39 - Website CD. The complete
content of www.linkwitzlab.com from November 1999 up to now. When printed out
it would be a book with over 500 pages. Having a CD allows you to search the
500+ photos and 400+ graphics of my website and to hear a number of my
38 - The Magic in 2-Channel
Sound Reproduction - Why is it so rarely heard?
Paper from the REPRODUCED
SOUND 2015 Conference of the Institute of Acoustics in the UK, where I
received the Peter Barnett Memorial Award for Education. PowerPoint
Slides and a Sound
Track (90 minutes with Q&A, 43.3 MB, 64kbps mp3, mono) allow you to
see and hear what I presented. You can also read it on
37 - Whatever happened to the quality of
reproduced sound in the home?
at the ALMA International Winter Symposioum, 2014, where I received the ALMA
Titanium Driver Award for Technical Achievement.
36 - Sound field Control for Rendering
Paper to be presented at the AES 52nd International Conference, "Sound
Field Control, Engineering and Perception",
Guildford, UK, September 2-4, 2013 - Abstract,
35 - My Search for the Ideal Stereo Loudspeaker
Paper for the AES 51st International Conference,
"Loudspeakers and Headphones",
Helsinki, Finland, August 21-24, 2013 - Abstract,
Presentation slides Finding the Prototype for Stereo Loudspeakers (pdf) & Talk (mp3, 18 MB,
34 - A Model for Rendering
Stereo Signals in the ITD-Range of Hearing
Paper presented at the 133rd AES Convention,
2012 October 26, San Francisco, CA - Preprint #8713
Abstract, Manuscript, Presentation
33 - Hearing spatial detail in stereo
Paper presented at the 26th TONMEISTERTAGUNG in Leipzig, Germany, 26 November 2010
in the session on Perception & Esthetics - Abstract - Manuscript
presentation and Talk (0:24 hrs, 11.3 MB, mp3)
32 - What Are the On-axis and Off-axis Frequency Response Requirements
for Stereo Loudspeakers?
The Burning Amp Festival in San Francisco, 30 October
Talk with Q&A (1:29 hrs, 21MB, mp3) - Presentation on YouTube - Slides -
31 - STEREO - From live to
recorded and reproduced - What does it take?
I wrote a 22 page article with 22 illustrations
for Linear Audio - Volume 0,
September 2010. Jan Didden is the Publisher/Editor of this new semi-annual 'bookzine'.
30 - STEREO - From live to
recorded and reproduced - What does it take?
presentation from Sacramento area DIY audio
group meeting. April, 2010
29 - The challenge to find the optimum
radiation pattern and placement of stereo loudspeakers in a room for the
creation of phantom sources and simultaneous masking of real sources. Expanded
presentation & discussion
Presented at the 7th AES Chile
November 5-7, Slide
28 - Electrical, mechanical and acoustic
filters in the design of a loudspeaker with dipole woofers
Presented at the 7th AES Chile
November 5-7, Slide
27 - The challenge to find the optimum
radiation pattern and placement of stereo loudspeakers in a room for the
creation of phantom sources and simultaneous masking of real sources
Presented at the AES 127th Convention in New York, 2009 October 9-12, Preprint
Manuscript, Abstract, Slide
Presentation and Sound
track (30 minutes, 14MB)
26 - Recording and reproduction over two loudspeakers
as heard live
Two papers presented at AES 126th Convention in Munich, May
Session: Recording, Reproduction, and Delivery
Siegfried Linkwitz: Hearing, loudspeakers and rooms, Preprint
Presentation 1 and Sound track 1
(14 MB), Manuscript
Part 2: Don
concepts and practices, Preprint #7671, Slide
Presentation 2 and Sound track 2 (14
25 - Phantom images in 2-channel audio
playback versus natural hearing processes, Power
Point slides from the Burning
Amp Festival, October 2008
24 - Accurate sound reproduction from two
loudspeakers in a living room, San Francisco AES Section
Meeting, May 2008. PowerPoint
slides and Sound track (21 MB).
<AES-SFO-May08> folder on the Website CD
contains the complete presentation and the 90 minute sound track with Q&A)
23 - Accurate sound reproduction from two
loudspeakers in a living room, AES
Section Meeting in London, November 2007. Listen to the Lecture
recording (1:33 hours, 24.5 MB) while viewing the slide
<AES-London-Nov07> folder on the Website CD
contains the presentation and the sound track with Q&A)
22 - Siegfried Linkwitz, Room
Reflections Misunderstood?, 123rd
AES Convention, New York, October 2007, Preprint 7162,
Manuscript, MS PowerPoint Presentation
21 - Why is Bass Reproduction from
a Dipole Woofer in a Living Room Often Subjectively More Accurate than from a
Monopole Woofer?, JAES, Vol. 51, No. 11, Nov. 2003,
Letters to the Editor, p. 1062. (Submittal)
Responses in Vol. 52, No. 5, May 2004, pp. 530-532
20 - The Audio Critic, Issue No. 29, Summer/Fall
2003, Letters to the Editor and
ensuing review after the ORION had
19 - Siegfried Linkwitz, Which loudspeaker
parameters are important to create the illusion of a live performance in the
living room?, 113th AES
Convention, Los Angeles, 2002, October 5-8, Preprint 5637, Abstract.
Overhead slides of the presentation.
===================== 0 - www.linkwitzlab.com website posted November
1 - Siegfried Linkwitz, Investigation of Sound Quality Differences between
Monopolar and Dipolar Woofers in Small Rooms, 105th AES
Convention, San Francisco, 1998, Preprint 4786, Abstract,
2 - Siegfried Linkwitz, Development of a Compact Dipole
AES Convention, San Francisco, 1992, Preprint
3431, Abstract, Manuscript
3 - Siegfried Linkwitz, A Loudspeaker Design for
Reduced Reverberant Sound Power
Output, AES Convention, New York, 1987, Precis, no Preprint available. Abstract in JAES,
Vol. 35, No. 12, December 1987
4 - Siegfried Linkwitz, Excursion-limited SPL
Builder, 4/84, Abstract,
Response to letters regarding Ref.12 in Speaker Builder
Mailbox, Abstracts, Letters
5 - Stiffer, Lighter Enclosures, SB 2/86
6 - Phase Information, SB 2/86
7 - Of Isobariks and Ferrofluids, SB 1/86
8 - Something Seems Amiss, SB 1/86
9 - Crossover Clarification, SB 2/84
10 - Linkwitz Design Developments, SB 1/84
11 - Linkwitz Query, 2/81
12 - Siegfried Linkwitz, A Three-Enclosure Loudspeaker System with Active Delay
and Crossover, Parts 1, 2, 3, Speaker
Builder 2/80, 3/80, 4/80. This is a revised reprint of: Loudspeaker System
Design, Wireless World, 1978, Abstract,
13 - Siegfried Linkwitz, Shaped Tone-Burst
Vol. 28, No. 4, April 1980, Abstract,
14 - Siegfried Linkwitz, Narrow Band Impulse Testing of Acoustical
AES Convention, Los Angeles 1978, Preprint
1342. Published as Ref. 13.
15 - Siegfried Linkwitz, Loudspeaker System
Design, Wireless World (now: Electronics
World+Wireless World), May/June/December 1978. Reprinted as Ref. 12. Abstract,
16 - Siegfried Linkwitz, Passive Crossover Networks for Noncoincident
Vol. 26, No. 3, March 1978, Abstract,
17 - Siegfried Linkwitz, Active Crossover Networks for Noncoincident
Vol. 24, No. 1, January/February 1976. Reprinted in Loudspeaker Anthology, Vol.1, AES
18 - Siegfried Linkwitz, Improved Headphone Listening - Build a stereo-crossfeed
circuit, Audio, December 1971, Abstract,
High-Resolution Audio, Workshop 6, 109th AES
Convention, Los Angeles, September 2000.
Chair: Malcolm O. J. Hawksford, University of Essex
Panel: Takeo Yamamoto, Pioneer Corp.
Mike Story, dCS Ltd.
Siegfried Linkwitz, Linkwitz Lab,
Kevin Halverson, Muse Electronics
Bob Katz, Digital Domain
Jim Johnston, AT&T-Research
San Francisco Section of the AES, February 1989
Elliott, Consultant in Electro-Acoustics, Palo Alto
Linkwitz, Hewlett-Packard Co., Santa Rosa, Graphics
Toole, National Research Council, Ottawa
- Investigation of Sound Quality Differences between
Monopolar and Dipolar Woofers in Small Rooms.
In acoustically small rooms the naturalness of low frequency reproduction may differ between dipolar and monopolar radiating woofers. The coupling of the two
types of sources to the modal structure of the room is investigated using
steady-state frequency response, cumulative spectral decay, energy-time curve,
modulation transfer function and shaped tone burst response. When sets of shaped
tone-bursts are used for measurement and listening, both frequency and time
domain attributes become observable which point to the perceived differences
between the two types of woofers. - e.g. mlt-bst0.gif,
mlt-bst1.gif, and listen to 100
Hz multi-bursts 100mbst4.wav.
with recorded burst signals for room and speaker tests is available.
For calculation of modes and other room parameters see modes1.xls
and Room acoustics.
- Development of a Compact Dipole Loudspeaker.
A relatively small size open baffle loudspeaker system has been developed using
conventional cone type electro-dynamic drivers to obtain sufficiently large
volume displacements. The 3-way system has dipole characteristics over the 20 Hz
to 1000 Hz frequency range for reduced interaction with the listening room.
Effects of the baffle shape upon the radiation pattern have been investigated.
Active crossovers and dipole specific equalization have been used to obtain a
flat frequency response. - e.g. cmp-dipl.gif,
- A Loudspeaker Design for Reduced Reverberant Sound Power Output.
The off-axis radiation from a loudspeaker in a normally reverberant listening
room contributes to the perceived on-axis sound. A dipole loudspeaker radiates
less power off-axis than a comparable closed-box loudspeaker with identical
anechoic on-axis sound pressure. Furthermore, the power response of a dipole is
more constant with frequency. Therefore, fewer room reflection and reverberation
effects can be expected. This paper describes a directional loudspeaker design
with 4-way active crossovers and response equalization. Conventional dynamic
drivers are used as dipole elements to reduce the acoustic size of the
loudspeaker and to control directivity. - e.g. pwr-resp.gif,
- Excursion-limited SPL Nomographs.
Some basic physics are presented in graphical format that relate the sound
pressure level generated by an acoustic source in free space to its piston
Too many speaker designs show either ignorance of these laws of nature or are
attempts to give the illusion of increased volume by substituting distortion for
their lack of sound output capability. - e.g. theory.gif,
Stiffer, Lighter Enclosures.
Bracing the internals of an enclosure to push panel resonances to above 1
kHz. Mounting a driver so that the basket-magnet mechanical resonance is not
Symmetric driver configuration (W-T-W) and the audibility of non-linear monaural
phase for 18 dB/oct, 24 dB/oct and delay derived crossovers.
Of Isobariks and Ferrofluids.
Undesirable effects of ferrofluid in a Dynaudio D28 tweeter are removed. The
formulas for the active equalizers, unfortunately, had some errors which have
been corrected in the *.gif files. - sb186-48.gif
Something Seems Amiss.
How much can you increase the driver output when you allow distortion?
The interaction between two crossovers.
The influence of the inherent woofer highpass behavior on the woofer to midrange
Phase correction for the spatial offset between the woofer and midrange drivers.
Linkwitz Design Developments.
Symmetrical driver configuration (M-T-M) for the satellites.
Woofer response equalization and cancellation of vertical rumble from the
turntable in the summed center channel woofer.
- A Three-Enclosure Loudspeaker System with Active Delay
This detailed description of a multiple-driver loudspeaker design covers driver
selection, enclosure design, active crossover, equalization and positioning.
Sufficient information is given to duplicate the system or to improve existing
systems by equalizing the low-frequency response or adding a separate woofer
box. - e.g. f0Q0.gif , f0Q0fpQp.gif
The material is still as valid today as it was when written in 1978. It covers
all aspects of closed-box loudspeaker design. I have since moved away from this
approach, because of the inherent difficulty to eliminate the characteristic box
sound and the strong interaction with the listening room at lower frequencies. I
prefer open-baffle designs. - e.g. PHOENIX
Take a look
at page 1 or the full
article (sb80-3wy.zip). I highly
recommend to study the material, regardless of whether you are building passive
or active speaker systems. At the very least it can serve as a review of all the considerations that should enter into the design of a loudspeaker.
13 - Shaped Tone-Burst
A properly shaped tone burst is used to evaluate the dynamic behavior of a
loudspeaker within narrow frequency bands. The raised-cosine envelope of a
five-cycle burst reduces the low frequency content of the test signal and
confines the spectrum to a one-third octave width. - e.g. 20brst1.gif
, and listen to 1 kHz 4-cycle Blackman windowed bursts 1kblkman4.wav.
The transient behavior of the loudspeaker is indicated by a change in the
envelope of the burst signal. The frequency response of the loudspeaker is
related to the maximum amplitude of the received burst. The relatively short
duration of the burst preserves time domain information and gives a slightly
smoothed frequency response.
Discrimination against echoes is obtained from the short duration of the shaped
tone burst. The influence of room reflections on the measurement is
A detailed circuit schematic for building a shaped tone-burst generator and peak
detecting receiver is provided. - e.g. brst_gen.gif,
A CD with recorded burst signals for room and speaker
tests is available.
- Passive Crossover Networks for Noncoincident Drivers.
Component values have been calculated for the normalized prototype of the 12 dB/oct
and 24 dB/oct crossover filter network under the assumption that it is driven
from a voltage source and loaded resistively. - e.g. passv-xo.gif
- Active Crossover Networks for Noncoincident Drivers.
The spatial separation between drivers in a loudspeaker system affects the
radiation pattern over the frequency range where more than one driver
contributes to the total acoustic output. An analysis of conventional crossover
networks shows that the main lobe of the radiation pattern shifts in direction
and increases in amplitude. A new network transfer function, which can easily be
realized with operational amplifiers, eliminates this problem. - e.g. xo12-24.gif
delay networks are used to compensate for offsets in the acoustical planes from
which the individual drivers radiate. - allpass.gif
The audibility of phase distortion is
investigated with the conclusion that it is undetectable for the proposed types
This paper is the origin of the "Linkwitz-Riley" crossover.
Russ Riley and Siegfried Linkwitz
September 2006, Douglas City, CA
|In the sixties,
early seventies, I
worked with Russ Riley at Hewlett-Packard's Palo Alto R&D laboratory
for the development of RF and Microwave test equipment. Like many other
engineers we had "G-Jobs", building such things as
electronic ignitions for our VW bugs and vans, FM receivers, phase-locked
pulse width FM demodulators, short-wave receivers, audio pre- and power
amplifiers, third octave audio analyzers, headphone equalizers, and of
course, loudspeakers. After measuring the acoustic and electrical
responses of commercial speakers we equalized them and tried to understand
why they were designed with strange looking driver layouts, used large
baffles, were stuffed with a variety of internal damping materials and
used various box stiffening and damping techniques. Eventually we
completely redesigned them and built our own speakers. Russ and his wife,
Vicky, an accomplished organist, always had the most critical and reliable ears. He
was an ingenious design engineer, a strong contributor, who inspired and
challenged many of us on our HP and unofficial design projects.
Russ retired after over 40 years
in R&D for HP/Agilent and now lives
with his wife in a remote mountain valley, in a genuine log cabin, amongst
pear, plum and walnut trees, berry bushes, chicken and deer, the sounds of a large creek, and
the pine and fir trees that climb up the slopes. He died peacefully
in his log cabin on December 6, 2010.
- Improved Headphone Listening - Build a stereo-crossfeed circuit.
A simple circuit is described that reduces the unnatural spaciousness of sound
reproduction and the complete separation between channels which does not
correspond to our normal hearing experience. This "super stereo"
effect, while impressive at first, becomes very tiring after a while. - Full
19 - Which
loudspeaker parameters are important to create the illusion of a live
performance in the living room?
The preference in loudspeaker product
design is for small size, while preserving maximum low frequency extension and
output volume. If the goal is to create a realistic reproduction of a live
event, then certain speaker parameters must be adequately controlled, such as
volume displacement, intermodulation distortion, stored energy and off-axis
frequency response. Components must be carefully selected for low distortion
performance. Parameters like phase linearity and cabinet diffraction are
sometimes overrated. Multi-channel speaker setups require propagation delay
correction and bass management, if not all speakers cover the full frequency
range. These issues are reviewed at the advent of high resolution surround
sound. The new technology can only fulfill its promise and expand into more than
a niche market, if capable loudspeakers are widely available.
22 - In a domestic living space a 2-channel monopolar and a dipolar loudspeaker
system are compared for perceived differences in their reproduction of acoustic
events. Both sound surprisingly similar and that is further enhanced by
extending dipole behavior to frequencies above 1.4 kHz. The increased bandwidth
of reflections is significant for spatial impression. Measured steady-state
frequency response and measured reflection patterns differ for the two systems,
while perceived sound reproduction is nearly identical in terms of timbre,
phantom image placement and sound stage width. The perceived depth in the
recording is greater for the dipole loudspeaker. Auditory pattern recognition
and precedence effects appear to explain these observations. Implications upon
the design of loudspeakers, room treatment and room equalization are discussed.
27 - The
challenge to find the optimum radiation pattern and placement of stereo
loudspeakers in a room for the creation of phantom sources and simultaneous
masking of real sources
Stereo sound reproduction relies upon the creation of an illusion. Ideally the
two loudspeakers and the room disappear, leaving only a phantom acoustic scene
to be listened to. The polar frequency response of a loudspeaker determines the
angular distribution of room reflections and their spectral content. The
placement of the loudspeakers relative to the room surfaces determines the
initial delay of the reflections. Together they affect the formation of phantom
sources. A proven loudspeaker and room configuration is proposed as starting
point for listening tests to determine the optimum loudspeaker radiation
pattern. It is an invitation to extend our understanding of the psycho-acoustic
processes that are involved with stereo listening in a room and to replace
anecdotal with scientific evidence.