Line 6 Helix Stadium Talk

[Lysander]

Null tests aren’t it but I wouldn’t want to abandon numbers if we can find a collection of measurements that are helpful in describing the behavior.

It's absolutely possible to quantify profiling performance in meaningful ways. LUFSs on null residuals just ain't it.

I'm convinced this trend came to be just because LUFS meters are pretty much standard on any DAW these days, and when you have a hammer...

 

[EOengineer]

There are some accuracy observations in this thread:

Post in thread '10 amp comparison'

Mar 22, 2026

I added the real Revv Generator MKIII I just picked up. It isn't mine, it is my mates. But my tech was looking at it, so thought I'd take the opportunity to bash on it a bit.

• Orvillain

• 

 

[MirrorProfiles]

Anecdotal, and i haven't shoot out all Agoura models yet, but the ones i have compared on my Stadium Floor sound very similar to good ole' HX - just more lively and dynamic.

The anecdotal experiences from you and others doesn’t seem to align with the actual audio for amps like the Rockerverb, 5150, SLO etc that have been posted in this thread. If there are amps that buck the trend, it would be great to hear examples as it may make it easier to determine the cause of the differences.

There are some accuracy observations in this thread:

Post in thread '10 amp comparison'

Mar 22, 2026

I added the real Revv Generator MKIII I just picked up. It isn't mine, it is my mates. But my tech was looking at it, so thought I'd take the opportunity to bash on it a bit.

• Orvillain

• 

These examples align with what I’m hearing too. Agoura often seems to need more extreme settings to match “normal” amp tones, and when things get pushed that extreme it doesn’t really sound natural.

FWIW I also consistently find Fractal models to sound darker than real world examples, and most of the tweaks I end up doing are to adjust for that. It doesn’t seem to straightforward to make that alignment in Agoura, and the differences seem a bit bigger than what I tend to find with Fractal.

 

[Orvillain]

I think the key quote I put in that thread:

Not once in my life have I ever turned up a treble or presence control on a real amp about 70-80% of the knobs travel, and gotten anything you could ever consider "dark"

And I really notice this on quite a few of the Agoura amps. The Quad Cortex EQ and depth/resonance or presence controls genuinely feel more akin to my real amps. More than Stadium and Axe FX III does even.

 

[AmuckRunner]

You can take two recordings of a real world amplifier, with the same DI signal running through it every single time, and those recordings will not null to -inf. But it doesn't mean the amp somehow changed; it didn't.

A deep null is useful. It tells you something. But it does not tell you everything, and it certainly does not prove equivalence or non-equivalence on its own.

you're right about -inf thing. But please note that i didn't mean null test number reflects every good and bad things in reproduction, as i mentioned "It is simply one of many possible performance metrics". My posted that reply to argue that null test is not totally meaningless.

"does it behave the same way, under all the conditions that matter?"

"all the conditions" is the hard part and null test comes handy even tho there are limitations you mentioned.
You can list up aspects of signal reprodution but, "how" is the question. Let's measure non-linear characteristics and responsible. I think it'll end up with another set numbers.

I think listening is far superior as a metric, even if it takes more work. All numbers can do is back up what you already hear. And if they don’t back up what you hear, they’re discarded because what we hear is the one that matters. The numbers are just fluff.

I agree. But we can't listen to everything. That's why i say null test is a guideline, not a hard rule to follow.

 

[Lysander]

The anecdotal experiences from you and others doesn’t seem to align with the actual audio for amps like the Rockerverb, 5150, SLO etc that have been posted in this thread.

Well, the Mandarin (Rockerverb 100 MKIII) happens to be one of the amps i tried against the old HX model and it's... very similar? Agoura is better in all the right ways, particularly when it comes to dynamics, but i'm definitely not getting these "drastic differences" you mention.

 

[MirrorProfiles]

Well, the Mandarin (Rockerverb 100 MKIII) happens to be one of the amps i tried against the old HX model and it's... very similar? Agoura is better in all the right ways, particularly when it comes to dynamics, but i'm definitely not getting these "drastic differences" you mention.

What do you think of the examples @Deadpan posted? Just curious on what your gauge of similar is

 

[Lysander]

What do you think of the examples @Deadpan posted? Just curious on what your gauge of similar is

I don't have a real MKIII to shoot it against, mind you, but it's interesting how the Agoura model sounds very close to @Deadpan 's own Proxy capture.

 

[EOengineer]

The anecdotal experiences from you and others doesn’t seem to align with the actual audio for amps like the Rockerverb, 5150, SLO etc that have been posted in this thread. If there are amps that buck the trend, it would be great to hear examples as it may make it easier to determine the cause of the differences.


These examples align with what I’m hearing too. Agoura often seems to need more extreme settings to match “normal” amp tones, and when things get pushed that extreme it doesn’t really sound natural.

FWIW I also consistently find Fractal models to sound darker than real world examples, and most of the tweaks I end up doing are to adjust for that. It doesn’t seem to straightforward to make that alignment in Agoura, and the differences seem a bit bigger than what I tend to find with Fractal.

In most cases I find my real amps through load boxes (or cabs) to have a liveliness and solidity to the topend that I still can’t get with a modeler.

Hx could get bright but usually not without getting somewhat brittle and weird in the representation of the top end and harmonics.

I pretty much have to go to my amps if I want anything really edgy.

 

[MirrorProfiles]

View attachment 60998

I don't have a real MKIII to shoot it against, mind you, but it's interesting how the Agoura model sounds very close to @Deadpan 's own Proxy capture.

Interesting - I found that although the old model was a little flat dynamically, its frequency balance seemed closer to his proxy capture, especially in the midrange and low end.

 

[Lysander]

I need to record a few clips with the test preset i made sometime this week, but with barely tweaked stocked presets Agoura and HX sounded very similar. Agoura feels much better to play thou.

Quite like the Mandarin HX, but i definitely like the Agoura version from 1.3 better.

 

[AZG]

Any news or hints about what is coming in 1.4 and when that might be? I know 1.2 was pre announced to be about Showcase, 1.3 about Proxy, but I don't remember anything about 1.4?

 

[Chocol8]

Regarding the discussion about null tests as a measure of accuracy of cloning.....

Null test is neither completely meaningless nor the ultimate measurement. It is simply one of many possible performance metrics. In my opinion, it is also a valid scientific measurement method. For example 'sum of error' is very standard way of measuring in signal processing field, I guess.

In a very specific case, where a clone reproduces the reference gear with 100% accuracy, the null test result would be negative infinity. There is no debate there.

If a clone is not infinitely perfect, then there are several possible outcomes. For example, clone X may reproduce transients better but be less accurate in the overall frequency spectrum. Clone Y may be better at mimicking note decay and cleaning things up. Clone Z may not be the best in either transients or spectrum, but may offer the best overall balance.

To those who argue that a single number cannot summarize the complex behavior of a cloned amp, I would ask: what is the alternative? Endless debate about what sounds better? And if you already have a well-established personal taste, then you probably do not need advice or guidance from others in the first place.

To follow the car analogy, imagine you are talking to two car dealers.

Car dealer 1:
“This car feels good, sounds nice, goes fast, and is fuel-efficient. That’s what I think, and other people agree.”

Car dealer 2:
“A number cannot represent the whole driving experience, but this car does 0–100 km/h in 5.3 seconds and gets XYZ MPG.”

Personally, I would choose dealer 2. Dealer 1 is not necessarily bad, but only if I can test the all available cars myself which takes much time and effort.

Coming back to modeling or cloning, a null test result cannot represent every aspect of the sound, but it can still be a useful guideline.

There is a lot you don't understand. Too much to retype, but to look for the discussion in the Kemper thread for where to start.

 

[fr8_trane]

Why would the old models suddenly be deemed inaccurate?

Theres a great video (link below) of a good player trying to dial in the HX Deluxe Vib to sound like his real deluxe. He ran into the same problem I did. The Deluxe vib is too bright and too scooped (as is the Twin). I actually commented saying the better comparison would have been the HX Deluxe Normal channel.

 

[Orvillain]

Dropbox

www.dropbox.com

Agoura Panama Blue (I know this is the OG - can't be helped right now!)
Axe FX III EVH5150III Stealth Blue
Quad Cortex EVH5150III Stealth Blue
Real 50-watt EVH5150III-50watt Stealth Blue