the Monitor 2
by Andrea Ciuffoli - starting in the 2008

INTRODUCTION

This project born to create a reference full range monitor loudspeakers to test my new amplifiers.
It is obvious that 3 are the min number of ways to create a true full range loudspeakers.
The midrange driver is responsible of the main frequency range so it should have the max quality possible.

COMPONENTS

• Audiotechnology  C-Quence15h used in the Sonus Faber Stradivari (value about 45000$)
• Hiquphon OW

• Seas CA26RFX

ENCLOSURE DESIGN

(click to enlarge)

The Recommended enclosure for the CA26RFX woofer has been calculated by Jon Paulsen of SEAS:

• QB3 alignment with 0.3 ohm source resistance (Inductor DCR)

• Box volume:  69 liters

• Port tuning: 32 Hz

• Port ID = 7cm - Port length = 10cm   or   Port ID = 8cm – Port length = 14cm

• Low frequency cutoff (-3 dB) = 36 Hz

 

After listener test I have used a longer port length 10 + (3 + 4) cm. The bass reflex tubes used are Intertechnik composed by these elements: JETSET70AT JETSET70MR JETSET70IT got from Audiokit webshop

CROSSOVER DESIGN

The crossover starting point for the midrange and tweeter is the design by Francisco of Audiohum

In a project like this the crossover design and the crossover components quality is very important so I have used only hi-end parts got from www.audiokit.it .

Torobar type on woofer and Tritec type on midrange and tweeter. Ultra-Low Loss polypropylene capacitors Audin Cap Plus and Audin Cap MKP-QS near my reference the "Auricap".

ENCLOSURE

To create a hi-end loudspeakers it is necessary build an enclosure without compromise and only a person with lot of experience in this filed can create a true good enclosure.

For this purpose I have used www.officinelettroniche.it of Ivan De Cesaris  based on the manufacture www.solo-legno.com 

NOTE: In the following photo I am on the right

MEASUREMENTS

I have used in all the measurements the Clio system by Audiomatica with the Transit by M-Audio to use the USB port of my portable pc (instead of the PCI audio board).

Follows the near field frequency band of the Audiotechnology  C-Quence15h without filter.

Follows the near field frequency band of the midrange and tweeter with the filter.

Follows the MLS and RTA at 2.5 meters on axe before bass reflex correction.