15 Years of
www.linkwitzlab.com
A Retrospective
When I launched this
website in November of 1999 with DIY plans for the PHOENIX open-baffle
loudspeaker, I wanted to spread knowledge, educate and preserve for the
future what I had learned from building loudspeakers for my personal
needs. I knew that even professional loudspeaker designers could benefit,
as I had heard many
speakers and hardly any rendered stereo sounds in outstanding naturalness.
For me un-amplified sounds and symphony hall experiences have always been
my hearing's references, not other loudspeakers.
I built my first
loudspeaker for my father, who had a large LP collection of piano music.
The design came from a 1957 TELEFUNKEN Laborbuch and used a single 8"
driver towards the top of a 1600 mm tall and 500 mm wide baffle across one
corner of our living room. The baffle was sealed to the walls at the top
and 100 mm open at the bottom for increased bass. The mono speaker worked
well as I remember.
My real interest was in
radio frequencies, not audio and therefore the Laborbuch. I was a Ham
operator (DJ1SX). After studying electronics and graduating from TH
Darmstadt I worked for a few months in the Zentrallabor of SIEMENS in
Munich on a tunnel diode based and therefore very fast switching
analog-to-digital converter.
That ended when In 1961 I
took the opportunity to work for 2 years in the Microwave Division of
Hewlett Packard Co in Palo Alto, California. Well, that turned into 37
years at HP's R&D laboratories for electronic test and measurement
equipment and it became also the beginning of my fascination with speaker
design.
I learned much about
listening and audio design from colleagues and friends at HP, such as Russ
Riley, Lyman Miller and Brian Elliott. I met also Laurie Fincham from
KEF's R&D, who was a customer for HP's Fourier Analyzer. We sent long
air-mail letters back and forth across the Atlantic, exchanging ideas,
questions and answers.
Towards the end of my
career at HP I partnered with Marshall Kay and Kurt Pasquale and designed
the Dvorak, Vivaldi and Beethoven open-baffle loudspeakers for Audio
Artistry. I pulled out of the partnership in 1999 and soon after started
this website in order to publicize for everyone's benefit what I had
learned about speakers, rooms and hearing. Any income should pay for my
hobbies. Indeed it has and also helped to pay some household bills in
retirement.
The initial PHOENIX demo
project from 2000 grew into a 6-baffle setup with the addition of THOR
subwoofers in 2001. Simplification came in 2002 in the form of the
2-baffle, 3-way ORION, which served my domestic needs really well. The
ORION was not only a DIY project, but was also available turnkey, superbly
crafted by Don Naples of Wood Artistry. Don Barringer, former recording
engineer for the US Marine Band and I spent endless hours refining the
electronic equalization of the speaker. I chose SEAS Excel midrange and
tweeter drivers for their consistency and performance in this all-out,
cost no objective design. The Peerless XLS woofers were chosen for their
quietness at large cone excursions, i.e. low distortion, when accelerating
air in an open baffle. I tend to push drivers to their physical limits and
they must deteriorate gracefully. Eventually SEAS developed a powerful
woofer driver that met my demanding dipole requirements. John Stone had
leaned on SEAS R&D for a long time to develop such driver and Olav
Arntzen came through on this major challenge. These woofers topped out the
ORION.
In 2012, after 10 years,
the ORION was eventually surpassed by the 2-baffle, but 4-way LX521. The
LX521 was designed from the ground up as an electro-acoustic transducer,
as a machine and not a piece of furniture, and strictly designed for
obtaining dipolar radiation behavior from the bass to the highest
frequency. The different SEAS drivers that I use are optimal for my
acoustic requirements. They were chosen from a selection of SEAS drivers
that John Stone had suggested and which I experimented with. All this in
the pursuit of illuminating the listening room in such a way that a
listener will perceptually ignore the room and the speakers and focus
attention solely upon the rendering of the recorded acoustic scene, upon
the auditory illusion. With the LX521 I have raised the bar for achievable
sound quality in the home.
In 2005 I introduced PLUTO,
a small, 2-way, omni-directional speaker. The 2" AURA tweeter was the
starting point for the design. SEAS provided an extremely capable woofer
driver. In the local hardware store I found the plumbing pipes and parts
for ready made enclosures. I needed such speaker for a small
vacation cottage, where ORION would not have had enough breathing room.
PLUTO was a much simpler DIY project and had its power amplifiers,
crossovers and equalization built into the base, and was ready to be
driven from an iPod.
My attempt to improve upon
the PLUTO design for the cottage room application led in 2014 to the
LXmini. I surprised myself a bit as to how effectively this speaker can
set up a large and transparent sound stage and deliver a dynamic
rendering. Using DSP technology and sounding similar to the LX521, the
LXmini raises the bar for sound quality from any 2-way speaker.
Madisound.com offers kits
of wooden parts and drivers for DIY assembly and completion of LX521 and
LXmini speakers. Frank Brenner of LINKWITZ.store can even provide these
speakers in nearly finished assembly, in selections of beautiful wood and
with a DSP and power amplifier module.
So here we are in November
of 2014, after about 50 years of a hobby, and a passion for natural sound
and music in a domestic setting. Often times I can now thoroughly enjoy
what I hear in my living room, and even if the recording/mixing engineer
could have done better, because the musicians and the music come
through.
It has been a satisfying
journey, the more so because I have heard about many of you PHOENIX, THOR,
ORION, PLUTO, PLUTO+, LX521 or LXmini builders, by following the
discussions on the OPLUG. I give Mike a big THANK YOU for starting the
forum soon after my website was launched and to Davey, mac, BrianL, popeye,
wizardofoz and the many others, who have given of their time and
expertise, which has kept my email inbox under control and provided
support where I could not have done it.
Some of you have followed
my writings since the 1976 'Active crossover networks for non-coincident
drivers' paper in the JAES or my 1978 Wireless World articles about
'Loudspeaker System Design'. Some, many?, have built more than one of my
designs. I read of your dedication and learning from the construction, and
how you felt rewarded by its outcome in looks and sound. It gives me joy
that I could add to the joy in your life.
Let's continue to have fun,
Siegfried Linkwitz
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