so I bought some speakers where the crossover need some fixing.
While in there I saw that the caps used were electrolytics and wants to replaced them with film caps. My issue is the size of the caps used.
I'm thinking that maybe this can be installed off-the-PCB using wire to extend the leads? and perhaps using some zipties to keep it in place?
Also, is it worth replacing the cement resistors with something like Mills wirewound?
Thanks a lot of the response!
While in there I saw that the caps used were electrolytics and wants to replaced them with film caps. My issue is the size of the caps used.
- 100uF 100V
- 22uF 100V
I'm thinking that maybe this can be installed off-the-PCB using wire to extend the leads? and perhaps using some zipties to keep it in place?
Also, is it worth replacing the cement resistors with something like Mills wirewound?
Thanks a lot of the response!
The best you can do is to put the crossover out. Extend the leads of the speakers, yes. Then you'll have the time and space to analyze, upgrade...
The 100 uF I suspect is ok a 2$ elcap. The 22 uF...
The 100 uF I suspect is ok a 2$ elcap. The 22 uF...
Replacing electrolytic capacitors with film capacitors can alter the sound of your loudspeakers, but not necessarily for the better.
The manufacturer may have balanced the crossover with the particular characteristic of electrolytics in mind.
It would be interesting to know which make and model of speakers you have bought.
The manufacturer may have balanced the crossover with the particular characteristic of electrolytics in mind.
It would be interesting to know which make and model of speakers you have bought.
I wouldn't agonise over replacing the resistors.
In my book, a resistor acts solely as a resistor at audio frequencies, regardless of type.
GM may disagree!
You get can 'premium' electrolytic capacitors which sit closer to the standard electrolytic caps in damage to the wallet: I've used "Elko" brand in 33 and 47 microfarad values and find them fine, although I didn't A/B them with the cheaper ones.
No way would I use a 100 microfarad cap.
Geoff
No way would I use a 100 microfarad cap.
Geoff
Resistor selection is all about power handling/heat rise, so normally only matters when building a resistor 'bank'/'grid' of small precision resistors for high power handling @ high SQ, though historically do like Ohmite quality 😉.
I would not want to change the value used by the manufacturer though without knowing (and testing with a scope) how that affects the sound
A metallised polypropylene self-healing type (MPP-SH) running capacitor is what I would use. Being industrial products, they're reasonably priced and easily available in any country from refrigerator / AC / pump spare shops. It may also be easier to find 50uF (2x) vs single 100uF. A smaller voltage (250V vs 440V) keeps the size small.
Example:
https://m.indiamart.com/proddetail/50-mfd-motor-run-capacitor-20958342030.html
EDIT: I currently use such capacitors to protect compression drivers in an active multi-way system with no problems.
Example:
https://m.indiamart.com/proddetail/50-mfd-motor-run-capacitor-20958342030.html
EDIT: I currently use such capacitors to protect compression drivers in an active multi-way system with no problems.
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I was surprised to find that a film cap sounded worse than the existing non-polarised electrolytic in one crossover. Electrolytics are not all created equal, and neither are film caps. I'd want to try DC Link caps, though.
So I was looking on eBay and came across 20uF 5% polypro motor starter caps. can these be used in place of the 22uF? (since it's within the tolerance of the elcap that's in there that's marked 22uF 20%.
Thanks again!
Thanks again!
I think you want motor run, not motor start. Maybe someone more technical could outline the difference.
When I did a cap shootout at one point the ordinary large round plastic motor runs were one of the worst. Surprised me.
When I did a cap shootout at one point the ordinary large round plastic motor runs were one of the worst. Surprised me.
How old are these speakers @mrjayviper?
Perhaps they're young enough that the electrolytic capacitors don't need changing?
Giving the make and model of the speaker as I asked (why so shy?) may allow us to access the crossover schematic and better comment on any necessary upgrading.
And, a photograph of the crossover board showing the current components in detail would be nice.
Perhaps they're young enough that the electrolytic capacitors don't need changing?
Giving the make and model of the speaker as I asked (why so shy?) may allow us to access the crossover schematic and better comment on any necessary upgrading.
And, a photograph of the crossover board showing the current components in detail would be nice.
The ESR of the electrolytic will be a factor in the overall "sound" of the crossover, esp given that a non-polar electrolytic is used in that position.. An equivalent film cap will have little to no ESR, and will sound different.
Large motor start capacitors are typically non-polar electrolytic. I've used them in crossovers, and those I've used were OK.
Starting capacitors are not rated for continuous operation, but a short time during which the motor is expected to pick up enough speed for the centrifugal switch to disconnect the auxiliary winding. Decent brands mention this period along with the recommended (max) drive cycle in their markings. As you have correctly guessed, these are less reliable than running caps, but cost substantially less money, even for high value capacitances. Maybe worth a try if you're tight, but no guarantees.
Example,
https://m.indiamart.com/proddetail/epcos-running-starting-capacitor-26007150748.html
You could always add a low-valued resistor to the PP cap to mimic the ESR of the electrolytic type. This value could be obtained using (some) multimeters or alternatively from the datasheet, either directly or from the dissipation factor (tan delta) at the given frequency (usually 100/120Hz).
If you don't mind, could you share the results, please ?
You can use 20uF in place of 22uF but it maybe better to use running caps vs starting types, preferably from a reputed brand.