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David Hafler (February 7, 1919 – May 25, 2003) was an
American audio engineer. He was best known for his work on an
improved version of the Williamson
amplifier using the ultra-linear
circuit of Alan
Blumlein.

In 1950, Hafler founded Acrosound with his colleague Herbert Keroes. This company was
primarily in the business of designing and manufacturing
transformers for tube amplifiers. Around this time Hafler and Keroes
popularized the ultra-linear
output-stage for audio amplifiers. However, the partnership did not
last.

In 1954 Hafler founded Dynaco
with Ed Laurent. Hafler was
instrumental in bringing affordable, high-quality audio kits to
hobbyists, making his name a household word in the US audio
community for many years.

In the 1970s Hafler promoted "passive pseudo-quadraphonics",
an inexpensive method of recreating ambient sounds at the rear from
ordinary stereophonic
recordings. Known as the "Hafler hookup",[1]
this consisted of two similar additional rear speakers, connected in
series (typically 8 + 8 or 16 ohms
total) between the live feeds to the front speakers. The crosstalk or loss
of stereo separation in the front speakers was generally less than 2
dB while the rear
sound level in a typical recorded live performance was about 7 dB
below the front, but clearly audible. The Dynaco QD-1 Quadapter
based on this idea, added a variable resistor to control the volume
of the rear speakers. This passive method worked fairly well
compared to the matrix decoders of the period, which attempted to
reconstruct a surround sound field from a two channel recording. It
has been observed that ambient sounds in a concert, such as applause
or coughs from the audience, are generally received in a
non-correlated phase by the stereophonic microphones,
while sounds from the musicians are generally in a more or less
synchronous phase. Thus, if rear speakers are fed with the
difference between the stereo channels, audience noises and echoes
from the auditorium can be heard from behind the listener.

In 1977, Hafler founded the David Hafler company in Pennsauken,
New Jersey (Philadelphia suburb). His first two products were the
DH-200 power amplifier and a companion preamplifier, the DH-101.
Also notable was the rugged DH-500 stereo amplifier which was rated
a 255 watts per channel and saw great success home, studio, and live
environments. Following the Dynaco business model, these units were
available in both kit form and factory assembled. Both units were
acclaimed for their breakthrough sound quality and exceptional
value. Both are still highly prized today. Hafler made several
different models of amplifiers and preamps over the years. Hafler
products were also fertile ground for improvements through upgrades
and modifications, that were done both by hobbyists and small audio
companies.

Hafler sold his company to the Rockford Corporation in 1987.
Today, the Hafler company primarily makes products for the
professional sound market.

The Hafler brand was purchased by Canadian based Radial
Engineering Ltd. in 2014. Radial is re-launching the Hafler brand of
high-fidelity audio products. [2]

David Hafler died May 25, 2003 in Philadelphia,
Pennsylvania,
USA.

References[edit]

^
Gerzon, Michael A year of
surround-sound. Hi-Fi News, August 1971

^
http://archive.constantcontact.com/fs173/1109101767207/archive/1118461981143.html

External
links[edit]

Stereophile Magazine biography and obituary of
David Hafler

Greg Dunn's Dynaco page containing Hafler newspaper
obituary

Persondata

Name

Hafler

Alternative names

Short description

American audio engineer

Date of birth

February 7, 1919

Place of birth

Date of death

May 25, 2003

Place of death

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/David_Hafler — Please support Wikipedia.
This page uses Creative
Commons Licensed content from Wikipedia.
A portion of the proceeds from advertising on Digplanet goes to
supporting Wikipedia.

344 videos foundNext >

Dr.David Hafler
Interview

Dr.David Hafler is interviewed by Richard
Cohen. http://www.nationalmssociety.org/

David Hafler DH-200
Mosfet

Sa distorsionnais pas ici c'est le
téléphone qui fourni pas lol Mr. Hafler je t'aime!! Premiere
essaie pour la David Hafler DH-200 (Mosfet) 100 watts canal
comme pré-ampli la Noresco 2570...

David Hafler 220 Power Stereo
Amplifer

David Hafler 220 Power Stereo
Amplifer.

*~*~* David Hafler DH-200 Power
Amplifier *~*~* OLD SCHOOL GOODNESS Part 1

AC/DC Converter (FOR CAR CD PLAYER): CAE
APS-55 SOURCE: Eclipse CD 3424 Car CD Reciever AMPLIFIER:
David Hafler DH-200 SPEAKERS: Speakerlab's {Can't tell you,
lets just say its there ...

Hafler 500 High End Stereo
Power Amp At Working Mans Price $475 714-548-0385

250 watts a wide and this is a very high
quality overbuilt power amp and offers high end sound at a
great price. You will hear things in your music you have never
heard like extra tone in...

WTNH News Channel 8 feature on
David Hafler, M.D., and Helen Langello

WTNH News Channel 8 health reporter Jocelyn
Maminta interviewed Yale Chief Neurologist David A. Hafler,
M.D., about the role of genetics and multiple sclerosis.
Hafler and the International...

*~*~* David Hafler DH-200 Power
Amplifier *~*~* OLD SCHOOL GOODNESS Part 2

AC/DC Converter (FOR CAR CD PLAYER): CAE
APS-55 SOURCE: Eclipse CD 3424 Car CD Reciever AMPLIFIER:
David Hafler DH-200 SPEAKERS: Speakerlab's {Can't tell you,
lets just say its there ...

Hafler DH-101
Preamplifier

A in depth look at David Hafler's DH-101
Preamplifier. This was The David Hafler Co. first product.
Several months later, the introduced the DH-200 Power
Amplifier to go along with it. Sold...

Sodium and MS

Dr. Kantor talks with Dr. David Hafler,
Chair of Neurology at Yale, about how Sodium may induce
inflammation.

*~*~* Old School Hafler DH-200
Power Amplifier *~*~*

Overview of the David Hafler DH-200 power
amplifier. A very heavy, powerful, clean, unit! Was
dis-assembled and re-assembled after old paste Thermal
compound was removed and re-applied.

344 videos foundNext >

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