[OSIB16]

I recently acquired a nice pair of Sonus Faber Concerto bookshelf speakers. They are the more desirable Mark 1 version. Amazing condition, with real walnut and leather cabinets. These things have got some serious potential, so I’m looking forward to upgrading the crossovers, including some modifications to the internal cabinet structure, which will add overall strength, and significantly reduce vibrations.










Here is a list of the tasks below…


1) REPLACE EXISTING FILM CAPACITORS

2) REPLACE RESISTORS

3) NEW UPOCC NEOTECH WIRE (TEFLON SLEEVES REMOVED AND SUBSTITUTED WITH PURE COTTON)

4) ALL WIRING TREATED WITH DEOXIT TO PREVENT ANY FUTURE OXIDISATION.

5) SPEAKER CABLE HARDWIRED DIRECTLY TO CROSSOVER.

6) NEW WIRE INDUCTORS.

7) CHANGE FROM BIWIRE TO SINGLEWIRE.

[OSIB16]

[S Clark]

Whichever of those iron core inductors goes directly to the woofer, I'd replace with an air core.  Certainly upgrade the tweeter cap and resistor. 
Iron core inductors, sand cast resistors... not what you'd hope for in a $2K bookshelf speaker. 
Hope you got a good deal on them. 

[OSIB16]

S Clark,
            Bought them for £415 (UK STERLING). The seller delivered them to me in person. The small red colour Iron Core Inductor is closest to the woofer, and agree with you about swapping it for an Air Core. However I will also replace the remaining inductors for Air Cores. I wonder if Sonus Faber will let Know know their Millihenri values? Will probably have to send them off to be properly measured. Do you reckon I should swap the 3.3uf Film Cap on the tweeter for a 2.2uf cap like the Mundorf Supreme Silver Gold?

[OSIB16]

I would like to fix that dip in the treble

[S Clark]

I would like to fix that dip in the treble

That first dip looks like a phase issue... possibly the result of the first order crossover on the tweeter. If you had a way to measure it, I'd try reversing the polarity on the tweeter and see what happens.   As far as testing the Henry measurements of the inductors, it would be as cheap to buy a meter as it would be to send them to be measured.
 https://www.amazon.com/Honeytek-Capacitance-Capacitor-Electronic-Measuring/dp/B08LYM533X/ref=sr_1_28?crid=23BAAB8QF5MHV&keywords=capacitance+multimeter&qid=1674623561&sprefix=capacitance+m%2Caps%2C314&sr=8-28

That looks like a nice woofer.  Contact Danny Richie to see if he has a crossover upgrade available for these speakers.  He's about as good as anyone in the business on passive crossover design. 

[OSIB16]

That first dip looks like a phase issue... possibly the result of the first order crossover on the tweeter. If you had a way to measure it, I'd try reversing the polarity on the tweeter and see what happens.   As far as testing the Henry measurements of the inductors, it would be as cheap to buy a meter as it would be to send them to be measured.
 https://www.amazon.com/Honeytek-Capacitance-Capacitor-Electronic-Measuring/dp/B08LYM533X/ref=sr_1_28?crid=23BAAB8QF5MHV&keywords=capacitance+multimeter&qid=1674623561&sprefix=capacitance+m%2Caps%2C314&sr=8-28

That looks like a nice woofer.  Contact Danny Richie to see if he has a crossover upgrade available for these speakers.  He's about as good as anyone in the business on passive crossover design.

Thanks for the tip, valuable info. However; Jeff’s going to help me get these things up and running.

[jbl]

You may also want to try adding a bypass capacitor for the tweeter and woofer.  Can really improve SQ.  I just helped my friend add two to his Spatial M4's.  Dramatically increased the size of the sound stage, increase detail and decay.  A significant improvement for a speaker that already sounds fantastic. 

[Stimpy]

...Do you reckon I should swap the 3.3uf Film Cap on the tweeter for a 2.2uf cap like the Mundorf Supreme Silver Gold?

I wouldn't change to a capacitor with a value other (smaller) than stock.  That would shift the crossover point higher in frequency, and probably cause a even bigger treble dip.

Also, any new capacitor will most likely have a different ESR (equivalent series resistance) reading than stock.  Could be higher, but usually lower.  That will affect the output level of the tweeter.  So, the tweeter's resistor might need to be changed to a greater resistance, to rebalance the tweeter to the woofer.  I'd get several resistors, with different values, to experiment to see which sounds best.

Oh, you'll most likely need a new crossover board for the woofer circuit.  Air core inductors will be much larger...!

Good luck.

[OSIB16]

JBL + Stimpy
                    I’m sticking with the same values, but Jeff is helping me to ensure that the replacement parts will be more precisely suited to this particular speaker model.