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". I have reversed the phase of tweeter.

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. 

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 and MLS at 2 meters on axe.