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Ultra-Linear Output Stages

This
Issue

This month's issue tackles ultra-linear mode, but
without an output transformer. The design principle is applied to
line stages, headphone amplifiers, and OTL power amplifiers.

In November, 1951 issue of Audio Engineering, by David Hafler and Herbert Keroes outlined a new way of
using tetrodes and pentodes, which they labeled "ultra-linear." This
article is out of copyright and is reproduced in our new section Classic
Magazine Articles. Expect to see new (old) articles with up
coming issues of the Tube CAD Journal.
Remember, if you have a request or suggestion
of your own for either an article topic or circuit, please
e-mail:

Editor

Ultra-linear
output stage of an amplifier

Devised in 1951 by David Hafler and Herbert
Keroes, the ultra-linear mode was created to cure the ills of both
triode and pentode amplifiers. Each amplifier type had its
adherents. The triode amplifier boasted a smooth, low distortion
sound and a low output impedance, but yielded only limited watts.
The pentode amplifier produced many more watts and a more
aggressive, exciting sound, but at the cost of greater distortion
and much higher output impedance. A middle ground was sought. If a
new tube could be designed, it would have to yield the average of
the pentode and the triode sound, argued Hafler and Keroes. But
rather than create a new tube, their solution was to create a new
transformer that would allow the pentode to be used in a new way.

In This
Issue

1
3
4
4
6
9
13
16
17
17
19

611676

Ultra-Linear Output Stages

Line Stage
Amplifier
The
Ultra-Linear Cascode
OTL
Power Amplifiers
Headphone
Amplifier
Differential
Input HP Amplifier
Extracting
Extra PS  Voltages
Ultra-Linear
OTL Power Amplifiers
Heater
Concerns
Output
Stage Design
The
Feedback Loop
E-mail
Publishing
Information
Glossary
of Audio Terms
Glass-Ware.com
Articles
Classic
Magazine articles

Pentode
connected

Triode connected

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