- Available as head or 1×12 Combo
- 2 channels ( High gain:Input 1, clean Input 2)
- Later Mark I models with reverb & graphic EQ
- Footswitch Gain Boost/EQ.
- Gain Boost Vol. 1
- Pull Bright Vol. 2
- Slave out
- Pre Amp / amp Junction Out
The very first Mark I was made in 1969, when Smith, as a joke, modified Barry Meltons Fender Princeton amplifier. He removed the standard 10 inch speaker and modified the chassis to fit the larger transformers that were needed by the 4-10 tweed Fender Bassman, the circuit that he had added into the 12 watt Princeton. Finally, mounting a 12 inch JBL D-120, a popular speaker of the time, Smith had created what would be the first Boogie.
Randall Smith took the hot-rodded Princeton into the front store. Coincidentally, Carlos Santana was present and played through the amp. Impressed, Santana told Smith, Man, that little amp really boogies!, thus providing the current name for the amplifier and the company.
The first Boogies are referred to as Mark Is, though they were not given this name until the Mark II was released. They were 60 or 100 watt combo amps with a 12-inch speaker, primarily Altec-Lansing 417-8H Series II. The Mark I had two channels: The Input 2 channel, voiced like the Fender Bassman, and the high gain Input 1 channel, which produced the overdriven Boogie lead sound used most notably by Carlos Santana on Abraxas, and by The Rolling Stones Keith Richards and Ron Wood, who used the amps live and in the studio from 1977 until 1993.
This amp in its original form is very collectable. Reverb was optional, and not present on many early Boogies. Later, Mark I models were available with reverb and/or graphic EQ.
Early models have slave out and reverb labeled on the back with Dymo stick; they do not have any pull lead capabilities on the volume controls. Later models had Pull Bright and Pull Boost on the volume controls. The front panel controls were Volume 1, Volume 2, Treble, Middle, Bass, and Master. These early models are fairly inconsistent, since many of them were custom models, made-to-order for various buyers.
Mesa/Boogie has stated the original and the reissue have a looser lead sound because the first two preamp stages occurs before the tone controls. In the later Mark II and III models, there is only one gain stage before the tone controls. This signal chain is an issue of some dispute among Boogie owners.