I have sourced parts from two online vendors in the USA,
Parts Express (Dayton brand) and
Madisound. I don’t know if they ship to Europe, or what it would cost. There are sources and makers in Europe, but I am not familiar with them.
I don't know how familiar you are with electronics or crossover building, so if I've dumbed this down too much, please accept my apology.
Resistor (R1)
Dayton – 1Ω – 10W –Part
004-1 – $1.49
Madisound – 1Ω – 15W – Part
15r1 – $0.50
Capacitors (C1 and C2)
Do not use electrolytic capacitors. Instead, use only lower priced metalized polypropylene (MPP) capacitors. There are many more expensive MPP caps, but they cost more and provide no audible benefit. Avoid them. These MPP caps are all very good quality and are available in the USA: Dayton or MDL XPP (both made in Taiwan), Solen (France), and Audyn Q4 (Germany). Prices are in US$.
For C1, a 5.3 µF cap is not available. Any capacitor within 10% of 5.3 µF will work in an audio crossover. That becomes anywhere from 4.8 to 5.8 µF. Order the 5.1 µF cap.
C1 5.3 µF
Dayton – 5.1µF – 250V – Part
027-423 – $2.99
MDL XPP – 5.1µF – 250V – Part
XPP-5.1 – $2.20
If you must have exactly 5.3 µF, use two caps wired in parallel with each other. Add the two values, 2.0 + 3.3 = 5.3:
Dayton – 2.0µF – 250V – Part #
027-414 – $1.73
Dayton – 3.3µF – 250V – Part #
027-420 – $1.92
– Or, 4.3 + 1.0 = 5.3:
MDL XPP – 4.3µF – 250V – Part
XPP-4.3 – $2.00
MDL XPP – 1.0µF – 250V – Part
XPP-1.0 – $0.90
C2 10 µF
Audyn Q4 – 10µF – 400V – Part
027-118 – $4.79
MDL XPP – 10µF – 250V – Part
XPP-10 – $4.30
Inductors (L1 and L2) – all Air Core Inductors
L1 0.15 mH
Dayton – 0.15mH – 18 AWG – Part
257-804 – $3.29
Madisound – 0.15mH – 19 AWG – Part
.15mhl – $2.70
L2 1.35 mH
Dayton – 1.5mH – 18 AWG – Part
257-832 – $9.49
Madisound – 1.5mH – 19 AWG – Part
1.5mhl – $8.40
For L2, a 1.35 mH inductor is not available. Order the next larger size, 1.5 mH, and unwind enough wire until it reads 1.35 mH on an inexpensive LC meter
such as this. Once you have unwound enough wire, cut off the excess wire, but leave enough length to work with.
Please note that in the US, wire thickness is measured in gauge (AWG). In Europe, wire thickness is measured in cross sectional area, mm². 18 AWG = 0.823 mm² and 19 AWG = 0.653 mm².
en.wikipedia.org