Those Seymour Duncan Powerstage amps are utter tripe

[Orvillain]

We could argue there's still something missing in the simulation or that it's still not 100% realistic, but what's already there is definitely redundant (frequency response being the most evident redundancy)

Even if the modeller has everything modelled, it still does not have a direct electro-mechanical relationship with the poweramp and the speaker. It simply isn't the same relationship that a valve poweramp has with the speaker.

The impedance relationship between a valve amp and its connected speaker is dynamic, in a way that a class D solid state power amplifier is not. It shifts and changes based on volume, voltage, and based on what the input signal into the amp is doing. The output transformer is a LOT to do with this too.

Again, I could be wrong and the more knowledgeable folk will correct me. But plugging a modeller - or even a tube based preamp for that matter - into a solid state amp and then plugging the solid state amp into a speaker, is not going to give you the same impedance reactivity as a valve amp would.

 

[Boudoir Guitar]

Even if the modeller has everything modelled, it still does not have a direct electro-mechanical relationship with the poweramp and the speaker. It simply isn't the same relationship that a valve poweramp has with the speaker.

The impedance relationship between a valve amp and its connected speaker is dynamic, in a way that a class D solid state power amplifier is not. It shifts and changes based on volume, voltage, and based on what the input signal into the amp is doing. The output transformer is a LOT to do with this too.

Again, I could be wrong and the more knowledgeable folk will correct me. But plugging a modeller - or even a tube based preamp for that matter - into a solid state amp and then plugging the solid state amp into a speaker, is not going to give you the same impedance reactivity as a valve amp would.

This is dumb. The whole point of a modeler is to model "connections" that don't physically exist. Its not like the speaker cab is acting in unpredictable ways that are impossible to model.

Have you figured out what causes the ball swelling? Allergy?

 

[Orvillain]

This is dumb. The whole point of a modeler is to model "connections" that don't physically exist. Its not like the speaker cab is acting in unpredictable ways that are impossible to model.

Have you figured out what causes the ball swelling? Allergy?

You simply don't understand the discussion topic.

We're not talking about modellers. We're talking about solid state amps.

 

[yeky83]

Even if the modeller has everything modelled, it still does not have a direct electro-mechanical relationship with the poweramp and the speaker. It simply isn't the same relationship that a valve poweramp has with the speaker.

The impedance relationship between a valve amp and its connected speaker is dynamic, in a way that a class D solid state power amplifier is not. It shifts and changes based on volume, voltage, and based on what the input signal into the amp is doing. The output transformer is a LOT to do with this too.

Again, I could be wrong and the more knowledgeable folk will correct me. But plugging a modeller - or even a tube based preamp for that matter - into a solid state amp and then plugging the solid state amp into a speaker, is not going to give you the same impedance reactivity as a valve amp would.

About Matching Your Cabinet's Resonant Frequency

This post is aimed at those who use a solid-state power amp into a conventional guitar cab. As is described in the post "About Speaker LF Resonance" a guitar cabinet has an impedance resonance in the low frequencies. This typically falls in the range of 50 to 100 Hz. A tube amp, being...

forum.fractalaudio.com

 

[DLC86]

Even if the modeller has everything modelled, it still does not have a direct electro-mechanical relationship with the poweramp and the speaker. It simply isn't the same relationship that a valve poweramp has with the speaker.

The impedance relationship between a valve amp and its connected speaker is dynamic, in a way that a class D solid state power amplifier is not. It shifts and changes based on volume, voltage, and based on what the input signal into the amp is doing. The output transformer is a LOT to do with this too.

Again, I could be wrong and the more knowledgeable folk will correct me. But plugging a modeller - or even a tube based preamp for that matter - into a solid state amp and then plugging the solid state amp into a speaker, is not going to give you the same impedance reactivity as a valve amp would.

Afaik fractal simulates all of that stuff and doesn't need to be phisically connected to the speaker to do so. If it has the SIC of the actual cab you're using (I've had the luck to have the SIC of one of my cabs added to the firmware) it should replicate all of those interactions correctly so, as Cliff has stated several times, the ideal setup is one with a perfectly transparent power amp.

Btw, a tube preamp and a modeler can't be considered the same scenario for the reasons above

 

[FractalAudio]

Yes, but (as far as I know, someone like @jay mitchell or @FractalAudio can correct me) a tube amp is not linear or static in this respect. The impedance interaction between the speaker changes across the frequency range, and certain styles of playing or certain note ranges will have a kind of response that is different to others.

At least this is what my ears tell me. I don't think it is the same thing as just linearly and statically boosting lows and highs like you would with an EQ.

I tried boosting the lows with the Powerstage 200 when I had it. It just made the whole thing sound even shitter. In fact adjusting the EQ at all coloured the signal in a really displeasing way.

Ignoring the effects of speaker displacement on speaker impedance the *voltage* out of a tube power amp is proportional to the speaker impedance. The speaker impedance is a function of frequency. This boosts the lows and highs.

The voltage clips at the power rails so the lows and highs clip before the midrange. Therefore when you push a tube power amp into clipping the mids get emphasized.

Negative feedback reduces the output impedance and therefore makes the voltage less dependent upon the impedance.

Most of these tube preamp things with integrated "power amp simulation" and IR loaders use a simple static EQ to model the power amp. The TMP also uses static EQ to model impedance dependency but "bakes it" into the IR (for some weird reason).

In a real speaker the impedance is dependent upon the speaker displacement. The voice coil inductance decreases as the coil leaves the gap. This makes sense because there's less magnet inside the coil and inductance is dependent upon the magnetic field. The low frequency resonance also changes with displacement via a more complex relationship. FWIW, our products model this stuff.

The moral of the story is that, yes, you can simulate a tube power amp (crudely) with a static EQ. It won't simulate the clipping but if it's a high-gain tone where the preamp is doing the distortion then it's probably good enough for that genre.

IMO "good" tube tone is a combination of preamp and power amp distortion. Relying on preamp distortion can make things sound a bit flat as preamp distortion lacks dynamics. Power amp distortion alone can be a bit flubby. If you balance the two you get a more dynamic experience with more "character".

 

[Orvillain]

Ignoring the effects of speaker displacement on speaker impedance the *voltage* out of a tube power amp is proportional to the speaker impedance. The speaker impedance is a function of frequency. This boosts the lows and highs.

The voltage clips at the power rails so the lows and highs clip before the midrange. Therefore when you push a tube power amp into clipping the mids get emphasized.

Negative feedback reduces the output impedance and therefore makes the voltage less dependent upon the impedance.

Most of these tube preamp things with integrated "power amp simulation" and IR loaders use a simple static EQ to model the power amp. The TMP also uses static EQ to model impedance dependency but "bakes it" into the IR (for some weird reason).

In a real speaker the impedance is dependent upon the speaker displacement. The voice coil inductance decreases as the coil leaves the gap. This makes sense because there's less magnet inside the coil and inductance is dependent upon the magnetic field. The low frequency resonance also changes with displacement via a more complex relationship. FWIW, our products model this stuff.

The moral of the story is that, yes, you can simulate a tube power amp (crudely) with a static EQ. It won't simulate the clipping but if it's a high-gain tone where the preamp is doing the distortion then it's probably good enough for that genre.

IMO "good" tube tone is a combination of preamp and power amp distortion. Relying on preamp distortion can make things sound a bit flat as preamp distortion lacks dynamics. Power amp distortion alone can be a bit flubby. If you balance the two you get a more dynamic experience with more "character".

Was hoping you'd chime in Cliff! Thanks in advance.

I guess central to this particular thread - solid state poweramps (like the Powerstage) - would you say it is possible to get the same speaker impedance reactivity when connecting one of these to your real world cabinet, when compared to a traditional valve amplifier connected to the same cabinet?

I understand this system can be modelled internally within the digital realm. My focus though is when you come out of the digital realm and back into the analog realm. It would seem to my laymen brain, that you lose the reactivity with the real physical speaker?

IE: Traditional valve amp into 4x12 cab is giving you an extra level of reactivity, that a valve preamp into a solid state poweramp and then into a 4x12, cannot give you.

I think you can even take modelling out of the discussion. I don't think it is very relevant.

 

[Boudoir Guitar]

You simply don't understand the discussion topic.

We're not talking about modellers. We're talking about solid state amps.

No. the issue is you are ignoring 1/2 of the discussion.

 

[DLC86]

I think the only thing a modeler can't replicate is the interaction with the outside world: a speaker, being a transducer, also acts as microphone and that is reflected on the impedance curve too (you can clearly see that the SIC changes if you measure it in different spots of a room or if there's some environmental noise), but those changes are tiny and pretty much irrelevant I think.

All other interactions are coming from stuff already modeled so I don't see why they couldn't be replicated.

 

[Boudoir Guitar]

Was hoping you'd chime in Cliff! Thanks in advance.

I guess central to this particular thread - solid state poweramps (like the Powerstage) - would you say it is possible to get the same speaker impedance reactivity when connecting one of these to your real world cabinet, when compared to a traditional valve amplifier connected to the same cabinet?

I understand this system can be modelled internally within the digital realm. My focus though is when you come out of the digital realm and back into the analog realm. It would seem to my laymen brain, that you lose the reactivity with the real physical speaker?

IE: Traditional valve amp into 4x12 cab is giving you an extra level of reactivity, that a valve preamp into a solid state poweramp and then into a 4x12, cannot give you.

I think you can even take modelling out of the discussion. I don't think it is very relevant.

Why what you lose what was modeled once you leave the digital world?

The issue isn’t whether the solid state poweramp can “recreate” something that has already been modeled. The issue is whether the power amp has an additional interaction with the speaker after one has already been modeled, or if the power amp has its own limitations that prevent it from providing an accurate analog of what was output from the digital parts at the desired level.

 

[Orvillain]

Why what you lose what was modeled once you leave the digital world?

I never said you lose what was modelled. I said you lose the reactivity with the speaker. Because the real world speaker that your SS poweramp is connected to, is not being loaded in the same way it would be with a valve poweramp.

So you have some reactivity in terms of the modelling with your amp modeller. But the real physical response of the speaker is different than it would be with your valve poweramp. You can have as much realism within the modeller as you want. But once it comes out of the digital realm, if you're putting it into a SS poweramp and then into a guitar cab, it literally isn't the same electro-mechanical relationship.

At least according to my understanding. I could be wrong, and I'd love for Cliff or Jay or someone else to clearly explain how.

And the reason I jumped in - just to state - is because this comment from @DLC86 :

I suspect the reason why some prefer this or tube power amps with modelers is exactly this emphasis on lows and highs that make all amps sound "bigger".

This seemed to me to be a misunderstanding about why people like valve poweramps. It has nothing to do with the lows and highs sounding "bigger" - or at least, that isn't the reason why. To me, the reason why is because the speaker has a specific kind of relationship with the poweramp, that you can hear and yes feel under the fingers.

Anecdotally, whenever I've used a solid state amp with my Axe FX 3 (although this is modeller agnostic) the feel has felt stiffer, less dynamic, less sag, and less of a push/pull feeling to the final output.

 

[Boudoir Guitar]

I never said you lose what was modelled. I said you lose the reactivity with the speaker. Because the real world speaker that your SS poweramp is connected to, is not being loaded in the same way it would be with a valve poweramp.

So you have some reactivity in terms of the modelling with your amp modeller. But the real physical response of the speaker is different than it would be with your valve poweramp. You can have as much realism within the modeller as you want. But once it comes out of the digital realm, if you're putting it into a SS poweramp and then into a guitar cab, it literally isn't the same electro-mechanical relationship.

At least according to my understanding. I could be wrong, and I'd love for Cliff or Jay or someone else to clearly explain how.

And the reason I jumped in - just to state - is because this comment from @DLC86 :


This seemed to me to be a misunderstanding about why people like valve poweramps. It has nothing to do with the lows and highs sounding "bigger" - or at least, that isn't the reason why. To me, the reason why is because the speaker has a specific kind of relationship with the poweramp, that you can hear and yes feel under the fingers.

Anecdotally, whenever I've used a solid state amp with my Axe FX 3 (although this is modeller agnostic) the feel has felt stiffer, less dynamic, less sag, and less of a push/pull feeling to the final output.

Ugh. The speaker impedance curve in the modeler is not about modeling the speaker. It’s about providing an accurate amp model.

If you get that right with a power amp that has high damping factor across freq etc response and can provide enough current to give an accurate analog of what it’s fed at the relevant level…all of which is highly questionable with the SD amps…the speakers are just there to move the air.

 

[Orvillain]

Ugh. The speaker impedance curve in the modeler is not about modeling the speaker. It’s about providing an accurate amp model.

If you get that right with a power amp that has high damping factor across freq etc response and can provide enough current to give an accurate analog of what it’s fed at the relevant level…all of which is highly questionable with the SD amps…the speakers are just there to move the air.

I never said that an SIC is about modelling the speaker. I don't know what it is about this concept that you're not understanding.

A speaker has a different relationship with a solid state poweramp amp than it does a valve poweramp. This electro-mechanical reality will have an impact upon the final tone, regardless of how advanced your modeller is.

 

[likitlikeyoulikeit]

 

[Boudoir Guitar]

I never said that an SIC is about modelling the speaker. I don't know what it is about this concept that you're not understanding.
. This electro-mechanical reality will have an impact upon the final tone, regardless of how advanced your modeller is.

Not if the relationship if the relationship it has is “yeah, we’re just here to move the air” (I.e., the amp has a high damping factor across the relevant frequency response) which is the part of the 1/2 of the conversation you seem unwilling to engage with.

 

[Orvillain]

Not if the relationship if the relationship it has is “yeah, we’re just here to move the air” (I.e., the amp has a high damping factor across the relevant frequency response) which is the part of the 1/2 of the conversation you seem unwilling to engage with.

But that isn't accurate. I am engaging with it. I'm telling you exactly what I think the differences are. Let me make it clearer:

Valve poweramp == Low dampening factor == speaker is able to move more freely == movement is to some extent more unpredictable.
Class D SS poweramp == High dampening factor == speaker is more controlled leading to a more precise response == movement is more predictable.

If your modeller is setup to give you a gooey squishy vintage style of tone, but you're using a Class D poweramp with a high dampening factor, then your modeller is setup to create one "feel" and your power amplification is setup to create another. There's an incongruence in the entire system there.

Speakers are not just there to move air.

 

[yeky83]

A speaker has a different relationship with a solid state poweramp amp than it does a valve poweramp. This electro-mechanical reality will have an impact upon the final tone, regardless of how advanced your modeller is.

The valve power amp interaction is modeled. And you can use a neutral power amp which is devoid of the interaction, to reproduce the modeled interaction.

If the modeling’s good and you know what you’re doing:
Modeled power amp interaction through a neutral power amp and speaker
=
Tube power amp and speaker

This has been covered many times over the years by the very people you’re asking explanations from, I already posted one link. You need to read it and try to understand. Here’s another:

Axe-Fx III Firmware Version 11.00 Public Beta

how did yall measure senior Cliff's infamous halfback?? That's two separate cabs in one

forum.fractalaudio.com

 

[Orvillain]

The valve power amp interaction is modeled. And you can use a neutral power amp which is devoid of the interaction, to reproduce the modeled interaction.

If the modeling’s good and you know what you’re doing:
Modeled power amp interaction through a neutral power amp and speaker
=
Tube power amp and speaker

This has been covered many times over the years by the very people you’re asking explanations from, I already posted one link. You need to read it and try to understand. Here’s another:

Axe-Fx III Firmware Version 11.00 Public Beta

how did yall measure senior Cliff's infamous halfback?? That's two separate cabs in one

forum.fractalaudio.com

You're gonna have to walk me through it. Pretend I'm stupid. Explain thoroughly.

 

[Boudoir Guitar]

But that isn't accurate. I am engaging with it. I'm telling you exactly what I think the differences are. Let me make it clearer:

Valve poweramp == Low dampening factor == speaker is able to move more freely == movement is to some extent more unpredictable.
Class D SS poweramp == High dampening factor == speaker is more controlled leading to a more precise response == movement is more predictable.

If your modeller is setup to give you a gooey squishy vintage style of tone, but you're using a Class D poweramp with a high dampening factor, then your modeller is setup to create one "feel" and your power amplification is setup to create another. There's an incongruence in the entire system there.

Speakers are not just there to move air.

Speakers are just there to move air. They may do other things, but the job of someone designing a neutral amp is to make sure those other things don’t impact the accurate reproduction of sound. Folks have been able to do this quite well for a long time.

 

[Boudoir Guitar]

You're gonna have to walk me through it. Pretend I'm stupid. Explain thoroughly.

On this topic, we don’t have to pretend