XPL200 Rehab

[Titanium Dome]

Here is the same area after it's been stained. Looks a lot better.

[Titanium Dome]

Steve Gonzales is the master of this technique, but here I've put some grain into the putty before staining.

Since this is at the top of the cabinet, you can see how much color the wood finish has lost. The top is completely faded and lifeless.

[Titanium Dome]

Good work Dome...keep us posted......

by the way..,,wasn't one of the mid-ranges flatten?? got a pix of that?

No, not me, but the Ti dome on one of the 095Ti 3" midrange drivers. It looks like someone pried the steel grille off the driver, scraped it against the dome, then poked it several times. I took the diaphragm out and manipulated it into a roughly dome-shaped driver again, but some of the dimples are deep and permanent.

The driver does work, but it's running below 4 OHMS (3.4 to be exact) while the undamaged 095Ti runs at 4.2 or so.

Luckily, the metal grille survived intact, but the O ring is long gone, so I'll have to find one to keep the metal grille in place.

[Titanium Dome]

I forgot to add:

Does not affect the sound.

Just in case I need to sell them later.

[Titanium Dome]

I found a source for an 8 OHM 095Ti diaphragm (NOS under $60), but the 4 OHM ones seem to be NLA/OOS.

For you technical guys, can the 8 OHM diaphragm be substituted for the 4 OHM? What are my options here?

TIA.

[Guido]

Why not use the D4R093Ti? Shouldn't be such a problem.
Oh, replace them in pairs

[DavidF]

The most exciting part is the bubbling of the veneer. In this bottom-lit shot, the shadows tell the story. This stuff is lifted in many places.

This was almost the deal breaker for me, when I saw these large patches of loose veneer.

How could this happen, I wonder. Were they parked too close to a radiator or some heat source? Anyway, a great job in getting that sorted out.

DavidF

[Earl K]

Hi,

I found a source for an 8 OHM 095Ti diaphragm (NOS under $60), but the 4 OHM ones seem to be NLA/OOS.

For you technical guys, can the 8 OHM diaphragm be substituted for the 4 OHM? What are my options here?

- You can't just substitute the 8 ohm part into a network designed for a nominal 4 ohm driver. You'll shift the crossover points for the 095 and most likely the sensitivity of the midrange area will also be wrong .

- Your options aren't that great. Here are some of them .

(1) Live with the "dimpled" 095ti. Only your eyes & ears will tell you if this is acceptable ( assuming you don't have the equipment to do distortion measurements )
(2) Buy a single replacement 4 ohm 095ti driver .
(3) Buy a replacement diaphragm that is the correct 4 ohm impedance . Perhaps, a 093 or a 095 will suffice . ( would be nice to see an impedance plot for a 095Ti )
(4) Install D4R093tTi diaphragms in pairs.
(5) Buy some 4 ohm, 030ti car units ( from eBay, currently shippied from Taiwan )
(6) Install a single 8 ohm 095ti diaphragm and rework the XPL200 crossover ( as best as can be achieved ).
(7) Install a two 8 ohm 095ti diaphragms and rework the XPL200 crossover for both boxes ( if doable ).

[Earl K]

(6) Install a single 8 ohm 095ti diaphragm and rework the XPL200 crossover ( as best as can be achieved ).

- If this is the route you decide you must take then,

(1) Study Don C's thread about his measuring the voltage drives for both the XPL200 & XPL200a networks . This thread is located HERE ! You'll need to be able to recreate these voltage drives so that you can compare your two different speakers. You may want to talk with Don about his approach. I think Don used 6 ohm dummy loads for all his drives. You could use that value or 8 ohm loads, as in the JBL Standard Test Fixture.
- What's important is the creation of a reliable visual reference for making comparisons between your modified and unmodified crossovers. ie; You'll want to get the voltage drive of the modified midrange section to match that of the unmodified crossover .

(2) Then read this other Don C thread on padding down the 093Ti. I've included this thread for reading because you might be forced to slightly pad down your speaker that has the "good" 095Ti . Don seemed to think the padding was desirable ( though that was for the 093Ti , I believe ) . I don't know if he actually implemented any of Giskards suggested mods for padding.

(3) An AC impedance plot for a 4 ohm 095Ti is highly desirable. You should make one or have someone do it for you. We need to know how it compares to the 093Ti.

(4) You'll need to normalize the 8ohm ( ? ) impedance of your 095Ti, down to around 5 ohms. I'm guessing that this is the impedance value needed as the load impedance for that part of the midrange circuit,( which is driver side of the fixed Lpad ). I've guessed at 5 ohms only because of the included impedance plot that Giskard produced quite some time ago ( for the 093Ti , not the 095Ti ). A 13.5 ohm resistor paralleled across an 8 ohm driver will give an approx. new value of 5 ohms. That assumes the AC impedance of your "8" ohm 095Ti is actually 8 ohms. It likely isn't / which again is why, for the sake of accuracy you need to get someone ( or yourself ) to run an AC impedance curve for the 8 ohm unit.

(5) It would also be really handy if you would make note of the stock R, C & L values for at least the midrange section of the 200s' network. I believe, no one has this network on paper .

(6) Working from the 200a network ( a dangerous presumption ), I calculate the working circuit impedance "amp side" of the fixed Lpad to be around 6 ohms. Meaning ; unless you need more padding in this circuit , a simple 1 ohm resistor placed in line , replacing resistors R10, R11, R12 & R13 should get you real close to a desired drop of around 5 to 6 db for the 095Ti . ( With these 2 new resistors, I've roughly calculated the total db drop in this midrange circuit to be now be between over 6 db . ) My calcs. could easily be wrong , plus they don't agree with some real voltage drop measurements which indicate about 5 db attenuation. This is one more reason why at this point you need to run new voltage drives with these two new resistor in place to see what the actual electrical attenuation is / and what the curves look like. After that is done , additional pad/ or circuit impedance correction can be done. Of course, if the 8 ohm 095Ti has a significantly different sensitivity figure from the 4 ohm unit, then pads will need to be adjusted to account for these acoustic differences ( the pads can always accomodate more attenuation if that's what's necessary )

????

<. EarlK

[boputnam]

Great job, Ti Dome. Thanks for making the effort to post the process. Lots of great experience showing through...

[Titanium Dome]

Hi,


- You can't just substitute the 8 ohm part into a network designed for a nominal 4 ohm driver. You'll shift the crossover points for the 095 and most likely the sensitivity of the midrange area will also be wrong .

- Your options aren't that great. Here are some of them .

(1) Live with the "dimpled" 095ti. Only your eyes & ears will tell you if this is acceptable ( assuming you don't have the equipment to do distortion measurements )
(2) Buy a single replacement 4 ohm 095ti driver .
(3) Buy a replacement diaphragm that is the correct 4 ohm impedance . Perhaps, a 093 or a 095 will suffice . ( would be nice to see an impedance plot for a 095Ti )
(4) Install D4R093tTi diaphragms in pairs.
(5) Buy some 4 ohm, 030ti car units ( from eBay, currently shippied from Taiwan )
(6) Install a single 8 ohm 095ti diaphragm and rework the XPL200 crossover ( as best as can be achieved ).
(7) Install a two 8 ohm 095ti diaphragms and rework the XPL200 crossover for both boxes ( if doable ).

I tried option (1), and my eyes will not permit it. My ears may be bad enough that the sound would pass muster, but my eyes still have enough acuity to say "No way." The rest I will pursue, though I've checked out the T030s on ebay and elsewhere and have some feelers out.

The (6) and (7) options are a last resort for me, inasmuch as I remain an untalented goober when it comes to networks.

I do have a lead on a 4 Ohm 095Ti diaprhagm, but I need to see a picture of it first.

[Titanium Dome]

After all the repairs, some gentle sanding, a final stain wash and touch up, sufficient drying time (48 hours) and a good wipe down, the two enclosures stand ready for the next step. I'm amazed at how well they turned out and at how exciting it is to see them looking like "new" again. They even smell "new."

The camera flash washes them out a bit and makes them look uneven, but they're turned out very uniform and dark.

[Titanium Dome]

I've been using Watco Finishing Oil for over 25 years, but never on a JBL before. Traditionally I've stuck with JBL's own recommended formula. These cabinets were the perfect candidates for the Watco treatment though, since they've been totally neglected and were in need of some real help.

Here's the can, ready to make its mark, so to speak.

[JuniorJBL]

Very nice job Dome!! Thanks for sharing

[Titanium Dome]

Here's look at the top of the cabinet after three applications. The sides were fine after the customary two applications, but the tops were so dry that they soaked up the first two coats almost immediately.

Once again, the camera flash makes the picture less than ideal, but you can see the improvement. In fact, I'll include the original "before" shot of the same top for contrast.