Speaker Impedance Curve - how to use when doing a Tone Match?

[BBN]

I have the Fractal LB-2 Load Box and I'm using it, along with the Tone Match feature, to try and recreate my current tube amps.
I am trying to understand where to set the Speaker Impedance Curve while tone matching, as well as after I'm done tone matching?

Reason I'm trying to better understand this is because in the Speaker Impedance Curve cab options - there is a 'Fractal LB-2' option. My assumption (which may be completely wrong) is that this option (of LB-2) is there for a reason.
If my Amp is set with the LB-2 Speaker Imp. Curve BEFORE I do the Tone Match, does this make for a better match? And then I am meant to update the Speaker Imp. Curve to (let's say 4x12 SLO) if I am going to then use this preset with a SLO 4x12 cab?

Or am I supposed to use this Speaker Imp. Curve both before AND after I Tone Match as well, because it would help the Amp behave better with whichever speaker cab I use? (which doesn't make sense in my mind).

Curious if anyone knows when/why is the proper time to use the 'LB-2' Speaker Imp. Curve in their Axe III ??

 

[mr_fender]

The frequency response of your real amp is going to be slightly colored by the physical impedance curve of the LB-2 when you capture your reference signal for the tone match. If you choose the matching LB-2 SIC (US or UK) in the amp block as well it should give you a closer match to the real deal, so the tone match should have less to compensate for that part of the power amp's response. The reference output of the LB-2 will be the amp's raw output signal (without the coloration of the speaker), so your input signal from the Amp block should be taken before the cab block as well. The tone match is basically giving you the tonal differences between the two signals, so the closer you can get the input signal to the reference signal to start with, the more accurate your end results will be. In this case, using the LB-2 with the matching SIC, it's compensating for the minor tonal differences between the amp's and model's tone stacks, tubes, etc. separate from the influence of the cab.

When using the preset later with the tone match, you'll then likely want to change the SIC to match the cab IR you're using in the preset. That said, there are no hard and fast rules, so try it both ways and see which one you prefer.

 

[BBN]

The frequency response of your real amp is going to be slightly colored by the physical impedance curve of the LB-2 when you capture your reference signal for the tone match. If you choose the matching LB-2 SIC (US or UK) in the amp block as well it should give you a closer match to the real deal, so the tone match should have less to compensate for that part of the power amp's response. The reference output of the LB-2 will be the amp's raw output signal (without the coloration of the speaker), so your input signal from the Amp block should be taken before the cab block as well. The tone match is basically giving you the tonal differences between the two signals, so the closer you can get the input signal to the reference signal to start with, the more accurate your end results will be. In this case, using the LB-2 with the matching SIC, it's compensating for the minor tonal differences between the amp's and model's tone stacks, tubes, etc. separate from the influence of the cab.

When using the preset later with the tone match, you'll then likely want to change the SIC to match the cab IR you're using in the preset. That said, there are no hard and fast rules, so try it both ways and see which one you prefer.

Thank you.
I am planning on doing a 'live' tone match with my Tube Amp speaker output going into the LB2. I will have no Cab block in my chain because I plan on using this match with a Mesa 4x12 cab.
So I will do the match using the LB-2 SIC, and then after my capture is complete, I'll see how that works out....and mess around with the SIC options that match my Mesa 4x12, to see if it yields a better result.

 

[GreatGreen]

Tone Matching is nothing more than a high resolution EQ applied after an Axe-Fx amp model. The idea is that you setup an Axe-Fx amp model as close as possible to your real amp, then the Tone Matching process listens to your real amp and the model and applies an EQ to eliminate the EQ differences between the two. Setting both your real amp and the amp model with the same impedance curve simply starts both amps out that much closer to each other so the Tone Match doesn't need to work as hard. Matching the impedance curve of the model to the reactive load is especially important if you are setting up your amp such that its poweramp is clipping, as that curve will directly impact the specific kind of poweramp distortion amp generates as well, and that accuracy will help you to minimize the differences when you're doing your own tweaking on the model beforehand.


While you’re doing the Tone Match, set the Axe-Fx Amp’s impedance curve to the same curve as you’re using with your physical load box.

This will eliminate the “impedance curve” as a variable and make the Tone Matched amp model that much more accurate to your real amp.

After you Tone Match your amp, feel free to set the tone matched amp model’s impedance curve to whatever you want, as the Tone Match process will have already been done and your real amp will have been captured to the most accurate degree possible with the Axe-Fx.

 

[BBN]

Tone Matching is nothing more than a high resolution EQ applied after an Axe-Fx amp model. The idea is that you setup an Axe-Fx amp model as close as possible to your real amp, then the Tone Matching process listens to your real amp and the model and applies an EQ to eliminate the EQ differences between the two. Setting both your real amp and the amp model with the same impedance curve simply starts both amps out that much closer to each other so the Tone Match doesn't need to work as hard. Matching the impedance curve of the model to the reactive load is especially important if you are setting up your amp such that its poweramp is clipping, as that curve will directly impact the specific kind of poweramp distortion amp generates as well, and that accuracy will help you to minimize the differences when you're doing your own tweaking on the model beforehand.


While you’re doing the Tone Match, set the Axe-Fx Amp’s impedance curve to the same curve as you’re using with your physical load box.

This will eliminate the “impedance curve” as a variable and make the Tone Matched amp model that much more accurate to your real amp.

After you Tone Match your amp, feel free to set the tone matched amp model’s impedance curve to whatever you want, as the Tone Match process will have already been done and your real amp will have been captured to the most accurate degree possible with the Axe-Fx.

Thanks, this is what I did (today).

The results were very good. I did find that messing with the Impedance Curve (after I did the tone match, with the curve set for the LB-2), was very necessary to get it to sound close to my actual amp. I just let a loop run and I scrolled through all the options. I'm using a Mesa Recto 4x12 (traditional size), and the Impedance Curve for the PV6160 (I believe) was what worked best.

Would love some opinions on - what are some other settings that would make sense to 'mess with' (other than anything/everything).
I'm using a Marshall JMP-1 preamp (which is in the Axe), with my Marshall 100/100 power amp (which has 6L6s).
I 'think' the JMP-1 within the Axe is using either the JMC900 or the Jubilee power amp.
So I changed the Tubes (before I did the tone match) to 6L6s...but what else should I mess with?
I know I can just try lots of controls and see what 'helps', but there are many many many knobs to touch....curious if anyone has any suggestions on where to start?