Features

This is a 25 watt, single channel, push-pull class A/B, all hand-wired (NO BOARD, PC, EYELET, OR OTHERWISE) amp sold as a separate head or paired with a 2x12 sealed infinite baffle 27x17x12" 8 ohm cabinet loaded with Jensen C12Q speakers. The amp ships with J/J (formerly Tesla) brand spiral-filament 12AX7 preamp, 12AT7 phase inverter and 6V6 power tubes. DC is supplied by a 5AR4 rectifier tube. The power and output transformers are from Weber. The amp is built on a non-magnetic piece of machined 5052 grade aluminum. It is strong, relatively lightweight and easy to drill if you ever want to add any additional controls or switches. I attempted to lay the circuit out in a simple way that allows quick identification of most of the key components. The wiring follows a basic color coding that makes it easier to trace elements of the circuit. The amp has a single channel. I got this idea from working on old amps from the sixties . I noticed that if I lifted one of the 220K mixer resistors that summed the two preamp channels, the remaining channel always sounded much fuller and alive by itself. Premium components are used throughout. At the time of this writing (April 2007), all of the parts are available off-the-shelf. The vendors (and part numbers) are available on my website. I located many key components on terminal strips to make for easy replacement. All the screws, nuts, bolts, hardware (besides the chassis) are easy to find and inexpensive. The tone and coupling caps are 715 series polypropylene 5% Orange Drops. The electrolytics are Sprague Atoms. The J/J multisection power supply capacitor adds simplicity and convenience. The stock EQ section uses a traditional shelving design.The component values are, however, tweaked somewhat. The result is fatter but still retains a nice sparking high end without the brittleness. The sound reflects my personal preferences but can easily be modified to suit your tastes. The resistors are mostly metal oxide 3% tolerance one-watters. These are favorites of mine because they are a lot tougher with tighter tolerances. Again, as with anything on the amp: If you don't like them, it is very simple to have them replaced with carbon composition or metal film. All potentiometers are 24mm Alpha. The entire circuit has a single "star ground" eliminating potential noise problems sometimes found in multiple ground systems. The non-magnetic aluminum chassis also contributes to low noise by excluding stray inductances. The head and speaker cabinetry is constructed of Cabinet Grade Okomue with poplar core. This is beautifully-veneered plywood with a high quality finish on both faces. It adds a wonderfully musical resonance along with strong durability. Nickel-plated steel hardware with heavy duty rubber feet and handle are standard. The cabinetry is wrapped with Kayline premium purple levant Tolex. (Yes. Other colors are available. I just thought purple was a cooler standard color than black.) E-mail me for any aesthetic finishing details. I can do natural wood, exotic finishes, even laser-etched artwork, whatever, just ask me. The Jensen C12Q speakers are, to my ear, the perfect choice for this amp. The special design ceramic has very warm low and low-mid response with smooth highs. The crunch is fat and well-dimensioned with plenty articulation without harshness. You can find dozens of amps very similar in design but I have not seen one to capture all of these features, especially at this price. Think of it as a reliable and flexible platform to customize to your own liking.

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