Stack
Active Member
I just redid the electrolytic capacitors in my JBL L5s, and decided to test the old ones to see how bad they really were.
Of the 10 total caps (5 per speaker), 6 tested very, very bad. Those 6 were all 20-80% over their rated capacitance. Only the 12 and 13 MFD caps were within the stated 10% tolerance.
The caps that went bad were T.I. branded nonpolarized caps. If you peek in through the woofer they're a very distinct bright orange color that you should immediately be able to pick out:
The JBL L5s are getting to the 30 year mark (they ran '92-'96), which is generally when you want to do the caps anyway, but given how far these were out in my pair, I'd consider doing it sooner than later.
I wish I'd taken more pics through the process, but if you're planning on tackling this project know that it's not super beginner friendly. I'm a fairly experienced DIYer and it took me an entire day to do right. You can get the board out through the woofer opening, but it was clearly placed with the rest of the speaker built around it.
Troublesome issues you'll encounter are:
- The upper screws holding the board in, which are difficult to access. You'll need a stubby phillips screw driver.
- A hidden screw in the top rivet of the power transformer. This will require a medium length screwdriver to get at; just tall enough to clear the transformer but stubby enough to avoid the lower midrange enclosure.
- The fact that they soldered all of the driver wires onto the board instead of using terminals, so you either have to unplug all the drivers and pop out the glue plugs holding them in place for the individual housings... or, as I did, cut the wires and install a bus bar with terminals so that you can just unplug them for servicing in the future.
- The fact that they used a figurative ton of hot snot to hold the caps in place.
- Some of the spaces for the caps are tight, so if you want to use polypropylene caps you'll need to be creative.
If you are experienced and decide to tackle this, here are the caps you'll need for a PAIR of speakers. All caps are NP (non-polarized) and rated at 100V:
- 80 MFD x2
- 128 MFD x2
- 12 MFD x2
- 13 MFD x2
- 47 MFD x2
Some of these proved hard to find in NP form, particularly the 128, so I wound up hooking a 120 and an 8 in parallel for that one. You're proabably fine if you can get in 5% of the rated value. Luckily they silkscreened the original values on the board so you can stray a little bit and still have the original values even if you don't write them down.
Given how out of whack the caps were, replacing them did have a noticeable effect on the sound quality, particularly the midrange. The midrange sounded much flatter before the replacement. After replacing the caps and running them in for a couple of hours (they'd been sitting in my closet for almost two years) the midrange is way more forward, as it should've been in the first place.
Of the 10 total caps (5 per speaker), 6 tested very, very bad. Those 6 were all 20-80% over their rated capacitance. Only the 12 and 13 MFD caps were within the stated 10% tolerance.
The caps that went bad were T.I. branded nonpolarized caps. If you peek in through the woofer they're a very distinct bright orange color that you should immediately be able to pick out:
The JBL L5s are getting to the 30 year mark (they ran '92-'96), which is generally when you want to do the caps anyway, but given how far these were out in my pair, I'd consider doing it sooner than later.
I wish I'd taken more pics through the process, but if you're planning on tackling this project know that it's not super beginner friendly. I'm a fairly experienced DIYer and it took me an entire day to do right. You can get the board out through the woofer opening, but it was clearly placed with the rest of the speaker built around it.
Troublesome issues you'll encounter are:
- The upper screws holding the board in, which are difficult to access. You'll need a stubby phillips screw driver.
- A hidden screw in the top rivet of the power transformer. This will require a medium length screwdriver to get at; just tall enough to clear the transformer but stubby enough to avoid the lower midrange enclosure.
- The fact that they soldered all of the driver wires onto the board instead of using terminals, so you either have to unplug all the drivers and pop out the glue plugs holding them in place for the individual housings... or, as I did, cut the wires and install a bus bar with terminals so that you can just unplug them for servicing in the future.
- The fact that they used a figurative ton of hot snot to hold the caps in place.
- Some of the spaces for the caps are tight, so if you want to use polypropylene caps you'll need to be creative.
If you are experienced and decide to tackle this, here are the caps you'll need for a PAIR of speakers. All caps are NP (non-polarized) and rated at 100V:
- 80 MFD x2
- 128 MFD x2
- 12 MFD x2
- 13 MFD x2
- 47 MFD x2
Some of these proved hard to find in NP form, particularly the 128, so I wound up hooking a 120 and an 8 in parallel for that one. You're proabably fine if you can get in 5% of the rated value. Luckily they silkscreened the original values on the board so you can stray a little bit and still have the original values even if you don't write them down.
Given how out of whack the caps were, replacing them did have a noticeable effect on the sound quality, particularly the midrange. The midrange sounded much flatter before the replacement. After replacing the caps and running them in for a couple of hours (they'd been sitting in my closet for almost two years) the midrange is way more forward, as it should've been in the first place.
