As a rule of thumb, when talking specifically about passive speakers, we only recommend using higher end and more expensive capacitors for crossover positions that are in direct line with the tweeters / mid-range.
For tweeters:
As tweeters are always the most revealing part of any speaker system, they are the most common place where high-end capacitors are used.
Depending on preference in sonic profile, we recommend our Superior, Silver, Alumen or Amber Z-Caps, as the best choice for tweeter capacitors.
For mid-range (mostly upper mid-range):
Using higher grade capacitors like our Superior, Silver or Alumen Z-Caps can add better performance/sound, but it will to a higher degree depend on driver model, crossover design and filter order, compared to tweeter capacitors.
For woofers (separate bass section) / lower mid-range:
We recommend choosing good quality, but lower cost capacitors, e.g., our Cross Caps, Standard Z-Caps, Compact MKT caps or electrolytic “eleCaps”.
Specifically for electrolytic capacitors, we recommend avoiding capacitors with less than a 35VAC rating and no more than a 10% tolerance on capacity.
From a technical perspective it would generally be complete overkill to use expensive high-end capacitors for the low frequency area (bass), as the improvements in performance / sound of higher-grade capacitors, would not be audible at such low frequencies.
For amplifiers:
The most common upgrades for amplifiers relates to upgrading coupling capacitors for tube amplifiers and/or to upgrade the power supply capacitors.
How much of a gain in sound quality and performance is gained from upgrading capacitors will depend on the amplifier itself and the speaker system used with the amplifier.
Just as with upgrading capacitors on passive speaker crossovers any improvements derived from upgrading coupling or power supply capacitors can to some listeners be profound where for others they may be subtle or even negatable.
Voltage Rating:
How much voltage a capacitor is rated for in volts DC / volts AC is determined by the capacitor type and by the strength / thickness of the dielectric insulation film used.
For most passive crossover applications is does not matter if the capacitor is rated at 100, 200, 250, 400, 630, 800 or 1200 volts DC.
When exchanging capacitors on passive speaker crossovers it is therefore not needed to exchange with capacitors that have the same voltage rating as the ones you are replacing.
It is more important to choose the right capacitor type, depending on wanting to exchange the capacitor type one to one or if the goal is to upgrade the capacitors.
However, for certain higher-end capacitor types used for crossover positions that are used in direct line with the tweeters or the upper mid-range, it is an advantage to use a capacitor with a thinner dielectric insulation film as it will allow for a faster reacting capacitor with less unwanted “memory” effect.
This is why we use a thinner dielectric insulation film for our pure aluminum foil “Alumen Z-Caps” and pure copper foil “Amber Z-Caps” as these are meant specially for crossover positions in direct line with the tweeters and upper mid-range.
All the audio grade capacitors offered by Jantzen Audio will have sufficient voltage rating for application on passive loudspeaker crossovers (for home use).
When using capacitors in amplifiers it is far more important to be mindful of the voltage load of the amplifier and choosing a capacitor with a sufficiently high voltage rating.
This is usually most important in relation to valve/tube amplifiers.
Series filters:
For series filters, we generally advise using the same grade of capacitors for all positions, as all capacitors are in direct line with the tweeters.
General thoughts on upgrading to a higher grade of capacitors/components:
There will of always be noticeable improvements in areas like transparency and detail richness, when going for the higher-grade capacitors or other components, but they can be subtle in their nature and for some the difference will be more profound than for others.
As most audiophiles will know, we are working with diminishing returns when it comes to the cost of better components versus the improvement / upgrade we get for that investment.
It will always be relatively costly to get those last bits of performance squeezed out of audio equipment, but for many audiophiles those subtle improvements are the pinnacle of the passion that is high-end audio and makes it worth the extra cost.
At the end of the day all it simply comes down to something as subjective as budget and what you are willing to invest and how valuable it is for you to gain even subtle improvements.
There is also such a thing as just enjoying the knowledge that we have upgraded to something that looks better and have a feel of quality to it, even if the actual improvement is subtle.
When we buy expensive audio equipment we can often find justification to spend even more to get that final feeling of satisfaction.