Mars EL84PP

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Mars

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Here I will post information regarding the Mars EL84PP kit and Stereo 20 amplifier.

IMG_1362 by Karel Mars, on Flickr

The EL84 tube is one of the stalwarts of the tube amplifier world, being used in famous amplifiers such as the VOX AC30 and LEAK Stereo 20.

If a pair of EL84's is configured as a push-pull amplifier, one can get up to 15watts of high quality sound. This kit is inspired by the Mullard 5-10 and Dynaco ST35 designs. Like the ST35, a dual pentode/triode (6U8) is used as a voltage amplifier and output tube driver. The EL84 pairs are cathode biased with individual, bypassed, cathode resistors for maximum reliability and increased DC current balance.

The transformers are tapped at 30% of the windings for ultra linear operation. This gives increased linearity, less distortion and more tolerance to loads that deviate from the standard loud speaker 4 and 8 ohm options.

IMG_5176 by Karel Mars, on Flickr

Solid state rectification is used and linearity is increased with global negative feedback.
 
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