Tube Tone With Out Tubes

[jonfields45]

An article not for the faint hearted, but interesting...

http://www.edn.com/design/analog/443...-without-tubes

[muscmp]

of course, these pedals were mostly used with tube amps, so that raises a big, HUH? would they turn solid state ones into tubes? uh, no! could you like them with any amp you use? of course since everything on the AGF is subjective. i just don't think so.

play music!

[donh]

The (click-bait) article ends by stating that tube sound only comes from tubes.

Tube sound only comes from tubes. Acoustic sound only comes from acoustics. Vinyl sound only comes from vinyl albums. Only organic carrots will taste like organic carrots. Only me will sound like me.

rock on . . . . . . . . .

[moon]

It's possible to make gold in a nuclear reactor.

But it's easier and cheaper just to go and get some gold.

[blue]

Wow... Pretty simplistic and narrow view of what tube tone is.

[jonfields45]

You guys are missing the point. The circuits that are used to create distortion without overdriving an actual tube amp are astoundingly simple, even the DSP based pedals, and all of them have their following of boutique minor variations. It is just an interesting look inside the little "black boxes". An actual circuit simulation of a simple tube amp, like a Tweed Deluxe, is still way beyond real time (and maybe impossible with acceptable phase delay). I found the piecewise DSP equation at the end interesting because even from a casual look you can see that it is not symmetric, which would be characteristic of overdriving a single final preamp tube stage, and I expected something more nuanced to combine class-A distortion of a final preamp stage with class A-B symmetrical distortion of a push-pull power amp (typical of everything more powerful than a Fender Champ).

[Archtop Guy]

There's a pretty good description of Line6's modelling equations on page 3.

BTW, as an EE and designer myself, I'll say that EE's have been talking / arguing about the whole tube / SS / modeling thing just as long as everyone else!

[zabdart]

Basically, the difference comes down to this: tube amps increase voltage, or the pressure of electrons flowing through a circuit, while transistors increase amperage or current. The significant difference is that if you hook your amp up to an oscilloscope and watch the differences in the sine wave it measures as you turn the volume up, once you pass the "clipping point" on a tube amp, the peaks and troughs of your signal will tend to flatten out, while on a solid-state amp they will get more pointy. Signal clipping is a strange sort of phenomenon. For some reason, when it occurs in a tube amp, you tend to lose some fidelity on your upper-order harmonics, while a solid-state amp will keep them intact and make them louder, and it's this characteristic which produces that "spikier" sound when a solid-state amp distorts.

[printer2]

once you pass the "clipping point" on a tube amp, the peaks and troughs of your signal will tend to flatten out, while on a solid-state amp they will get more pointy.

I don't know about that.

[donh]

Originally Posted by printer2

I don't know about that.

I do
.

[printer2]

Originally Posted by donh

I do
.

Well when scope a SS amp going into clipping I get squared off peaks, where the supply rails have no more to give. Not sure where the voltage comes from to get pointy above that.

[terrapin]

IMO, Tube tone without Tubes is a classic example of an Oxymoron.

[donh]

Originally Posted by printer2

Well when scope a SS amp going into clipping I get squared off peaks, where the supply rails have no more to give. Not sure where the voltage comes from to get pointy above that.

There is way more to it than this, but you did notice that the SS devices produce squared off peaks. Did you manage to notice that tube devices when overdriven produce rounded off peaks? Hmmmm?

Originally Posted by terrapin

IMO, Tube tone without Tubes is a classic example of an Oxymoron.

You got that right!!!!! :-)

[jetcode]

Much of getting a great guitar sound with tubes has to do with using tube rectifiers which sag when the signals run hot. This effect creates a natural compression. Speakers are part of the sound as well. I used a Zoom modeler years ago with a reissue Bassman 4x10 and it sounded killer. Some of the best rock guitar sounds I have ever heard. The Bassman makes a huge difference in the sound. Diodes do not sag. This makes for more headroom but less sweetness and no compression. When CBS took over Fender they switched to higher voltages for more power which resulted in louder amps with less tonal color.

While the digital domain is ripe for modeling a real guitar sound requires hardware not just DSP algorithms.

[redir]

Originally Posted by jetcode

Much of getting a great guitar sound with tubes has to do with using tube rectifiers which sag when the signals run hot. This effect creates a natural compression. Speakers are part of the sound as well. I used a Zoom modeler years ago with a reissue Bassman 4x10 and it sounded killer. Some of the best rock guitar sounds I have ever heard. The Bassman makes a huge difference in the sound. Diodes do not sag. This makes for more headroom but less sweetness and no compression. When CBS took over Fender they switched to higher voltages for more power which resulted in louder amps with less tonal color.

While the digital domain is ripe for modeling a real guitar sound requires hardware not just DSP algorithms.

Yeah even an electric guitar is ultimately heard acoustically.