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Loudspeaker Designs and Articles for the DIY Enthusiast
Invictus: (adj.) Incapable of being conquered, overcome, or subdued. Invincible.
Synonyms: unbeatable, unconquerable,  invulnerable, unshakable, indomitable,
impregnable, unassailable, insuperable, indestructible, supreme, insurmountable,
irrepressible
Preface

I went back to my 2 channel roots this time. A classic two way design using a pair
of top shelf drivers. This design is capable of providing exceptional performance
for those who eschew HT in favor of a simpler, and perhaps more satisfying format
for music. While many 2 way designs exhibit limited performance in some aspect or
another, the Invictus does a remarkable job of checking all the boxes. It is truly
master of its fate and captain of its soul..  
Major specifications

A 2 way design using the Scan Speak 18W8531G and the CSS LD25X

Nominal Impedance: 8 ohms The impedance minima is 6.6 ohms, but spends much of its
time above 10 ohms. This will be an easy load for just about any amplifier, but it is not the most
sensitive design, and likes the higher voltage rails of a more powerful amplifier to play at
concert levels.  

Dimensions: external:
MLTL Tower: 8.5”w x 43.5”h x 15.5”d  
Sealed Tower 8.5”w x 36”h x 9”d

Basic Sensitivity: Estimated at 83 dB/2.8v/1m

Max SPL: Max SPL 97 dB at Xmax 101 dB at Xlim (Modeled SPL for Sealed version)
Main / Design Goals

Asking any two drivers to cover nearly 10 octaves is a tall order, and most 2 way designs have to give something up due to the inherent limitations of the
chosen drivers. Most designs either give up the lowest octave, exhibit limited SPL capabilities, or the woofer struggles to reach up to the crossover
frequency, often leaving audible aberrations in the power response as a result.

The Invictus ameliorates these issues by using more capable, albeit more expensive drivers. Yes, it is an expensive 2 way, but the design is reasonably cost
effective compared to a 3 way design of similar performance. It offers a simpler construction, a lower crossover parts count, and consequently fewer parts to
upgrade, should you want to go upscale with the crossover components.

The Invictus is offered in both a MLTL tower, a smaller, slimmer sealed tower, and also a sealed bookshelf enclosure.    
A two way design using
top shelf drivers
3 different enclosure variations
Links to:

Main / Design Goals

Driver Selection

Sealed tower Cabinet construction
Sealed Bookshelf cabinet construction
MLTL Cabinet Construction

Crossover Design

Measurements
More Measurements

Listening Impressions
Important Note:
In an effort to release this design as soon as
possible, I did the cabinet work, and left them in
an unfinished 'au naturale' state. -Except this
one, which I had fun Photoscaping, They
deserve better, and I hope to get them all
dressed up in their finery soon.