Heritage Audio 8173 80 Series EQ

The Heritage Audio 8173 module is engineered to fill input module slots of the vintage 80 Series sound mixing consoles. 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. Heritage have decided to keep the 1073 Baxandall shelving lo and high EQ bands as they sound amazing, but have implemented a choice of 3 high shelving frequencies, à la 1084.

Special care has been taken in sourcing the correct components ensuring the closest performance to original units as possible. Custom polystyrene and polypropylene film tone capacitors have been developed to closely match the Siemens Styroflex and Mullard Mustard types of the late 60s/early 70s. Custom input transformers have also been co-designed with Carnhill Transformers' Oxford factory to Heritage's special requirements, ensuring correct harmonic distortion content and saturation points.

The Heritage Audio 8173 is entirely handmade in Heritage's facilities in Spain, employing the same old-fashioned wiring and soldering techniques of the 70s. All its circuitry is held in five plug in cards.

Features:

• 80 dB Class A microphone preamplifier, HI-LO selectable minimum input impedance, balanced and floating, high-gain positions show a higher impedance, ideal for old ribbon mics
• 10 dB Class A Line amplifier, bridging input impedance, balanced and floating Class A, single ended, 2N3055 driven high headroom output stage
• High Frequency: ±16 dB selectable frequency shelving at 10, 12 or 16 kHz, Baxandall type
• Low Frequency: ±16 dB with selectable frequency shelving of 35 Hz, 60 Hz, 110 Hz & 220 Hz, Baxandall type
• 1081 Upper Mid Frequency: ±18 dB peaking, fixed ‘Q’, selectable center frequencies of 1.5 kHz, 1.8 kHz, 2.2 kHz, 2.7 kHz, 3.3 kHz, 3.9 kHz, 4.7 kHz, 5.6 kHz, 6.8 kHz, and 8.2 kHz , inductor based
• 1081 Lower Mid Frequency: ±18 dB peaking, fixed ´Q´, selectable center frequencies of 220 Hz, 270 Hz, 330 Hz, 390 Hz, 470 Hz, 560 Hz, 680 Hz, 820 Hz, 1000 Hz, and 1200 Hz, inductor based
• High Pass Filter: 18 dB per octave slope, switchable between 50 Hz, 80 Hz, and 300 Hz, inductor based (although push button switches has been used instead of the classic rotary switch, the circuit is the same exact one found in vintage 1073s, sacrificing only one frequency choice for space issues, real estate is tight inside these modules)
• EQ Button: Switches the equalizer on or off
• Phase Button: Flips phase 180 degrees

Specifications:

• Microphone input impedance: HI, 1200 Ohm minimum, LO, 300 Ohm minimum, higher gain positions gradually have greater impedances, optimum for lo gain ribbon mics, input is transformer balanced and floating
• Line input impedance: 10 kOhms bridging, transformer balanced and floating
• DI input impedance: Greater than 2 Megohms, unbalanced
• Output impedance: Less than 75 Ohms, transformer balanced and floating, to drive a load of 600 ohms (factory terminated)
• Maximum output: Greater than +26 dBu into 600 ohms
• THD: Less than 0.025% at 1 kHz, less than 0.05% at 100 Hz
• Frequency response: 20 Hz (+0.3 dB) to 20 kHz (-0.2 dB)
• Maximum gain: Slightly greater than 80 dB
• Noise: Less than -100 dBu
• Power consumption: 110 mA per rail @±16 VDC