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Excerpt From article
By Emile Menasché
Onstage, Jul 1, 2001
"Unlike most modeling amps, the Cyber-Twin doesn't use digital technology to replicate a collection of specific amps. Instead, the preamp section contains two 12A×7WA tubes. The performance of these tubes changes depending on which Drive Type you're working with; the amp actually switches hardware circuits so the tubes behave as they would on the original amps.
You get four types of tube amps to choose from, and each type offers a number of gain curves ranging from clean to dirty: Tweed Tube (three gain curves), Blackface Tube (three), Hot Rod Tube (three), and HMB Tube (three). The last one is designed to emulate a Marshall-type sound, and Fender's use of HMB (“Her Majesty's Bassman”) is a sly reference to the first Marshall amps, which were based on early Fender Bassman circuits. In addition to the tube sounds, you get a solid-state Dyna-Touch circuit, which offers four gain curves.
The Cyber-Twin's switchable tube circuitry would be cool enough, but the Tone Stacks take it over the top. Each Tone Stack digitally replicates the EQ circuit of a family of amps. Four types are represented: Tweed, Blackface, British (based on Marshall circuitry), and Modern. One of the Cyber-Twin's most powerful features is its ability to mix and match any Tone Stack with any Drive Type. You can also position the Tone Stack before or after the drive stage in the signal chain.
It's hard to overstate the Tone Stacks' effect on the character of each Drive Type. For example, a Blackface Tone and Blackface Drive combination yields a bright, relatively clean sound that's slow to break up. When it does, the overdrive emphasizes the upper end of the guitar spectrum, dishing out that trademark bell-like Blackface sound. Mate the Blackface to a Tweed Tone Stack, and the tone and gain structure change completely. The sound is darker, fatter, and quicker to reach saturation. Switch to the British Tone Stack, and things change again: now the midrange takes on a more solid flavor, and the Modern Tone Stack saturates the preamp for performance reminiscent of an early Mesa Boogie. Put the Tone Stack after the Drive Stage, and the tone changes again: it's thinner and more cutting, with less body. Through all these changes, you don't touch the amp's tone controls — but when you do, the behavior of each control varies depending on the Tone Stack and Drive Type. This is powerful and complex stuff.