Description

This is a custom push-pull amplifier design using triode-wired 12W6 output tubes. Proudly designed and hand-built in Florida USA using high quality long-life components. Conservatively rated for 6 watts per channel, the amplifier can also use 12V6, and the more common 6V6. The output tubes are biased Class A at ~70-75% to provide long life. ***Due to the heater current requirements, the amplifier DOES NOT support the use of the 6W6 tube. When wired for triode operation, the 12W6 is a wonderful sounding tube and although this is a push-pull circuit, this amplifier produces a sound profile with the warm, richly textured presentation of a single-ended design. I describe the sound of this amp as having a very deep 3 dimensional sound stage with a silent black background. The sound of a triode wired 12W6 is very close to a 45 triode. The same holds true for using the 12V6 or 6V6. This amp is perfect for those who like to use NOS (new old stock) tubes that are available at very reasonable prices compared to more popular tube types and don't mind making rather easy circuit configuration changes on their own amplifier. The driver tubes for the amplifier are NOS 6J51P wired for triode operation. The driver tube can be substituted directly with a 6EJ7 or EF184. With an easy adjustment of the driver circuit, 6J9P-E, E180F, 6688 can also be used. The driver tube uses a MOSFET constant current source (CCS) as the plate load to provide a very linear drive signal that is direct-coupled via a step network to set the bias for the phase splitter. The phase splitter is a unique concertina style that uses MOSFETs instead of a vacuum tube to provide a transparent drive signal to the output tubes. For phase splitter duty, a MOSFET is like the perfect vacuum tube. The solid-state devices used in this amplifier do not take away from the tube character of the amp and only serve to improve the performance. In order to use 6 volt heater power tubes with this amplifier, a jumper wire is moved to change the heater voltage from 12 volt to 6 volts. When using the 12V6 or 6V6 there are 2 jumpers on the power tube boards that are moved to change the power tube bias setting. Includes two (4) NOS 12W6GT power tubes, and two (2) NOS 6J51P driver tubes. Frequency Response: 20-20kHz +/- 0.5dB Power Output: 6 Watts RMS per channel Input Sensitivity: less than 1VRMS for rated output Speaker Output: 6 ohm - can use 4 or 8 ohm speakers Output Noise: less than 1mV - virtually non-existent Power input: 120VAC @ 80 watts - fused @ 2A Slo-Blo Size: 14"W x 11.25"D x 7"H with tubes installed Weight: 15 lbs. Automatic Output Tube Bias - no periodic adjustment required Bourns Input Attenuator Volume Control Fused IEC Power Entry Module Neutrik RCA input jacks Pomona 5-way speaker binding post Metal Film/Wirewound Resistors as appropriate Low-Noise Ultra-Fast Solid State Diode Rectified Power Supply Nichicon 105°C Power Supply Capacitors All components sized appropriately for wattage & voltage Power cord included A schematic diagram will be included with amplifier. The life of the vacuum tubes themselves are based on many factors and it is difficult to estimate their life although 3000-5000 hours is not unusual for the power tubes, possibly longer for the driver tube. Amplifiers like this and others are available as custom-ordered units as well. Inquiries welcome. Warranty: Two years parts and labor to the original purchaser, under normal use, for manufacturing defects, not including tubes. Return shipping paid by Nature Coast Electronics. PLEASE NOTE: The vacuum tubes get hot while the amplifier is in operation. Do not touch the exposed vacuum tubes while the amplifier power switch is on. It is also normal for the transformers and top plate of the amplifier to get quite warm during normal operation. The circuitry contained within the amplifier operates at high voltages. Do not remove the bottom cover of the amplifier. Refer servicing to qualified service personnel. The amplifier will be shipped without the tubes installed. If you are not familiar with installing the vacuum tubes for the amp, please consult with a qualified person for assistance, or message me here.