{"product_id":"thoress-dual-function-amplifier-dfamp-forforstaerker","title":"THÖRESS Dual Function Amplifier \"DFAmp\" Forforstærker","description":"\u003cp\u003eBestillingsvare - Forventet leveringstid 4-8 uger!\u003c\/p\u003e\n\u003cp\u003eOur Dual Function Amplifier (DFAmp) represents an ultimate implementation of a\u003cbr\u003eline control amplifier and a headphone driving amplifier, both functions of which are\u003cbr\u003eperformed by the same minimalist vacuum tube circuit with very low output\u003cbr\u003eimpedance. Such providing the amplifier with an outstanding ability to\u003cbr\u003esimultaneously drive long cable runs and headphones with an impedance as low as\u003cbr\u003e50 ohms or even lower. The DFAmp also features unique tone control facilities\u003cbr\u003e(timbre registers) and a custom designed remote volume control presented with\u003cbr\u003etypical THÖRESS style and attention to detail.\u003cbr\u003eThe sonic presentation of the DFAmp is of utmost refinement in line and headphone\u003cbr\u003edriving mode and thus will easily measure up to the highest expectations of every\u003cbr\u003ediscerning music lover. And as such is perfect complement to our Parametric Phono\u003cbr\u003eEqualizer and our all-tube or EHT Mono Amplifiers.\u003cbr\u003eBUILT\u003cbr\u003eThe amplifier is built with meticulous hand construction using our proven point-topoint wiring techniques. Much care has been taken in arranging each aspect of the\u003cbr\u003einternal construction to ensure low noise performance, ease of service and the\u003cbr\u003ehighest reliability, and for many years to come.\u003c\/p\u003e\n\u003cp\u003eTOPOLOGY\u003cbr\u003eThe amplifier is entirely based on SINGLE-ENDED ZERO-FEEDBACK schematics.\u003cbr\u003eDecidedly ignoring the fact that many music lovers still persistently believe in the\u003cbr\u003emyth that balanced technology (and the associated cable configuration with XLR\u003cbr\u003econnectors) is generally superior to single-ended concepts. Readers who want to\u003cbr\u003elearn more about our view on balanced techniques and our general design approach\u003cbr\u003eare encouraged to read the paper (THÖRESS - Behind the Curtain) downloadable on\u003cbr\u003ethe ABOUT button of our website. More specifically, the circuit of the DFAmp consists of a 12J5GT triode gain stage\u003cbr\u003efollowed by a unity-gain current buffer employing a 12GN7 power tube operated in\u003cbr\u003etriode mode with high idle current. The 12J5GT an octal-base single-triode from the\u003cbr\u003efamous ?J5\/?SN7\/?A4 family of tubes with fairly low transconductance developed in\u003cbr\u003ethe early times of tube electronics. Whereas the 12HG7 is a fairly late (all-glass)\u003cbr\u003edevelopment with high gain and very high transconductance, making it an ideal\u003cbr\u003echoice for buffer applications. Both tubes are unarguably among the most linear\u003cbr\u003eamplification devices ever developed in the history of electronic technology and as\u003cbr\u003esuch are a perfect choice in the context of minimalist zero-feedback circuit design.\u003c\/p\u003e\n\u003cp\u003eGT SELECTOR\u003cbr\u003eThe DFAmp allows for subtle tone control via 4 on-the-fly selectable preset timbre\u003cbr\u003eregisters on two different gain levels implemented by means of a 6-position rotary\u003cbr\u003eswitch which we call GT Selector (G\/AIN and T\/ONE, Empfindlichkeit \u0026amp; Klang).\u003cbr\u003eNotably, the timbre registers do NOT rely on conventional clumsy and sound\u003cbr\u003edestructive tone control circuitry. Each register is realized smartly by interposing\u003cbr\u003esolely one additional capacitor (per register and channel) to the circuit! Two\u003cbr\u003epositions of the GT selector are assigned with neutral tonality (perfectly flat\u003cbr\u003efrequency response). The mapping between selector positions, gain and sound\u003cbr\u003eeffects is described by the chart below.\u003cbr\u003ePosition 1 2 3 4 5 6\u003cbr\u003eGain (-)6db (-)6dB (-)6dB Full gain Full gain Full gain\u003cbr\u003eBass Bass(+++) 0 Neutral Bass(++) Bass(+) Neutral\u003cbr\u003eTreble Treble(++) Treble(+) Neutral 0 0 Neutral\u003cbr\u003eThe timbre registers are useful for restoring tonal imperfections of the listening\u003cbr\u003eprogram, often given by a lack of extension on one or both ends of the audio band.\u003cbr\u003eAnd for equalizing the response of individual headphones. The tone function\u003cbr\u003eassigned with pos1 of the GT selector can also be used for counteracting the\u003cbr\u003eloudness effect (weaker perception of bass and treble frequencies at low listening\u003cbr\u003eloudness). In practice, a combination of all three equalizing purposes will likely be\u003cbr\u003esimultaneously applicable.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003eVOLUME CONTROL\u003cbr\u003eA high grade motor-driven dual-potentiometer is employed for (manual and remote)\u003cbr\u003evolume control. These parts are made to our taper specifications by ALPS in Japan so\u003cbr\u003eas to allow for conveniently fine volume adjustment. Each individual potentiometer\u003cbr\u003eis selected from a large production batch for exceptionally good channel balance\u003cbr\u003ewith respect to rotational angle by careful measurement.\u003c\/p\u003e\n\u003cp\u003eOUTPUTS\u003cbr\u003eThe circuit of the DFAmp simultaneously terminates in a frontal toggle switch which\u003cbr\u003efeeds two adjacent 2x6.35mm jack socket headphone outputs KH1 and KH2, and a\u003cbr\u003etriple output on the rear panel (master output, 3x2 RCA jacks). The master output\u003cbr\u003ejacks are connected to the circuit permanently whereas KH1 and KH2 can be\u003cbr\u003edisengaged by setting the toggle switch to the middle position. Thanks to the triple\u003cbr\u003eoutput it is possible to simultaneously drive up to three power amplifiers or two\u003cbr\u003epower amplifiers and an active sub-woofer module without further adaptation. \u003c\/p\u003e\n\u003cp\u003eINPUTS\u003cbr\u003eThe DFAmp comprises 6 line level inputs (2x6 RCA jacks) divided in 3 groups with\u003cbr\u003edifferent gain and input impedance characteristics as described below.\u003cbr\u003eHigh Gain on Inputs #1, #2, #3\u003cbr\u003eThe gain on inputs #1, #2 and #3 is 26dB (20-times) when the GT selector rests in\u003cbr\u003epos4\/5\/6 and 20dB (10-times) for all other selector positions, pos1\/2\/3. These\u003cbr\u003einputs have a comparatively high input impedance of 80.000 ohms and are suitable\u003cbr\u003efor classic analogue program sources such as phono preamplifiers, tuners or reel-toreel tape machines.\u003cbr\u003eMedium Gain on Inputs #4, #5\u003cbr\u003eInputs #4 and #5 are appropriate for high output program sources such as CD\/DVD\u003cbr\u003eplayers, stand-alone DACs or streamers, offering 18dB gain (8-times) when the GT\u003cbr\u003eselector rests in pos4\/5\/6 and 12dB (4-times) for the other selector positions,\u003cbr\u003epos1\/2\/3. The input impedance on these two inputs is 30.000 ohms.\u003cbr\u003eLow Gain on Input #6\u003cbr\u003eInput #6 (input impedance 30.000 ohms) is assigned with exceptionally low gain of\u003cbr\u003e10dB (3-times) and 4dB (1.5-times) with GT selector in pos4\/5\/6 and pos1\/2\/3\u003cbr\u003erespectively. It is reserved for sources with exceptionally high output characteristic\u003cbr\u003eas they are found on some CD players and DACs with vacuum tube output circuitry. It\u003cbr\u003ecan also be used for the purpose of enhancing the impact of the timbre registers, as\u003cbr\u003edescribed in the user manual. Summarizing, the gain pattern on the inputs is\u003cbr\u003e (20, 20, 20; 12, 12; 4)dB and (26, 26, 26; 18, 18; 10)dB\u003cbr\u003ewith GT selector in pos1\/2\/3 and pos4\/5\/6 respectively\u003c\/p\u003e\n\u003cp\u003eMAINS TRANSFORMER\u003cbr\u003eThe DFAmp is equipped with a proprietary mains transformer produced in-house to\u003cbr\u003eensure the highest possible quality. This part has been specifically designed for low\u003cbr\u003ebody noise emission and low leakage. Nevertheless, it is mounted to the chassis via\u003cbr\u003eisolation elements in order to eliminate even the slightest interference of residual\u003cbr\u003etransformer vibrations with the circuit. Since the mains transformer is produced inhouse we can easily built transformers for all kinds of mains voltages on demand, for\u003cbr\u003eexample for 100Vac (Japan), 120Vac (USA, Canada), 220Vac (South-Korea, China,\u003cbr\u003eThailand, Indonesia) or 245Vac (Australia).\u003c\/p\u003e\n\u003cp\u003eF E A T U R E O V E R V I E W\u003cbr\u003e• Ultimate vacuum tube line control and headphone driving amplifier.\u003cbr\u003e• Both functions performed by the same minimalist single-ended zero-feedback\u003cbr\u003ecircuit utilizing 2x12J5GT+2x12GN7 tubes.\u003cbr\u003e• 6x line inputs (6x2 RCA jacks), with gain pattern (3x26dB; 2x18dB; 1x10dB).\u003cbr\u003e• Triple master output with very low output resistance (3x2 RCA jacks).\u003cbr\u003e• 2x toggle-selectable headphone outputs (2x6.35mm jack sockets).\u003cbr\u003e• Remote volume control via motor-driven dual-potentiometer with excellent\u003cbr\u003echannel balance and low angle sensitivity for conveniently fine volume\u003cbr\u003eadjustment.\u003cbr\u003e• Four on-the-fly selectable tone control presets entangled with a 6dB gain\u003cbr\u003eattenuator circuit implemented via 6-position rotary dial (GT selector).\u003cbr\u003e• Full hand construction, point-to-point wiring throughout.\u003cbr\u003e• Ultra low noise and low leakage mains transformer manufactured in-house for\u003cbr\u003e230Vac, 100Vac (Japan), 120Vac (USA, Canada), 220Vac (South Korea, China,\u003cbr\u003eThailand, Indonesia), 240Vac (UK) or 245 Vac (Australia).\u003cbr\u003e• Nonmagnetic aluminum casework, front and rear panel with anodized printing,\u003cbr\u003epowder coated lids, dimensions: 434x434xH154mm, 154=134+20\/footers.\u003cbr\u003e• Dimensions of the crate: 650x650x350 mm. Shipping weight 11.7Kg.\u003cbr\u003e\u003c\/p\u003e","brand":"Thöress","offers":[{"title":"Default Title","offer_id":56854695117131,"sku":null,"price":82000.0,"currency_code":"DKK","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0994\/7991\/2779\/files\/thoeress-dual-function-amp-1.jpg?v=1774091047","url":"https:\/\/sallingboeaudio.com\/products\/thoress-dual-function-amplifier-dfamp-forforstaerker","provider":"Sallingboe Audio","version":"1.0","type":"link"}