Adventures in Fractal's Dual Rectifiers

[Orvillain]

When was the last time you retubed it? TBH the Axe-Fx sounds much better IMO. It's beefy and thick like a good Recto should sound. Your amp sounds anemic like the power tubes are worn out.

Oh lordyyyyy... I don't agree with that at all Cliff. No siree.

I think that high-end "smoothness" that the Axe has (and I think this is the same thing with the Satch JVM) is not really what we're after. These amps do seem to sound better and closer to our real ones, once you crank the HF Reso and preamp high-cut frequency.

Are there any other parameters we should tweak in order to add/restore that high frequency aggressive thing that makes your ears hurt, but that real amps actually do in spades?

<ducks>

 

[Orvillain]

The graph is too busy with repeating colors, I can't see much.
So does your real recto matches the model at lower master volumes?

Yeah, too many data points. I'll export a bunch of clearer ones and upload them.

 

[James Freeman]

Question, are the HF/LF Reso values in the Speaker tab multipliers from the nominal (flat) impedance?
ie. 16ohm nominal, LF Reso=7 so 16*7 = 112 ohm at the resonance peak?

Reason I'm asking is my gigantic DIY 1x12 has a quite narrow resonance peak at about 96Hz, it sounds massive with my tube amp and I want to replicate that.

 

[Orvillain]

So here are the "low volume" rectos overlaid...

Here are the mid volume ones:

And here are the loud as fuck ones:

Hopefully you can see that the Axe FX III Recto2 model flattens out in the high frequencies a lot more than my real one is doing. Now true enough, the Axe III graphs are measured across a wider volume sweep range. But above 2.5 on the Axe III definitely results in a more subdued high frequency range at these settings - only using the 'tone' page.

 

[FractalAudio]

So here are the "low volume" rectos overlaid...
View attachment 15368

Here are the mid volume ones:

View attachment 15369

And here are the loud as fuck ones:
View attachment 15370

Hopefully you can see that the Axe FX III Recto2 model flattens out in the high frequencies a lot more than my real one is doing. Now true enough, the Axe III graphs are measured across a wider volume sweep range. But above 2.5 on the Axe III definitely results in a more subdued high frequency range at these settings - only using the 'tone' page.

Turn down the MV and it won't flatten out as much. The reason it's flattening out is the virtual power amp is being overdriven.

 

[Orvillain]

Turn down the MV and it won't flatten out as much. The reason it's flattening out is the virtual power amp is being overdriven.

Yes absolutely! I'm not complaining, just comparing the behaviour across the model versus the real amp. I think the model is actually really accurate!

But again, 3 o'clock on the real amp is not really the same as 3 o'clock on the model. There are always going to be some amount of differences here I think; component tolerance variations are probably a big part of it. But I guess there is more to it than that.

 

[FractalAudio]

I have Mesa stamped STR 443’s in there that I bought new and haven’t been used a ton (bought them in the last year or so and I’m not gigging/rehearsing with the amp so it doesn’t get used that much). I can check my 6L6 stash for others but these should be fresh and in the right bias range for the amp.

I would say that I can match the tone of the Fractal amp by turning the master up or using a reactive load. But I can’t get the same range of tones from the model.

I have also matched this amp in the room pretty closely to a Dual Rec MW and Triple Rec. The Line 6 model also gets close. In all of those cases, the master volume changes how much of that top end sizzle is there.

Check your Speaker page. I just found a bug where the SIC isn't being loaded in some cases. It loads the Resistive Load SIC instead of the correct one.

If the curve is flat then go into the Advanced settings, make sure Auto Dyna-Cab Impedance is OFF and then select (or reselect) the desired SIC.

 

[Orvillain]

Bear in mind, the flattest one was with the master volume at 7:

The one that is closest to the real amp at 11 o'clock (master volume at 2.5):

They're roughly the same region of the knob travel.

 

[texhex]

I've just accepted that the AXE models match Cliff's reference amps and how they were modeled (tubes, effects loops, master volumes, build date of the amps, loads, and all the other factors, etc.).

Only in the cases, and they are rare, where after a new firmware update causes an amp I know in the AXE to be way off compared to how it sounded prior to the firmware update (i.e. a bug with the new model) or Cliff discovers some other bug afterwards. Other AXE users generally catch these too and they are reported and fixed. The JVMHJS and one of the Diezels had this happen a few firmwares ago and they were reported and fixed.

After I did the tone match test where the controls on the BE-100 were exact compared to my amp 2018 BE-100 (which I believe is the same version as the AXE), I'm comfortable knowing that if I can get the AXE model to sound the way I want it to, then I don't really care if it the dials match (because they won't).

If you have the exact same physical amp that is in the AXE, and you want the AXE model controls to match exactly, tone match it against the real amp with all the controls on 5 and it should match. I'm guessing that there would be cases where the MV would still be off though comparatively. Otherwise dial in the AXE models until you like the way they sound.

I frequently have to use some combination of the Treble, Presence and High Treble pots in the AXE but I also like my tone with a little more high end.

 

[Orvillain]

RE: FX loop tone-suck. Does that mean I should probably try to avoid 4-cable-method with a Recto??? Or just accept the tonal adjustment?

 

[FractalAudio]

Here is our reference Dual Channel Multi-Watt vs. the model. MV at 4.0, Presence at maximum. Green trace is amp, blue trace is Axe-Fx.:

This is with a high-level signal slamming the amp so the preamp is distorting fully.

Once my arthritis calms down a bit I'll go and lug the OG Dual Rec out of storage and measure that.

 

[FractalAudio]

RE: FX loop tone-suck. Does that mean I should probably try to avoid 4-cable-method with a Recto??? Or just accept the tonal adjustment?

Good question. The loop definitely sucks tone. Whether that loss is acceptable is something only you can answer.
The loop design is puzzling. It's a tube-buffered loop so the parts are there to do a nice, transparent loop but the implementation...

There's also a bright cap on the loop Output pot so you can tell they were trying to compensate for the tone suck.

 

[FractalAudio]

Here's the same test with the MV at around 2 o'clock on the amp. I had to raise the MV to about 3 o'clock on the model to match. This is not unusual as log taper pots aren't terribly accurate in that region.

 

[Orvillain]

Here's the same test with the MV at around 2 o'clock on the amp

Holy moly. Is that using a loadbox, or cab in the room?? Coz that would probably destroy the hateful neighbour two roads over from me!

 

[2112]

@MirrorProfiles I've never owned one of the Mesa 4x12's. They were unobtainium here for a long time! Would still love to grab an OS 4x12 some day for the full Recto experience.

I used to gig my Recto with a Marshall 1960A with G12T75's and Ragdoll's Back to Zero album was the same amp through a Marshall 1960BV with the stock Marshall branded V30's.

 

[FractalAudio]

Holy moly. Is that using a loadbox, or cab in the room?? Coz that would probably destroy the hateful neighbour two roads over from me!

A load box. If that were a cab my cats would be permanently traumatized.

 

[State of Epicicity]

 

[Jarick]

I never got along with Rectos as much as I tried, but I should spend some time with the models.

Absolutely love the constructive discussions here.

 

[FractalAudio]

Here's our OG Dual Rec compared to the model. Presence all the way up, MV around 9 o'clock. Nearly identical.

 

[eggpl@nt]

Here's our OG Dual Rec compared to the model. Presence all the way up, MV around 9 o'clock. Nearly identical.

View attachment 15385