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

 

 

What's new

 

LX - Store

 

Conversations
with Fitz

 

OPLUG
Forum

 

Basics

The Magic in 2-Channel Sound

Issues in speaker
design

Dipole models

Active filters

Amplifiers etc

Microphone

FAQ's

Loudspeakers

Crossovers

Room acoustics

Stereo Recording and Rendering

Audio production

Conclusions

 

Projects

Your own design

LXmini

LXmini+2

LXstudio

LX521.4

LX521
reference

ORION
challenge

ORION-3.4

PLUTO-2.1

WATSON-SEL

PLUTO+
subwoofer

THOR
subwoofer

PHOENIX
dipole speaker

Three-Box active
system (1978)

Reference
earphones

Surround
sound

Loudspeaker
& Room

 

Resources

Publications

Sound recordings

Links

Other designs

My current setup

About me

Site map

 

HOME

 

------------------
Digital Photo
Processes

 

------------------
The
Sea Ranch

 

------------------
My Daughter
the Jeweler

 

What's new

 

LX - Store

 

Conversations
with Fitz

 

OPLUG
Forum

 

 

 

Introduction  
Design
 
Construction
Amplifiers
Digital System
Analog XO/EQ
Gallery

 

Construction materials

After you have purchased the Construction Plans and collected all the parts and materials it only takes a 3-day weekend to build a pair of LXmini and to hear in your place outstanding quality sound. If you can work with a jig saw, a drill, screw driver and crimping tool, then you are set to succeed. If not, then you might ask a friend to help you, or hire a high school kid. No soldering is involved, only glue and screw.

The materials cost for this project breaks down like this:

LXmini Construction Plans:    $105
4 SEAS drivers:    $320
miniDSP 2x4 in a box:    $115
2way Advanced plug-in:  $10
USB power supply:    $15
PVC/ABS pipes, couplers, cups:    $60
Hardboard, Plywood, Feet:    $25
Screws, spade lugs, cable clamps, terminal blocks, grip handle:    $20
60 ft of18 Gauge speaker cable, plugs:    $30

.... which adds up to $700. In addition you need four identical power amplifiers with 50 W to 100 W into 8 ohm capability and with high (>20) damping factor. More power is not necessary. 

Alternatively two 50 W to 100 W into 8 ohm capable amplifiers with high (>20) damping factor could be used for the woofers only, where the chosen equalization of the low frequency response depends upon a high damping factor. Two smaller power amplifiers with 5 W to 10 W capability and <0.5 ohm output impedance could drive the midrange/tweeters without significantly affecting the frequency response and output volume capability. But the voltage gain of the low power amplifiers should be identical to that of the woofer amplifiers, which requires the addition of an input gain stage. This then opens the door to using "First Watt" style power amplifiers for the midrange/tweeter.

A miniDSP 2x4 HD ($205) and 2x4 HD1 plug-in ($10) instead of the miniDSP 2x4 unit and 2way Advanced plug-in provides preamplifier functionality by having remote volume control capability. It also adds digital signal input capability for streaming music directly from a computer or CD player.

miniDSP 2x4

miniDSP 2x4 HD

Construction of the LXmini is brought into reach for everyone by a 24 page PDF with 3200 concise words of text and illustrated with 37 graphics and photos. Buying the plans is a low risk investment. You could gain years of musical enjoyment at the highest level of sound reproduction.

 

 

LXmini Construction Plans

  • The LXmini Construction Plans are available as PDF only. I will normally send them within 48 hours after being notified by PayPal. 

  • To order the LXmini plans send a $105 payment via PayPal to sl@linkwitzlab.com with subject line "LXmini plans". 
    Indicate your preferred email address for the file transfer (2.5 MB) and give me your name and country/state for my records. 
    You can also order by sending a Money Order, Cashier's check or personal check made out to Siegfried Linkwitz at 15 Prospect Lane, Corte Madera, CA 94925, USA. Include your email address.

  • I provide an Owners Support Page for updates to the LXmini.
    Questions for help should be posted on the OPLUG forum.  

  • Have fun!

 

 

Construction Parts

Madisound offers a LXmini Speaker Kit containing the four SEAS drivers, a miniDSP 2x4 and damping material, a wood parts kit, as well as other useful hardware for $472.

           

PVC/ABS Schedule 40 pipes of 4" and 3" diameter, end caps, rubber couplers, 2-conductor wires, terminal blocks, screws, a crimping tool, silicon adhesive, etc. can be found at your local hardware store. The pipes need to be cut to specified lengths and several holes drilled into them. No soldering is involved.

 

Construction Parts

magicLX521 offers a LXmini Speaker Kit, complete with modern high density wooden material parts, US Standard pipes, caps and couplers, screws, wires, Speakon connectors, rubber feet, damping material and four SEAS drivers for 499. They also offer different material pipes and in the future a power module with built-in xo/eq DSP and four Class-D amplifiers. 

                

 

PowerBox 4180 & PowerBox 4400 pro configurations for LXmini, LXstudio and LX521 Turnkey Systems or Kits and a Price List.

 

The ease of construction and the price put the LXmini within reach of many audiophiles and music lovers. Some universal CD/DVD players have built-in volume control, which makes a preamplifier unnecessary. The audio output from a smart phone or tablet is usually not sufficient to drive the LXmini to maximum volume, but provides in many situations enough sound. 

A pair or more of LXmini is a "must-have" valuable reference and tool for professionals in the audio industry, like for speaker designers, amplifier designers, equipment reviewers, recording/mixing and sound production engineers, microphone designers, 3D sound algorithm designers, psycho-acoustic researchers and codec developers.

 

Upgrade from PLUTO to LXmini

The power amplifier section of the PLUTO electronic module is ideally suited to drive the LXmini. For such use the overall voltage gain is increased to 34 dB. Some circuit connections have to be removed and others added. Woofer and full-range amplifier input connections have to be provided. The PLUTO module could become a stand-alone power amplifier for the LXmini. Details have been posted on the LXmini owner support page. 

I do not plan to provide guidance for modifying the mechanical design of PLUTO. Follow the LXmini instructions for that. The low end response, which is determined by the air volume and amount of stuffing in the pipe, may be different from the LXmini in your PLUTO implementation. Measure the response with a microphone 0.5" from the woofer cone and equalize it by following the approach in the LXmini configuration file for the miniDSP 2x4. Take it as a learning project and consult with the OPLUG

Consider your options 
My recommendation is: Share your current satisfaction with PLUTO by making someone else happy with it, or put it to different use. Then build the LXmini from scratch. 
Alternatively, dismantle your PLUTO, reuse woofer drivers and modify the electronic modules, and rebuild everything else according to LXmini plans.
And foremost: Have fun!

 

 

Note: All material is copyrighted and for the personal, non-commercial use by the person who bought it from LINKWITZ LAB.
It may not be passed on in any form for use by others. | Terms & Conditions |

 

*****************************************************************************************************************************************

 

 

 

 

 

 

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: 08/21/2017   -  1999-2017 LINKWITZ LAB, All Rights Reserved