At sometime in the past, I read that certain axial film capacitors degenerated over time. If I remember correctly, the end caps of said capacitors were identified by colour. Unfortunately I cannot remember what that colour was.
I have some crossovers from Electrovoice which each contain three axial film capacitors - 2uF, 12uF and 21uF. I suspect they were constructed circa 1970. As mentioned in the thread title, their end caps are red in colour. Should these concern me?
As far as I can tell the variable resistors in the crossovers do function but how they affect the sound seems quite subtle to me.
The speaker system in which I installed them is a 3 way using EV 12" woofer, EV MR10 horn midrange and EV T35 tweeter. I cannot say that I am thrilled with how the system sounds. My perception is they are overly bright and adjusting the tweeter and midrange variable resistors produces a perceptible but negligable change.
The thought occured that perhaps those film capacitors are out of spec under load. The readings I obtained from a DMM with the capacitors out of circuit were within tolerance so I left them in place.
Since they are 55 or so years old, are they due (or past due) for replacement?
I have some crossovers from Electrovoice which each contain three axial film capacitors - 2uF, 12uF and 21uF. I suspect they were constructed circa 1970. As mentioned in the thread title, their end caps are red in colour. Should these concern me?
As far as I can tell the variable resistors in the crossovers do function but how they affect the sound seems quite subtle to me.
The speaker system in which I installed them is a 3 way using EV 12" woofer, EV MR10 horn midrange and EV T35 tweeter. I cannot say that I am thrilled with how the system sounds. My perception is they are overly bright and adjusting the tweeter and midrange variable resistors produces a perceptible but negligable change.
The thought occured that perhaps those film capacitors are out of spec under load. The readings I obtained from a DMM with the capacitors out of circuit were within tolerance so I left them in place.
Since they are 55 or so years old, are they due (or past due) for replacement?
They look like polypropolene as metal film was in its infancy then.
A 21uF PMP cap will be very large, non polarized electrolytics were also used for larger values in some cases.
PMP capacitors don't deteriate over time. The get damaged with over current but not likely in this situation as the speech coils would most likely blow first.
Out of spec under load ... how would you measure that? Use a proper capacitance and ESR meter. A DVM only gives an approximation.
A 21uF PMP cap will be very large, non polarized electrolytics were also used for larger values in some cases.
PMP capacitors don't deteriate over time. The get damaged with over current but not likely in this situation as the speech coils would most likely blow first.
Out of spec under load ... how would you measure that? Use a proper capacitance and ESR meter. A DVM only gives an approximation.
If they say Temple on them and have multiple "÷" marks on the body, those are notorious from early Advent speakers and similar. The early 70s would be the right time frame. I've thought they are electrolytic, but can't offer any proof. The ones in a pair of early Advents of mine measured poorly. I agree with advice above to replace.
These are film caps. Film caps do normally not degrade over time, electrolytics do.
The red end are not end caps, it's the color of the epoxy used to manufacture them. They are supposed to be this color.
There's nothing wrong with them but if you insist on mucking things up, sure, replace them.
Use the exact same capacitance value as that determines the speaker frequency response as designed.
Jan
The red end are not end caps, it's the color of the epoxy used to manufacture them. They are supposed to be this color.
There's nothing wrong with them but if you insist on mucking things up, sure, replace them.
Use the exact same capacitance value as that determines the speaker frequency response as designed.
Jan
No, I have no deisre to change them. My post was mearly to learn if there is or was a particularly notorious capacitor with a certain colour end. If those I am dealing with had such a caution attached I would change them but otherwise no. I would not change them on a whim.
Earlier today a friend stopped by and I asked her the listen to and give an opinion on a selection of four speakers as I switched between them. Included were the Electro Voice. Those were what she picked as sounding best of the four.
Could be that a speaker system with a horn midrange and tweeter is just not my cup of tea.
Solen produced a large batch during the late 80ies, i believe, which had the unfortunate inclination to turn into a dead short for no apparent reason. Have seen and tested many of those.
There was a red type made by Hunts that are in the category of shoot on sight, but I think they were a much lower range of values. I find them in some British tuners.
If you arent satisfied with your system's sound, first swap the midrange and tweeter connections to the xover, as the 2nd filter from the bottom surely is a 1st order high pass, and the top one appears to be a mid pass.
Best regards!
Best regards!
Interesting suggestion. Over the past few days I've been shifting the contents of my living room to opposite sides and currntly there are three other pairs of speakers stacked on top of the Electro Voice. When I have better access, I may try that. Easily reversable if unsatisfactory.
I made the rear baffle boards easily removable by using tee-nuts. It would also be a good opportunity to stuff some insulation inside the cabinets which I never did when I put them together.