{"product_id":"trilogy-931i-headphone-amplifier","title":"Trilogy 931i Headphone Amplifier","description":"\u003cp\u003eThe 931i is Trilogy's headphone amplifier — the 931, upgraded in 2019. The original brief was to keep the essential elements that made the 933 successful at a significantly lower cost. It is a fully discrete design with no generic integrated circuits, so Nic Poulson controls every crucial parameter of the active circuit and optimises it for this application alone. The small, light drivers in headphones sit very close to the ear and are ruthlessly revealing.\u003c\/p\u003e\u003cp\u003eThe audio circuit operates in pure single ended Class A with active constant current sources. Each channel has a single continuously biased output device, so the output is free from crossover distortion and the device is held at a constant temperature. An oversized linear power supply gives the active circuitry good operating headroom. Two stereo line inputs feed an audio grade ALPS volume control, and branded components are used throughout.\u003c\/p\u003e\u003cp\u003eThe output devices dissipate enough heat to need a heatsink. An extruded off-the-shelf part would have served; Trilogy uses a custom CNC machined one instead. Semiconductors are sensitive to mechanical vibration and their characteristics vary with temperature, so attaching the output devices to a high mass with a low resonant signature and large thermal inertia is worth the cost. Assembly is done entirely by hand in Trilogy's UK workshops. Standard finish is a soft natural silver, with lustrous paint finishes optional.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTopology:\u003c\/strong\u003e fully discrete, no integrated circuits; pure single ended Class A with active constant current sources; one continuously biased output device per channel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOutput power:\u003c\/strong\u003e 800 mW into 60 ohms; 200 mW into 300 ohms\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOutput impedance:\u003c\/strong\u003e 10 ohms or less\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInputs:\u003c\/strong\u003e 2 stereo line, 4 RCA phono sockets; 50 kohms or greater\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVolume control:\u003c\/strong\u003e audio grade ALPS\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGain (max):\u003c\/strong\u003e 18 dB\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFrequency response:\u003c\/strong\u003e 20 Hz – 20 kHz +\/- 0.5 dB\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDistortion (THD):\u003c\/strong\u003e 0.05% or less, 10 mW into 300 ohms\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSignal to noise ratio:\u003c\/strong\u003e 85 dB A weighted or better\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePhase:\u003c\/strong\u003e phase correct (non inverting)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDimensions \/ weight:\u003c\/strong\u003e 140 x 237 x 50 mm \/ 1.7 kg; 16 W\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Trilogy","offers":[{"title":"Default Title","offer_id":49211057537243,"sku":null,"price":2250.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1363\/6553\/files\/931i-TONE2_2000px.jpg?v=1788280129","url":"https:\/\/almaaudio.com\/products\/trilogy-931i-headphone-amplifier","provider":"Alma Music and Audio","version":"1.0","type":"link"}