{"product_id":"thoress-eht-mono-single-ended-hybrid-triode-power-amplifier","title":"THÖRESS EHT MONO Single-Ended Hybrid Triode Power Amplifier","description":"\u003cp\u003eBestillingsvare - forvent 4-8 ugers leveringstid!\u003c\/p\u003e\n\u003cp\u003ePris er for et sæt monoblokke!\u003c\/p\u003e\n\u003cp\u003eTHÖRESS is pleased to launch the Hybrid Triode Mono Amplifier (EHT Mono\u003cbr\u003eBlock), our latest achievement. The most powerful amplifier model of our product\u003cbr\u003eline delivers 30, 40 or 50 watts of output power into a 8, 6 or 4 ohm load\u003cbr\u003erespectively, combined with very low output resistance (high damping factor). Such\u003cbr\u003eproviding excellent drive capability for loudspeakers with medium to low efficiency\u003cbr\u003eor with critical impedance behavior which may present a challenge for our all-tube\u003cbr\u003esingle-ended triode amplifier models. While offering the same level sonic excellence\u003cbr\u003ewithout involving exotic and costly power tubes.\u003cbr\u003eThe sonic presentation of the EHT Monoblock is of the utmost refinement and easily\u003cbr\u003emeasures up to the highest expectations of even the most critical and experienced\u003cbr\u003emusic lover. And of course it is a perfect complement to our DFAmp or FFPre.\u003cbr\u003eBUILT\u003cbr\u003eThe amplifier is built with meticulous hand construction using our proven point-topoint wiring techniques, whereas much care has been taken in arranging each aspect\u003cbr\u003eof the internal construction to ensure low noise performance, ease of service and\u003cbr\u003ethe highest reliability for many years to come.\u003c\/p\u003e\n\u003cp\u003eTOPOLOGY\u003cbr\u003eThe amplifier is based on a unique minimalist SINGLE-ENDED ZERO-FEEDBACK\u003cbr\u003evacuum tube MOSFET hybrid topology which we call EHT Topology (E\/intakt H\/ybrid\u003cbr\u003eT\/riode). Decidedly ignoring the fact that many music lovers still persistently believe\u003cbr\u003ein the myth that balanced technology (and the associated cable configuration with\u003cbr\u003eXLR connectors) 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.\u003c\/p\u003e\n\u003cp\u003eSTABILITY\u003cbr\u003eThe Amplifier operates with impeccable thermal stability and is fully short-proof at\u003cbr\u003ethe output without the aid of any kind of (sound degrading) protection circuitry.\u003cbr\u003eMoreover, a switch-on delay module (another protective feature often found on\u003cbr\u003ecommonly constructed solid state or hybrid amplifiers) is also omitted because no\u003cbr\u003edisturbing noise or harmful signal is developed at the output when the amplifier is\u003cbr\u003epowered on or off.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003eEHT PRINCIPLE\u003cbr\u003eThe EHT topology consists of a SINGLE-ENDED TRIODE GAIN STAGE followed by a\u003cbr\u003ecurrent buffer in form of a unity gain MOSFET OUTPUT STAGE, also operated in\u003cbr\u003esingle-ended (class-A) mode with high idle current. It allows to fully exploit and mate\u003cbr\u003ethe most desirable characteristics of both vacuum tubes and solid state devices\u003cbr\u003edetermined by their very nature. Despite its elegance and extremely high sonic\u003cbr\u003ecapability, it has never been utilized in a serial audio product before, as far as we\u003cbr\u003eknow. Probably on account of its low power efficiency and because its\u003cbr\u003eimplementation is rather tricky.\u003cbr\u003eThe EHT topology represents the PUREST form of all possible single-ended triode\u003cbr\u003epower amplifier configurations!\u003cbr\u003eSpecifically it can be shown that a higher output power can be more easily obtained\u003cbr\u003ewith the EHT than with the all-tube amplification principle, without compromising\u003cbr\u003esound quality. Due the fact that the typical all-tube impedance matching output\u003cbr\u003earrangement consisting of a power tube loaded by an iron-cored output transformer\u003cbr\u003ewith high step-down ratio can be omitted. As a matter of consequence, the voltage\u003cbr\u003eswing required from the driver for a specific power output is up to 10 times (!!!)\u003cbr\u003elower for the EHT configuration compared to an all-tube circuit. Resulting in a\u003cbr\u003eproportional reduction of non-linear distortion as a quite substantial benefit.\u003c\/p\u003e\n\u003cp\u003eGAIN \u0026amp; BASS BOOST SELECTOR\u003cbr\u003eThe EHT Mono Amplifier allows for on-the-fly adjustment of the voltage gain of the\u003cbr\u003eamplifier by means of a 6-position rotary switch on the rear panel adjacent to the\u003cbr\u003einput jack. When the gain switch rest in positions 5 or 6 the mid-band gain is 10dB\u003cbr\u003e(3-times) whereas the bass response of the amplifier is mildly boosted. The mapping\u003cbr\u003ebetween selector positions, gain and sound effects is described by the chart below.\u003cbr\u003ePosition 1 2 3 4 5 6\u003cbr\u003eGain 4dB, (1.5x) 11dB, 3.5x 18dB, 8x 26dB, 20x 10dB, B+ 10dB, B++\u003c\/p\u003e\n\u003cp\u003eNotably, the bass boost functions do not rely on clumsy and sound degrading\u003cbr\u003econventional tone control circuitry. They are realized in a smart way by interposing\u003cbr\u003esolely one additional capacitor (per channel) to circuit.\u003cbr\u003eThe gain selector allows the user to match the gain of the power amplifier to the\u003cbr\u003egain of the line device with respect to the efficiency of the loudspeaker. Optimal gain\u003cbr\u003ematching between these components is desirable in order to avoid idle noise issues\u003cbr\u003eand to allow for conveniently fine volume adjustment.\u003cbr\u003eThe bass boost functions are usefull for a variety of applications...Equalizing\u003cbr\u003eloudspeakers with slim bass response or limited bass extension. Adjusting the low\u003cbr\u003efrequency response of the system to the acoustical conditions of the listening\u003cbr\u003eenvironment (small loudspeakers in large rooms!). Restoring tonal imperfections of\u003cbr\u003ethe listening program, often given by a lack of bass extension. Or simply for\u003cbr\u003eactivating a more full-bodied presentation in case the user is in the mood for\u003cbr\u003elistening to music in an enriched and laid back way.\u003c\/p\u003e\n\u003cp\u003eTUBES\u003cbr\u003eIn order to obtain the relatively high power output with our EHT Monoblock with\u003cbr\u003elowest possible distortion it proved advantageous to extend the basic EHT schematic\u003cbr\u003eby adding a powerful unity-gain vacuum tube buffer (12HG7 power tube operated in\u003cbr\u003etriode mode) inbetween the triode gain stage (7A4 triode) and the MOSFET output\u003cbr\u003estage.\u003cbr\u003eThe 7A4 tube is an Loctal-base single-triode from the famous ?J5\/?SN7\/?A4 family of\u003cbr\u003etubes with fairly low transconductance developed in the early times of tube\u003cbr\u003eelectronics. Whereas the 12HG7 is a fairly late (all-glass) development with high gain\u003cbr\u003eand very high transconductance, making it an ideal choice for buffer applications.\u003cbr\u003eBoth tubes are unarguably among the most linear amplification devices ever\u003cbr\u003edeveloped in the history of electronic technology and as such are a perfect choice in\u003cbr\u003ethe context of minimalist zero-feedback circuit design.\u003c\/p\u003e\n\u003cp\u003eMAINS TRANSFORMER\u003cbr\u003eThe EHT Mono Amplifier is equipped with a mains transformer produced in-house\u003cbr\u003efeaturing a dual-coil winding structure over a large tape wound cut core (C-core),\u003cbr\u003ewhich has been optimized for low body noise emission and low leakage.\u003cbr\u003eNevertheless, it is mounted to the amplifier chassis via isolation elements in order to\u003cbr\u003eeliminate even the slightest interference of residual transformer vibrations with the\u003cbr\u003ecircuit. Since the mains transformer is produced in-house we can readily customize\u003cbr\u003ethe amplifier for all kinds of mains voltages, such as 230Vac, 100Vac (Japan), 120Vac\u003cbr\u003e(USA, Canada), 220Vac (South Korea, China, Thailand, Indonesia), 240Vac (UK) or 245\u003cbr\u003eVac (Australia).\u003c\/p\u003e\n\u003cp\u003eF E A T U R E O V E R V I E W\u003cbr\u003e• Vacuum Tube MOSFET Hybrid Power Amplifier offering 30, 40 or 50 watts\u003cbr\u003eof output power into a 8, 6 or 4 ohm loudspeaker load respectively,\u003cbr\u003eutilizing two vacuum tubes (7A4 and 1x12HG7).\u003cbr\u003e• Ultimate sonic excellence on par with no-compromise all-tube single-ended\u003cbr\u003etriode amplifiers, without involving exotic and costly power tubes.\u003cbr\u003e• Excellent driving capabilities for critical loudspeaker loads due to very low output\u003cbr\u003eimpedance (high damping factor).\u003cbr\u003e• Unique minimalist EHT schematic.\u003cbr\u003e• Total avoidance of sound degrading protection circuitry.\u003cbr\u003e• On-the-fly adjustable gain via 6-position rotary switch on the rear panel\u003cbr\u003eentangled with bass boost facilities implemented without clumsy and sound\u003cbr\u003edegrading conventional tone control circuitry.\u003cbr\u003e• High grade electrolytic capacitors made in Germany in the power supply.\u003cbr\u003e• Low noise dual-coil C-core mains transformer made in-house, for for 230Vac,\u003cbr\u003e100Vac (Japan), 120Vac (USA, Canada), 220Vac (South Korea, China, Thailand,\u003cbr\u003eIndonesia), 240Vac (UK) or 245 Vac (Australia).\u003cbr\u003e• Full hand construction, point-to-point wiring throughout.\u003cbr\u003e• Nonmagnetic aluminum casework, front and rear panel with anodized printing,\u003cbr\u003epowder-coated lids.\u003cbr\u003e• Dimensions 434x454x184 mm, 184=20 (feet)+134+30 (tubes over case),\u003cbr\u003e454=434+20 (speaker binding posts), weight 15Kg.\u003cbr\u003e• Dimensions of the shipping crate: 650 x 650 x 350 mm.\u003c\/p\u003e","brand":"Thöress","offers":[{"title":"Default Title","offer_id":56854655598923,"sku":null,"price":96800.0,"currency_code":"DKK","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0994\/7991\/2779\/files\/thoeress-eht-mono-1.jpg?v=1774089491","url":"https:\/\/sallingboeaudio.com\/products\/thoress-eht-mono-single-ended-hybrid-triode-power-amplifier","provider":"Sallingboe Audio","version":"1.0","type":"link"}