QUATTRO, built by Carlo
Copyright 2019 © Troels Gravesen

Quattro mk2:
In the end here is my report on the construction of the quattro mk2 speakers, I started a year ago and thought I was done in four months but I was wrong... at first listen I didn't like my new loudspeakers very much and I thought I threw my money away, but that was only the starting point of a  burn out and refinement process that lasted very long and involved countless tests and modifications.
Initially I considered my Quattro construction to be rather lifeless, in particular the mid-bass seemed backward and did not do justice well to the male voices such as those of Leonard Cohen and Johnny Cash. To solve this problem I made a series of changes and in the end I got what, at least for my ears, is an excellent result. The more substantial changes were in the amount of acoustilux used which was significantly reduced and in the fine tuning of the crossover with the replacement of the two resistors in R2011 with a single 4.7 ohm Mundorf M-resist 20 W while the tweeter resistor was finally settled on 5,6 ohm.
One thing I learned from this construction is that when you use high quality drivers and crossovers parts, like in this case, even very small changes can cause big differences in the final result, and I mean really big! My final version of Quattro mk2  have some weaknesses (but which speaker does not have any?) but also some truly excellent performances in the aspects that most interest me.
From the point of view of the most misunderstood audiophilia it could be said that they do not have a great extension to the extreme frequencies and that the bass could be more articulated, but on the other hand they have the qualities that any lover of music  and Hifi in the best sense of the term are more at heart: coherency, timbre fidelity and naturalness.
The midrange of the Quattro is super smooth and extremely detailed and human voices are so good to die for. Quattro excel in the reproduction of jazz and vocal music but they also go very well with the classical one. In comparison with my Harbeth SHL5 plus monitors maybe they lose something on the side of transparency but they win in everything else, they are speakers that, in my setup, you can listen to for hours without ever getting tired because they simply play music in the right way!
Thank you Troels for the magnificent work!