Mercuriall released Spark

[Barmaleus]

@alteregoxxx

So I tried to translate your very tech question to my colleagues with no luck Being a non-developer myself it's hard to grasp the essence of the question.

Could you, if possible, write in a bit easier language or form the question a bit differently/more precisely? I'll then try again :DD

[alteregoxxx]

I agree in all you describe, but this happens inside the amp itself and has to be modeled.

The guitar is not affected because its is just loaded by the 1 meg resistance.

Nope.
Again, the guitar is loaded by the parallel of 1Meg ohm and the tube input impedance. And their parallel is not a constant value of 1 MOhm, hence, the signal that feed the Tube gets low pass filtered.

[alteregoxxx]

@alteregoxxx

So I tried to translate your very tech question to my colleagues with no luck Being a non-developer myself it's hard to grasp the essence of the question.

Could you, if possible, write in a bit easier language or form the question a bit differently/more precisely? I'll then try again :DD

Sure!

Amp Sim world signal chain:
Guitar-->D.I.-->Tube Amp Sim Input

Real world signal chain:
Guitar-->Real Tube amp input


Now:

D.I. input impedance = 1 MOhm @20Hz-20Khz, hence flat, constant, purely resistive in the audio band

Real Tube Amp input impedance= (tipically) 1 MOhm at 20Hz, decrease to 75 KOhm at 20Khz (I'm considering as example the JCM800 input stage) due to parasitic capacitance of vacuum tubes.

Guitar output impedance: high, Ohmic-Inductive-Capacitive

Coupling such an high output impedance voltage source (The guitar) to two systems having such a different input impedance (D.I. vs Real Tube amp) cause the signal that reaches the input stages, Amp sim vs Real amp, to be identical up to about 2Khz, but different from 2Khz to 20 Khz, up to about 3-4 dB.

Hope now is more clear, otherwise I can create and send you some LTSpice graphs

[jbraner]

Hi,
Does the demo version add some "crackling" noise besides the occasional dropouts? I'm not sure if it's something i need to work out or if it's just part of the demo

I'm not too bothered though - as I'm going to wait for ReAxis first (I think I'll prefer the Mesa sounds over the Marshall ones).

[jbraner]

To answer my own question - it was operator error.
Spark Demo works fine here - and sounds great! (once you dial in some sounds)

Let's see what the ReAxis launch and Black friday bring - maybe it will be worth it to pick them both up!
(I already have U530)

[jbraner]

Well, waddya know? A Halloween sale!
Bought.

Here's a question - what are the (eq) versions of the speakers? ie what is eq'd (to what)?
Anybody know?

[Barmaleus]

@alteregoxxx
Thanks a lot! This is much clearer, will translate and ask from wise people

@jbraner
Uh, sorry, I got no email notifications about your messages in this topic for some reason...
Glad Spark is working fine for you =) And thank you for your support!

The EQd versions of the cabs have less pronounced low frequencies resonance.

[jbraner]

The EQd versions of the cabs have less pronounced low frequencies resonance.

Thanks!

Spark is working great here!
I wish there was some sort of preset management though - outside of the DAW presets. SONAR is acting funny, and sometimes not saving them properly. I'm just making a set of "goto" presets to get started with - and as I go back to tweak them, there are FX set that I'm *sure* I disabled (and saved the preset).

After I'm comfortable with the models, I won't need the presets much - but they're good for getting started

[Barmaleus]

Indeed, no built in preset manager in Spark. Not sure yet if this is going to be addressed =(

There is a built in preset manager in ReAxis though! =)

[jbraner]

There is a built in preset manager in ReAxis though! =)

Woo Hoo!

[Barmaleus]

@alteregoxxx

So I tried to translate your very tech question to my colleagues with no luck Being a non-developer myself it's hard to grasp the essence of the question.

Could you, if possible, write in a bit easier language or form the question a bit differently/more precisely? I'll then try again :DD

Sure!

Amp Sim world signal chain:
Guitar-->D.I.-->Tube Amp Sim Input

Real world signal chain:
Guitar-->Real Tube amp input


Now:

D.I. input impedance = 1 MOhm @20Hz-20Khz, hence flat, constant, purely resistive in the audio band

Real Tube Amp input impedance= (tipically) 1 MOhm at 20Hz, decrease to 75 KOhm at 20Khz (I'm considering as example the JCM800 input stage) due to parasitic capacitance of vacuum tubes.

Guitar output impedance: high, Ohmic-Inductive-Capacitive

Coupling such an high output impedance voltage source (The guitar) to two systems having such a different input impedance (D.I. vs Real Tube amp) cause the signal that reaches the input stages, Amp sim vs Real amp, to be identical up to about 2Khz, but different from 2Khz to 20 Khz, up to about 3-4 dB.

Hope now is more clear, otherwise I can create and send you some LTSpice graphs

The answer I got - "We are modeling internal resistance of a guitar pickup and its interaction with the tube's input stage." Hope it makes sense =)

[jbraner]

Here's another quick question.

First let me say that I don't have a "real" Marshall, only these virtual ones

People use TS (etc) pedals in front of these amps, to increase the signal going in to the amp. I've noticed that that's what some of the presets do too - TS on max level, min drive - and it sounds great.

But we also have an input control, in the digital world - so if I increase the "input" level, is that really achieving the same thing as using a TS in front of the amp?
I play strats and a tele, so I keep the "input" low - around 2 or 3, and use my ears (there are no meters ) if I think I need to raise it (like on some clean settings).

So the real question is this:
What's the difference between sticking a stompbox in front of these amps - and raising the "input" level?
Thanks.

[EvilDragon]

Just raising input level is a clean boost. TS is never a clean boost

[Barmaleus]

Here's another quick question.

First let me say that I don't have a "real" Marshall, only these virtual ones

People use TS (etc) pedals in front of these amps, to increase the signal going in to the amp. I've noticed that that's what some of the presets do too - TS on max level, min drive - and it sounds great.

But we also have an input control, in the digital world - so if I increase the "input" level, is that really achieving the same thing as using a TS in front of the amp?
I play strats and a tele, so I keep the "input" low - around 2 or 3, and use my ears (there are no meters ) if I think I need to raise it (like on some clean settings).

So the real question is this:
What's the difference between sticking a stompbox in front of these amps - and raising the "input" level?
Thanks.

Rising the input level is like using hotter pickups =)
Using TS before the amp is like... well, going through the pedal's circuit, thus affecting the signal in a totally different way.

[jbraner]

Thanks for the replies.

Just raising input level is a clean boost. TS is never a clean boost

Well, I figured that - but is the virtual stompbox actually boosting the input to the amp? There are no meters

Rising the input level is like using hotter pickups =)

So what are the implications - other than (unwanted) distortion?
If I go too high, does it make the amp treat my strat signal like it's got hotter pickups?
I thought the "input" was just used to make sure you have "enough" signal going in to the amp (gain staging) because we're coming in through an audio interface, and we want a decent signal, but not clipping. I never considered using this "creatively", as in, "the Marshall is gonna sound really sweet because I'm giving it a hotter signal than normal"

If there was a meter here, I'd just be looking that there was "enough" (say -6db max) but not "too much" to cause clipping, or digital distortion.

Using TS before the amp is like... well, going through the pedal's circuit, thus affecting the signal in a totally different way.

Sure, but *only as far as signal level* - does raising the the TS "level" raise the signal going in to the amp just like the "input" knob does?
I know they're totally different types of signal - but just level...