Loudspeaker Designs and Articles for the DIY Enthusiast
Jim Holtz's:

Big sound from a monitor sized
speaker design using high
value drivers.
Major specifications

An 3 way vented design with The Dayton RS225-8 aluminum cone woofer, the Dayton RS28F fabric dome tweeter, and the Vifa NE149W-04 reed paper
cone neodymium driver housed in an open back cylindrical enclosure.  

Nominal Impedance: I'll call this one 6 ohms as the impedance curve flirts with, but never quite reaches 4 ohms at any frequency, and spends as much of
its time above 6 ohms as it does below.    The impedance is above 7 ohms below 60 H. The minima is 4.3 ohms at 100 Hz, and again dips below 5 ohms
between 500 and 1000 Hz, but then increases to above 7 ohms at higher frequencies. The worst amplifier load is 5.4 ohms and -40 degrees at 73 Hz. This
suggests an easy load for any reputable 6 ohm rated amplifier.

Dimensions: external: 11" wide, 24" tall, 15.5" deep

Basic Sensitivity: Approximately 84 dB / 2.83v / 1 meter  

Max SPL: (Modeled at woofer published Xmax) 104 dB / 1meter
Main / Design Goals

The design goals I established for this project were to challenge my full sized Statements overall performance in a smaller monitor sized speaker with a
special focus on the midrange. This isn’t a cost no object design but rather a high value design that controls costs but still provides top notch performance
that will equal or challenge the best.

Curt and I have talked frequently over the past few years about what is the secret ingredient in a speaker that makes a listener go “WOW”? It always comes
back to the midrange. It’s got to be right to have a truly enjoyable speaker that accurately reproduces a live acoustic performance. Every top end driver
design has its virtues. However, the best drivers all share one characteristic, hard and stiff cones regardless of the material used in its construction. We
also agreed that the ones we liked the best were often based on a form of advanced paper construction. Not always, but often.  There is a naturalness to
the mid-range sound of a high tech paper cone driver when combined with a well-designed crossover that takes you to the original performance with a
realism that is hard to duplicate.
Links to:

Main / Design Goals

Driver Selection

Cabinet Construction

Crossover Design


Listening Impressions