If I may, there are several other questions I have. They are all related to understanding the reasons for the original crossovers and making informed decisions while upgrading parts.
With poly caps, I was going to go with Dayton Audio. There were PMPC and DMCP. The PMPC is priced higher and has copper leads. Is this an advantage? Or possibly a drawback, given what you mentioned earlier regarding copper.
There is no advantage or drawback, other than price, if you choose the PMPC or DMCP capacitors. They have the same construction (other than the leads) and the same sound quality.
When choosing capacitors, the most important thing is getting the correct capacitance value. For most all crossover parts (capacitors, inductors or resistors) a general rule-of-thumb says crossover part values that vary by about 10% are OK. So, as long as you actually get the capacitance as specified in the crossover schematic, or are within 10% of that value, you’re doing the best you can.
The Dayton Audio capacitors are metalized polypropylene (MPP) caps, made in Taiwan. Overall, they’re inexpensive, but they’ve been recognized for years as having very good quality. Among the audio parts that Parts Express sells, their house brand capacitors are perhaps the best known among DIY builders. These caps are sold in two price levels, one with 1% tolerance (the PMPC line), and the other with 5% tolerance (the DMPC line). As far as I can tell, there is no difference in these caps other than the tolerance. After they’re made, in one large manufacturing run, they go through several quality control inspections, including testing for capacitance. If a cap deviates from its intended capacitance by 1% or less, its sold marked with 1% tolerance (PMPC). If the capacitance deviates by more than 1%, but less than 5%, its sold at a lower price marked with 5% tolerance (DMPC). If it deviates by more than 5%, it isn’t sold in the USA by Parts Express under the Dayton Audio name.
I once had the opportunity to speak at length with Darren Kuzma, who at the time was the parts manager for Parts Express. He often came to DIY Speaker Builder meetings around the country. He was popular because he always brought along freebies to give away. He was highly experienced at DIY speaker building, crossover design, as well as the manufacturing of speaker parts of all kinds and price levels in China and Taiwan. We mainly spoke about the new (at the time) Dayton Reference Series aluminum cone drivers he developed and had manufactured in China under contract. But, when I asked him about Dayton caps, he did confirm what I described above about the Dayton MPP caps. He also told me they were manufactured in Taiwan by a well-known electronics manufacturer named Bennic. That was some time ago, and I don’t know for certain if Parts Express still sells capacitors made by Bennic under contract. However, these caps are still considered very good quality and their price makes them an excellent value.
Another advantage of owning an LCR meter, is that you can easily measure the capacitance of any capacitor you buy. Among the various Dayton Audio caps I’ve purchased, ALL of them measured, in my hands, as nearly exactly their labeled value. It didn’t matter if it was a 1% or 5% cap. After seeing that, I only buy the 5% caps.
Solen and Audyn Q4 caps are also very good quality and sell at slightly higher prices. If I can’t find a Dayton 5% cap in the size I’m looking for, I order either a Solen or an Audyn Q4. Their only possible disadvantage is that most of them have failure ratings of 400V instead the 250V of the Daytons. Being able to withstand higher voltages before failure, does make for a physically larger capacitor. However, it does not make for improved sound quality.
