Very late to the game on this one, I did try the demo quite awhile back, but just did not realize that the program allowed the user to tweak the internal parameters of the gain stages, including even the Koren’s triode model parameters for the individual tubes used in the ampfiliers! So what we have here is essentially a tube amp breadboard as much as Spice can be considered as one! Unlike all other guitar amp modelers on the market, Peavey has taken a different approach in the UI, this is really a program designed by geeks for other geeks 😉
However, ReValver was never meant to be a full-blown circuit simulator, after all, its target customers are guitarists not electrical engineers. So in the program, only certain components and selected parameters are at the users’ control, unlike Spice where everything single components can be customized. As for the tubes, the selection is limited to just a handful of commonly used audio types, and the gain stage only comes in one flavor – the common cathode amplifier aka the “Plate Follower”. Perhaps in the next release of the program, Peavey will offer pentode preamp tubes and other circuit topologies such as the cathode follower, paraphase and cathodyne phase inverters.
In any case, I think the program still offers an interesting alternative to try out various amplifier designs – perhaps a bit wacky I must admit, with the whole design process turned upside down – using a guitar amp modeler to come up with real amplifier designs, whoa?!
Anyway, I compared two versions of the AX84 SEL, by tweaking some of the bias parameters, while they did sound different, the differences were pretty minor, perhaps the changes I made was too subtle… Loading other models, especially those with cold-biased stages, then the difference in sound were quite dramatic. So more investigations are needed to find out just how much “granularity” we can get out of the simulator…
Given the large variation in real tubes’ parameters, even the possibility to get a rough idea of how the amp might sound is already better than Spice in my opinion. I think this can turn out to be a time-saver, at least, worth a try… Anyway, it is yet another tool to add to my ever growing design arsenal!