Wish Virtual FX Loop between preamp & poweramp

Ugly Bunny

Power User
Inspired by a thread on TGP, it would be neat to be able to put effects or a parametric EQ between the pre and power amp. Could be a toggle that would allow you to pop in a "vFX Loop Send" and "vFX Loop Return" ("v" stands for virtual) blocks and anything you want between them. This would allow you to goose the power amp section however you like or, if you like the particular way a delay hits the power amp, you could do that instead of putting the delay after the amp & cab blocks.

I understand that we can't separate the preamp and power amp due to IP protection, but a "closed" system like this would be great, I think.

(apologies if this has been wished for before; the search function is less than useful and I can't open the spreadsheet on this PC for some reason; mods feel free to delete).
 
IMO it would be unnecessary complication. You have a whole ton of tools you can put before or after each block to tailor the sound to your liking. Obsessing over what real amps do is not doing you, the player any favors when you can shape the sound way beyond what is possible reasonably in a real rig.

I think this same thing has been requested years ago already.
 
That's fair; there are those that would say the tone is different if you put, for instance, a parametric EQ before the preamp as opposed to before the cab, but i could be wrong. Maybe it's all the same or inconsequential. I just think someone like Cliff who can hear the difference between basically 27 identical power amp tubes would appreciate being able to put FX or EQs before the power amp vs after the power amp. Maybe it's all the same. I've never personally compared, so you're probably right. Again, this was inspired by a TGP thread who suggested a PEQ would be ideal before the power amp. Cheers!
 
+1

I have wanted this before as well, I really hate the effect the preamp has on delays and reverbs, but I love the way the power amp compresses and slightly distorts them. It is a lot more subtle than the preamp compression/distortion.

This is the way that I ran my effects before getting an FM3, the closest I have gotten is adding a tube comp at the end of the signal chain. Its not the same thing, but it keeps my levels more even when running heavy reverb or delay.
 
On Ax3 (not sure about FM3 but guessing the same), for EQ at least, this can be done by setting the amp block eq to "pre P.A."
 
+1 and why. Amps like Blackstar HT100 MKII have eq filters all over the damn place 7 if I'm not mistaken. I cant tell ya how many hours I've spent trying to get the AFX III to sound the same as that amp. In my opinion no, that amp shouldn't be modeled and added to available Fractal amps. But where your playing with someone that uses that amp its a real PITA trying to get even close.
 
On Ax3 (not sure about FM3 but guessing the same), for EQ at least, this can be done by setting the amp block eq to "pre P.A."
True, but this just the EQ. The wish is to make the amp block like a real amp with an FX loop where you could put your time-based effects so that everything passes through the power amp and then out to the cab.
 
True, but this just the EQ. The wish is to make the amp block like a real amp with an FX loop where you could put your time-based effects so that everything passes through the power amp and then out to the cab.
I was only referring to eq - we have the ability to move eq into a traditional loop position (not obvious to many I suspect) - agreed, it can't be done for other fx. I've wished for the same thing with different words (mix and match pre/power amps) - not holding my breath as its been asked for many times over the years, and often the reason cited as to why it's not possible is that it somehow reveals design secrets - I've never understood this reason and why IP is suddenly exposed if pre/pwr amps are separated, or why that security hole can't be closed. One can kind of
get around it using 2 amp blocks, one with power amp modelling off, and with the second one being a tube pre model with power amp parms copied from another model but not ideal since some power amp parms are not accessible to end users. Personally I don't have any particular affection for fx to be pre power section vs post but I understand some do.
 
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This is an interesting idea. For a while in the late 80's I had a Marshall 4211 2x12 combo. I had a Mk1 Quadraverb (the great, great grandfather of the axeFX) and Yamaha SPX50D in the FX loop. I found I could get a drive sound I liked from the pre, process it with delays and verb, then push the power amp to crunch things up a bit. This only worked at home, not on stage as it was a 100 watt amp, but the general idea of a 'clean' preamp tone + FX + power amp crunch makes me think this is what Alex Lifeson was doing around the Power Windows era of Rush.
I think it's a great idea.
 
+ 1000 on this wish list.
On a real amp with a loop, where do you put the FX? In the loop of the amp which is after the preamp and before the power amp!
No one says, "hey sound man, here is my FX processor, put it on the board's insert on my mic'd channel".
This makes complete sense, and I can not believe it has not been implemented.
 
I can not believe it has not been implemented.
not sure why you can't believe it - afaik no modellers facilitate it - as mentioned above and many times before, something about it exposing IP which is the part I'd like to understand the "why" of, and asked about several times here and elsewhere - don't think I ever even found an atrempt at an explanation anywhere.
 
+ 1000 on this wish list.
On a real amp with a loop, where do you put the FX? In the loop of the amp which is after the preamp and before the power amp!
No one says, "hey sound man, here is my FX processor, put it on the board's insert on my mic'd channel".
This makes complete sense, and I can not believe it has not been implemented.
Fx loops in real amps are a compromise because it's not so easy to have "post-amp" effects like it is on digital modelers without adding another poweramp in the mix (like a Fryette Power Station). Which is extra gear, cost and weight. All the fx you would use in the loop will sound better after the amp and you can run as much poweramp distortion as you want without the effects becoming distorted as well.
 
All the fx you would use in the loop will sound better after the amp.
Not sure that's universally true - some prefer the flavour of some fx into power amp distortion (not to mention wanting to isolate p.a. sound).

What intrigues me about this subject, is that an obvious use case / feature (fx after pre + before p.a. and/or isolating p.a.) is not provided in most/all modellers due to concerns about IP protection? say whaaaat? I get IP is a valid concern but what does modelling an almost universal amp design aspect (fx loops) have to do with IP protection?, and why is it impossible to allow users to isolate p.a. sound while protecting IP? - seems quite bizarre to me (but won't, when some day, I find out the technical reason).
 
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Not sure that's
universally true - some prefer the flavour of some fx into power amp distortion (not to mention wanting to isolate p.a. sound).

What intrigues me about this subject, is that an obvious use case / feature (fx after pre + before p.a. and/or isolating p.a.) is not provided in most/all modellers due to concerns about IP protection? say whaaaat? I get IP is a valid concern but what does modelling an almost universal amp design aspect (fx loops) have to do with IP protection?, and why is it impossible to allow users to isolate p.a. sound while protecting IP? - seems quite bizarre to me (but won't, when some day, I find out the technical reason).
I assume for IP protection if you could separate preamp and poweramp then it would be easier to reverse engineer the modeling by measuring each individually, how they interact etc.

But the people who want poweramp distortion with effects in the fx loop are going to be very few. I just don't see it being worth the dev effort to add the feature as it makes things more complicated for very little benefit.
 
I assume for IP protection if you could separate preamp and poweramp then it would be easier to reverse engineer the modeling by measuring each individually, how they interact etc.
yes - that's the typical answer but does not explain why? we have drive pedal models that can be isolated without IP concern afaik? we can turn off p.a. modelling and isolate the pre section without IP concern? what is it about isolating p.a. that's so unique / risky, and why can't those IP issues which have nothing to do with the user facing functional design, be mitigated without locking down a feature that would otherwise likely be provided?

But the people who want poweramp distortion with effects in the fx loop are going to be very few. I just don't see it being worth the dev effort to add the feature as it makes things more complicated for very little benefit.
There are lots of features provided that not so many use (though we don't really know very accurately who uses what), and, even if no one prefers fx in the traditional fx loop position, many have requested an fx loop feature in order to isolate + mix/match p.a. and pre models - it's a common and repeating request. Not providing it has nothing to do with demand for it, it's not provided due to obscure IP reasons (obscure at least to typical owners for which IP protection architecture in the product is not relevent to thier usage). Again, not saying its incorrect, just curious about the reasoning which is pretty much universally mysterious accross all modellers and most plugins.
 
Fx loops in real amps are a compromise because it's not so easy to have "post-amp" effects like it is on digital modelers without adding another poweramp in the mix (like a Fryette Power Station). Which is extra gear, cost and weight. All the fx you would use in the loop will sound better after the amp and you can run as much poweramp distortion as you want without the effects becoming distorted as well.
Why do real amp manufacturers add FX loops in an amp?
The answer is for the same reason we who would want this WISH to become a reality.
 
Not sure that's
universally true - some prefer the flavour of some fx into power amp distortion (not to mention wanting to isolate p.a. sound).

What intrigues me about this subject, is that an obvious use case / feature (fx after pre + before p.a. and/or isolating p.a.) is not provided in most/all modellers due to concerns about IP protection? say whaaaat? I get IP is a valid concern but what does modelling an almost universal amp design aspect (fx loops) have to do with IP protection?, and why is it impossible to allow users to isolate p.a. sound while protecting IP? - seems quite bizarre to me (but won't, when some day, I find out the technical reason).
I agree with you. Doesn't seem to make any sense why this could not be done and how separating the pre and power amp make it a risk???
 
I agree with you. Doesn't seem to make any sense why this could not be done and how separating the pre and power amp make it a risk???
Not providing it has nothing to do with demand for it, it's not provided due to obscure IP reasons (obscure at least to typical owners for which IP protection architecture in the product is not relevent to thier usage). Again, not saying its incorrect, just curious about the reasoning which is pretty much universally mysterious accross all modellers and most plugins.
I assume for IP protection if you could separate preamp and poweramp then it would be easier to reverse engineer the modeling by measuring each individually, how they interact etc.
don't think I ever even found an atrempt at an explanation anywhere.

As is so often the case, the information is out there. This is from Preamp and power amp modeling:
"It's not impossible but it has implementation difficulties. The main problem is that the amp block is nonlinear and therefore oversamples the data. Any effect inserted between the virtual preamp and power amp would need to also run at the oversampled rate which means many times the CPU usage. For example, if the amp block is running 8x oversampled then the CPU usage for any effect inserted would by 8x as much (I'm not going to disclose our actual oversample rate). The other way is to downsample back to native sample rate, run the effect(s), and the upsample again. No problem right? Except the no-free-lunch theory gets in the way. Downsampling and upsampling add latency." [14]
 
As is so often the case, the information is out there. This is from Preamp and power amp modeling:
yes, that speaks to inserting fx between pre / p.a., but not really to the more popular request to be able to just isolate p.a. models (turn preamp off), or, have dedicated p.a. models (Mesa 20/20, 50/50, Marshall 9100 ...) which typically draws in the mysterious IP related reasoning.
 
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Interestingly, of all the plugins and modellers I've had (and that's a sh#tload), Positive Grid's BiasAmp is the only one I came across that facilitates p.a. models isolation - too bad their stuff sucks to my ear.
 
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