Tuesday, February 14, 2012

"Paris Duo" - 6EM7 monoblock power amplifier

Building on the success of the Paris amplifier (dual mono construction) I was asked to build a pair of monoblocks. Paris Duo has a two stage power supply filter using a small choke and resistive network with large electrolytic capacitors. Tightly twisted wire-wrap wire feeds the signal to the first triode and the same wire connects to the speaker binding posts.

The power transformer is rubber mounted to reduce resonance on the cast Al chassis. The finish is epoxy enamel paint with an acid etch primer. The tube compliment is a 5Y3 rectifier and Sylvania (NOS USA) 6EM7. A small Hammond choke and Edcore 10W output transformer are inside the heavy chassis. There is also a EMI mains power filter in the chassis and a choke on the power lead. The bottom of the chassis is drilled for cooling with a layer of bitumanised heavy Al foil to control resonance. Soft silicon feet secure the amplifier and also help provide resonance and vibration control.

The sound is similar to the original Paris amp with an ultra clear mid-range, heavy in detail and good bass extension. In room testing proves a low 40hz tone with only a modicum of attenuation. Treble is on the sweet side rather then bright and is extended. An excellent sounding amp providing a touch over 2W of delivery.