It is also compatible with the Heritage Audio Frame 8 and Rack 2 powered enclosures. The 8173 could be easily described as a 1073 with the mid bands of a 1081. We´ve decided to keep the 1073 Baxandall shelving lo and hi eq bands as they sound amazing, but have implemented a choice of 3 hi shelving frequencies, a la 1084. Special care has been taken in sourcing the correct components that ensure performance will be as close to a 1070s unit as it is possible nowadays. Custom polystyrene and film tone capacitors have been developed to closely match the Siemens Styroflex and Mullard Mustard types of the late 60s and early 70s. Custom input transformers have also been co designed with Carnhill Transformers´ Oxford factory to our special requirements. The Heritage Audio 8173 is entirely handmade in our facilities in Spain, employing the same old-fashioned wiring and soldering techniques of the 70s. All its circuitry is held into five plug in cards.