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    Building, troubleshooting and testing of these amplifiers should only be
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50FE5 push pull stereo

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D

davorin

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Joined 2005
Small stereo push-pull amp with 2x6201 (ECC81/12AT7) and 4x50FE5 tubes with 30VA main transformer (115V+115V/15V+15V; "C"-core), and isolation transformer (230V/115V) as a main transformer. Not need feedback in output triode-mode, but sound good in pentode-mode also. Output tubes works in class A with Ia~100-105mA each. Maksimum output power is 2x~10W in pentode-mode, and ~2x4W in triode-mode. Very small inner resistance and good linearity of output tubes provides very good sound in pentode-mode, like some another tubes in triode-mode.
 

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D

davorin

Member
Joined 2005
The frequency range with these transformers was quite linear in the range of ~ 30Hz-30kHz (the iron core OT was with oriented plates), but I subsequently replaced all the transformers (OT due to better adaptation to the output tubes impedance, and MT due to lower heating!).
 

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