Amp/Preamp Asylum

Posted by mwhouston (D) on February 03, 2017 at 17:20:30

Yet another 6L6 SE UL power amp in a gift wine box. This time the blond box has been stained and lacquered. Two layers of staining and three coats of lacquer provide a deep rich looking finish. The component quality has been raised for this build and the power supply (with external tranni box) substantially beefed-up. Why another similar amp - because they just sound so very good.

The external transformer box houses two 160VAC transformers and connects to the amp via a male and female XLR connection. One for the 12VAC for the tube filaments and the other for the 250VAC HT voltage. Internally there is a two stage rectifier and filter network with over 800uf of storage capacitance. Rectification is via a 1A rectifier bridge which produces over 400VDC. This is limited and filtered to 295VDC for the HT for the 6L6s. This is further limited and filtered to 280VDC for the 12AT7. Tube compliment is the same as the first amp - matched JJ 6L6s and Psvane top-of-the range 12AT7 "T" series MKIIs. These tubes and this combination of tubes produces an extremely accurate and tonally rich sound for just a simple two stage amp.

Mundorf MCap Supreme Silver and Oil caps are used for the inter-stage and Edcor 15W OPT UL trannies for the output. Resistors used are both metal film and carbon film. By-pass (Ck) caps are low ESR and NP types. All hookup wire is Cat5 solid core with no shielded wire and WBT silver solder is used in the audio path. All filtering and by-pass caps are snubbed by 0.1uf poly caps. Earthing wire and filament wire is all 10A rated and the amp is hum and noise free. There are no problems producing 40Hz with rock solid bass and mid-range. Voice is earthy and detailed music has excellent rhythm and flow. An astounding 3W, two stage amp.
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Edits: 02/03/17