They generate different amplifier sounds based on digital models of various popular amplifiers. The models include Fender twin and deluxe, Mesa/Boogie Rectifier, Diezel Boutique, Krank Krankenstein, Vox AC30—and a large collection of Peavey amps like the 6505, XXX, and JSX. In addition to these amp models, these amps feature 11 editable pre-amp effects (All But Vypyr 15), 11 editable rack effects, on-board looper (Vypyr 30, 60, 75, 100, 120), MIDI input (Vypyr 30, 60, 75, 100, 120), and USB 2.0 connectivity (Vypyr 60, 75, 100, 120). The battery powered "Nano Vypyr" was introduced in 2012 as a competitor against other small portable modeling amps like the Roland Micro Cube and Fender Mini-Mustang. The Vypyr 60 and Vypyr 120 amps as well as the Vypyr 120 head feature 12AX7 and 6L6GC tubes. In 2013, an enhanced line of Vypyr amps was released. Called the "Vypyr VIP" series (short for "variable instrument input"), the VIP 1, VIP 2, and VIP 3 retain all the programmed models of the original Vypyrs, but also possess the ability to serve as acoustic guitar amps, as well as bass guitar amps. They are also programmable by way of computer software link. TNT series bass amplifiers The TNT Series bass amplifier first entered the market in the late 1970s as a 45-watt combo with one 15-inch speaker. The high-power TNT bass amplifier series was introduced as a 150–200 watt bass combo primarily equipped with a Scorpion or Black Widow 15-inch woofer. The TNT series was recently updated to 600 watts, under the title Peavey Tour TNT 115. It is currently the most powerful bass combo sold by Peavey. 400BH Series Bass Amplifiers The 400 BH power amp module was used in a range of bass amps during the early 1980s, commencing with the MKIII Bass Head in 1979. The MKIV Bass Amp head unit, introduced in 1981, offers a range of functions. It is air cooled, features protection circuitry, and is capable of around 300/350 watts RMS safely into 2 ohms. The 2 ohm load rating is very stable (this amp actually operates at less than 2 ohms), enabling the use of multiple mix and match speaker systems to improve acoustic efficiency and sound stage options. In contrast, typical modern musical instrument amps are usually limited to 4 ohms speaker systems. Circuit board layout is conservative, easy to access, repair or modify. Dynamics and reliability are excellent.