Description
Nakamichi 620 Power Amplifier - Black, fully working condition, 3 month warranty Nakamichi 620 Power Amplifier - Black, fully working condition, 3 month warranty Here we have a piece of late seventies vintage equipment from Japanese company Nakamichi. Highly specified for its time this power amplifier claims to be practically unbreakable. In fully working order, and fair cosmetic appearance – well it is over 40 years old; it will be suitably well packaged for courier shipment Nakamichi Say…. Research and engineering of the calibre that brought you the world famous Nakamichi cassette decks, now brings you a beautiful and unusual power amplifier, which, were it not for its power output, would be mistaken for a superb preamplifier. It should not be surprising that Nakamichi can develop such an incredible amplifier. Although much of the excellence of Nakamichi cassette decks can be attributed to advanced magnetic head technology and sound mechanical engineering, none of it would have been possible without an extensive knowledge of low noise, low distortion solid state electronic circuitry. Over twenty years of close work with transistor circuits of far greater complexity than most preamplifiers and power amplifiers, have given Nakamichi Research an advantage that perhaps not even manufacturers specializing in electronics can match. This advantage is clearly evident in the Nakamichi 620. Distortion is so low that a completely new method of measuring and stating THD had to be employed. Even the best distortion analysers available today cannot give an accurate picture of the 620s distortion partially because the measurement is masked by noise, which, by the way, is more than 120 dB below rated output! The distortion specification was obtained with the aid of a Bruel and Kjaer model 3348 Real Time Analyser. 5 PPM (parts per million) is equivalent to 0.0005%, and at these very low levels PPM becomes a more practical way of stating distortion than per cent. The 620 contains circuitry not found in any other power amplifier. Nakamichis Complete Mirror push-pull circuitry delivers performance unlike any other full-complementary design. The 620s ample power output backed by a power supply of tremendous reserve capacity, assures ultra-clean reproduction even with low efficiency loudspeakers. Nakamichis Complete Mirror design brings a level of performance to class B amplifiers that was formerly associated only with class A amplifiers. The 620 is closer to a pure class B amplifier than anything else that has gone before. The first stage of the 620 is a differential amplifier with current mirror loading. The final section of the amplifier is a four stage push-pull circuit. All four stages are full complementary direct coupled, and each stage employs a unique double NPN/PNP combination for the positive and negative halves. This design eliminates the errors inherent in even the most carefully matched pairs of NPN/PNP output devices. These errors, furthermore, are eliminated without the use of bias diodes, bias adjustments and high idle currents. The 620, in fact, idles at approximately 1/20 the current of conventional class B power amplifiers of comparable output power. This new approach takes full advantage of class B efficiency with the freedom from switching and crossover distortions that was once thought possible only with class A amplifiers. Many amplifiers become unstable when presented with an unusual load, such as an electrostatic loudspeaker. Some amplifiers even suffer from the capacitance in speaker wire. The 620 has been fully tested into all types of reactive loads. Although the 620s power transistors are operated well within their safe areas, a unique current controlling circuit protects the amplifier from short circuits and other failures. Unlike most current limiters, which tend to activate prematurely, the protection circuit in the 620 senses both voltage and current. The circuit is so fool proof that it never interferes with normal operation of the amplifier; its effectiveness is witnessed by the fact that the 620 can withstand a short circuit almost indefinitely. Specifications: Power output: 100 watts per channel into 8? (stereo) Frequency response: 5Hz to 100kHz Total harmonic distortion: 0.005% Damping factor: 100 Signal to noise ratio: 120dB Semiconductors: 3 x ICs, 46 x transistors, 41 x diodes Dimensions: 400 x 189 x 248mm Weight: 12.5kg Manufacturer : Nakamichi Model : 620 Serial Number : B46709 Packaging : N/A Accessories Included : N/A Price When New : ? Shipping Shipping cost:Please contact us or check listing info. If you are outside the UK you will need a shipping quote BEFORE buying. Delivery time:48 hours Payment We accept the following payment methods: Paypal Credit/Debit Card BACS Please contact us if you have any questions. Service Established in 2003, 2ndhandhifi is the UKs largest stockist of used quality audio equipment. All items are checked before despatch and guaranteed for 30 days for ebay buyers to give you peace of mind that the item will arrive safely and work exactly as per ebay descriiptions. This means that all items described as used will be in good working order but may show minimal cosmetic marks resulting from everyday use. Any more significant cosmetic issues will be highlighted in the listing if present. We accept most payment methods but card payment to our shop is preferred. We use a reputable overnight courier service - items will be despatched next working day for delivery the next working day after that, but you are welcome to collect from our sister shop in Stockton on Tees if you prefer. Check our feedback if you have any doubts about the validity of this auction or us! We are a business so (although most times we do) we cannot always answer emails over the weekend so please try to ask Monday to Friday. Important 1. If there is no buy it now price stated, please dont ask - it is intended to be an auction which will run until its end time. 2. If you are outside the UK mainland please ask us for a shipping quote BEFORE placing a bid or clicking “Buy it Now”. If you dont ask, it means you will accept our quote. We do not cut corners on shipping, we only use reliable shipping companies, and we dont profit from the shipping prices we quote. 3. 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