Hi *, This is the second version of the Modeling Forum Community Posting. The intent of the post is to help in discussions between the differences between the terms "solid state", "digital", "emulator", "modeler", "profiler" etc. The post below is the summary of discussions involving a number of TDPRI people, please refer to the discussions on the first version of the post http://www.tdpri.com/threads/modeling-analog-digital-solid-state-community-posting.578753/ and to the original threads http://www.tdpri.com/forum/modeling...1482-modeling-analog-digital-solid-state.html and http://www.tdpri.com/forum/modeling...-emulating-digital-solid-state-draft-2-a.html to see the cast of characters contributing. If you have a strong disagreement with the post, it is useful to browse through those original discussions as your disagreement has almost surely been discussed at length. A lot of the disagreements boil down to differing points of view on ill-defined terms like "modelling". Here goes, hope this is helpful especially to newcomers! ------------------------------------------------------------- There's a lot of confusion surrounding the terms listed in the subject. For example we see posts confusing "solid state" with "digital" and "emulation" with "modeling". This post tries to clarify that confusion for the benefit of anyone reading. First let's talk about the terms that are well defined. 1) solid state: this is a pretty old fashioned term actually, all it means for the purposes of amplifier discussions is : no tubes. Technically it means that all the electronic components are constructed out of solid materials. Vacuum tubes are of course not solid -- that's the distinction. Solid state doesn't mean anything else except "no tubes". "Transistor" amps are solid state amps (as long as they don't contain some tubes too, in that case they are called "hybrids"). 2) analog/analogue and digital : analog circuits work on an incoming signal as a continuous value, and the various pieces of the circuit work in the same way. Digital circuits work basically on numbers, doing operations on those numbers. For a guitar amplifier, the input signal is converted to a sequence of numbers, then inside the amp calculations are performed on those numbers resulting in an output signal. Analog vs digital is not strictly related to solid-state/transistor/tube. All the combinations are possible, although digital tube amp (all tubes, no transistors or chips) would be as big as a house. There are even hybrids out there that have for example (the Vox Valvetronix) a tube-based analog preamp and a digital modeling section. In this post, we focus on digital modeling amplifiers since this is the digital forum (but see the final section for a couple remarks on this). Digital modeling amplifiers work by converting an input signal at some point to a stream of digital values, doing computations on this input signal, converting the processed signal back to analog so it can drive a speaker (or line out jack). The computations done are designed so that the analog output (or sound coming out of the speaker) sounds like a guitar coming out of a real amplifier, in most cases out of a specific amplifier like at 57 Twin, Vox AC30, etc. Manufacturers don't in general tell you exactly how their products are doing the calculations. There are a couple of known cases, and the others most likely work more or less in the same way. One way to do it is to have software that responds to a digital input signal in the same way that a component would respond to the corresponding analog signal. Now if you have such software for tubes, capacitors, resistors, etc, you can connect them all together so that you have a software version of a tube amp's circuitry, and in principle this software "model" of the amplifier will react to a guitar input signal the same way as the real amp. A specific example of an amp that does it this way, at least partially, is the Blackstar ID TVP series (you can dial in which output tubes are "used"). The challenge in this approach is that a real tube or transformer is a complex thing that responds in a different way depending on a bunch of factors; manufacturers will likely make compromises in how realistic the software is, to keep costs down. Another approach, taken as far as we know only by the Kemper Profiler, is to figure out what the software model should be by direct measurement. So instead of calculating the response component-by-component, their software directly (via a microphone) measures the end-to-end response of the entire amplifier. The calculations are often (always?) done in both cases by fast DSP (digital signal processing) chips. We had a lot of discussions here about various terms such as "profiler", "emulator", and "modeler". Profiler is pretty easy, see above ... so far as we know there is only one of these (the Kemper) so definition is easy in this case. We "decided" that an emulator was best defined as an amp that tries to recreate one or more specific amplifiers by making "virtual circuits" that are identical to the target amp's circuits. Examples are the Blackstar ID TVP already mentioned and the Fender Cyber Twin. The toughest definition is that of a modeler. The best "definition" we could give this is, any amp that can be configured to "sound like" multiple other amps, or that allows you to construct a very wide range of specific tones, by choosing different combinations of settings. Some objected that the profiler should not be called a modeler, saying a profiler works with a profile and a modeler with a model; on the other hand, in both cases the intent and much of the technology is the same. Hope this post helps further understanding and useful discussion in this forum! === Appendix We don't include analog amps in this forum, we do mention that analog modeling amps do exist, in the sense that the intent in those cases is to recreate, or at closely resemble, sounds specific to other amps: The Tech 21 Trandemark amps are based on the Sansamp pedals, which the company labels as "analog modeling" ... the "calif/british/tweed" switches on these analog amps have essentially the same purpose as the "Black Panel", "Brit Combo" and "Tweed" selector on a (digital) Roland Cube. The Peavey Transtube circuitry is analog, but designed specifically to reproduce how a tube circuit responds, just like the Blackstar TVP does in digital software One could take this to the extreme and even claim that an Egnater Tweaker could be called a modeling analog tube amp, given its switches "vintage/modern" and "usa/ac/brit"!