Restoring old speakers

[tylaw321]

Hey guys, first time poster here. I've been using my dad's old "Prophile" speakers that he bought new from a local shop in the 80s. Here's an older thread I found discussing them: https://audiokarma.org/forums/index.php?threads/jsg-prophile-speakers-anyone-heard-of-them.648356/

I'd like to restore these speakers and was hoping to get some help from the experts on here. Here are some images to go along with the questions below: https://imgur.com/a/6GizNdU

• I'd like to first replace the capacitors. There are three wired in parallel - 4., .22 and .47 uF.
  • Is there a reason why they didn't just use a 4.7 uF here? Can I just buy a 4.7 uF with an equal voltage rating and be ok?
    
  • Is there a decent brand of caps I should use for this application? Ideally I'd like to spend <$50 for both speakers' caps combined, but would spend more if I knew it was going to make a substantial difference or increase lifetime substantially.
• When I pulled out the speakers I noticed a ton of sound isolation foam that had degraded and fell apart within the cabinets. I threw out all the old foam. Do I need to replace the foam here? Is there a certain foam I should be using or can I just grab whatever sound isolation material they sell at the local music store?
• There's a red coiled component wrapped in plastic as part of the circuit. Maybe an inductor? Do I need to replace this?
• Is there any reason to replace the speakers themselves?
• Does it look like I need to refoam the speakers?
• There's some sort of knob/potentiometer on the speaker terminals (where you connect the speaker wire). What is the function of these knobs?

If anyone can help me out with any of these questions I would be beyond grateful!

 

[bakes]

Hey guys, first time poster here. I've been using my dad's old "Prophile" speakers that he bought new from a local shop in the 80s. Here's an older thread I found discussing them: https://audiokarma.org/forums/index.php?threads/jsg-prophile-speakers-anyone-heard-of-them.648356/

I'd like to restore these speakers and was hoping to get some help from the experts on here. Here are some images to go along with the questions below: https://imgur.com/a/6GizNdU

• I'd like to first replace the capacitors. There are three wired in parallel - 4., .22 and .47 uF.
  • Is there a reason why they didn't just use a 4.7 uF here? Can I just buy a 4.7 uF with an equal voltage rating and be ok?
    
  • Is there a decent brand of caps I should use for this application? Ideally I'd like to spend <$50 for both speakers' caps combined, but would spend more if I knew it was going to make a substantial difference or increase lifetime substantially.
• When I pulled out the speakers I noticed a ton of sound isolation foam that had degraded and fell apart within the cabinets. I threw out all the old foam. Do I need to replace the foam here? Is there a certain foam I should be using or can I just grab whatever sound isolation material they sell at the local music store?
• There's a red coiled component wrapped in plastic as part of the circuit. Maybe an inductor? Do I need to replace this?
• Is there any reason to replace the speakers themselves?
• Does it look like I need to refoam the speakers?
• There's some sort of knob/potentiometer on the speaker terminals (where you connect the speaker wire). What is the function of these knobs?

If anyone can help me out with any of these questions I would be beyond grateful!

First, welcome! Both to AK and an addictive hobby/ In order of your bullets:
1. Measure the combined capacitance, if it's 4.7 there's no reason not to use a 4.7 uF cap. Same or better voltage rating. Go with a poly cap. I like Solen, but Dayton caps are pretty solid for the money. However, as the caps in place are pretty damn good caps, if they measure in spec, keep them.
2. I would replace the degraded foam with something similar if you can locate it. You should be able to find similar acoustic wedge foam on the e-auction site. Alternately, some Dynamat on the walls and Acousti-Stuf or similar polyeill would likely work well. May have to trual and error the amount of stuffing if it's different,
3. That's an inductor. They don't generally go bad so no need to replace it.
4. Do not replace the drivers.
5. If the foam surrounds are crumbly or not at all supple and flexible, replace them. Refoaming them is easy, and there are several sources - Rick Cobb (looonetunes2001 on the e-auction site) is whom I primarily get mine from, but there are several other sources as well. It almost looks like they have been recently refoamed.
6. It's likely a level adjustment knob for the tweeter; with the speakers on very low volume, twist it and see if the tweeter volume changes. It may need to be cleaned using contact cleaner.

Prophiles are damn good speakers IMO, Good luck!

 

[tylaw321]

Thank you so much, this is so helpful! They're really great speakers and I'm glad they'll be straightforward to restore.

 

[Bill S]

Cool listening room. Like the artwork.

 

[tylaw321]

Thanks! It's the lead guitarist of the band Phish

 

[tyella]

Good write-up, bakes!
I agree, those caps are probably fine. If you want to satisfy your curiosity and check them, you can pick up one of these (or similar) for testing capacitance. Not military spec, but will get you in the ballpark.

edit: that's a kit, sorry. Here's one already built.

 

[tylaw321]

I didn't read bakes response closely and bought a few new caps online. I went with claritycap CSA poly caps after seeing some positive reviews. Interested to see if I hear a difference. I think I'll replace them either way so I'm not worried about them going out of tolerance - the old ones have to be 40-50 years old.

Will this do the same function as what you linked to above? I just realized my multimeter won't read non-polarized caps.
https://www.amazon.com/Pocketable-M...t=&hvlocphy=9005767&hvtargid=pla-845729973092