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The Lighthouse contemporary style integrated amp

The design of The Lighthouse integrated amplifier has involved aesthetics as a priority while its design is about tube and high technology. Everything started a couple of years ago when a friend of mine asked me for thinking about an easy to build DIY amp project at a very low retail price. So easy that he could even make it. It finally led to a stereo single ended tube amplifier called "6Y6 amplifier kit" suggested at 300€ retail price. I stocked three of them that i sold in a few weeks. The first one was installed by another good friend of mine in a coffee shop in Brittany, the second one was purchased by a very good customer of mine and the last one was sold as an assembled kit for another good friend of mine, Philippe F. I put it into a wooden box of bottle of wine in vertical position with the tubes at the very top of the box. Like a lighthouse... He liked it very much both in sound and aesthetic terms, so he decided to help me financially in manufacturing a small series of 10 amplifiers like his "lighthouse" with a high end finish. Ladies and gentlemen, The Lighthouse !

The components

This is the "6Y6 amplifier kit" composition based on an original schematic by madotec. The kit is including the full set of components i.e. carbon film resistors, power wound resistors, filtering capacitors, decoupling and coupling film capacitors, rectifiers, transistors (yes, there are very helpful bipolar transistors somewhere in the circuit...), power supply transformer, output transformers, smoothing inductance, tube sockets, N.O.S tubes and a complete installation manual. This kit is still available.

The prototype

A prototype was assembled and fully tested with different tubes and different components. It has been listened during several hundreds of hours and some slight modifications were implemented. The final schematic is to a 2-stage single ended topology with a N.O.S 12J5 triode as a gain stage and a N.O.S 6Y6 pentode as an output tube. The circuit is implemented in an original way with some specific solutions and some high tech components i.e. current source, polypropylene film capacitors, Silicon Carbide rectifiers and so on.

Arcajou workshop

The construction of the definitive wooden cabinet of The Lighthouse was entrusted to Arcajou company in Brittany. Arcajou is managed by Pierre Gueney, a Philippe F.'s friend who is graduated from the famous Ecole Boulle in Paris. The box is handmade of 12 mm birch plywood finished in mouse grey satin lacquer as standard (other RAL colours and wood veneer as options, quotation on request), the top side is covered with a polished piece of 14mm thick black marble glued on 5 mm spacers so that the heat is getting out of the box. Extremely classy. The construction is in two parts that overlap, one into the other. The main part receives all the components and the connectors, then it slips into the other part that creates the left and right sides as well as the front side. A pure cabinetmaking work.

Detail of construction
The overlapping
Testing

As soon as the boxes are assembled, they are expedited to Madotec, Paris, where the components and the connectors are installed into the main part. Then everything is wired and checked visually. When completed, the amp is switched on and tested statically (measurements of voltages and currents at different locations of the circuit). When everything is fine, the amp is put under a first listening test in order to confirm everything is fine dynamically. Then the amp is starting a 24-hour burn-in process to make the internal temperature increases and to check if anything gets unstable and/or unstressed with temperature raising. For the burn-in process we connect the Lighthouse outputs to power resistors. We use a specialist CD with random signals for burn-in purposes during 6 hours, then we swap to a CD of music for the remaining 18 hours.

Tubes close-up

The Lighthouse is delivering 2 x 6 W (4 ohms). It has one Neutrik RCA input and one pair of M-Connect female copper-beryllium banana connectors as loudspeaker outputs on each channel. The sensitivity is about 560 mV for full power, input impedance is 100 K and volume control is an Alps Blue potentiomer. There are four holes and four screw inserts under the Lighthouse for 6 mm spikes if necessary. Dimensions : 150 x 410 x 150 (W x H x D) w/o tubes, weight : 8.5 kg. Price : 1150 euros (inc. 20% VAT, shipping costs not included).

Created By
Dominique Mafrand
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Credits:

Dominique Mafrand

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