ISO audio grade/Crossover bipolar capacitors

ranukic

Active Member
Hey,

I picked up (2) pairs of HPM 100's...now before you say not another freggin HPM thread please finish reading because I have searched on our site and can't find the answers I am looking for.

Looking over the SWN-117 & SWN-158 schematics and to me it makes sense to replace the electrolytic capacitor but I can't locate an audio grade 0.15uf/63v bipolar electrolytic lead type capacitor. Has anyone found an acceptable capacitor? My go-to is mouser for audio grade capacitors but they never seem to have audio grade bipolar type.

Is it recommend that I change out the 3uf/100 & 4.4uf/100 mylar film capacitors? If so, what is recommended? I saw one guy use (2) capacitors in parallel to achieve the rating of what was removed. However from what I have read MF types shouldn't go bad.

Also, I watched a couple youtube videos on restoring crossovers and those people were upsizing the resistors, the coils....why?

Thanks, James
 
Hey,

I picked up (2) pairs of HPM 100's...now before you say not another freggin HPM thread please finish reading because I have searched on our site and can't find the answers I am looking for.

Looking over the SWN-117 & SWN-158 schematics and to me it makes sense to replace the electrolytic capacitor but I can't locate an audio grade 0.15uf/63v bipolar electrolytic lead type capacitor. Has anyone found an acceptable capacitor? My go-to is mouser for audio grade capacitors but they never seem to have audio grade bipolar type.

Is it recommend that I change out the 3uf/100 & 4.4uf/100 mylar film capacitors? If so, what is recommended? I saw one guy use (2) capacitors in parallel to achieve the rating of what was removed. However from what I have read MF types shouldn't go bad.

Also, I watched a couple youtube videos on restoring crossovers and those people were upsizing the resistors, the coils....why?

Thanks, James

For the .15uf cap you just need to replace that with a film. If you want to go with Mouser then I’d just get some Panasonics or similar. I usually buy my crossover parts from Parts Express, they have some .15uF polypropylenes.

Mylar Film don’t necessarily need to be replaced, but with improvements in capacitor technology you can now replace them with a much better polypropylene film. I usually replace all mylar with poly unless the speaker just really isn’t worth it. Same with electrolytic, always go with poly unless the value is so high it prohibits.

People can replace the resistors with higher wattage ones so they don’t get so hot or stressed, also could go with better quality. Remove the sandcast and place in some nice dale/mills. Same with inductors. You could remove the iron core and replace with air core inductors if you want to go with better quality components. It can get expensive pretty quickly, just depends on what you want to spend.

Dan
 
A lower gauge (thicker wire) has lower resistance, so lower losses and less effect on damping factor, i.e. the back EMF produced as the driver returns to the rest position.

Air-core inductors are superior to iron-core inductors because the core cause distortion. Using a core is a less expensive way to increase the inductance without adding copper wire, and it also reduces the physical size. (Nowadays it's all copper. In the 1970s some speaker manufacturers briefly used aluminum wire for the inductors as the price of copper was increasing. Copper pigtails or solderless connectors had to be crimped onto the ends for attachment into the circuit.)

Polyester (tradename "Mylar") has a dielectric absorption roughly ten times that of polypropylene film. This retains current, essentially causing signal averaging and thus distortion. Does this matter in practice? Probably not. But I completely agree with saabracer23 that better capacitor technology now exists, so use poly film.

Bypassing larger capacitors with smaller values (0.1 uF and 0.01 uF in parallel) improves the HF response because smaller capacitors better respond to faster-changing signals. Does that matter? Well, do an A/B comparison and you can likely hear it.

Electrolytic capacitors cause distortion and should not be used. (The signal has to travel through an aluminum-oxide dielectric which acts like a rectifier.) Film in the size you cited is inexpensive and quite small, so no reason to not upgrade to film. The Parts Express Dayton house brand is what many use, as it is inexpensive and good quality.

Tiny changes across the board add up to big improvements, and the crossover is a crucial part of the speaker.
 
Thank you both for the great detailed answers. I will definitely let you know what I end up going with.

Thanks again,
James
 
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