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

[Chris Hurley]

I haven't used the QC but I've used the others and I repeatedly rank the Fractal as the best of the bunch. Kemper would be my second choice even though it never sounded closer than "sorta close" any of the six or so times I had one. It isn't bad at all- it is noticeably different.

The Fractal is so close you can use it to see if a tube amp is doing something unusual. I had a Synergy Fryette module and I noticed some fizz on the note decay. I fired up the Fractal model of that amp and the fizz was there. Case closed.

The Fractal is a tractor trailer load of swiss army knives. I take that back... It is a sea-going tanker vessel full of swiss army knives. It is amazing what it does.

Still, I sometimes enjoy the experience of using a regular tube amp. I am certain that I am not alone. The tactile experience of the knobs and switches is gratifying to me at times. I also noticed that on a switcher I could get to where I couldn't tell a difference, if I played one for a while and switched to the other, I could tell a difference again and had to adjust a little more. Some of that may just be minor volume differences.

I would encourage people not to sell off anything that is hard to replace that they love in order to buy a Fractal. Something common that you can buy all day long? Sure- sell it off. Something special? You may eventually be sorry. I'm not taking anything away from the Fractal- it is awesome. I'm just saying a special tube amp that you can't easily replace? Maybe not.

 

[FractalAudio]

I should probably reiterate what I posted earlier:

MAKE SURE YOU SET THE OUTPUT MODE OF THE AMP BLOCK TO "SS PWR AMP + CAB".

The default output mode assumes the speaker is a monitor-type speaker. It models the compression of the guitar speaker and transient response and assumes the reproduction speaker is "ideal".

SS PWR AMP + CAB mode turns off the speaker modeling aspect because you're using a real guitar speaker.

 

[pipboy90]

Nice. Are you disabling power amp simulation? Also, which impedance curve are you using?

With the LXII, power amp simulation is enabled and I just choose whatever impedance curve sounds the best to me in terms of what tone I'm dialing in at the time.

Afaik the LXII is pretty much a stereo version of the Power Station poweramp.

In most aspects it is, but David Phelge from Fryette has said on TheGearPage that the LXII has higher quality transformers than the Power Station. His comment is here: https://www.thegearpage.net/board/index.php?threads/fryette-lxii-power-amp.2108247/#post-29759783

I should probably reiterate what I posted earlier:

MAKE SURE YOU SET THE OUTPUT MODE OF THE AMP BLOCK TO "SS PWR AMP + CAB".

The default output mode assumes the speaker is a monitor-type speaker. It models the compression of the guitar speaker and transient response and assumes the reproduction speaker is "ideal".

SS PWR AMP + CAB mode turns off the speaker modeling aspect because you're using a real guitar speaker.

Does the SS PWR AMP + CAB setting disable the Speaker Drive, Speaker Thump, etc, settings when selected, or do we still need to zero them out? If it doesn't disable them by default, could you make that happen?

 

[la szum]

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.

Smart people pay attention. Thanks, Cliff. Always a treat to see you breaking stuff like this down for the masses.

 

[JTI]

The problem is the "right" options to use it with aren't very plentiful. The Matrix I had was a quiet turd and there was a rash of "they don't support their products" postings on here. Whether that is true or not is up for debate I guess but it is a cause for pause. So that leaves the rest of these class D turds that are NEVER going to live up to be their equivalent of the FAS device you are connecting to it.


That's why I just run it through the Mustang FX return or some studio monitors and call it a day

 

[DLC86]

I had raised this question previously on this forum - whether Hypex or Purifi (high end class D) poweramps would yield better performance in a power amp + cab setting. I would be very curious to hear from the main man himself @FractalAudio, whether that would be an avenue to pursue?

This discussion made me look into hypex amps and found this site which sells diy kits:
https://www.soundimports.eu/en/ucd400-stereo-kit.html

On the same site just the board + power supply is around 240€ (not much more expensive than an icepower module) instead of 670€.. so the case and a few connectors seem to be a bit pricey

 

[AtomicBlaze]

(Lpc)

I changed my order to a LPC in alpine white.

 

[FractalAudio]

The problem is the "right" options to use it with aren't very plentiful. The Matrix I had was a quiet turd and there was a rash of "they don't support their products" postings on here. Whether that is true or not is up for debate I guess but it is a cause for pause. So that leaves the rest of these class D turds that are NEVER going to live up to be their equivalent of the FAS device you are connecting to it.


That's why I just run it through the Mustang FX return or some studio monitors and call it a day

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.

 

[lastcaress83]

MAKE SURE YOU SET THE OUTPUT MODE OF THE AMP BLOCK TO "SS PWR AMP + CAB".

The default output mode assumes the speaker is a monitor-type speaker. It models the compression of the guitar speaker and transient response and assumes the reproduction speaker is "ideal".

SS PWR AMP + CAB mode turns off the speaker modeling aspect because you're using a real guitar speaker.

My Matrix GT1000fx is arriving tonight. I’m stoked because I have doubts concerning the power section of my Tube Amp Expander. Is there anything else I should adjust for a power amp? Speaker drive? Thump?

 

[RevDrucifer]

Those do look really killer and tempting, it definitely has the look I am after. What is the neck profile like on those is it more of an ESP Eclipse shape or Gibson LPC shape, do they still make them or do you have to buy them used?

Right between an Eclipse and a Gibson LPC, I’d have to play either again side by side, but I do believe it skews more Gibson than ESP. It really doesn’t feel any different than the more recent LPC’s I’ve played (90’s/00’s models).

They just stopped making them in September, speculation is that they stopped after the Dean lawsuit to save themselves the trouble, even though they’re only sold in Japan, unless you buy on Reverb. I got mine on Reverb from a seller based in Japan, Gakkido, they took care of all the customs payments and everything, I just paid a flat fee and a week later it was at my door. With my Solar I had to pay for it to clear customs first. That said, there ARE still new/inbox models. I was the first person to touch mine out of the factory, it still had the foam wrap all around it and the factory string tag. I’m not sure how much longer you’ll be able to find new ones for, but for $1000, it’s pretty damn hard to shake a stick at!

 

[FractalAudio]

My Matrix GT1000fx is arriving tonight. I’m stoked because I have doubts concerning the power section of my Tube Amp Expander. Is there anything else I should adjust for a power amp? Speaker drive? Thump?

Turn Speaker Drive and Thump off to start. You may want to turn them up if you're listening at lower volumes.

 

[RevDrucifer]

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.

Watch out, that can go both ways; I use the PS170 and tell everyone how great it is with my FM9.

That said, if someone made something to power cabs with, or even powered cabs, that were perfect to pair with a Fractal unit, I’d rather own that than anything else. Hint hint winky face.

 

[pipboy90]

Turn Speaker Drive and Thump off to start. You may want to turn them up if you're listening at lower volumes.

Are Speaker Drive, Thump, and the other parameters still active when SS AMP + CAB is selected?

 

[alethomantis]

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.

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?

 

[alethomantis]

This discussion made me look into hypex amps and found this site which sells diy kits:
https://www.soundimports.eu/en/ucd400-stereo-kit.html

On the same site just the board + power supply is around 240€ (not much more expensive than an icepower module) instead of 670€.. so the case and a few connectors seem to be a bit pricey

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.

 

[la szum]

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.

Do amps with DSP add latency, and speakers connected to them with their own DSP??

 

[FractalAudio]

Do amps with DSP add latency, and speakers connected to them with their own DSP??

Yes.

 

[la szum]

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.

 

[bdrepko]

With the LXII, power amp simulation is enabled and I just choose whatever impedance curve sounds the best to me in terms of what tone I'm dialing in at the time.

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

 

[pipboy90]

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

I heard the same, but it makes the sound very flat and boxy. You’re essentially removing most of the low and high end from the sound, which is what happens with a real resistive load.

I reached out Fryette to ask what they recommended and they said to keep the impedance curves on, and even activate the presence and deep buttons on the front of the LXII if you prefer the sound. If it sounds good, it is good.

I can post the full email if you’d like.