Axe-FX III with Real cab vs. the Real thing

[DLC86]

The NC400 boards seem to be very popular in the "audiophile" community: https://www.soundimports.eu/en/hypex-nc400-mono-kit.html

They do need to be paired with an appropriate switching power supply though, although there are also models (NC500MP) which have it onboard but they are hard to come by for non-OEM customers.

Do you happen to know what's the difference between the UcD and NC series (aside from power ratings)?

 

[northern_fox]

Thanks a lot for the detailed response! So the larger rack amps like QSC or Crowns store more transient energy and would therefore reproduce those palm mute transients more consistently?

I had a crown macrotek 2402 for a minute that sounded incredible but also sounded like a jet engine with its fans, was 50+ lbs naked, full rack depth and required a 20A circuit - YMMV on what matter most

 

[OrganicZed]

Yikes. I bet that can add up if there are those additional sources coming into play that some
of us may not have considered before.

If you use a wireless system, a digital mixer, and power amplifier that has DSP the latency can be creeping into the low double digits before you add any amp modeling.

 

[ApocalypticKatana]

Possibly. Hypex has much better damping specs. Never researched Purifi.

A lot of it is about transient energy storage. A tube amp stores a LOT of energy. Take a typical 100W tube amp like a Diezel. It will typically have 220uF of reservoir capacitance and a B+ of 450V. The energy stored is 22.3 Joules!!!

Now take a typical consumer Class-D "500W" power amp (actual continuous power about 100W). They usually have voltage rails around 50V and 680uF or so of capacitance. The energy stored (assuming bipolar supplies) is 1.7 Joules.

The tube amp has over 13 times the energy storage. So those palm mute transients are reproduced accurately. The Class-D amp runs out of gas.

For example, if your transient duration is, say, 100ms, and you're pushing a full 100W then the energy required is 10 Joules. The Class-D amp simply can't do it.

It's one of my pet peeves. People use cheap, low-end, consumer grade Class-D power amps and then make bold proclamations that the models don't sound as good as the real amp without understanding even a lick of the physics involved.

I put an Axe-Fx through a Crown X2 once and it Marty McFly'd me.

I'd love a Tech Notes section I.E https://forum.fractalaudio.com/forums/tech-notes.77/

on this and maybe some recommendations on some power amps to pair with the fractal hardware or modelers in general

 

[deathbyguitar]

I'd love a Tech Notes section I.E https://forum.fractalaudio.com/forums/tech-notes.77/

on this and maybe some recommendations on some power amps to pair with the fractal hardware or modelers in general

I agree wholeheartedly. I also think it would be helpful to mention what specs are most important in a power amp. That way we can all look at spec sheets of different products and make informed decisions.

 

[yek]

The QSC GX are very good.

Yek runs off and buys loads of QSC stock

 

[TSantaCruz]

There are plenty of good solid-state power amps but they aren't cheap. The QSC GX are very good. Crown are probably good but not sure about latency.

I see that the QSC GX has a couple different circuitry options. The GX3 is class B and the GX5-GX7 are 2-tier class H. Which one do you think would be the better option?

 

[My name is mud]

What are the recommanded settings when you just put a amp block from the axe 3, in the return of a tube head + real cab ?
Thank you

 

[cole lewis]

I see that the QSC GX has a couple different circuitry options. The GX3 is class B and the GX5-GX7 are 2-tier class H. Which one do you think would be the better option?

H comes after B so it must be betterer

 

[Michael R]

@FractalAudio Would a SS power amp that has an output transformer do the job?

 

[BBN]

Hmm...I've got a bunch of Crown ITech's, maybe I'll give one a run this weekend in the basement.

 

[crdark]

There are plenty of good solid-state power amps but they aren't cheap. The QSC GX are very good. Crown are probably good but not sure about latency.

Even the small QSC GX 3 is too overpowered for me
I use the SD Powerstage 170 at lower volumes and I'm actually quite happy with the right speaker impedance curve in the AxeFX.

 

[Chris Hurley]

Cool. I have heard a few people mention using the resistive load when using a tube poweramp.

If you don't you tend to end up with too much of the speaker reactivity since you're getting it twice. Instead of using the resistive load type, you can also dial down the resonances if you prefer a little bit of the effect.

It also probably depends on which tube poweramp. There may be some that dampen the impedance curve effects with heavy negative feedback.

 

[alethomantis]

Do you happen to know what's the difference between the UcD and NC series (aside from power ratings)?

I believe the NC series is a newer design. Better performance across the board but I'd be hard pressed to tell what it means in practical terms.

 

[NeoSound]

We recently did a blind A/B test:

The cabinet was a stereo 2x12.

Into one side was a Deluxe Reverb. Into the other side was the Axe-Fx into a Matrix amp. The side which each was plugged into was randomized between tests.

The Axe-Fx's speaker impedance curve was set to match the cabinet (it's one of the stock curves). The knobs on the model were set to match the knobs on the amp.

The volume levels were matched.

A footswitch was connected to switch back-and-forth between the amp and the Axe-Fx. The tester was unaware which side of the cabinet was the amp or the Axe-Fx.

In every case the tester picked the device plugged into the right side of the cabinet as sounding "better", regardless of whether it was the Axe-Fx or the amp.

Form you own conclusions.

Wife always sat the left side of the tester?

 

[DLC86]

I believe the NC series is a newer design. Better performance across the board but I'd be hard pressed to tell what it means in practical terms.

Yep, yesterday I dug a bit deeper and the difference is basically that, the UcD is almost 20 years old, while the NC is being replaced now with two new series, NCx and Nilai, the latter being the best regarding noise, THD and output impedance.
But the price for those is definitely higher than the UcD series.

 

[lastcaress83]

What are the recommanded settings when you just put a amp block from the axe 3, in the return of a tube head + real cab ?
Thank you

https://wiki.fractalaudio.com/wiki/...e_power_amp_for_guitar_.28or_head_or_combo.29

 

[yek]

 

[Darrin66]

I'd love a Tech Notes section I.E https://forum.fractalaudio.com/forums/tech-notes.77/

on this and maybe some recommendations on some power amps to pair with the fractal hardware or modelers in general

+1

 

[lauke-lux]

You forgot a 5th choice

It's both OK but I prefer an FRFR backline and keep the possibility to choose different cab IR s (and not having to complexify my patches to adapt with a real speaker out and FRFR to FOH).

That's exactly my case

Edit : read the complete thread and thinks this is one of the best on the subject. Question : does this "stored energy" apply even for an FRFR backline?