pic.1  Audio Note Kit4 push Pull Amplifier
front view
pic.2 Audio Note Kit4 push Pull Amplifier
internal view
pic.3 Audio Note Kit4 push Pull Amplifier
parts of the kit
pic.4 Audio Note Kit4 push Pull Amplifier
circuit diagram
Audio Note Kit`s Forum on Audio Asylum
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Introduction
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The KIT 4 is our introduction to Valve Amplifier Kit building. A low cost kit that any beginner will be able to construct. Ease of construction is facilitated by the signal circuitry and power supply unit being mounted on printed circuit board. The kit uses two Oto (Audio Note product) output transformers. The circuit consists of two 6V6GT tetrodes running in Push-Pull class A, yielding about 10 watts, driven by a 6SN7GT and a ECC83 input stage. A superb kit needing reasonably efficient loudspeakers.
The Audio Note Kit4 push pull amplifier:
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Kit4 is a stereo 10 Watt per channel push pull amplifier using selected valves and components it a tried and tested configuration. The valve complement consists of one ECC83 (12AX7) low noise double triode , one 6SN7 double triode and two 6V6 beam tetrodes per channel . These valves were chosen primarily for their sound quality but also for their availability and low replacement cost . The 6V6 although less well known than its big brother the 6L6 is one of the sweetest sounding valves around. The 6SN7 and ECC83 work together to extract the maximum musicality from the output valves.
- The audio circuit is straightforward : the ECC83 is used as the input stage and phase splitter, one section recieves the incoming signal and amplifies it by approx 40 times. The second section of the ECC83 takes its input from the potential divider connected between the anodes of the two sections and generates the phase inverter signal.Local feedback keeps the “in-phase” and “phase-inverted” signals exactly in balance, this type of phase splitter is known as the floating paraphase or see saw circuit and was chosen for its sound quality and ability to accomodate the variations caused by the ageing of the valves.
- The following stage is a resistor –capacitor coupled Anode follower 6SN7, this stage amplifies the signal again and drives the output valves, push pull pentode connected 6V6’s These are coupled to an in house designed AudioNote ouput transformer(as used in the highly acclaimed OTO amplifier) with 4 and 8 ohm secondary tappings.
- The circuit incorporates approx 11db of overall feedback to control the dynamic behaviour of the amplifier and to allow it to drive complex loads. The feedback is taken from the output transformers secondary back to the input valves cathode. Compensation components are the 560pf capacitor across the feedback resistor and the 820pf cap across the input valves anode resistor, these ensure stability.
- The power supply is again conventional , using solid state rectification and a high grade capacitor input filter with further filtering and decoupling to eliminate hum.
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The sensitive input stage is DC heated to reduce hum problems , whilst the drvier(6SN7) stage and output tubes are AC heated.
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The whole amplifier is housed in a non magnetic aluminium chassis and finished with 2.5 mm thick acrylic front and back plates.
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What`s under the bonnet? - the Audio Note Kit4 push Pull Amplifier
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pic.5 - internal side view of the Audio Note Kit4 push Pull Amplifier Kit(1)
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pic.6 - internal side view of the Audio Note Kit4 push Pull Amplifier Kit(2)
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Available Options and Prices
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STANDARD: Standard version.
Price (1off) - £500.00 + vat + carriage
SPECIAL OFFER: 10% off all upgrade components used on your Audio Note kit purchased through us. See the www.hificollective.co.uk shop. To take advantage of this discount orders must be called through on 01908 217202.
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Related links
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Customer gallery
General upgrade information
Kit 4 schematic diagram
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