Wish Blocks between Preamp and Power amp.

Tom Morris

Tom Morris

Power User
Would love to be able to put blocks in between the Preamp and power amp of the amp block. Was thinking maybe Preamp Send and Power amp Return blocks. Maybe add a loop page in the amp block to enable said loop? That way you could leave the amp block as it is now without splitting it into two blocks. Or maybe globally

I know its kind of a rare request but if you think about it, it would be more kin to an amp that has an FX loop.

For my needs I could really use two filter blocks in between the pre and power amp. Damn you Blackstar ISF!
 
+1

Always upvote more options and options that allow creative routing.

I do agree though, that you'd probably be hard pressed to tell the difference between just putting the effects after the amp and before the cab versus using this new 'virtual FX loop' in the amp. Interesting idea.
 
Budda said:
Isnt putting something after the cab block the same as an effects loop, tonally, or am I mis-remembering?
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It's not the exact same. If the power amp is running clean and linear, then your delays and reverbs and even EQs should end up with the same results regardless of order. But if you're using effects that aren't linear (like drive pedals or power amp distortion) then order matters. For instance, if you have power amp overdrive on your tone then your reverb or delay in the loop will also be overdriven by that.

Avoiding that with preamp distortion is exactly why effects loops exist. Reverb and delay are usually best done after all gain stages so the repeats don't get varying levels of distortion. The only reason effects loops aren't after the power amp is because handling 100w signals is much harder to do than line level, so effects loops are the real world compromise. So arguably, the Axe only allows the "better" or "idealized" approach, rather than the compromised real world one we have with effects loops.

But they are different. OPs example of wanting to filter the signal before the power amp is definitely one where filtering it after would have a different result if there's power amp distortion.

Tom Morris said:
Would love to be able to put blocks in between the Preamp and power amp of the amp block. Was thinking maybe Preamp Send and Power amp Return blocks. Maybe add a loop page in the amp block to enable said loop? That way you could leave the amp block as it is now without splitting it into two blocks. Or maybe globally

I know its kind of a rare request but if you think about it, it would be more kin to an amp that has an FX loop.

For my needs I could really use two filter blocks in between the pre and power amp. Damn you Blackstar ISF!
Click to expand...

Any way you could replicate those filters by using the Amp block Output EQ, positioning it pre-PA and creating a parametric curve which represents both those filters?
 
IronSean said:
It's not the exact same. If the power amp is running clean and linear, then your delays and reverbs and even EQs should end up with the same results regardless of order. But if you're using effects that aren't linear (like drive pedals or power amp distortion) then order matters. For instance, if you have power amp overdrive on your tone then your reverb or delay in the loop will also be overdriven by that.

Avoiding that with preamp distortion is exactly why effects loops exist. Reverb and delay are usually best done after all gain stages so the repeats don't get varying levels of distortion. The only reason effects loops aren't after the power amp is because handling 100w signals is much harder to do than line level, so effects loops are the real world compromise. So arguably, the Axe only allows the "better" or "idealized" approach, rather than the compromised real world one we have with effects loops.

But they are different. OPs example of wanting to filter the signal before the power amp is definitely one where filtering it after would have a different result if there's power amp distortion.



Any way you could replicate those filters by using the Amp block Output EQ, positioning it pre-PA and creating a parametric curve which represents both those filters?
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All this.
 
True on FX shouldn't matter. But as I said I'm trying to recreate an amp that isn't modeled and the only way to do that is with two filters in between the Pre and Power amp.

Then I still have an IR issue or recreating the line out of the amps simulation.

Just no damn way to recreate the BLACKSTAR HT100 MKII with the fractal.

I know people will say tone match it and capture your own IR. Even that won't recreate that stupid ISF circuit in the BLACKSTAR and whatever they did to the line out cab sim.

On the bright side I only have 2 more months of dealing with that amp so I will have two for sale if anyone is interested.
 
IronSean I don't believe so. Its two filters that sweep with one pot.

Due to the filtering it seems like there are two tone stacks. For low end its shifted higher than any amps in the AFX 300Hz area, closest amp I would say is the Solo 88 lead. Not sure on Mids its scooped yet lots of upper Mids. High end is really high so much so I cant find any IR from anyone that has that much sizzle, even with the cab block high set at 20,000.

If any anyone interested wants to read what's going on in the ISF circuit check out this page.
http://www.midboost.com/workbench/blackstar-fly-3#blackstar-fly-3-isf-circuit

All I'm really concerned with is the USA curve as they call it rather than the British.
 
Tom Morris said:
True on FX shouldn't matter. But as I said I'm trying to recreate an amp that isn't modeled and the only way to do that is with two filters in between the Pre and Power amp.

Then I still have an IR issue or recreating the line out of the amps simulation.

Just no damn way to recreate the BLACKSTAR HT100 MKII with the fractal.

I know people will say tone match it and capture your own IR. Even that won't recreate that stupid ISF circuit in the BLACKSTAR and whatever they did to the line out cab sim.

On the bright side I only have 2 more months of dealing with that amp so I will have two for sale if anyone is interested.
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I'm not sure why you want to recreate that exact amp though? They are not that unique sounding so suitable alternative should be easily found in the hundreds of amp models in an Axe-Fx.

Looking at the patent, plus the marketing, the ISF feature seems to aim to replicate what you get with different tone stacks. Well, the Axe-Fx can go way further than that because you can actually change the tone stacks! So to do what the ISF control claims to do, try experimenting with the different tonestack options in the amp block.

I don't think you will see the feature you are requesting because for the most part it's just not necessary. WIth input and output EQ options right in the amp block you already have super powerful shaping options on top of all the other advanced controls.
 
If you only care about the ISF circuit at one specific setting, then you don't need to replicate the whole thing with two filters, just create an EQ curve that matches it and put it after the amp (and this is actually exactly what tonematch is good at). You can also use the graphic EQ in the amp block and match the curve that way if you really need it between pre and post.
 
Hasn’t Cliff stated in the past he doesn’t want to separate pre and power amp modeling due to concerns with other brands being able to copy some of his algorithms ?
 
The ISF control very smoothly shifts the effect of the tone stack to higher and lower frequencies. It changes the practical value of the slope resistor and the treble pot in unison. That keeps the BMT tone controls relatively stable while shifting their overall effect up or down in frequency. Similar to a parametric frequency shift for the mid-cut. But, the ISF circuit shifts the whole tone circuit. An "American/Twin Reverb" tone stack works on frequencies a few hundred Hz lower than a "British/Plexi" tone stack. They were both created by Leo Fender. Leo largely used the low shifted tone stack. Marshall used the the more upwardly shifted tonestack (same as the '59 Bassman.) Both "American" and "British" tonestacks are the same circuit -- with different value components. "Tonestack Freq" on the "Preamp" page may already be handling the same function as an ISF control. That is, shifting the tonestack frequency contour effect to higher or lower positions in the amps bandwidth. Or, the "Tonestack Freq" control may simply be changing the virtual value of the slope resistor or the treble cap in the virtual tonestack. I can't say which, for sure -- I would like to know myself. But, I suspect it is the former.
 
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Postretro said:
The ISF control very smoothly shifts the effect of the tone stack to higher and lower frequencies. It changes the practical value of the slope resistor and the treble pot in unison. That keeps the BMT tone controls relatively stable while shifting their overall effect up or down in frequency. Similar to a parametric frequency shift for the mid-cut. But, the ISF circuit shifts the whole tone circuit. An "American/Twin Reverb" tone stack works on frequencies a few hundred Hz lower than a "British/Plexi" tone stack. They were both created by Leo Fender. Leo largely used the low shifted tone stack. Marshall used the the more upwardly shifted tonestack (same as the '59 Bassman.) Both "American" and "British" tonestacks are the same circuit -- with different value components. "Tonestack Freq" on the "Preamp" page may already be handling the same function as an ISF control. That is, shifting the tonestack frequency contour effect to higher or lower positions in the amps bandwidth. Or, the "Tonestack Freq" control may simply be changing the virtual value of the slope resistor or the treble cap in the virtual tonestack. I can't say which, for sure -- I would like to know myself. But, I suspect it is the former.
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Tonestack Freq frequency scales all the capacitors in the virtual tone stack. Even better than changing the slope resistor.
 
Is there anything that cannot be currently achieved with the existing tone stacks and Output EQ? (it is called output EQ, but you can set the location Pre-P.A)
 
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FractalAudio said:
Tonestack Freq frequency scales all the capacitors in the virtual tone stack. Even better than changing the slope resistor.
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This is so perfect. I love tube amps -- just pure love. I love tube amps by the ton. But, digital just out-mods tube amps by so much. Eventually, digital amps will be created from the ground up, out of virtual components that can't be manufactured, operating at virtual voltages that Tesla could only imagine -- while sleeping -- with switchable mojo algorithms. It's the end times -- signs and wonders.
 
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