Crossovers and capacitance value

[gruggn]

Hi everyone,

About a year ago I bought a pair of used Revel F30 that has been working great, however they are not approved in the looks department by my SO and it is time to do something about it.
This is not a question about how to finish the speakers but a question about crossovers. These speakers are from the early 2000's and the crossovers have electrolytic capacitors with "exotic" values on them.

So to the question:
-Is it worthwhile to change out old capacitors, I can measure them with a multimeter.
-How much capacitance drift really matters in the real world, lets say they are specced to +/-2% and the drift is 4% or even 10%?
-Where in the world can I find capacitors with the values needed; 386uF:2%, 884uf:2% and so on.

Below is a picture of what the crossover for the bass looks like.


Thankful for any help.

 

[wwenze]

-Is it worthwhile to change out old capacitors, I can measure them with a multimeter.
Yes/No/Maybe. If the capacitors are clearly broken or clearly about to be broken it makes sense to change them. If the capacitance is off too much, change them. If it is off by a little, I will change them if it's easy to change, otherwise I won't. If I have a bunch of free capacitors lying around and easy to change, I will.

Note that capacitor age only really comes into question when the speaker is >10-20 years old. And even then I worry more about the drivers themselves than the capacitors.

-How much capacitance drift really matters in the real world, lets say they are specced to +/-2% and the drift is 4% or even 10%?
Not really. A few % drift only results in a fraction of dB difference with the filter response. Your speaker positioning results in bigger differences than that and few people care.
What is more critical is they may hint of catastrophic failure in the future e.g. losing 80% of capacitance or getting nonlinear response i.e. shorts.

-Where in the world can I find capacitors with the values needed; 386uF:2%, 884uf:2% and so on.
You don't unless you order-make them or search really hard. Instead you put multiple capacitors in parallel or in series to get the capacitance you want. 386 is 330 + 56, 144 i might just use 150, 884 is 820 + 68 = 888 close enough

Perfect value is necessary if you're selling the product and someone might pick it up for a spinorama. But second-hand owners are not sending these for spinorama and are just trying to get the product working. The final quality depends on how much money you throw, and rough crossovers have good price-performance while identical crossover may cost as much as new speakers, on top of the unknown condition of your drivers.

 

[MAB]

Hi everyone,

About a year ago I bought a pair of used Revel F30 that has been working great, however they are not approved in the looks department by my SO and it is time to do something about it.
This is not a question about how to finish the speakers but a question about crossovers. These speakers are from the early 2000's and the crossovers have electrolytic capacitors with "exotic" values on them.

So to the question:
-Is it worthwhile to change out old capacitors, I can measure them with a multimeter.
-How much capacitance drift really matters in the real world, lets say they are specced to +/-2% and the drift is 4% or even 10%?
-Where in the world can I find capacitors with the values needed; 386uF:2%, 884uf:2% and so on.

Below is a picture of what the crossover for the bass looks like.
View attachment 534167

Thankful for any help.

It's unlikely that anything is bad about the capacitors in your crossovers. You need a multimeter that explicitly tests capacitors. Here is a 50 year old pair of Yamaha speaker capacitors for example.

Vintage Yamaha NS-18 Speaker Measurements

I just bought a pair of used Yamaha NS-18 speakers from a local sale. They are from the early '70s, about 50 years old. Here is a 1973 print ad with the NS-18 and siblings: I used an online translator on the the text that describes the driver technology.:cool: They feature an ear-shaped...

www.audiosciencereview.com

In took out the electrolytic and tested it using a DATs. I also confirmed using an HP LCR meter with a bias adapter to see if it had odd behavior with applied voltage, which was totally unnecessary but seemed potentially interesting. All I found was a perfectly fine capacitor so I re-soldered it to keep things original.

So not likely you will find issues. It's a fine-looking crossover from great sounding speakers that are unfortunately somewhat odd-looking. May I ask how the crossover and the disapproval of the speaker's looks are related?

 

[gruggn]

Perfect value is necessary if you're selling the product and someone might pick it up for a spinorama. But second-hand owners are not sending these for spinorama and are just trying to get the product working. The final quality depends on how much mone

Thank you for the reply. This makes sense and its probably just me overthinking it. I am using room correction via MiniDSP flex and two subs which makes the difference.

-Is it worthwhile to change out old capacitors, I can measure them with a multimeter.
Yes/No/Maybe. If the capacitors are clearly broken or clearly about to be broken it makes sense to change them. If the capacitance is off too much, change them. If it is off by a little, I will change them if it's easy to change, otherwise I won't. If I have a bunch of free capacitors lying around and easy to change, I will.

Note that capacitor age only really comes into question when the speaker is >10-20 years old. And even then I worry more about the drivers themselves than the capacitors.

-How much capacitance drift really matters in the real world, lets say they are specced to +/-2% and the drift is 4% or even 10%?
Not really. A few % drift only results in a fraction of dB difference with the filter response. Your speaker positioning results in bigger differences than that and few people care.
What is more critical is they may hint of catastrophic failure in the future e.g. losing 80% of capacitance or getting nonlinear response i.e. shorts.

-Where in the world can I find capacitors with the values needed; 386uF:2%, 884uf:2% and so on.
You don't unless you order-make them or search really hard. Instead you put multiple capacitors in parallel or in series to get the capacitance you want. 386 is 330 + 56, 144 i might just use 150, 884 is 820 + 68 = 888 close enough

Perfect value is necessary if you're selling the product and someone might pick it up for a spinorama. But second-hand owners are not sending these for spinorama and are just trying to get the product working. The final quality depends on how much money you throw, and rough crossovers have good price-performance while identical crossover may cost as much as new speakers, on top of the unknown condition of your drivers.

Thank you for the insight. They seem pretty easy to change and I am prepared to throw a little money on them, its just a question of finding values that are in range, which you helped me with. Since the old ones may drift in the 5-10% range new one should probably be close enough to "in spec" so to say.

 

[gruggn]

It's unlikely that anything is bad about the capacitors in your crossovers. You need a multimeter that explicitly tests capacitors. Here is a 50 year old pair of Yamaha speaker capacitors for example.

Vintage Yamaha NS-18 Speaker Measurements

I just bought a pair of used Yamaha NS-18 speakers from a local sale. They are from the early '70s, about 50 years old. Here is a 1973 print ad with the NS-18 and siblings: I used an online translator on the the text that describes the driver technology.:cool: They feature an ear-shaped...

www.audiosciencereview.com

In took out the electrolytic and tested it using a DATs. I also confirmed using an HP LCR meter with a bias adapter to see if it had odd behavior with applied voltage, which was totally unnecessary but seemed potentially interesting. All I found was a perfectly fine capacitor so I re-soldered it to keep things original.

So not likely you will find issues. It's a fine-looking crossover from great sounding speakers that are unfortunately somewhat odd-looking. May I ask how the crossover and the disapproval of the speaker's looks are related?

Thanks for the reply.

So what I hear is they may be fine for another 20 years and I should leave them alone since they will hold up in the meantime.
Crossovers and looks are not related, it was merely a little backstory as to why I was opening them up in the first place