Mudlark A205, 20-watt per channel, Class A2 triode amplifier
Silicon Chip Publications Pty. Ltd; Brookvale NSW
- Land
- Australien
- Hersteller / Marke
- Silicon Chip Publications Pty. Ltd; Brookvale NSW
- Jahr
- 2005
- Kategorie
- NF-(Niederfrequenz-) Verstärker oder -Mixer
- Radiomuseum.org ID
- 324357
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- Anzahl Röhren
- 6
- Anzahl Transistoren
- Halbleiter vorhanden.
- Halbleiter
- Hauptprinzip
- NF-Verstärkung; Hi-Fi-High End Produkte
- Wellenbereiche
- - ohne
- Betriebsart / Volt
- Wechselstromspeisung / 240 Volt
- Lautsprecher
- - Dieses Modell benötigt externe(n) Lautsprecher.
- Material
- Metall, SICHTBARE RÖHREN
- von Radiomuseum.org
- Modell: Mudlark A205, 20-watt per channel, Class A2 triode amplifier - Silicon Chip Publications Pty.
- Form
- Tischgerät, Truhenform, meist mit Deckel (NICHT Schrägpult).
- Bemerkung
-
The Mudlark A205 is a 3-stage lower-powered single-ended design using two paralleled triode-connected beam power pentodes. It also does not use a conventional output transformer but uses a choke as the combined plate load for the triodes, with the output signal being capacitively coupled to a 100 V transmission line transformer. Other novel features include positive drive (class A2) via an emitter follower to the grids of the output valves and quite a complex power supply which includes protection for the valves.
The A2 designation stands for class A2 operation. This refers to class-A which involves positive drive to the grids of the output valves on positive signal peaks for increased efficiency and higher power (sometimes called "extended" class-A in valve literature).
The circuit is unconventional because of the emitter follower used to drive the grids of the output valves and in the use of a choke as the plate load instead of a conventional output transformer.
The circuit is a “parafeed” configuration which uses a relatively low-cost high impedance choke as the load for the plates of the output valves and a capacitor to couple the audio signal to the primary of the output transformer. As a result, there is zero DC in the primary winding, so the output transformer can be much smaller and lower in cost without sacrificing quality.
It also incorporated a delayed B+ soft start circuit.
The Mudlark A205 comes in two parts, the main amplifier, and the separate transformer power supply box.
Designed by David Whitby and published as a kit in Silicon Chip, August & September 2005.
Specifications:
Output power: 20 watts per channel into 8Ω Input sensitivity: 360mV for 10W into 8Ω Signal-to-noise ratio: 67dB unweighted (22Hz to 22kHz); -91dB A-weighted, both with respect to 20W into 8 Ω.
Harmonic distortion: typically, <1.5% at listening levels. Frequency response: ±3dB, 12Hz-57kHz Damping factor: >6 with feedback, >2 without.
- Literaturnachweis
- -- Original prospect or advert (Silicon Chip, August & September 2005.)
- Autor
- Modellseite von Gary Cowans angelegt. Siehe bei "Änderungsvorschlag" für weitere Mitarbeit.
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