L19 recapping and modding questions

[natenkiki2004]

Hey all. New to this forum but I've been here before while researching things. A buddy of mine gave me a pair of JBL L19A's that needed new foam surrounds. I'm in the process of cleaning them up and prepping them for replacement but I'm wondering about the crossover. I came across this:
http://www.audiokarma.org/forums/showpost.php?p=2580248&postcount=62

Does that seem accurate? I don't really like the Dayton brand (seems like cheap stuff to me) but I had a hard time sourcing Vishay or Mundorf caps with the proper values. I believe in the schematic it calls for a 7uF and 18uF cap but those seem hard to find. I don't know if I NEED new caps, I was just advised to replace them and for $40 total for the Dayton, it seems alright. For suggesting caps, I do like detailed bass as well as overall clarity leaning more towards neutral.

Aside from that, I've ordered binding posts. Any suggestions on fun/cheap mods for these?

[natenkiki2004]

Bump.

I did some looking around and found ClarityCap from Madisound. Anyone have experience with these? The schematic does call for 18uF and 7uF caps. ClarityCap has a 18uF but not a 7uF. I could just wire a 6uF and 1uF in parallel for that and be plenty good right? Or would it be ok just to get a 6.8uF cap and save a couple bucks?

[grumpy]

Mundorf ... L19A? I would seriously ponder the cost/value ratio. You could probably
pick up some L96/4313b type speakers for that kind of $$$.

I've had good luck with Sonicaps in other designs (probably 2x the Dayton cost though).
No direct experience with ClarityCaps.

Yes, you can parallel 6 + 1uF parts and get 7uF... or go with 6.8uF and hope the mfg
doesn't serve up a batch on the low side of the specified tolerance. I doubt anyone would
be able to hear the difference, regardless... but we are talking about tweaking caps for
sound in a 30+ year old, paper dome/cone tweeter, two-way design, yes? :)

... a nice design, and one I own examples of (4301B and L19 versions :o:), but still...

[natenkiki2004]

Yea, I've looked more and I don't really want to spend more than $60 in a recap. I really enjoy these L19's though. I stepped up from those popular Best Buy Insignia speakers and it's a world of difference. Knowing the price of these L19's used, I know I won't be upgrading for a long time so I'd like to put some money into them to make them last a long time. I'll probably go with the ClarityCaps since they have the spot-on values instead of the Dayton's which are 6.8 and 20uF.

*EDIT*
I've noticed that the 4301B uses 16.5uF instead of the 18uF that the L19 uses. Same woofer and all, just a different cap. Would it be worthwhile to go that route or should I stick with the original 18uF?

I've also seen people have 0.01uF bypass caps, what's the deal on those? How are they used and should I use them?

I know how to solder and I know how to work computers like nobodys business but when it comes to pure electronic design with schematics and values, I just get lost :)

[natenkiki2004]

Bump?

[grumpy]

If you really are inclined to try this (it does sound like fun):

get some spare 1.5uF caps and try it yourself :) (16.5+1.5 in parallel gets you 18uF)
see which you like better.

with the newer, presumably more capable caps, adding a paralleled
.01uF cap (polystyrene or polypropylene) is likely to be less noticeable.
With the older mylar caps, it apparently was worthwhile to bypass them
in higher frequency parts of the crossover.

Nevertheless, it doesn't cost much to prove it to yourself.

[natenkiki2004]

Alright, I'll save money and skip the bypass cap. I've been trying to look online and understand what the capacitance does in terms of sound signature. What possible difference could I expect for 16.5uF vs 18uF? I'm tempted to go 16.5uF since that's what the "pro" series used with the same enclosure and woofer.

[grumpy]

If I had to guess, I would expect the small change in effective crossover would
mitigate a small broad peak near the crossover frequency (shooting for a flatter
response with the control monitor vs. leaving a presence peak in the home system).

For whatever reason (probably visual), I like the 4301 better (slightly).

[natenkiki2004]

Yea I like that JBL blue and HF control in the front. But the L19's still look good too :)

I think I'll go for the 16.5uF then, I really don't see any reason not to, if nothing else it's bragging rights :P

[natenkiki2004]

I think you mis-read or I mis-spoke. I've put many hours on them with the stock caps, they sound great. I refoamed them and then used them (didn't use them at all with the original foams) and found out that my refoam job (first one I've ever done) failed and they were slightly off center causing the woofers to rub at very low frequencies. I've disassembled them and am awaiting a new kit, this time with shims (I did read the guide here, very helpful but I still failed).

The caps do work fine but everyone I've come across has suggested replacing the caps. I'm a little light right now so I can't drop $50 on new caps AND $30 on the surround kit. Once I redo the surrounds, I'll continue to listen to them with the stock caps until my budget allows me to upgrade the crossovers. Then I'm going to oil the cabinets, get some rubber feet and enjoy them for many years :P

[natenkiki2004]

What happened to that guy's posts? I had a reply typed out and left the computer. Came back and saw they were gone. Can you delete your own posts? Anyway, I lost the reply with having to login. I mentioned something about that when I do the crossover upgrades, I will strictly adhere to the original schematics for values. I've wasted $25 on surrounds already, I've got to spend another $30 for surrounds and parts then $80 for caps, resistors, inductors and some 18awg wire so that there is absolutely no bottleneck in the speaker. $140 totally invested, I know I can sell these for $200-$300 since they will be just about perfect when I'm done (I'll oil the cabinets too). Even if there's no improvement with the caps (I'm inclined to believe there will be a significant improvement), I'll still be able to get my money back out quite easily.