{"product_id":"heritage-audio-herchild-670-ardent-edition-stereo-tube-compressor","title":"Heritage Audio Herchild 670 Ardent Edition Stereo Tube Variable-Mu Compressor","description":"\u003ch2\u003eHeritage Audio Herchild 670 Ardent Edition Stereo Tube Variable-Mu Compressor\u003c\/h2\u003e\n\n\u003c!-- Video Section with Keyword Title --\u003e\n\u003cdiv style=\"margin:20px auto 10px auto; text-align:center; max-width:800px;\"\u003e\n  \u003ch2 style=\"font-size:20px; margin-bottom:12px;\"\u003eHeritage Audio Herchild 670 Ardent Edition Overview\u003c\/h2\u003e\n\n  \u003ciframe src=\"https:\/\/www.youtube.com\/embed\/Vmi2afERnFU?si=5gjHyNIaoVzJFwEE\" frameborder=\"0\" allowfullscreen style=\"width:100%; max-width:800px; height:450px; display:block; margin:0 auto; border-radius:8px;\"\u003e\n  \u003c\/iframe\u003e\n\u003c\/div\u003e\n\n\u003c!-- Section 1 --\u003e\n\u003cdiv class=\"par-section\"\u003e\n  \u003cdiv class=\"par-image\"\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0646\/4031\/9643\/files\/Heritage_Audio_Herchild_HA670_Ardent_Edition_front_on_view.png?v=1771376789\" alt=\"Heritage Audio Herchild 670 Ardent Edition stereo tube compressor\"\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"par-text\"\u003e\n    \u003ch2\u003eThe Ardent Modifications That Shaped Led Zeppelin III\u003c\/h2\u003e\n    \u003cp\u003e\n      In the early 1970s, the engineers at Memphis' Ardent Studios quietly modified their Fairchild 670 units with faster attack and release time constants — tuned to better serve the demands of modern tracking at the time. These changes were first put to work on Jimmy Page's acoustic guitar performances for Led Zeppelin III, and remained one of the studio's best-kept secrets for over four decades. Heritage Audio worked directly from the original handwritten modification notes, spending months with the Ardent team to nail every time constant to specification. The result impressed Ardent's engineers so thoroughly that they retired all four of their original Fairchild units and replaced them with Herchild models.\n    \u003c\/p\u003e\n    \u003cp\u003e\n      Produced only on request and in strictly limited quantities, the Herchild 670 Ardent Edition is handmade in Heritage Audio's factory in Madrid, Spain. Ownership means joining a list of artists and engineers who have recorded at Ardent — Led Zeppelin, ZZ Top, Stevie Ray Vaughan, Isaac Hayes, R.E.M., The White Stripes, Bob Dylan, and dozens more — all connected by the same modified Fairchild sound now available in reliable, serviceable hardware.\n    \u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003c!-- Section 2 --\u003e\n\u003cdiv class=\"par-section reverse\"\u003e\n  \u003cdiv class=\"par-image\"\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0646\/4031\/9643\/files\/Heritage_Audio_Herchild_HA670_Ardent_Edition_rear_view.png?v=1771376790\" alt=\"Heritage Audio Herchild 670 Ardent 22 tubes 9 transformers variable-mu\"\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"par-text\"\u003e\n    \u003ch2\u003e22 Tubes, 9 Transformers, and Program-Dependent Compression\u003c\/h2\u003e\n    \u003cp\u003e\n      Like the standard Herchild 670, the Ardent Edition is built around 22 NOS military-grade 6BA6 variable-mu tubes and nine custom transformers running at high voltage. This depth of analog hardware ensures the program-dependent soft-knee behavior that defines the Fairchild — compression that starts gently on small peaks and builds progressively toward brick-wall limiting on loud transients, responding to the music rather than a fixed ratio.\n    \u003c\/p\u003e\n    \u003cp\u003e\n      Direct front-panel access to the DC Threshold gives you continuous control over the ratio and knee from hard limiting to transparent compression, a feature the original required an internal screw to access. The all-tube sidechain circuit includes a high-pass filter with four selectable frequencies (50, 100, 200, and 350 Hz) to control low-frequency influence on gain reduction — an essential tool for modern mixing and mastering that the original never offered.\n    \u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003c!-- Section 3 --\u003e\n\u003cdiv class=\"par-section\"\u003e\n  \u003cdiv class=\"par-image\"\u003e\n    \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0646\/4031\/9643\/files\/Heritage_Audio_Herchild_HA670_Ardent_Edition_studio_view.png?v=1771376790\" alt=\"Heritage Audio Herchild 670 Ardent Edition LAT VERT mid-side four modes\"\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"par-text\"\u003e\n    \u003ch2\u003eFour Operating Modes Including Full LAT\/VERT Mid-Side Processing\u003c\/h2\u003e\n    \u003cp\u003e\n      The Herchild 670 Ardent Edition operates in four distinct modes. IND runs each channel independently for dual-mono use. LINK connects both channels with compression driven by the channel with the highest control voltage, giving you true stereo compression. LAT\/VERT provides full mid-side processing, compressing lateral and vertical elements of a stereo signal separately for increased mix width, depth, and focus. LAT\/VERT LINK does the same using the average control voltage of both channels.\n    \u003c\/p\u003e\n    \u003cp\u003e\n      These modes make the Ardent Edition equally powerful as a tracking compressor, a stereo bus processor, or a precision mastering tool. Extremely low distortion and self noise below -82 dBu mean it can sit permanently in the most critical signal chains. As an authorized dealer, Pro Audio Reserve ensures you receive a genuine Heritage Audio product backed by full manufacturer warranty and long-term support.\n    \u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003ch3\u003eHighlights\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eUltra-limited stereo Fairchild 670 recreation with Ardent Studios modifications\u003c\/li\u003e\n  \u003cli\u003eAttack and release times precisely matched to Ardent's modified vintage units\u003c\/li\u003e\n  \u003cli\u003eOriginally used on Jimmy Page's acoustic guitar tracks for Led Zeppelin III\u003c\/li\u003e\n  \u003cli\u003e22 NOS military-grade 6BA6 variable-mu tubes and 9 custom transformers\u003c\/li\u003e\n  \u003cli\u003eClass A, fully tube-based variable-mu compression\u003c\/li\u003e\n  \u003cli\u003eProgram-dependent soft-knee compression with progressive ratio\u003c\/li\u003e\n  \u003cli\u003eFront-panel DC Threshold for continuously variable ratio\/knee control\u003c\/li\u003e\n  \u003cli\u003eAll-tube sidechain circuit\u003c\/li\u003e\n  \u003cli\u003eSidechain filter: Off, 50 Hz, 100 Hz, 200 Hz, 350 Hz\u003c\/li\u003e\n  \u003cli\u003eFour operating modes: IND, LINK, LAT\/VERT (mid-side), LAT\/VERT LINK\u003c\/li\u003e\n  \u003cli\u003eFrequency response: 40 Hz – 15 kHz (±1 dB)\u003c\/li\u003e\n  \u003cli\u003eSignal-to-noise ratio: 120 dB\u003c\/li\u003e\n  \u003cli\u003eSelf noise: less than -82 dBu\u003c\/li\u003e\n  \u003cli\u003eTHD: less than 1% at any level up to +18 dBu (no limiting)\u003c\/li\u003e\n  \u003cli\u003eMaximum output: +30 dBu (clipping point)\u003c\/li\u003e\n  \u003cli\u003eInput impedance: 2 kΩ | Output impedance: 600 Ω\u003c\/li\u003e\n  \u003cli\u003e6U rackmount, handmade in Madrid, Spain on request only\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHeritage Audio Herchild 670 Ardent Edition Specifications\u003c\/h3\u003e\n\n\u003ctable style=\"width:100%; border-collapse:collapse; border:1px solid #ccc;\"\u003e\n  \u003cthead\u003e\n    \u003ctr style=\"background-color:#f2f2f2;\"\u003e\n      \u003cth style=\"text-align:left; padding:10px; border:1px solid #ccc; width:35%;\"\u003eSpecification\u003c\/th\u003e\n      \u003cth style=\"text-align:left; padding:10px; border:1px solid #ccc;\"\u003eDetails\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eCompressor Type\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eTube variable-mu compressor\/limiter\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eNumber of Channels\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e2 (stereo)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eCircuit Design\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eClass A, fully tube-based, handwired\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eTubes\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e22 NOS military-grade 6BA6 variable-mu tubes\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eTransformers\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e9 custom transformers\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eFrequency Response\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e40 Hz – 15 kHz (±1 dB)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eSignal-to-Noise Ratio\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e120 dB\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eSelf Noise\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eLess than -82 dBu\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eHarmonic Distortion\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eLess than 1% at any level up to +18 dBu output (no limiting)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eMaximum Output Level\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e+30 dBu (clipping point)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eInput Impedance\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e2 kΩ\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eOutput Impedance\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e600 Ω\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eTime Constants\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e6 Ardent-specific attack\/release settings (faster than standard 670)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eSidechain Filter Frequencies\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eOff, 50 Hz, 100 Hz, 200 Hz, 350 Hz\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eOperating Modes\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eIND, LINK (stereo), LAT\/VERT (mid-side), LAT\/VERT LINK\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eAnalog Inputs\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e2 x XLR\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eAnalog Outputs\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e2 x XLR\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eRack Spaces\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e6U\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eDimensions (W x H x D)\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e19\" x 10\" x 8\" (482 mm x 265 mm x 200 mm)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eWeight\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e29.3 lbs (13.3 kg)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003ePower Source\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eStandard IEC AC cable (\u0026gt;200W)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003e\u003cstrong\u003eManufactured\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eMadrid, Spain (ultra-limited, produced on request only)\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\n\u003ctable style=\"width:100%; border-collapse:collapse; border:1px solid #ccc;\"\u003e\n  \u003cthead\u003e\n    \u003ctr style=\"background-color:#f2f2f2;\"\u003e\n      \u003cth style=\"text-align:left; padding:10px; border:1px solid #ccc;\"\u003eIncluded Items\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eHeritage Audio Herchild 670 Ardent Edition Stereo Tube Compressor\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr style=\"background-color:#fafafa;\"\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003ePower Cable\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd style=\"padding:10px; border:1px solid #ccc;\"\u003eUser Manual\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Heritage Audio","offers":[{"title":"Default Title","offer_id":48015792111771,"sku":null,"price":10999.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0646\/4031\/9643\/files\/Heritage_Audio_Herchild_HA670_Ardent_Edition_front_view.png?v=1771376890","url":"https:\/\/proaudioreserve.com\/products\/heritage-audio-herchild-670-ardent-edition-stereo-tube-compressor","provider":"Pro Audio Reserve","version":"1.0","type":"link"}