab, but replicate it physically as closely as possible.
 
John nailed it. Just use the actual Vox speaker with the Axe (remove at least one of the wires connecting the Vox its speaker first.)

Or get an LB-2 and run the AC30 into an IR and through that same 12" QSC.
 
Thanks to both of you. I don’t expect them to sound exactly the same but the real amp is just more organic somehow and would like to capture some of that if I could. What speakers would you recommend @Admin M@ ?
 
I'd try to find an IR --- ANY IR --- that makes the K12 sound closer to what I was hearing. The DE-PHASE parameter in the cab might also help. Amp block and EQ is all you have left. It's really just not apples to apples. I'll leave FRFR recommendations to others.
 
If you were to separate the two halves of a Vox AC15 you'd have a small, naked "head", and a 1x12 speaker cabinet. To compare apples to apples, you want another copy of that cabinet that you can drive with your Axe Fx. So how would you do that?

Well, ideally you'd start with a 25W Celestion Greenback, since that is what is in a contemporary Vox AC15 combo amp. Then you would put it into an enclosure that is as similar to the AC15's enclosure as you can find (too many people discount or trivialize the impact the enclosure has on the final sound you hear). Then you would hook up a super clean power amp to that. Not a guitar amp, but an amplifier whose primary design mandate is to simply reinforce sound, not color it, which also means neutralizing or disabling its tone stack (if it even has one), and you're ready to rock and roll.

Obviously that isn't easy or cheap to do, but reaching a theoretical ideal never is. ;)
 
Haha thank John Cooper! Though maybe better off just buying my own Vox I’d say! Tried the de-phase parameter - thank you for the suggestion Admin M@ and will try some IR’s tomorrow to see what it does for me. The two are close but just missing something.
 
App12 said:
Thanks to both of you. I don’t expect them to sound exactly the same but the real amp is just more organic somehow and would like to capture some of that if I could. What speakers would you recommend @Admin M@ ?
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it's not more organic...it's just the way sound bounces around with an open back cab in a room. it's nothing to do with the amp or the Axe, it's not something you can replicate without using the cab itself.
 
[QUOTE=" The two are close but just missing something.[/QUOTE]

Try tone matching. A while back I was trying to get the 59 Bassman in the Axe FXII to sound like my real one with no luck. I set the Axe FX 59 Bassman knobs the same as my real one and used the closest IR I could find, then I miked up my real Bassman and did a tone match. It sounded pretty good. I was going to do the same with my Vox AC30 but haven't gotten around to it yet. I may try some of the things the others have suggested in this thread. Good info.
 
jlynnb1 said:
it's not more organic...it's just the way sound bounces around with an open back cab in a room. it's nothing to do with the amp or the Axe, it's not something you can replicate without using the cab itself.
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With the Vox I am hearing all the sounds from a 15” speaker bounce around my room. With the Axe/QSC I am hearing a 1” microphone (or whatever size it is) capture of a section of an original 15” speaker being played across the whole of my 12” speaker that is bouncing the sounds around my room. Depending on the mic, the number of mics used and their placement when creating the IR there is a lot of sound information that is probably not making it into the IR vs all the sound / frequencies / harmonics (however you want to define it) coming out of the actual amp.

As suggested, I will try out some IRs today and try do a tone match as well (thank you for that suggestion - would not have thought of it). Playing live or recording the advantages of the Axe far outweigh using a real amp but think I will look into buying an amp to be able to pull out when I want it.
 
What speaker is in your AC15? You may have a blue bulldog in it and it delivers a completely different sound than greenbacks.

That said, I can relate to what you experience and imho it’s got nothing to do with real cab in room vs. modelled miked cab. When I listen to records of me playing my miked real AC they sound fullbodied with rich harmonics. The records of me playing the model in the axe sound much less lively, even dull by comparison. I haven’t gotten around to do much tweaking in order to achieve better results, but those tweaks could surely only change nuances of the sound whereas the whole flavour is different. Haven’t tried to tonematch my AC yet though. IMHO the AC models are not the best in the Axe, other amps are way better modelled imho, eg. marshallesque ones.
 
guitardoc said:
...it’s got nothing to do with real cab in room vs. modelled miked cab.
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Indeed there are many factors that determine the results you'll get from an Axe Fx, but the difference between a real cab in an open room and a modelled mic'ed cab is certainly one of those factors, and it is going to be responsible in part for the kinds of differences the OP is detecting. Even if all the other relevant parameters in the sim were adjusted just right, the intrinsic difference between a live room cab and a cab IR would still impose its (unwanted) effect, and you'd more than likely need to take extra steps to compensate for it.

Now, it is not uncommon for cab IR alchemists to produce a reasonable simulacrum of that "in the room" sound by combining room mics and grill mics. This blend of mics yields a rough approximation of what the ear might hear at an average "playing position". But it is a fragile solution; walk around your AC15 and notice how different the amp sounds to your ears as you do so. By its very nature a cab IR can't really reproduce that phenomenon because the mics are placed in very constrained positions during impulse measurement and can't follow you around the room as you move in real-time. The modulation you'll hear instead is that of your amplified speaker system as you walk around it, which is not quite the same thing.

I think with enough tweaking you can always stumble upon a matched tone, but if the OP's goal is to set all the knobs on the sim exactly as they are on an actual amp, and make no other changes, the resulting comparison will always suffer due in part to the "live amp/cab in a room" syndrome.
 
App12 said:
With the Vox I am hearing all the sounds from a 15” speaker bounce around my room. With the Axe/QSC I am hearing a 1” microphone (or whatever size it is) capture of a section of an original 15” speaker being played across the whole of my 12” speaker that is bouncing the sounds around my room.
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I doubt that any of the factory IR's in the Axe or created that simply. IR's should also capture room effects as well.

As was pointed out, though, listening to an open back cab v. closed back cab is going to be hard to get over the "amp in the room" effect for comparison.

I have found a lot of variation in "openness" between factory IR's. Don't be scared to try an IR that doesn't seem to match the real cab too much, you might get different results. Pin the cab selection window and the audition as many IR's as you can.
 
Thanks to everyone for the feedback
And advice! So far I have not found an IR that captures the organic nature (or whatever you want to call it) of the real amp but will keep looking. Given that it is all just 1’s and 0’s I am sure that they will come up with a way to click a button to simulate the missing harmonic richness (or, again, whatever you want to call it). Till they do though, I picked up a lightly used AC15 to play when I want that amp in the room sound.
 
Here a real comparison: apples to apples :)

I have an AC15 H1tv handwired in my studio with an Alnico Blue speaker. For me, its way easier to get a better sound when i use axe fx and the same speaker (in this case the whole amp as cabinet) with matrix power amp. So in my case its literaly comparing axe fx to real ac15 both going through the same speaker. i dont think there is anything missing with the axe vox simulations.

Shoot an IR of the speaker if you have the tools, record axe with that IR and mic the Vox and record...that would give you the chance to really compare them with same speaker.
 
App12 said:
Thanks to everyone for the feedback
And advice! So far I have not found an IR that captures the organic nature (or whatever you want to call it) of the real amp but will keep looking. Given that it is all just 1’s and 0’s I am sure that they will come up with a way to click a button to simulate the missing harmonic richness (or, again, whatever you want to call it). Till they do though, I picked up a lightly used AC15 to play when I want that amp in the room sound.
Click to expand...

I think if you take your real AC15, put it in a different room and mic it up (with a decent mic of your choice), then play through that using your studio monitors or headphones then you will find the same issues that you have with finding the perfect IR. Of course the more you fiddle with the position of the mic on the amp's speaker you will eventually find the ideal tone, but in most cases this won't be the first position of the mic that works for you. IRs are basically the same, you need to search through a lot to find the one that captures that perfect 'position' for your preference.

I'm not sure it will ever be possible to catch that amp in a room sound with modelling IRs, but the AFX has definitely nailed it for studio/live use (i.e. unless if you go the Matrix/cab route then you get a better chance with amp in the room as well).
 
Hi again app12,
Also - have a fiddle with some room reverb - sometimes that can be the missing link though it may seem counterintuitive.
Thanks
Pauly
 
Ultimately, there is no way to exactly recreate the sound of a speaker cabinet in a room with FRFR. Just as you can't recreate the sound of a saxophone in a room, or a piano in a room or anything else. The speaker in cabinet is a resonating instrument in itself and should not be confused with speakers for sound reproduction: which is what FRFR does.

A sax has sound coming from the bell, sound from the keys, etc.: and it all mixes together in space. A guitar speaker cabinet has a resonance, and a speaker which is beaming a different frequency profile and phase relationship at various angles off the central axis and this all mixes together in space so that no location sounds exactly the same as any other: One step away sounds different, even to the extent that what one ear hears is subtly different from the other just by moving the head. This sense of subtle difference sounds "organic". An open backed cabinet and room reflections ups the ante. This is why engineers speak of a sweet spot for the mic: as every placement sounds different. And why IR mixes combining different mic placements might be preferred for a more general character profile. FRFR is designed to recreate sound that will be the same over a much wider field, and so has greater phase and time coherency in space. And a consistent sound field for an audience.

So, the choice is to use a cabinet and adjust amp models to work with the limited range that speaker allows. Which may be all one needs. Or use FRFR and have an infinite palette of speaker IRs to work with, which will open up a vastly greater range of amp tone options as well, but with a slightly different 3D experience. That said. I've been able to get very close to my actual speakers. A little reverb and enhance for in the room ambience from stereo output. Over the more than a year I've had the AX8: I've gone from preferring using a real cabinet to preferring FRFR in stereo for most situations.
 
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