• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Recapping JBL L250Tis - Finally Done

Zonker92

Zonker92

All shiny and chrome
Recapping JBL 250Tis - Finally Done

My goal here was to upgrade the L250Ti caps, signal-path resistors, the the woofer coil. I tried not to spend a fortune but achieve good results while keeping the specs original. Note the even those these crossovers came out of sequentially numbered speakers, one of the boards is tan and the other is blue. Also, at least one of my "before" photos is generic (from another poster).

Here is the schematic:

N250Ti Factory Schematic.jpg

(R3 is missing, but it's 5.1 ohms on the 108H shunt.)

Here is how the board looked originally:

IMG_4021.JPG

Removing the caps from the board required some leverage, as they were glued down. I heated a metal putty knife blade with a propane torch to scrape off the hot glue residue. (I don't have an "after" shot on the glue.)

I put the boards on a piece of plywood with a metal strap to support them, so I wouldn't keep flexing the wires (at the top left below you can see a 24 uF Solen that I wound up replacing with parallel Jantzen Standards (22 uF + 2.2 uF), because the last two Solens I needed were out of stock):

IMG_4024.JPG

Most of the components are marked clearly, but not the off-board resistors. I wound up sliding a razor blade between them to cut the glue, then using a metal putty knife gently to force them apart slightly, then shining a light between them to read the numbers. After a lot of rumination and second-guessing, I finally figured out which was which. From top to bottom (that is, with the writing on the board oriented properly), they are:

IMG_4102.JPG

I replaced the signal-path resistors (and, by accident, one of the attenuator resistors) with Mills 12-watt resistors. I replaced the shunt caps mainly with Jantzen Standards, and a few Solens and Jantzen cross-caps, of the same value. I replaced the signal-path tweeter cap (2.7 uF) with a Jantzen Silver, the 104H midrange cap (10 uF) with a Jantzen Superior, and the 108H mid-bass driver (40 uF) with parallel ClarityCap SAs (39 + 1). I bypassed every cap (or set of parallel caps) with one Audiocap Theta .01 uF. I replaced the 6.0 mH woofer coil with an ERSE Super-Q of the same value. I bought everything from Parts Express except the resistors (Parts Connexion), ClarityCaps (Madisound) and some of the Thetas (Opentip). It was NOT cheap. The ERSE coils are $25 a pop. The resistors and bypass caps are over $4 each. The higher-end Jantzens and the big ClarityCaps are around $50. Apiece.

I mounted the new coil on some plywood, stacked up and screwed to the crossover board. I glued everything down with Goop and replaced the original tie-wraps.

IMG_4127.JPG

It's been a month since I started this project, so I can't say I really remember precisely how they sounded before, and I now have a "new" Adcom GFA-5800 amp (250WPC) driving them, but I do like how they sound now. :D

(I posted this over on L-H, too.)
 
Last edited:
Register to hide this ad
nicely done! those original TI caps are OK but nothing special, despite being used in a lot of great speakers. i think you chose your improvements wisely.

if you saved your old inductor, it would be worth checking DCR to see how different the new ERSE is. if much lower, you might notice slightly stronger bass now, but usually this isn't a problem. on some older speakers with really small-gauge inductors, the upgrade to a large gauge can be pretty noticeable and even unwelcome if the speaker was bass-heavy to begin with.
 
Thanks! I really appreciate the kind words! :D

I was curious, so I did check the respective DCRs. IIRC the old one was about 0.4 ohms and the new one 0.3; they were damn close.
 
Looks incredible! Great work. That is one seriously intimidating cross over.

I'm about to embark on recapping my L56's (a whopping six capacitors.) I kinda wish I had a nice board to work with like these. I foresee trouble in desoldering multiple component leads from one terminal strip hole (especially considering the generous amount of solder they used.) I better let the desoldering iron heat up for a while!

My circuit uses 0.068µf bypass caps but I'm having trouble finding them in audio-specific caps.
 
Thanks! I saw your thread. I had to deal with that same solder issue on many of the resistors. I wound up cutting the leads off and then melting the solder while using needle nose pliers to pull the leads out. Some desoldering braid or a solder sucker will then clean things up.

I would NOT try to find exact 0.068 bypass caps. The exact value is not necessary. I would just use 0.01 Audiocap Thetas from Parts Express, or the Vishays someone (?) sells, which are cheaper.

Have fun!
 
Zonker92 said:
I would NOT try to find exact 0.068 bypass caps. The exact value is not necessary. I would just use 0.01 Audiocap Thetas from Parts Express, or the Vishays someone (?) sells, which are cheaper.
Click to expand...

except that .1 would be more appropriate than .01, at least from a mathematical standpoint.
 
Sorry, Zonker! Yes, thanks so much. I ordered a few from PX, along with the rest of the caps needed to recap my L56's.
 
Howdy, Jon! I wish I could answer your question unequivocally, but the best I can say is, I think so.

The problem is, there was maybe a month in which I had the speakers taken apart for this job. When I fired them back up again, I had new crossovers, reconed midranges, refoamed woofers and replacement cabinets. I also went from a tube amp with 35 WPC to a solid-state amp with 250 WPC. And I added a preamp. Compounding all this, I am a devout skeptic when it comes to my ability to remember how something sounds, especially after a month.

So the best I can say is, the speakers sound terrific, and I think maybe yes, they sound better. I also suspect the bass is better; tighter and stronger.
 
Oh my, you did that sooo wrong !!!

kidding,

I bet it sends power to the speakers with ease now, those old resistors sure looked used and old, nice work !!!

The only thing I would say, unless you did it, but on the weighty, large mass heavier parts, you might want to add some silicon sealer for extra springy support from vibration.That seemed to be the most that went wrong with any crossover, most of the time, and it would be an easy fast thing to do.

They MUST sound better than the old parts.
 
Hey, thanks, man! Much appreciated.

I slathered a ton of Goop(R) under all the parts, especially the heavy caps, so they didn't budge when I tugged on them. They'll all glued to each other too.

And yes, I think they sound fantastic; I just don't have a direct A-B to confirm. :)
 
Hey, thanks! :D

Yeah, I went through a lot of options picking those caps. I kept buying cheaper ones, and my buddy kept egging me to get fancier and fancier ones, so I kept returning them and buying better ones. I drew the line at putting Z-Superiors on the 108Hs (lower mid drivers) (40 uF in high-pass caps = 15 + 15 + 10) though; that would have been crazy huge and crazy expensive. :eek:
 
You must log in or register to reply here.
Back
Top Bottom