Push-Pull Transformers

Output Transformer Comparison Part 2 - Single Ended Transformers

This article was originally featured on the "Tube Kingdom" 2004 Spring issue Vol32. (The "Tube Kingdom" is a quarterly publication from Stereo Sound Publishing Inc.) The title of this article is "10 Output Transformers Sound Comparison on 300B / 6BQ5 Single-Ended Amplifiers". Mr. Tadaatsu Atarashi constructed the power amplifiers, and Mr. Atarashi replaced output transformers each time before conducting the listening test. Along with Mr. Atarashi, Mr. Hirokazu Shinoda and Mr. Ryuichi Sato took notes for sound characteristic on each transformer.

Comparison Parameters

Test A: PL83 (similar to 6BQ5) Single-Ended Power Amplifier with Hashimoto PT-100 Power Transformer.

Test B: WE300B(A) Single-Ended Power Amplifier with Tango No. 1150B Power Transformer

Software

	"Koibumi - Miyuki Nakazima" Yamaha Music Communicaions: YCCM-00044
	"Sayonara today" by Hiroyasu Yaguchi FINEQ RECORDS: FINEQ1002
	"Stereo Sound Reference Record" Phillips SSPH-3001

Reference Equipments

CD Player - Studer A730

Attenuator - TechLab 600 Ohms Type T

Speakers

	Western Electric 594A
	Western Eelctric 31A
	Jensen 825
	Jensen L20

Schematics

Test A: PL83 (similar to 6BQ5) Single-Ended Power Amplifier

Test B: WE300B(A) Single-Ended Power Amplifier

Ten output transformers from five manufactures were compared on this test. These five companies include Lundahl in Sweden, Tango, Hashimoto, P&C, and Andix. Hashimoto Electric sent two models for this test; the H507S, the H20-3.5U, and the H30-3.5S. Here are opinions on Hashimoto transformers from three testers.

	Mr. Atarashi's Opinions	Mr. Shinoda's Opinions	Mr.Sato's Opinions
Hashimoto H507S: Used on Test A	Rich, smooth, and elegant sound Realistic image	Good balanced sound Feel the presence of music hall Three dimensional Good cost performance	Good low Musical sound Nice vocal
Hashimoto H20-3.5U: Used on Test B	High quality and elegant sound Balanced and smooth Feel the presence of musicians Natural	Well balanced at high level Rich, but with sharp and clear image	Sound with warmness Nice vocal Analog like sound
Hashimoto H30-3.5S: Used on Test B	Well balanced sound As if listening to real voice without the amplifier Realistic	Dense, but sensitive sound Music draws attention of listeners Very realistic piano sound	Rich, soft, and balanced sound Wanted to hear more energy

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