Hi, I have a pair of Infinity Qb speakers (first owner, bought them in 1979) and never replaced the capacitors.
Now, after 46 years, I thought It would make sence to at least check if updating the capacitors does brings anything (my Luxman L81 amplifier of the same age is getting a complete revision with recapping of all electrolytic capacitors anyway).
Searching the internet I found that Infinity used a lot of different parts for the crossovers of the Qb series.
The ones I found seem to use film capacitors of 6.8 μF for the tweeter. I assume that these are the original capacitors, because it is sometimes stated that you better not replace them because it impacts the true "Infinity sound".
Now the point is that my crossover uses an electrolytic capacitor of 6.8 μF (bottom right in below picture).
I read everywhere that replacing an electrolytic capacitor with a film capacitor reduces the ESR and you better compensate for that using a resistor, because the speaker designer most probably took the ESR into account for the crossover design.
Well, I have the impression that the speaker designer of Infinity did not take it into account, because non of the crossovers with film capacitors in the tweeter circuit use a resistor in series. You could argue that the ones with a potentiometer in the tweeter circuit do have a resistor in series, but they are the older design, so it is not to compensate for ESR after replacing an electrolytic.
It looks like Infinity didn't worry to much about the impact of the ESR on sound quality and used both electrolytic and film capacitors purely based on availablity (or cost?).
My conclusion from this: I can exchange the electrolytic for a film capacitor and don't have to worry too much about the impact on sound quality.
Am I correct?
Now, after 46 years, I thought It would make sence to at least check if updating the capacitors does brings anything (my Luxman L81 amplifier of the same age is getting a complete revision with recapping of all electrolytic capacitors anyway).
Searching the internet I found that Infinity used a lot of different parts for the crossovers of the Qb series.
The ones I found seem to use film capacitors of 6.8 μF for the tweeter. I assume that these are the original capacitors, because it is sometimes stated that you better not replace them because it impacts the true "Infinity sound".
Now the point is that my crossover uses an electrolytic capacitor of 6.8 μF (bottom right in below picture).
I read everywhere that replacing an electrolytic capacitor with a film capacitor reduces the ESR and you better compensate for that using a resistor, because the speaker designer most probably took the ESR into account for the crossover design.
Well, I have the impression that the speaker designer of Infinity did not take it into account, because non of the crossovers with film capacitors in the tweeter circuit use a resistor in series. You could argue that the ones with a potentiometer in the tweeter circuit do have a resistor in series, but they are the older design, so it is not to compensate for ESR after replacing an electrolytic.
It looks like Infinity didn't worry to much about the impact of the ESR on sound quality and used both electrolytic and film capacitors purely based on availablity (or cost?).
My conclusion from this: I can exchange the electrolytic for a film capacitor and don't have to worry too much about the impact on sound quality.
Am I correct?
