Hi all!
Everything began two days ago from a speaker calibration on my Denon AVR-X2600H and Audissey mic. I got a phase error on my front speakers. Of course, I checked everything and it was properly wired. Next, I used a 1.5V battery test and the woofer was sucked in the box but the center and the satellites worked ok, meaning the woofers were pushed out if I test the + on battery with + on speaker connector.
Then I took out the crossover and the circus began... 🙁
I want to upgrade my crossovers. I have some questions:
P.S.: If you need the values of the other/all components, please don't hesitate to ask.
Everything began two days ago from a speaker calibration on my Denon AVR-X2600H and Audissey mic. I got a phase error on my front speakers. Of course, I checked everything and it was properly wired. Next, I used a 1.5V battery test and the woofer was sucked in the box but the center and the satellites worked ok, meaning the woofers were pushed out if I test the + on battery with + on speaker connector.
Then I took out the crossover and the circus began... 🙁
I want to upgrade my crossovers. I have some questions:
- The original crossover has two electrolytic capacitors of 75uF, 100V, 105C, NP in series for woofer and mid speakers. I want to upgrade all the capacitors to film/foil audiograde ones (ClarityCap, Mundorf, Jantzen etc.). I cannot find this 75uF value, only 68uF or 82uF. Which of these values do you recommend using as replacements? I searched for electrolytic capacitor of 75uF but no luck. I cannot find this value.
- The polarity markings for the woofer on the board I think are wrong: the + is common with - of midrange speakers. That is why when using the battery test the woofer is sucked in the box, not pushed out. I inversed the wires of the woofer and I got an increase in bass at around 160Hz (using a stereo Zoom microphone and Visual Analyzer 2022) but I cannot tell if it is sounding better or worse because I haven't got the time to listen to some music. I took the crossover out again to take pictures.
- The tweeter has a polyswitch resettable thermistor protection. On the board it is printed PTC / 050. The component has these markings: a T letter with the top line shaped (I think it's the brand of the component) / R60 / 050 / 752A. I found this one but I don't know if it is similar in specs: https://ro.mouser.com/ProductDetail/Littelfuse/60R050XU?qs=aZoEvtLPFVdPtJRElpFk5w==
Is it ok?
P.S.: If you need the values of the other/all components, please don't hesitate to ask.
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Welcome to the forum!
1. Two 75 uF in series are equivalent to 37.5 uF. By wiring standard values 33 uF and 4.7 uF in parallel you can achieve 37.7 uF.
1. Two 75 uF in series are equivalent to 37.5 uF. By wiring standard values 33 uF and 4.7 uF in parallel you can achieve 37.7 uF.
2. In a 2nd order crossover, the phase shift is 180 degrees and it is worth while to ensure that the bass and middle speakers are acoustically in phase by wiring them electrically anti-phase. This is to avoid a dip in response around the frequency of crossover.
3. If the polyswitch has a resistance of a fraction of an ohm, then it is in good condition and not in need of replacement.
If you don't intend playing your system at potentially driver destroying levels, then you could omit the polyswitch and replace it with a wire link.
If you insist on replacing the polyswitch (ptc resistor), the site below allows you to determine a suitable replacement by inputting power handling and impedance parameters into a calculator. Note, situated below the calculator, the specific instructions for entering the power handling of a tweeter.
https://www.lautsprechershop.de/hifi/ptc_en.htm
If you insist on replacing the polyswitch (ptc resistor), the site below allows you to determine a suitable replacement by inputting power handling and impedance parameters into a calculator. Note, situated below the calculator, the specific instructions for entering the power handling of a tweeter.
https://www.lautsprechershop.de/hifi/ptc_en.htm
P.S. If it's just a single 75 uF capacitor you want to emulate, then connect a 68 uF and 6.8 uF in parallel to give 74.8 uF
I can source 75 uF MKP polypropylene film capacitors: https://willys-hifi.com/collections...lene-capacitors-400v-5?variant=36530270535839
Note, however, (a) the cost of £32 each, and, (b) the physical size of 60x53 mm (think of the space available on your crossover board!)
You may now understand why the manufacturer chose to use NP electrolytic capacitors!
Use your 1.5V cell to verify the polarity of the woofer, and a response measurement to see the polarity of the others working with it.