It's Done! 1957 Eico HF-52 Tube Amp • Final Fixes • How Ultra-Linear Works • Bench Tests • Demo

Welcome to part six of the Eico HF-52 tube amplifier series. In parts one through five I repainted, rebuilt and demonstrated the 1957 amp. And this episode, I’ll polish and install the brass faceplate and tube shields, add decals, discover a problem, fix a problem, and, explain how ultra-linear feedback works. Stay tuned to the end, too, when you’ll get a chance to hear the amp for yourself. And, no. This time I’m not just going to record the amp playing through a speaker.

Here are the topics covered in this video and the time stamps:

0:00 Intro
0:36 Polishing The Brass Faceplate With Simichrome
0:59 Using Solvent To Remove Paint Spots
1:14 Installing Faceplate and Knobs
1:24 Making and Applying Label Decals
1:57 Polishing The Tube Shields
2:04 Did I Fix The Amplifier Hum?
2:20 I’ve Got Problems
2:46 Hammering Out The Issue
3:17 Output Transformer Primary Wiring
3:42 Negative Feedback and Ultra-Linear Circuits
3:59 What Does Non-Linear Mean?
4:18 The 60/40 Split
4:49 Bench Tests
4:55 Wattage Power Output Test
5:02 Frequency Response Test
5:09 Hum & Noise Test
5:18 THD vs Frequency Test
6:13 Audio Demonstration From Direct Speaker Output

To see more of my bench test videos, please see:
Dynaco SCA-80 P9: https://youtu.be/-RBHnTfo1f4
McIntosh MC2105 P8: https://youtu.be/o6GcHO6Y9Eo
Kenwood KA-76. 100 watts? Yeah, Right: https://youtu.be/0VnzFPmKNTo

To see all the videos in this series, click:
https://youtube.com/playlist?list=PLCH_MMh8A6cFPhBj0lYWDR5ZBRmQB2Dbg

To visit my Amazon Shop, click here:https://www.amazon.com/shop/fluxcondenservintageaudioelectronics

#tubeamp #tubeamplifier #highfidelity #1950s

Vacuum tube amp repair, restoration and demonstration.