AFIII Dual Recto with the LB-2 vs the Axe-Fx III and more

Guitarjon

Fractal Fanatic
Hey guys,

Got myself a Dual Rectifier, simply because I've wanted one forever.
It sounds really good through the Fractal X-Load LB-2, really love that device.

All this gear called for a comparison so that's what I made.
Would love to know your thoughts.
Don't want to say too much about my favorites yet but it's safe to say that the Fractal does a GREAT job!!

Enjoy:

 
Definitely your best video yet. Good job buddy! This confirmed two things that I always thought to be true. BIAS is one of the worst modelers out there and Overloud TH3 is the unsung hero. :)

I feel like with the Axe-Fx III you could get even closer by changing the speaker resonances around but I'm not at all sure how the loadbox reacts when compared to a 4x12.
 
Learn to do a real-time tone match and those tiny differences between the real amp and the model will be gone.

True, but when I dialed in the amp model I felt it was 'close enough' ;)
You're righ though, if I match the model to my amp (which I will soon) it will probably sound 99.99% the same.
 
The Axe-Fx had less treble than the real amp. This shouldn't be the case. Makes me think that the Hi-Cut was engaged in the Cab block or the Master Volume was too high. The Red mode of a Recto has no negative feedback so the highs compress very early on the MV knob. It is crucial to adjust the MV to get the right amount of power amp compression.

This is another great use of the Tone Match block. Set up a real-time tone match and use the Monitor page to observe the difference in frequency response between the model and amp. Set Drive, Bass, Mid, Treble and Presence to the same positions as the amp to start. If the plot shows the high end boosted then the MV is too high. If the high end is rolled off then the MV is too low. Once you've got the MV right you can fine tune BMT, etc.

In fact all the modelers and plug-ins had less treble than the real amp which makes me think something was amiss in the setup. It's possible that the input of the audio interface was being overdriven for the real amp recording. A slight bit of overdrive will add treble since it will add high frequency harmonics.

With all that said I felt the Axe-Fx was the closest but it should've been closer. I doubt there's that much difference between the Recto you used and our reference amp. Our reference amp is a relatively new one (probably 2014 or so) but I don't think the circuit has changed much, if at all, from the black diamond-plate version.
 
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The Axe-Fx had less treble than the real amp. This shouldn't be the case. Makes me think that the Hi-Cut was engaged in the Cab block or the Master Volume was too high. The Red mode of a Recto has no negative feedback so the highs compress very early on the MV knob. It is crucial to adjust the MV to get the right amount of power amp compression.

This is another great use of the Tone Match block. Set up a real-time tone match and use the Monitor page to observe the difference in frequency response between the model and amp. Set Drive, Bass, Mid, Treble and Presence to the same positions as the amp to start. If the plot shows the high end boosted then the MV is too high. If the high end is rolled off then the MV is too low. Once you've got the MV right you can fine tune BMT, etc.

In fact all the modelers and plug-ins had less treble than the real amp which makes me think something was amiss in the setup. It's possible that the input of the audio interface was being overdriven for the real amp recording. A slight bit of overdrive will add treble since it will add high frequency harmonics.

With all that said I felt the Axe-Fx was the closest but it should've been closer. I doubt there's that much difference between the Recto you used and our reference amp. Our reference amp is a relatively new one (probably 2014 or so) but I don't think the circuit has changed much, if at all, from the black diamond-plate version.

I didnt use any high cuts or filters in this video.
The master volume on the real amp was set higher than on the Axe Fx.
I used my Axe Fx III as soundcard and the level was nowhere near clipping.
For the real amp I used the cab block but with no room or pre amp engaged etc.
Maybe I'll try to get a little closer soon.
It would be interesting to try a tonematch too!
 
I didnt use any high cuts or filters in this video.
The master volume on the real amp was set higher than on the Axe Fx.
I used my Axe Fx III as soundcard and the level was nowhere near clipping.
For the real amp I used the cab block but with no room or pre amp engaged etc.
Maybe I'll try to get a little closer soon.
It would be interesting to try a tonematch too!

There isn't necessarily a 1:1 correspondence between the MV on the amp and model. The amp MV at 4 might be equal to the model at 1. All depends on the taper of the pot in the amp which changed over the years.
 
I'm not 100% sure but I think this is the new new new Dual Recto with the power switching capabilities right? It can sound a bit different to the older Rectifiers right? I've owned two Single Rectos, two Dual Rectos, a Rev G, Roadster and a Road King 1 and I would say many of them sounded different to each other. Usually the presence control reacted differently depending on the amp, channel and mode.
 
Here's a comparison of our reference mid-2010s Dual Rectifier vs. the model. Channel 3 Red Modern. All pots on the amp at 5 (noon) except MV which is around 4. Adjusted the model's MV so the Tone Match monitor display was flat which was also around 4. Had to increase the model's bass to 6 to match the amp which means our amp's bass knob is a little above nominal.

Clip order is:
Axe-Fx
Amp
Axe-Fx w/ Tone Match

www.fractalaudio.com/tmp/recto_test.mp3
 
Here's a comparison of our reference mid-2010s Dual Rectifier vs. the model. Channel 3 Red Modern. All pots on the amp at 5 (noon) except MV which is around 4. Adjusted the model's MV so the Tone Match monitor display was flat which was also around 4. Had to increase the model's bass to 6 to match the amp which means our amp's bass knob is a little above nominal.

Clip order is:
Axe-Fx
Amp
Axe-Fx w/ Tone Match

www.fractalaudio.com/tmp/recto_test.mp3
I ran that through Ozone and got this:


Just to be clear, that means that in this comparison the Axe-Fx still has around 1,5dB up to 2,0dB more high end with the bass knob at 6 while the Recto had it at 5 if I'm correct.

I've always been into getting the Axe-Fx to sound like my real amps without tone matching because that isn't IMO too difficult and this way I have more than a snapshot of the tone and I feel like I can use the EQ knobs just like the real thing. Here's a thread I posted way back of how I got my Axe-Fx II to sound like my Mesa Dual Rectifier Roadster (Road King's smaller brother): https://forum.fractalaudio.com/threads/quantum-recto-2-vs-mesa-boogie-dual-rectifier.104388/

Essentially my tips for matching my Roadster sound with the early Quantum firmware were:
  1. Master level really low. 1-2 matched my Roadster cranked. I set it at 1.5.
  2. Gain at 12 o'clock is the same but around 3 o'clock on the amp was close to 6.5 on the Axe-Fx.
  3. Speaker low resonance with my Mesa 4x12 cab was 103hz and Q at 1.0.
  4. Presence knob didn't react the same way. At 12 o'clock it was the same but I got closer by lowering the bass knob instead of touching the presence knob.
Just to be clear, this was comparing a Dual Recto amp sim to a Roadster that is the "more expensive" Dual Recto with more channels and all that so maybe the amp isn't quite the same even though I remember talking with @FractalAudio about the schematics and they looked identical.
 
I ran that through Ozone and got this:


Just to be clear, that means that in this comparison the Axe-Fx still has around 1,5dB up to 2,0dB more high end with the bass knob at 6 while the Recto had it at 5 if I'm correct.

I've always been into getting the Axe-Fx to sound like my real amps without tone matching because that isn't IMO too difficult and this way I have more than a snapshot of the tone and I feel like I can use the EQ knobs just like the real thing. Here's a thread I posted way back of how I got my Axe-Fx II to sound like my Mesa Dual Rectifier Roadster (Road King's smaller brother): https://forum.fractalaudio.com/threads/quantum-recto-2-vs-mesa-boogie-dual-rectifier.104388/

Essentially my tips for matching my Roadster sound with the early Quantum firmware were:
  1. Master level really low. 1-2 matched my Roadster cranked. I set it at 1.5.
  2. Gain at 12 o'clock is the same but around 3 o'clock on the amp was close to 6.5 on the Axe-Fx.
  3. Speaker low resonance with my Mesa 4x12 cab was 103hz and Q at 1.0.
  4. Presence knob didn't react the same way. At 12 o'clock it was the same but I got closer by lowering the bass knob instead of touching the presence knob.
Just to be clear, this was comparing a Dual Recto amp sim to a Roadster that is the "more expensive" Dual Recto with more channels and all that so maybe the amp isn't quite the same even though I remember talking with @FractalAudio about the schematics and they looked identical.
I was just trying to get in the ballpark. Had I spent more than a couple minutes I could've gotten the response within a dB. I didn't touch anything but MV and bass. Lowering the presence knob probably would've corrected that last little error. The knobs in an amp have tolerances typically of 20% which is huge. That means 5 on one amp might be equal to 4 (or less) on another amp or the model.

The point I was trying to make was that Jon's clips were much different than expected and my own recordings do not show the same marked difference even though the Axe-Fx was the closest of all the digital products tested. Every digital product lacked high end in comparison to the real amp which indicates a systemic issue.
 
I got that point across. I was actually trying to make the same point that even with just a few tweaks you can nail some real amps and you don't have to use tone matching for anything else but measuring how close you are. :) It's really interesting to hear about that 20% tolerance though. So when people share their amp settings you shouldn't stick to them 100%.
 
I got that point across. I was actually trying to make the same point that even with just a few tweaks you can nail some real amps and you don't have to use tone matching for anything else but measuring how close you are. :) It's really interesting to hear about that 20% tolerance though. So when people share their amp settings you shouldn't stick to them 100%.

A typical pot used in a guitar amp has a tolerance of ±20%. On top of that there is the matching of the taper. The taper can also be off as much as 20% at the midpoint.

So if we take, say, a 100K linear taper pot that's perfect it will have a resistance of 50K at the midpoint. We assume perfect pots in the models. However an actual amp may have a pot that's low by 20% so that would be 80K. If the taper is perfect then it's only 40K at the midpoint (20% error). If the taper is off then it might only be 32K at the midpoint for a total error of 36% (!!!). To get the same response on the model you would need to set that control to 3.6 instead of 5.0. That's an absolute worst case and I've never seen that but I routinely see pots that are 20% off at the midpoint.
 
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