Single Ended Amp Conversion
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Single Ended Amp Conversion

Single Ended Amp Conversion

Description:

Published: April 29, 2018 0 0 182
By: Joseph Erdy, Cal Poly San Luis Obispo
Category: Engineering
Hashtags: #Amplifier #amplifiers #Audio #audioamp #audiodesign #audioengineer #Design #Electric #Electrical #ElectricalDesign #ElectricalEngineer #Electricalengineering #Electronic #Electronics #Engineering #hifi #Mechanical #MechanicalEngineering #Music #Project #Solidworks #tube #Tubes #vacuu #vacuumtubeaudio #vacuumtubes

I picked up an old tube-based laboratory bandpass filter that was discarded. The challenge in this project was to keep as much of the old equipment in place while converting it to a single-ended power amp. The components were in excellent condition and the case was of beautiful quality, so I really wanted to preserve what was left of the filter while turning it into something more useful. I opted for a simple pentode-mode single-ended amp using EL84 tubes. The pre-amp uses 12AT7 tubes cascaded in a mu-follower configuration for maximum gain. The power supply is a stabilized 250V for minimal ripple and distortion. The audio circuit has global negative feedback from the speaker output back to to the cathodes of the pre-amp. This really tightens up the bass and raises the maximum power.