----- Experience in your own room the magical nature of stereo sound -----



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dipole speaker

Three-Box active
system (1978)



& Room




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the Jeweler


What's new


LX - Store


with Fitz






   What's new?


          Siegfried Linkwitz (1935-2018). 

           A warm hearted  freethinker, pioneer, innovator and friend passed away. It´s sad.....    Frank Brenner

           "Celebration of Life" for Siegfried Linkwitz, Sunday October 14, 1:30PM - 4:00PM, 
         at the Mill Valley Community Center ,180 Camino Alto, in Mill Valley, 8 miles north of the Golden Gate Bridge.
Everyone is welcome!


  • 09 August 2018
    BURNING AMP - Sunday Sept.30th  in San Francisco - 
    There will be a LXmini +2 demo. We plan to have a new balanced version of Nelson Pass` analog JFET buffer/equalization/crossover for LXmini / LXmini+2 / LXstudio. Hope to see you at Ft Mason. Regards, Frank Brenner.
  • 28 January 2018
    - The Emotiva A-800, 8 x 50W amplifier, could be a low cost, satisfactory performance solution for LXmini, or LXmini+2, or LXstudio applications. 

  • 22 December 2017
    - DNA and Its Epigenetic Potential, an Antenna for Cosmic Emissions:
                Driving Force in Evolution and Energy Transmission?

  • 20 December 2017

    Please note:

    I no longer sell directly any of my previously offered software or hardware products. I have retired.

    Construction plans for LINKWITZ LAB designs, parts kits and turnkey loudspeaker systems are available from www.magicLX521.com

    Construction plans for LINKWITZ LAB designs and parts kits are available from 

    The Construction plans are required license to purchase parts kits and assembled systems. 
    | Terms & Conditions |

    The OPLUG Forum is the place for advice and help

    Have fun!

  • 10 December 2017
    - Here are three books well worth exploring, as you wonder about our place in the universe

  • 6 December 2017
    - From 2008 to 2017

  • 26 November 2017
    BURNING AMP-2017
    - Baffle Diffraction Versus Neutral Sound Dispersion - one of four presentations, which are now on YouTube

  • 15 November 2017 -  BURNING AMP
    We played the LXmini+2 loudspeaker system driven by an ASP, which was derived by Nelson Pass from my original DSP transfer functions to our mutual satisfaction and enjoyment.
    More photos ...
    Nelson Pass - Siegfried Linkwitz - Frank Brenner
    We collaborated on analog crossover/equalizers (ASP) for LXmini and LXmini+2. They will become available in the DIYAUDIO STORE

    5 November 2017
    BURNING AMP - Next Sunday in San Francisco - 
    I plan to give a talk about "Baffle design, diffraction, radiation pattern and stereo imaging" (PDF). Nelson Pass will bring a pair of LXmini with LXsub2 and his 2-way and 3-way Analog Signal Processors using only JFET buffer stages for equalization and crossovers. Frank Brenner will bring a proto of his PowerBox with 2-way and 3-way ASP built-in.

  • 26 October 2017
    Links - Bruno Putzeys' thoughts on MQA

  • 9 September 2017
    LXmini ASP - An update of the Analog Signal Processor, Burning Amp 2017 and an interview with Nelson Pass

  • 5 September 2017
    LX521.4 ASP - Analog Signal Processor assemblies and printed circuit boards 

  • 4 September 2017

    Links - Interview with 'Esprit Yoga Magazine'


    Skype Satsang with Mooji

    Living in the Joy of Our Natural Being


  • 5 August 2017
    Links - Artificial accuracy - The Metrology of Quality, Quantity and Convenience - Context and Stories

  • 1 August 2017
    Links - A story of purpose - The two most important days of our lives ...

  • 1 August 2017
    http://LXspeakerfactory.com/ - LXmini, LXmini w/Subs, Orion4d turnkey systems. California Audio Show 2017 - CAS7 Awards

  • 1 July 2017
    Sea Ranch - As seen through the eyes of a famous architect's son

  • 27 June 2017
    Links - What happens in your brain when you pay attention?

  • 26 June 2017
    Recent reading - Books of interest to me

  • 25 June 2017
    Peter Aczel - A dear friend has died  


  • 12 June 2017
    My current setup - I am done and happy - 

  • 14 May 2017
    Archimago's Musings - On Being an Audiophile, Rationality, and Respectability (Thoughts on the Hardware Audiophile Hobby)

  • 13 May 2017
    Links - What is so special about vinyl?

  • 11 May 2017
    LX-Store - Analog Signal Processor - ASP.4 - for the LX521.4 loudspeaker

  • 11 May 2017
    Links - Dynamic Range: No Quiet = No Loud

  • 10 May 2017
    Links - Music with a Cochlear Implant?

  • 10 May 2017
    Links - Archimago's Musings - A 'more objective' take on audiophile topics among other thoughts ... 

  • 10 May 2017
    Links - American Radio History - a nice archive of old audio related publications

  • 24 April 2017
    LXmini ASP - Analog crossover/equalizer for the LXmini

  • 20 April 2017
    LX521 Supplies - Updates about my LX521.4 Systems and ASP.4

  • 8 April 2017
    My current setup - Hurrah! - ASP.4 System's exemplary performance confirmed to me at today's Open House:


  • 3 April 2017
    Issues in speaker design - Power amplifier distortion at 1 W & 100 mW output for a 1 kHz and 5.5 kHz sine tone combination 

  • 1 April 2017
    Issues in speaker design - Group delay distortion at the low frequency end of a loudspeaker

  • 26 March 2017
    Open House in Corte Madera --- Saturday, April 8, 2017, from 11 am to 5 pm.
    Hear the LX521.4 loudspeaker with PowerBox 6pro NCore and compare it to the LX521.4 with ASP.4, OPPO Sonica DAC and AT528NC 8-channel power amplifiers. Have some fun during Tax time.
    Send me an email  with number of visitors, for time of your arrival and for directions to my house. 
    Review: My current setup  

  • 17 March 2017
    My current setup - I intend to upgrade my LX521.4 electronics in Sea Ranch

  • 16 March 2017
    Links - Technology Trends - High Resolution Audio 

  • 4 March 2017
    Links - The Art of Listening - from the artist's and producer's perspective 

  • 28 February 2017
    www.magicLX521.com - OPEN HOUSE in Stuttgart, Germany, on Saturday, March 25th.
    Contact Dr. Frank Brenner for directions

  • 25 February 2017
    Links - Interview with industrial designer Dieter Rams

  • 22 February 2017
    KII Audio THREE loudspeaker - Yesterday I listened to the remarkable Kii-THREE loudspeaker

  • 11 February 2017
    www.magicLX521.com - Dr. Frank Brenner has opened the magicLXaudio store.

    Here you find the LX521, LXstudio, LXmini+2 and LXmini offered as kits and turnkey systems of the highest quality.
    PowerBox electronics use Hypex NCore modules and DLCP for lowest distortion, multi-channel power amplification. 
    A re-clocker is offered, which completely removes jitter from a USB audio data stream. 
    The store fulfills my dream of giving ready access to sound reproduction equipment of the absolutely highest performance,
    to help music lovers who need more than my DIY construction plans to put together an LX loudspeaker system.

  • 9 February 2017
    Publications - The Magic in 2-Channel Sound Reproduction - Why is it so rarely heard?

  • 30 January 2017
    Engineering information - Loudspeaker Systems with Optimized Wide-Listening-Area Imaging 

  • 29 January 2017
    Linkwitz Lab inspired designs - LX521 from Switzerland, the French part

  • 29 January 2017
    Linkwitz Lab inspired designs - A 3D-printed desktop 'LXmini'

  • 29 January 2017
    Linkwitz Lab inspired designs - The Manger driver used as dipole

  • 28 January 2017
    Engineering information - SEAS DXT wide dispersion tweeter

  • 28 January 2017
    Linkwitz Lab inspired designs - The Ultimate DIY Sound System Is at Hand

  • 26 January 2017

    The LXmini+2 or  LX521.4 with PowerBox setups render stereo recordings to a degree of realism that I had never experienced before.

    LX Loudspeaker Audition -
    Corte Madera, 1/21 &1/22, 2017

    Here was an opportunity to hear the LXmini+2 driven from a PowerBox 6pro NCore from www.magicLX521.com.

        OpenHouse-Jan2017.jpg (146735 bytes) from OPLUG
    LXmini+2 at Burning Amp 2016

    Equal time was spent to listen to the PB 6pro Master with an additional PB 6pro Follower driving left and right speakers of the LX521.4 system. 

    Either system can provide a fully satisfying and realistic sound experience of emotional impact.

  • 14 January 2017
    Other designs - BeoLab90 Loudspeaker - I had a chance to listen and I am impressed

  • 12 January 2017
    Other designs - Lexicon SL-1 Loudspeaker - A unique design with horizontal beam steering

  • 8 January 2017
    LX loudspeaker audition --- Open House in Corte Madera --- January 21 and 22, 2017 --- Saturday and Sunday from 10 am to 5 pm.
    Frank Brenner and I installed a second PowerBox 6pro NCore into my system and I now can also drive the LX521.4. - Fantastic!
    Compared to the LXmini+2 driven from a single PowerBox the LX521.4 has obviously higher output capability at all frequencies and/or lower distortion. But in all other respects the music and acoustic scene experiences are remarkably similar. The LX521.4 gives a convincing sound illusion regardless of the type of music played and yet the speakers are revealing of every subtle detail in the recording to a mix and mastering engineer. 

    During the Open House I will demo the LXmini+2 and LX521.4 full-range systems driven from NCore PowerBoxes. I can also change over to the LXmini and/or my miniDSP4x10HD and ATI amps system, if desired. 

    Frank Brenner will not be present. He had to cancel his visit.

    Send me an email  for number of place reservations at either 10:00 am, 11:30 am, 1:00 pm, or 2:30 pm and for directions to our house. 

  • 18 December 2016
    LX521.4 builders might check their Owner Support page for an ASP.4 proposal

  • 22 November 2016
    Links - Room Acoustics for Listening

  • 21 November 2016
    So, what? - Come into my parlor, said the spider ...

  • 17 November 2016
    LXmini+2 with PowerBox 6pro NCore - Fantastic! The most realistic rendering of sound events and sound scenes,
    which I have ever heard in my living room!  

  • 16 November 2016

    Read more about BA 2016 at www.magicLX521.com

    Read about possible LXmini+2 Stereo System demo's

    Burning Amp 2016
    We showed the LXmini+2 driven by a PowerBox 6pro - NCore. Input to the PowerBox came from music files on the Hard Drive of my Laptop PC using JRiver for playback. The electrical USB output signal was converted to optical by a AFI-USB HF Noise Blocker & Re-clocker before being applied to the DLCP in the PowerBox.

    This is an absolutely superb audio system. It was immediately apparent to our listeners, even in the highly reverberant acoustics of the very large demo room at Fort Mason. More about the sound ...

    Frank Brenner and I plan to have an Open House in Corte Madera  in January, probably Saturday and Sunday, 1/21 & 1/22, if Frank Brenner can get his A380 flight schedule aligned with that date. 


  • 3 November 2016
    3.4 - The LXmini woofer - A new chapter in 'My Conversations with Fitz'

  • 2 November 2016
    Burning Amp 2016 - Sunday, November 13, is coming up fast. My plans have changed. I will bring LXmini+2 speakers to be driven from a PowerBox 6pro NCore, which Frank Brenner (www.magicLX521.com) will have flown in on the day before. (He pilots a Lufthansa A380 from Frankfurt.) 
    The PowerBox combines a Hypex DLCP with six NCore power amps, 2x100W, 2x125W, 2x250W. So it is able to feed all LXmini, LXmini+2 and LXstudio from one single unit (€2490 plus VAT). For LX521.4, it takes one PowerBox 6pro NCore per side.

  • 26 October 2016
    Links - Loudspeaker Cabinet Diffraction

  • 12 October 2016
    Burning Amp 2016 - Sunday, November 13. I will bring the LX521.4 speakers and Frank Brenner (www.magicLX521.com)
    his PowerBox 4180 (Hypex DLCP with UcD power amps) to drive them.

  • 12 October 2016
    Other designs - ONO Audio and the LXmini

  • 4 October 2016
    Acoustics and Mechanics - My conversations with Fitz continue

  • 19 September 2016
    LX-Store - Updated list of ATI power amplifiers, which are in production and available from Linkwitz Lab
    for LXmini, LXmini+2, LXstudio and LX521.4 loudspeaker products. ATI just introduced the AT52xNC line of 
    Hypex NCore based power amplifiers. 

  • 12 September 2016
    LXmini owners using the miniDSP 2x4HD please see the new photo on the support page for correct input and output cable connections.

  • 7 September 2016
    LX-Store - Store for LXmini, LXmini+2, LXstudio and LX521.4 loudspeaker products

  • 17 August 2016
    If you are using the miniDSP 4x10HD for the LXmini, LXmini+2, LXstudio or LX521.4 loudspeakers, 
    then check your LX-Support-Page for the latest update.

  • 14 August 2016
    My conversations with Fitz - Acoustics and Mechanics

  • 8 August 2016
    Publications - STEREO - From live to recorded and reproduced - What does it take?

  • 8 August 2016
    My conversations with Fitz - Hearing - Part 2

  • 3 August 2016
    My conversations with Fitz - Perception

  • 26 July 2016
    My conversations with Fitz - Reality and Meaning

  • 23 July 2016
    My conversations with Fitz - Me and the Planet

  • 19 July 2016
    My conversations with Fitz - ..... come into my parlor said the spider ..... The Creation
    I sidetracked for a while as I was trying to explain Hearing and the Association Model of Hearing in pictures
    and got into the concepts of 'Gestalt generation' and 'Gestalt recognition'.
    I will get back to Acoustics and Hearing soon.

  • 14 July 2016
    Other designs - The Beanstalk CJK loudspeaker

  • 30 June 2016
    Links - A Meta-Analysis of High Resolution Audio - Perceptual Evaluation

    26 June 2016
    But first you want to experience LXmini or LX521 ??

  • 25 June 2016
    My conversations with Fitz
    - Our conversation continues. It's all about "acoustic size"

  • 21 June 2016
    About me
    - Coverage of Audio Artistry Vivaldi, Dvorak and Beethoven loudspeakers 
    in the The Audio Adventure magazine from some 20 years ago

  • 20 June 2016
    HOME - I cleaned up the HOME page for fast access to essential topics

  • 19 June 2016
    Terms & Conditions
    - I have added item 6) about selling loudspeakers, which are clearly inspired by a Linkwitz Lab design 

  • 15 June 2016
    Your own design - My conversations with Fitz

  • 23 May 2016
    Music - Anouar Brahem and Mason Bates, beautiful and interesting music and sounds I recently listened to

  • 1 May 2016
    LX521.4 owners might check update 11). 
    It's what I am listening to these days

  • 25 April 2016
    Links - ECMA-407 and Telecommunications in the 21st Century

  • 25 April 2016
    Links - Reverberation ...and how to remove it

  • 21 April 2016
    LXmini+2 - Construction Plans are now available

  • 19 April 2016
    OPEN HOUSE - Saturday & Sunday, May 14 & 15, 2016, between 10:00 am and 5 pm
    You are invited to come to The Sea Ranch, CA and listen to my LXmini and LX521.4 loudspeakers as set up in our Sea Pine Cottage.
    Also meet Nelson Pass - my neighbor and friend - who will be present.
    Send me an email  with names, day and time of visit and to receive directions to our house. 
    Since The Sea Ranch is a 3 hour drive from San Francisco you may want to stay overnight and make a beautiful weekend vacation out of this trip. Check with VRBO or VacationHomes for renting a house at Sea Ranch. The small town of Gualala at the north end of Sea Ranch has motels, restaurants, shops and what else one might need for a vacation. The closest large town is Santa Rosa, about a two hour drive away.

  • 14 April 2016
    LXmini - Gallery
    - LXmini Speaker Build from Kit

  • 12 April 2016
    - Floyd Toole: Room reflections and Human Adaptation for Small Room Acoustics

  • 4 April 2016
    OPEN HOUSE - Sunday, April 17th, 2016, between 10:00 am and 4 pm.

    You are invited to come to our home in Corte Madera, CA and listen to LXmini, LX521.4 or LXstudio loudspeakers. Hear the new LXmini+2, a refinement of the LXmini by the addition of compact dipole subwoofers.

    Meet Dr. Frank Brenner from www.magicLX521.com who will be visiting on his layover day between flights from Frankfurt to San Francisco and back to Frankfurt as the captain of a Lufthansa A380. This is a rare opportunity to meet him.

    Send me an email  for number of place reservations at either 10:00 am, 11:30 am, 1:00 pm, or 2:30 pm and for directions to our house. 

    Get your Taxes done by April 16th and enjoy the freedom!

  • 29 March 2016
    Loudspeakers - Loudspeaker system design - This page was no longer accessible after I had rearranged pages some time ago. 
    The presented material is fundamental and educational, like a "Loudspeakers 101" course.

  • 25 March 2016
    Amplifiers etc - Amplifier distortion, amplifier and/or driver limited SPL, speaker cables & interconnects

  • 17 March 2016
    Links - The Universal Sense - How Hearing Shapes The Mind

  • 11 March 2016
    Audio production - Streaming DSD files

  • 5 March 2016
    My Daughter the Jeweler - Surprise someone you love with a little gift!

  • 2 March 2016
    Other designs - Mellow Acoustics combined a smaller ESL63 like top with a dynamic woofer  

  • 2 March 2016
    The Sea Ranch - The remodeled Sea Pine Cottage is our second home. LXmini and LX521.4 play here to my fullest satisfaction. Look at my setup and associated equipment.

  • 24 February 2016
    about me - The UK audio magazine Hi-Fi News & Record Review reports on me and my work for rendering sound scenes in their March 2016 issue:
    hfn-cover.jpg (151954 bytes) hfn-page1.jpg (382556 bytes) hfn-page2.jpg (394450 bytes) hfn-page3.jpg (412955 bytes) hfn-page4.jpg (413150 bytes)


  • 24 February 2016
    Links - Optimizing the directivity index of a 2-way loudspeaker

  • 21 February 2016

    magicLX521 - Dr. Frank Brenner's comments about our Open House yesterday. I will have such event again in the future.

    "A unique opportunity to listen to LXmini, LXstudio and LX521, presented by the designer himself.... and to experience Eike and Siegfried Linkwitz` overwhelming hospitality. 

          The interested audience got familiar to the design priciples of these outstanding loudspeaker system. Time for discussion and questions . And of course time to hear these unconventional loudspeakers perform, fascinating the audience with their stable, live-like illusion of musical performance, that does n o t collapse when leaving the "sweet spot". Visitors could convince themselves by wandering around in the room: The phantom imaging remains stable, no matter where you listen from. 
          No Room correction at work, no fancy room treatment, no boutique cables. But intelligent engineering and a huge wealth of experience allowed the design of these transducers, that work so well with the room.
          All rounded up by Eike's fantastic catering (home-made Brownies and more). Thank you! 

          Highly recommended, try to get a ticket for a possible future session!"


  • 11 February 2016
    Links - Acoustic power radiation from loudspeaker cabinets

  • 10 February 2016
    Amplifiers - PLUTO amplifiers for LXmini

  • 21 January 2016
    You are invited to come to our home in Corte Madera, CA and listen to LXmini, LX521.4 or LXstudio loudspeakers on 
    Saturday, February 20th, 2016, between 10:00 am and 4 pm
    Meet Dr. Frank Brenner from www.magicLX521.com who will be visiting on his layover day between flights from Frankfurt to San Francisco and back to Frankfurt as the captain of a Lufthansa A380. This is a rare opportunity to meet him.
    Send me an email  for number of place reservations at either 10:00 am, 11:30 am, 1:00 pm, or 2:30 pm and directions to our house. 

  • 7 January 2016
    Links - Psychoacoustically based 3D recording techniques on the revised Hauptmikrofon.de website

  • 20 December 2015
    Links -  Rationalism versus Empirism

  • 10 December 2015
    You are invited to come to our home in Corte Madera, CA and listen to LXmini, LX521.4 or LXstudio loudspeakers on 
    Saturday, January 23rd, 2016, between 10:30 am and 6 pm
    . Bring along who needs to be pleased.
    Send me a note for number of place reservations at either 10:30 am, 12:00 noon, 1:30 pm, 3:00 pm, or 4:30 pm and directions to our house. 
    All filled up.

  • 10 December 2015
    The Magic in 2-Channel Sound - Comments by James Heddle 

  • 7 December 2015
    My Daughter the Jeweler - Have a look!

  • 22 November 2015
    Peter Barnett Memorial Award - I received it at the IOA Conference on REPRODUCED SOUND 2015 in the UK

  • 21 November 2015
    The Magic in 2-Channel Sound
    - John Watkinson talks about "The Importance of Directivity in Loudspeakers"

  • 19 November 2015
    The Magic in 2-Channel Sound -  My paper with the title "The Magic in 2-Channel Sound Reproduction - Why is it so rarely heard?"
    from the IOA Conference on REPRODUCED SOUND 2015 in the UK.

  • 31 October 2015
    Coming up November 10th is the IOA Conference on REPRODUCED SOUND 2015. I will give a talk and paper with the title:
    The Magic in 2-Channel Sound Reproduction - Why is it so rarely heard?

  • 25 October 2015
    Other designs - BeoLab 90 with DSP controlled and adjustable directivity

  • 20 October 2015
    Links - Music Theory & MIDI Encoding

  • 19 October 2015  
    NOTE - The mailbox at is 100% full. I am trying to resolve that problem. 

  • 19 October 2015
    -  "In Linkwitz' room, you don't  feel listening to loudspeakers, but to a musical performance"  -  
    Lyman Miller (center), former HP colleague, audio projects collaborator, and involved with music recording at Stanford University and other places.      More photos here.

  • 12 October 2015
    LX521 Supplies - PowerBox 4180 and PowerBox 4400 pro from magicLX521.com for LXmini, LXstudio and LX521.4

  • 12 October 2015
    LX521 Supplies - A reworked ASP pcb for 3-way LX521 construction will be offered by "makonats" 

  • 12 October 2015
    Links - Jeff Hawkins of Numenta gives a fascinating talk about pattern recognition in the brain in response to changing sensory input data streams.

  • 12 October 2015
    An article about Linkwitz-Lautsprecher written by Schoeps Microphone Technical Director Joerg Wuttke (ret.) will be published in "Das Musikmagazin für Ärzte, tonart  4 | 2015", which is an insert to the Gerrman Ärzteblatt.

  • 10 October 2015 
    Burning Amp 2015
    on Saturday, October 17th, in Redwood City, CA. See diyAudio for schedule and exhibitors.
    I plan to demo the LXmini and LXstudio with the PowerBox from magicLX521.com
    Dr. Frank Brenner, designer of the PowerBox, is scheduled to pilot a Lufthansa A380 from Frankfurt to SFO the day before 
    and will be present on his layover day.  

  • 6 October 2015
    Rocky Mountain Audio Fest, Denver, CO, October 2-4
    Time to pack up! - A big THANK YOU to Adam and Brian from Madisound, to John, Olav, Claus and Grete from SEAS for their help in making Room 514 such an attraction. Thank you to Don from TheOrionSpeakers.com for taking over the demo's to give me lunch breaks and to Brian L and Jeff B from the OPLUG for running a Q&A session about DIY construction of speakers. Thank you to my wife Eike who paid attention, support and loving help in many situations, accommodated our visitors and circulated about 600 Show Times Tickets. She also took pictures, more of which are on this page.


  • 29 September 2015
    Rocky Mountain Audio Fest, Denver, CO, October 2-4
    Download the Show Times for LXmini & LX521.4 and a List of demo equipment with prices 
    used in Room 514 by LINKWITZ LAB with Madisound and SEAS.

  • 28 September 2015
    Rocky Mountain Audio Fest, Denver, CO, October 2-4
    If this weekend's demo has you interested in building your own pair of LX521s or LXminis but want to know:
    - how to integrate this into your existing system
    - what is involved in building / what skills are needed
    - how to get started
    - where to get the components you need
    - how to get answers when you run into problems
    - what NOT to do...
    Join us for an informal question-and-answer with several members of the oplug-support.org forum. 
    Learn from those who have "been there - done that".  BrianL
    Saturday, 5 pm to 6 pm, Room 514, LINKWITZ LAB

  • 8 September 2015  
    NOTE - The mailbox is 100% full. I am trying to resolve that problem. 

  • 8 September 2015
    www.magicLX521.com - LXmini prototype with 3D-printed woofer basket and top section 


  • 8 September 2015 
    Advertisement by www.magicLX521.com  in: Das Musikmagazin für Ärzte, tonart  3 | 2015 , an insert to the Gerrman Ärzteblatt.

  • 24 August 2015
    Links - Nelson Pass talks about power amplifiers

  • 21 July 2015
    It is not too soon to think about attending an interesting audio event later this year

    - October 2-4, Rocky Mountain Audio Fest, Denver, CO. 
      With support from Madisound and SEAS I plan to demo the LXmini and LX521.4 in Room 514
    using two Emotiva XPA5 amps and a miniDSP 4x10 Hd.

    - October 17th, Burning Amp 2015, Redwood City, CA, diyAudio
      I plan to demo the LXmini and LXstudio with the PowerBox from magicLX521.com
      Dr. Frank Brenner is scheduled to pilot a Lufthansa A380 from Frankfurt to SFO the day before 
      and will be present on his layover day.  

    - November 10-12, Institute of Acoustics - REPRODUCED SOUND 2015, Moreton-In-Marsh, UK.
      I plan to talk about "The Magic in 2-Channel Sound Reproduction - Why is it so rarely heard?"

    - After that, November 23rd, my 80th Birthday, and Thanksgiving with family

  • 8 July 2015
    Links - 24/196 Music Downloads  ... and why they make no sense

  • 5 July 2015
    Links - "The Audio Critic" and Peter Aczel's "Audio Legacy"

  • 9 June 2015

    I just spent several hours listening to the LXmini when driven by the first production sample of the PowerBox from magicLX521. Together with Dr. Frank Brenner, and an Academy Awards nominated audio producer, we three compared the Hypex DSP and UcD amplifier based PowerBox in my listening room to my typical LXmini setup with miniDSP 4x10 Hd and AT1806 amplifiers. I am just astounded how much more is in the LXmini system in terms of low end definition and overall refinement of sound when connected to the PowerBox. We all heard the remarkable ease, openness and neutrality. And I had thought all along that I had a pretty decent setup and that it would be difficult to get even more out of the LXmini! While I can still proudly demo and listen to my LXmini system even with the miniDSP 2x4 and Emotiva amps, it is difficult to forget this comparison session.


  • 8 June 2015
    The Sea Ranch - Here are photos that will bring back memories to some of you from a time when we rented our two cottages, 
    1990 to 2011, and you could audition ORION in one and PLUTO in the other. 

  • 3 June 2015
    LXmini - Wood Artistry builds LXmini

  • 3 June 2015
    Please note that I will be out of email reach from June 12 to July 1 and cannot respond to documentation requests

  • 3 June 2015
    Links - Floyd Toole lectures about Sound Reproduction

  • 1 June 2015
    LX521.4 - The LX521.4 Construction Documentation is now accessible to owners and buyers of LX521 documentation

  • 29 May 2015
    Other designs - Kii Audio THREE cardioid loudspeaker 

  • 21 May 2015
    Links - Do you know your PSA? - Singing the Prostate Cancer Blues - 

  • 20 May 2015
    Other designs - JBL M2 Master Reference Monitor

  • 13 May 2015
    LX521 - Examples of power amplifier IM distortion at 1 W and below

  • 10 May 2015
    Links - DIY power amplifiers with extremely low distortion

  • 6 May 2015
    LXstudio - The LXstudio Construction Plans are now available

  • 28 April 2015
    Links - Mono to Stereo Upmixing

  • 23 April 2015
    Madisound will exhibit the LXmini at AXPONA in Chicago, April 24-26, Room 302

  • 24 February 2015
    Links - WIZARDS OF SOUND - THE NEW YORKER writes about the Meyer Sound Constellation Acoustic System and the San Francisco Symphony SOUND BOX.

  • 23 February 2015
    Other designs - Commercial designs: Fullrange cardioid speaker by Dutch & Dutch

  • 17 February 2015
    Other designs - DIY Designs: Cardioid as sum of monopole and dipole speakers

  • 13 February 2015
    Links - The High Resolution Audibility Test

  • 1 February 2015
    Links - Ken C. Pohlmann, Principles of Digital Audio

  • 1 February 2015
    Links - J. Blauert, Communication Acoustics

  • 15 January 2015
    Links - Experts ask the Experts about Sound Recording and Sound Reproduction
    To me one of the most significant events at the Rocky Mountain Audio Fest 2014 was the "Experts ask the Experts" exchange of viewpoints regarding sound recording and sound reproduction. 

    The discussion was honest and enlightening to both experts and audience. The explanations could help audiophiles to understand some of the limitations involved in recording and reproduction, and to appreciate the work done and to make educated choices. 


  • 8 January 2015
    Stereo Recording & Rendering 101 - Definition of processes

Happy New Year 2015 
to all LINKWITZ LAB speaker builders, past, present and future!

In 2015 I plan to extend the LX speaker family from the analog LX521 and the digital LXmini by adding three new members: LXstudio, LX521.3 and LX521.4. This will provide an upgrade path for LXmini builders to LX521 levels and be a revisit of the LX521 using DSP for equalization and crossovers. 

For the LXstudio I add to the LXmini pair the two open-baffle woofers of the LX521 and use the miniDSP 4x10Hd for xo/eq. A prototype is already running and impresses me with its fast dynamics, 3D rendering and expected extension of bass. The 4-piece system provides greater flexibility in room placement than the LX521.

For the LX521.3 and LX521.4 systems I plan to start out from acoustic measurements again, expecting more options in driver equalization from a DSP unit than was practical with the ASP. The LX521.3 will be a 3-way active system including the existing passive crossover, while the LX521.4 will be a 4-way active system and require an additional pair of power amplifiers.

Those are my plans. Let's hear what materializes. 

Spread the word to your friends: 
Highly realistic 3D sound reproduction from stereo is also possible in their rooms and is within their reach!  
Spread the fun!


  • 14 December 2014
    Links - ECMA-407: A New 3D audio codec implementation up to NHK 22.2 with RVC-CAL

  • 13 December 2014
    Links - SOUND BOX with Meyer Sound Constellation Acoustic System

  • 10 December 2014
    Pluto Ultimate Stereo - All-in-One Reference Quality Omni Speaker System & Wireless 24/96 HD Audio Player
    (Website under construction)

  • 26 November 2014
    A Retrospective - 15 Years of www.linkwitzlab.com

  • 21 November 2014
    Issues in speaker design - Woofer equalization in LXmini

  • 7 November 2014
       Links - Spatial Audio: Reconstructing Reality or Creating Illusion?


  • 27 October 2014 - Rocky Mountain Audio Fest 2014
    Sound demonstrations of the LX521 and LXmini at the ROCKY MOUNTAIN AUDIO FEST in Room 418 alternated between speakers every hour and drew great acclaim for the naturalness of presentations. The speakers generated much interest for the LX521 and LXmini DIY materials and driver kits, which were shown in adjacent Room 417 by Madisound and SEAS.

    The AudioTraveler - RMAF 2014: Madisound and the paradise that awaits

    Enjoy the Music.com - RMAF 2014: Madisound Speaker Components

    We had many visitors come back repeatedly for listening to more music or to bring their friends to share the experience. The LXmini created lots of astonishment and excitement. It put a smile on many a face. The LX521 impressed with resolution and dynamic range from delicate to raw power.

    stereophile - RMAF 2014: Reichert on Sunday

    OPLUG - RMAF 2014 Linkwitz Lab Show Report?

    One of the most significant events at the show was the "Experts ask the Experts" exchange of viewpoints regarding sound recording and sound reproduction. The discussion was honest and enlightening to both experts and audience. It was recorded and I hope it will be published soon and without edits, helping audiophiles to understand the issues, to appreciate the work and to make educated choices. 

    stereophile report: RMAF 2014: Music & Seminars

    - Tsunoda Naotaka, Sony Headphones - Siegfried Linkwitz - Peter Mcgrath, Wilson Audio - Richard Schram, Parasound - Cookie Marenco, Blue Coast Records - Jack Vad, San Francisco Symphony Recordings producer/engineer -


  • 16 October 2014
    HIFI ZINE reports on California Audio Show 2014

    PMCs fight it out with LXminis

  • 14 October 2014
    Links - "A call for an open source loudspeaker project"

  • 2 October 2014
    LX521 - Stereo sound system configuration

  • 30 September 2014
    ROCKY MOUNTAIN AUDIO FEST - "Experts ask the Experts" - This should be an interesting exchange of viewpoints regarding sound recording and sound reproduction

  • 22 September 2014
    LXmini - A reference quality stereo sound system

  • 17 September 2014
    Links - Ecma publishes the world’s first 3D audio standard

  • 3 September 2014
    LXmini - Digital Stereo Sound System

  • 24 August 2014
    ROCKY MOUNTAIN AUDIO FEST - October 10-12, 2014 - Madisound-SEAS-Linkwitz Lab - Room 417 & 418
     Rocky Mountain Audio Fest I will be there with the amazing LX521 and the new LXmini Reference Loudspeakers and demonstrate them in Room 418 each day of the show.
LX521 at 9 am, 11 am, 1 pm, 3 pm, 5 pm
LXmini at 10 am, 12 am, 2 pm, 4 pm

It is time to make your travel arrangements to the Denver Tech Center, if you have not done so already.

The sound you hear in Room 418 should be your reference for the show.

  • 20 August 2014
    Links - ECMA-407, the world’s first 3D audio standard is coming

  • 15 August 2014
    LXmini - Amplifier and Gallery pages added

  • 8 August 2014
    Sound recordings - West Side Story, San Francisco Symphony

  • 26 July 2014
    Links - The Distortion of Sound

  • 14 July 2014
    LXmini - Construction Plans released

  • 9 July 2014
    Links - SOUND AND RECORDING - Applications and Theory, written by Francis Rumsey and Tim McCormick

  • 7 July 2014
    Links - We need to talk about SPEAKERS ...

  • 5 July 2014
    Links - Floyd Toole is "Reflecting on Reflections" in the June 2014 issue of the JAES

  • 3 July 2014
    Links - Berliner Philharmoniker in the Digital Concert Hall - A great musical and visual treasure! 

  • 24 June 2014
    LXmini - A new, small speaker with the promise of producing Reference Quality Sound in any size room

  • 21 May 2014
    Loudspeaker & Room - Test and measurement of loudspeaker and room interaction

  • 21 May 2014
    Sound recordings - Discover Internet Radio broadcasts

  • 28 April 2014
    LX521 - Sound as close to Live - as the Recording provides!
    www.magicLX521 offers the fully assembled and finished LX521 at promotional prices during their Titanium Driver Award campaign. 

  • 8 April 2014
    The Audio Critic - Peter Aczel reviews the LX521 Reference Loudspeaker

  • 1 April 2014
    Ping Tests - WATSON loudspeakers outdoors of SPC

  • 28 March 2014
    Links - Line array dipole for a Concert Hall sound system

  • 26 March 2014
    Links - Fundamentals of sampled signals, DAC's and the reconstruction into analog signals are illustrated in an Agilent Application Note

  • 24 March 2014
    Dipole prototypes - Public Address column loudspeaker 

  • 19 March 2014
    Ping Tests - Experiments to understand what matters to the creation of a 3D auditory phantom scene from two loudspeakers and in different rooms

  • 8 March 2014
    diyAudio - "Extreme Open Baffle Active Speaker inspired by Linkwitz LX521"

  • 23 February 2014
    www.6moons.com - Review of Chinese-built Pluto Ultimate, which is now available from www.plutospeakers.co.uk in the UK 

  • 23 February 2014
    www.hifiwigwam.com - Review of Chinese-built Pluto Ultimate, which is now available from www.plutospeakers.co.uk in the UK

  • 2 February 2014
    LX521 Photos & Comments - Ein Hör-Erlebnis in Stuttgart

  • 16 January 2014
    Links - "SAVE THE STEREO" and "Pure Audio to Health" 

  • 12 January 2014
    About me - "The Titanium Driver Award" from ALMA International

  • 8 January 2014
    Loudspeakers - "Whatever happened to the quality of reproduced sound in the home?"

  • 29 December 2013
    My current setup - Audio/Video in our home on the Pacific Coast

  • 6 December 2013
    NUTSHELL HIGH FIDELITY - A most interesting website

  • 3 December 2013
    Pluto Ultimate - Reviewed by "Hifi Pig"

  • 27 November 2013
    LX521 - Listening room with rear wall reflections

  • 20 November 2013
    ALMA International - 2014 Winter Symposium - I will talk about: "Whatever happened to the quality of reproduced sound in the home?"

  • 17 November 2013
    PLUTO - Photos of Chinese market PLUTO System 

  • 27 October 2013
    Construction Plans for LX521, ORION and PLUTO can be sent as PDF 

  • 23 October 2013
    stereophile completed its report on RMAF-2013. The LX521 was not mentioned, though the reporter assigned to the floor was in our room, listened to his CDs, took notes and visibly enjoyed what he heard. I must assume that stereophile did not consider the LX521 to be of interest or educational value to their readership. Frequency independent directivity for minimum perceptual interaction with the room is found in hardly any commercial loudspeaker design, as can be seen in the photos from the show. Our demo gave immediately recognizable proof of its benefits. The LX521 sends a message to the loudspeaker industry, a message that would be inconvenient to stereophile's top advertisers.  
    If there were fewer visitors to RMAF, we would not have known. Our room was packed almost all the time and many music lovers returned for more, enjoying the clarity, timbre, dynamics and spatial rendering, and thus the believability of the auditory illusion.

    ULTRA HIGH-END surprisingly includes the LX521 in its coverage of RMAF. The reviewer apparently failed to recognize the significance of the design in comparison to every other loudspeaker at the show. Our emptied out hotel bedroom had no acoustic treatment. But what is "ultra high-end" all about? In this category of audio the price of the equipment usually far exceeds any realistic gain in performance. Who is the audience? I want to satisfy individuals who are still familiar with live (unamplified) sounds in a performance space, or who play an instrument, or make recordings. It ought to and can be done in such a way, that many can afford the pleasure of hearing great recordings convincingly rendered in a normal living room. 

    Confessions of a Part-Time AUDIOPHILE gives an informative report. But the quoted prices are per pair, not per side, and so the total for a Madisound supplied LX521 Kit plus the prerequisite Linkwitz Lab Construction Plans comes to around $3200. Handout
  • 20 October 2013
    Assemblies - A listing of sources for full assemblies and subassemblies of LX521, ORION and PLUTO loudspeakers

  • 16 October 2013
    Links - International Conference on Spatial Audio

  • 15 October 2013
    Rocky Mountain Audio Fest - 2013, Oct. 11-13  -------  Handout 
    I gave 10 minute talks about  *** Stereo is a Magic Trick ***  in room 418 
    Friday: 2 pm, 5 pm and Saturday: 11 am, 2 pm, 5 pm and Sunday: 11 am, 2 pm
RMAF brought over 400 visitors to our room giving them an auditory experience and appreciation of stereo they never could have had before the advent of the LX521. I surprised myself several times about the speaker's bass output capabilities when hearing new material that visitors brought. We shocked more than one well known loudspeaker designer by the transparency, clarity and dynamics of close to live-like sounds produced by these speakers, and by the believability of an auditory scene devoid of loudspeakers. It was a most enjoyable magic trick, people got lost in the music and many listeners came back to our room for more. As one person wrote to me afterwards: "Your room at the show was 'Hotel California' - the room where people kept entering but never left."

The speakers were assembled from a Madisound flat-pack of wood parts. We used the Madisound assembled and tested ASP. The 12 drivers are all SEAS designs and Olav Arntzen, R&D manager at the time, was more than pleased to hear what his products allowed me to develop. John Stone, US representative of SEAS, played an important role by leaning on R&D for accomplishing certain driver modifications that were needed in open baffle applications.

We used a BelCanto (CD2) CD player with built-in preamp and volume control to drive the ASP. Connected to it were two Emotiva (XPA-5) 5-channel amps with 200W/channel output, driving bottom and top woofers separately, midranges and tweeters with 4 channels per side.

  • 15 October 2013
    Videos taken by Linear Integrated Systems at the Burning Amp Festival - 2013 (The audio is severely clipped in my talk) 
    stereophile reports a slow burn at 12 noon, but attendance was merely 10% down by the end of the day compared to last year.


        From left, Juha Backmann (Nokia) thanks the invited speakers: 
        Axel Grell (Sennheiser), Siegfried Linkwitz, and Ilpo Martikainen (Genelec)

  • 1 August 2013
    AES 51st Conference - "Loudspeakers and Headphones", Helsinki, Finland, 21-24 August, 2013

  • 27 July 2013
    LX521 Supplies - What do you need?

  • 27 July 2013
    PLUTO-2.1 System - It will be announced to Chinese audiophiles on 28 July 2013 by HIFIDIY.NET 
    with Pluto advertisement at http://bbs.hifidiy.net/forum.php and home page www.linkwitzworks.com

  • 23 July 2013
    LX521 Supplies - Assembled DSP and LX521 Configuration File

  • 3 July 2013
    Home - From where and in what numbers do visitors come to this website? 

  • 1 July 2013
    LX521 Description - An updated spreadsheet to find the optimum toe-in angle and an analysis of reflection delay and attenuation for dipole and monopole sources in different size rooms

  • 1 July 2013
    Stereo Recording and Rendering - Sound Field Control for Rendering Stereo - 1

  • 29 June 2013
    Audio production - An interview with Keith O. Johnson of Reference Recordings

  • 29 June 2013
    LX521 DSP challenge - A complete DSP solution with digital and analog interfaces

  • 26 June 2013
    LX521 Description - A spreadsheet to find the optimum toe-in angle and an analysis of reflection delay

  • 25 June 2013
    LX521 DSP challenge - Digital Crossover/EQ with Open-Source Software: HOWTO

  • 25 June 2013
    Links - Introduction to Sound Recording

  • 22 June 2013
    LX521 Photos - Different implementations of the speakers

  • 16 June 2013
    Recording and Rendering - Sound Field Control for Rendering Stereo - 2

  • 14 June 2013
    LX521 Supplies - Madisound now offers the assembled and tested Analog Signal Processor

  • 7 June 2013
    LX521 Description - The Listening Room

  • 5 June 2013
    Other designs - Dipole polar response. Synergy Horn from a distance 

  • 29 May 2013
    Links - Bruno Putzeys on Amplifiers and Class D

  • 26 May 2013
    Links - Boyk on Piano

  • 26 May 2013
    ORION-5 - A source in the UK to hear and buy the complete loudspeaker system 

  • 22 May 2013
    Publications - Papers to be presented at the AES 51st and AES 52nd International Conference

  • 6 May 2013
    LX521 monitor - Madisound now ships Flat Pack Cabinets

  • 4 May 2013
    Issues in speaker design - Further thoughts about "Group delay and transient response"

  • 19 April 2013
    DSP challenge - We have an efficient solution for LX521 stereo setups

  • 13 April 2013
    Audio production - San Francisco Symphony - Channel Classics - McGill University - Pentatone Classics - DGG

  • 8 April 2013
    DSP challenge - updated

  • 7 April 2013
    Links - Linear Audio publications and Jan Didden's personal website

  • 4 April 2013
    DSP challenge - One possible alternative to the LX521 ASP

  • 29 March 2013
    Links - Evaluation of Time-Frequency Analysis Methods and their Practical Application

  • 28 March 2013
    Links - KLIPPEL - Online Training

  • 24 March 2013
    Publications - Updated links

  • 23 March 2013
    LX521 - Assembling Top baffle, Woofer baffle and Bridge

  • 23 March 2013
    LX-521 - Designing a DSP based equalizer/crossover

  • 21 March 2013
    ORION-4 - Reports from AXPONA 2013 in Chicago

  • 10 March 2010
    Design Models - Point dipole and point monopole in a circular baffle

  • 4 March 2013
    Stereo Recording and Rendering - Recording in a virtual acoustic space

  • 25 February 2013
    LX521 supplies - Promotional offer for cabinets from MagicLX521 opening its store

  • 30 January 2013
    Links - MUSIC TO YOUR EARS, a most interesting article in the current issue of THE NEW YORKER

  • 21 January 2013
    LX521 supplies - Cabinet Kit from Germany

  • 15 January 2013
    LX521 monitor - Photos & Comments about the LX521

  • 10 January 2013
    Digital Photo Processes - Five years later

  • 9 January 2013
    ORION challenge - Peter Aczel of The Audio Critic describes 'The Final Mod: Orion 3.3.1SN'

  • 8 January 2013
    LX521 monitor - The first pairs are playing in Germany and USA 

  • 8 January 2013
    Links - Dynamic Space Stereophony

  • 5 January 2013
    Sound Recordings - I added some of my favorite music videos to the list

  • 2 January 2013
    Stereo Recording and Rendering - Subjective evaluation of phantom acoustic scenes

    2012 to 2007




What you hear is not the air pressure variation in itself 
but what has drawn your attention
in the streams of superimposed air pressure variations 
at your eardrums

An acoustic event has dimensions of Time, Tone, Loudness and Space
Have they been recorded and rendered sensibly?

Last revised: 09/21/2018   -  © 1999-2017 LINKWITZ LAB, All Rights Reserved