Recapping xover worth it?

[ifsixwasnin9]

Is it worth it to recap vintage JBL L110 xover (3 alum. caps ea.) if the speakers work well and caps do not have any damage? (Every time I try to improve on something I end up ruining something good. I remove the mid controls and end up denting the tweeter, etc. Recapping my Sansui 517 amp was a nightmare.)

 

[Swerd]

Is it worth it to recap vintage JBL L110 xover (3 alum. caps ea.) if the speakers work well and caps do not have any damage? (Every time I try to improve on something I end up ruining something good. I remove the mid controls and end up denting the tweeter, etc. Recapping my Sansui 517 amp was a nightmare.)

I considered answering your other post where you had a photo of your crossover. But someone else said what I would say, "if it ain't broke, don't fix it."

I don't see anything in the photo that suggests a failed crossover component.

What do you think is wrong with your speakers? Are they 2-ways or 3-ways? Do you know what circuits on the crossover board go to the woofer, tweeter, or mid? Do you have a schematic diagram of the JBL L110 crossover?

In my general experience with some DIY speaker building, I've found the crossover design is critical for a good sounding speaker, but the build materials of the crossover components – as long as they perform as the design calls for – is much less important.

There is a lot of uniformed talk on internet audio forums about recapping amps and speakers. Although some aged amps benefit from replacing aged or failed power supply capacitors, I've never encountered an old crossover in a speaker that works like that. Don't confuse these different uses of capacitors.

There is also a lot of misinformed talk on internet about the "different sounds" that can be had by replacing speaker crossover caps with caps of some expensive or exotic construction. In my experience, as long as a cap has the correct capacitance value according to the crossover design, replacing it with another cap of the same value but of different construction, will make no audible difference.

Besides, those non-polar electrolytic caps in your crossover (those 3 shiny ones) are probably much smaller than metalized polypropylene caps of similar value. That will probably force you to build a whole new crossover board. That will be a lot of work you may not have anticipated.

 

[Steve81]

There is a lot of uniformed talk on internet audio forums about recapping amps and speakers. Although some aged amps benefit from replacing aged or failed power supply capacitors, I've never encountered an old crossover in a speaker that works like that. Don't confuse these different uses of capacitors.

Interesting. I've spent some time on the Klipsch forums and read about people recommending recapping older Heritage speakers since the values of the electrolytic capacitors would have drifted over the course of a few decades. People did tend to notice the differences before and after, but then again bias could play a factor there.

 

[Swerd]

Interesting. I've spent some time on the Klipsch forums and read about people recommending recapping older Heritage speakers since the values of the electrolytic capacitors would have drifted over the course of a few decades. People did tend to notice the differences before and after, but then again bias could play a factor there.

This is what I meant when I said "uninformed talk" about capacitors. Much of it is based on repeated hearsay, based on little or no facts.

True, some very old electrolytic capacitors have been known to drift over the years, but it's rather easy to attach the leads of an LC meter and find out. I suspect I'll be out of spec long before those caps are .

 

[Swerd]

I found a JBL L110 schematic and someone else's crossover photos for comparison. There are two different schematics labeled N110 and N110A. I think N110 applies for the OP.

 

[ifsixwasnin9]

"if it ain't broke, don't fix it."

The other post was only in reference to the very large plastic caps because I didn't know what type they were. Yes, I have a schematic and know where each driver is connected on the xover.

I've read a lot about recapping of vintage equipment and improvement of sound, performance, etc. And that over time capacitors dry out and don't perform like they should.

All drivers do work so I guess that means the caps are OK. I mean I don't know what the speakers sounded like when they were new. (I wish I did.) I do notice that the drivers might be unbalanced (poorly designed xover? damaged xover?) because I can hear small pockets in the sound that are not as strong as others. (ie I can distinctly hear each individual driver (at a distance) and not one overall (balanced) sound. Maybe my ears are overly sensitive being a musician.)

But the speakers are not close to the point where I think they're unlistenable so I think my best bet is to leave the xovers alone. I do think the xovers could probably be re-designed for a better sound.

Thanks for your good feedback and knowledgeable reply - saves me a headache. (Majority of what I read now about recapping I take with a grain of salt.)

(Matching aluminum axial caps that I've found that are in-stock online at Digikey, Mouser have much larger capacitor values than original caps.)

 

[Swerd]

I've read a lot about recapping of vintage equipment and improvement of sound, performance, etc. And that over time capacitors dry out and don't perform like they should.

It is conceivable that these caps were once in spec, but due to age are now out of spec. My experience with non polar electrolytic (NPE) caps, such as the 3 shiny ones in your photo, has been that they are cheaply made and have sloppy tolerances. I've found that if I need two that are a given value, such as 6.8 µF, I may have to buy 10 or 20 caps, and measure each one to find two that are within 10% of that value. How do we know if all those aged NPE caps were ever the intended capacitance value when they were new? All the audio forum talk about aged NPE caps drying out and getting out of spec, makes the assumption that they once were in spec.

For new crossovers, I avoid using NPE caps for that reason. I get inexpensive metalized polypropylene (MPP) caps, not because they are "better sounding" caps, but because they almost always measure the same as their printed value. To measure them, I use a relatively inexpensive (about $45) LC meter I found on Amazon.

All drivers do work so I guess that means the caps are OK. I mean I don't know what the speakers sounded like when they were new. (I wish I did.) I do notice that the drivers might be unbalanced (poorly designed xover? damaged xover?) because I can hear small pockets in the sound that are not as strong as others. (ie I can distinctly hear each individual driver (at a distance) and not one overall (balanced) sound. Maybe my ears are overly sensitive being a musician.)

But the speakers are not close to the point where I think they're unlistenable so I think my best bet is to leave the xovers alone. I do think the xovers could probably be re-designed for a better sound.

Redesigned crossovers are a whole different matter. For that, you should find a way to have one of these L110s tested and measured. It is possible that the L110 crossovers might be improved. But this job requires someone who knows what they're doing. Read this older thread where I went through this process on some old JBL L100s with plenty of help from a knowledgeable friend. http://forums.audioholics.com/forums/diy-corner-tips-techniques/25014-vintage-jbl-west-coast-sound-becomes-%85.html.

Where are you located? The guy who did that work, Dennis Murphy, is in Bethesda, MD.

Another thing I noticed on the N110 schematic, is the presence to two variable L pads. Do they work without generating noise (sounds like static) or cutting in and out as you turn the knob? Most of these variable L pads oxidize with age, and fail or work intermittently. You can try spraying the shafts with Caig Deoxit.

(Matching aluminum axial caps that I've found that are in-stock online at Digikey, Mouser have much larger capacitor values than original caps.)

If you replace caps while staying with the original design, be sure to maintain the capacitance values (microfarads µF). Varying ±10% from the original value in the schematic is OK. The other rating caps have is voltage, such as 100 V, which is a thermal failure rating. You can go higher, such as 250 V, without changing the function of the cap, but be aware that caps with higher voltage ratings will be physically larger and may not fit on your board in the same space as the old cap occupied.