Vintage xover replacements?

[midlife]

I would like to find a suitable xover for a vintage L88 speaker system. Good oem or aftermarket. What are my options? thanks.

[Mr. Widget]

Look at post #2 below:

http://www.audioheritage.org/vbulletin/showthread.php?t=278


Widget

[hjames]

Look at post #2 below:

http://www.audioheritage.org/vbulletin/showthread.php?t=278

Widget

Wow, its super basic - just 4 parts - unbelievable!

One cap, one choke (already got that part if you have the original xover),
one resistor, one Lpad ...!

[midlife]

Look at post #2 below:

http://www.audioheritage.org/vbulletin/showthread.php?t=278


Widget
Maybe I could do this, never have before. My dc electrical experience is from slot car building? If I take the project on where would I get the components? Lpads? What elec value would I be looking for component wise? Would I use the elec values on the jbl schematic? The L88s I have are pristine except for melted down xovers, so I hate to see them destined for the parting out process. thanks for your recommendations.

[Mr. Widget]

If I take the project on where would I get the components?

http://www.parts-express.com/air-core-inductors.cfm

http://www.parts-express.com/crossover-capacitor-index.cfm

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=196

http://www.parts-express.com/wizards/searchResults.cfm?FTR=mills&search_type=main&WebPage_ID=3&searchFilter=mills&x=0&y=0


You can't screw up too much... buy parts at which ever price level you feel works for you... just about everything listed here is superior to what JBL used back then.


Widget

[midlife]

I know its simple, but again I have never done this before. The closest resistor to original value (2.5 ohm, 10w) is 2.5o @ 12w, that shouldn't be an issues? And there are alot of cap design choices, whats up with that? Will a 15 watt L pad be sufficient? When I put this together do I have to consider polarity on the xover components and how will I get the driver polarity correct? thanks.

[Mr. Widget]

10 watts or 12? 12 is slightly better, but essentially the same thing... any audio grade non-inductive resistor will work. These Mills resistors are top drawer. There is no polarity issue with any audio grade cap... these are all sufficient. Use a Dayton cap, they are good enough and inexpensive. Inductors have no polarity. Use any air core inductor... larger gauge wire has lower resistance. Your system will have the correct polarity if you follow the schematic.

As for a 15watt L-pad? Don't cheap out here... use at least a 50 watter... not that the power requirement is needed.


Widget

[midlife]

If I need an exact oem value (6uf) on the caps, I may have to use something other than Dayton, as they offer 5.6 or 6.2? Also is .29dcr too high for the air core windings? (that is a 18ga Jantzen) thanks

[Mr. Widget]

You can build exact cap values by simply paralleling them and adding their values. I'd typically go with a bigger gauge coil, but I imagine you'll be fine with that coil.


Widget

[midlife]

Has anyone used the Dayton pre-assembled xovers? Parts Express sells them. Would refurbishing the old ones or building my own have any advantages over the Daytons? Are Lpads needed in a fresh xover? (the daytons don't have them).

[jblsound]

Has anyone used the Dayton pre-assembled xovers? Parts Express sells them. Would refurbishing the old ones or building my own have any advantages over the Daytons? Are Lpads needed in a fresh xover? (the daytons don't have them).

The pre-made XOs need to have the same values as the JBL schematic. And as you're rebuilding/replacing theXO might as well replace the Lpads.

[midlife]

The pre-made XOs need to have the same values as the JBL schematic. And as you're rebuilding/replacing theXO might as well replace the Lpads.
Do you mean the same xover points, or the same electronic component values? If the aftermarket xovers cross the signals at close to the same hz and has similar efficiency and power capacity....shouldn't it work well? thanks.

[4313B]

Do you mean the same xover points, or the same electronic component values? If the aftermarket xovers cross the signals at close to the same hz and has similar efficiency and power capacity....shouldn't it work well? thanks.Nope.

I've posted the various voltage drives of vintage JBL's over the years and it is easy to see they don't follow any kind of textbook filter formulas.

[midlife]

Nope.

I've posted the various voltage drives of vintage JBL's over the years and it is easy to see they don't follow any kind of textbook filter formulas.
Sorry, this is my first attempt at this; so the "nope" in your reply refers to the first or last of my questions. More to the point, I am converting L88s to three ways. HF-033, MID-Le5, LF-123A. The original xovers have seen better days, and they were 2 ways. I cannot build my own xovers, not enough know how, so Daytons pre-assembled 3 ways are a poor choice? I think the hz cross is 750 and 5,500. Best options for a novice?? thanks.

[BMWCCA]

I cannot build my own xovers, not enough know how, so Daytons pre-assembled 3 ways are a poor choice? They're unlikely to produce a correct balance between the drivers and you'll have no way to adjust them.
Best options for a novice?? Have someone here build a pair for you, using maybe something like this N88 network schematic (1,500Hz and 6,000Hz): http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L88%20Plus%20ts.pdf

or, since you've swapped UHFs from what the L88-Plus would use, maybe the N150 (1000Hz, 4,000Hz) here (http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L150%20ts.pdf), or a combination, since that one at least uses the 033.

or just try to find one of the used pairs that could show up on Ebay. Regardless, you'll likely have spent more than a decent pair of L166s or L112s would have cost once you're done. If you just like the boxes you have, look for a pair of vinyl-covered 4412As and "decant" them. ;)

It might be a nice time to consider the Econo-wave, too!

:dont-know

[midlife]

I got the L88s cheap and they are super clean, except for toasted xovers. I would like to do a take off on the 88plus to 3ways, and already had the 033s. Your link to the L150s, I assume, is a recommendation of the 150 xovers. I have been watching ebay and those xovers don't pop up alot. I do see some L36 electronics that seem to be rather close to what I believe I would need. Have any other recommendations? And who would build what I need? And yes I did research the econowave, wish I was but I'm not quite ready for that. thanks.

[Wagner]

10 watts or 12? 12 is slightly better, but essentially the same thing... any audio grade non-inductive resistor will work. These Mills resistors are top drawer. There is no polarity issue with any audio grade cap... these are all sufficient. Use a Dayton cap, they are good enough and inexpensive. Inductors have no polarity. Use any air core inductor... larger gauge wire has lower resistance. Your system will have the correct polarity if you follow the schematic.

As for a 15watt L-pad? Don't cheap out here... use at least a 50 watter... not that the power requirement is needed.


Widget

The 50 watters from Parts Express are too large if he wants stock hole spacing. The one that resembles an old Aetna-Pollack is nearly 2"s in diameter and the square one that reminds you of Alps is too large as well, IF, like I say, he wants factory spacing.
Good luck,
Thomas

[Wagner]

I got the L88s cheap and they are super clean, except for toasted xovers. I would like to do a take off on the 88plus to 3ways, and already had the 033s. Your link to the L150s, I assume, is a recommendation of the 150 xovers. I have been watching ebay and those xovers don't pop up alot. I do see some L36 electronics that seem to be rather close to what I believe I would need. Have any other recommendations? And who would build what I need? And yes I did research the econowave, wish I was but I'm not quite ready for that. thanks.


I have to know; how did someone "melt" and "toast" the networks in (2) boxes but the drivers all escaped untouched?

Just curious,
Thomas

[Wagner]

?
Thomas

[Wagner]

Sorry, this is my first attempt at this; so the "nope" in your reply refers to the first or last of my questions. More to the point, I am converting L88s to three ways. HF-033, MID-Le5, LF-123A. The original xovers have seen better days, and they were 2 ways. I cannot build my own xovers, not enough know how, so Daytons pre-assembled 3 ways are a poor choice? I think the hz cross is 750 and 5,500. Best options for a novice?? thanks.


If you can hook the speaker wires up correctly from your amp to your speakers (in phase) and have the mechanical ability to tie your shoes, you can construct and L100 network + an inductor.
Just go where the schematic takes you, as others have suggested.

Good luck,
Thomas

[BMWCCA]

"vinyl-covered 4412As"?Have you seen them any other way? ;)


LX22, L20T, L1, L26, L80T, L96, L5, L112, 4412A, L7, L150A, 030, 4345-BA

[midlife]

I have to know; how did someone "melt" and "toast" the networks in (2) boxes but the drivers all escaped untouched?

Just curious,
Thomas
I got the 88s and they are clean as a whistle, hooked them up and they sound like they are wrapped in a blanket. And they also need way more volume than my other speakers. So I remove the woofers to discover the xovers which are contained in a cardboard wax filled tube to have most of the wax melted out of them and puddled on the cabinet floor. I am making some assumptions here (yes I've heard about assumptions) and that is the xovers have some problems. So if I am going to take on my first speaker project why not add a Le5s, change the HFs to 033s and put in a 3way xover? And of course I didn't ohm the 123s but I will. Looking for a simple xover solution, that works, and doesn't give a novice too much grief...

[midlife]

I got the 88s and they are clean as a whistle, hooked them up and they sound like they are wrapped in a blanket. And they also need way more volume than my other speakers. So I remove the woofers to discover the xovers which are contained in a cardboard wax filled tube to have most of the wax melted out of them and puddled on the cabinet floor. I am making some assumptions here (yes I've heard about assumptions) and that is the xovers have some problems. So if I am going to take on my first speaker project why not add a Le5s, change the HFs to 033s and put in a 3way xover? And of course I didn't ohm the 123s but I will. Looking for a simple xover solution, that works, and doesn't give a novice too much grief...
Yep, thats my story and I'm stickin' to it....Looking for an effective xover, that works and doesn't give a novice too much grief. thanks.

[Zilch]

I don't get this.

You're converting them to pseudo-L100s.

There's four caps and two L-pads required.

[Just do it.... :) ]

[midlife]

I don't get this.

You're converting them to pseudo-L100s.

There's four caps and two L-pads required.

[Just do it.... :) ]
I know how to listen to speakers not very experienced in their repair...but enough said, I'll build the xovers myself. :o:

[Zilch]

I don't know what to say. You've done a change-up on us here, going from rebuilding existing L-88 crossovers to converting them to L-100s with "wrong" (but maybe better, actually,) tweeters. If they're not L-88 Plus, I have to question whether the components are even going to fit in there.

Post a pic of your front baffles. Do they look like mine?

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=18146&stc=1&d=1157248542

Also, what is the DC resistance of each of your woofers?

What's a "Plus" look like after conversion?

[midlife]

I don't know what to say. You've done a change-up on us here, going from rebuilding existing L-88 crossovers to converting them to L-100s with "wrong" (but maybe better, actually,) tweeters. If they're not L-88 Plus, I have to question whether the components are even going to fit in there.

Post a pic of your front baffles. Do they look like mine?

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=18146&stc=1&d=1157248542

Also, what is the DC resistance of each of your woofers?

What's a "Plus" look like after conversion?
The baffles I have are what you have pictured. I intend to remove the existing port and tweeter partial baffle and install one that fits across the entire available space (left to right), and then cut the neccessary holes for HF and Mid speakers, in a mirror image configuration. Then install a rear firing bass tube on the back wall. All of this I can handle, it was the crossover that I knew I would need help with. DCR values; 123a-6.3, 033-4.8, the Le5s I do not have yet. This is something I want to do, not something that has to be done.

[Mr. Widget]

.

[midlife]

.
Yes, exactly like that, just 033 tweets and I'm guessing this box now uses a rear bass port. :applaud:

[Mr. Widget]

.

[midlife]

Yep, more like that. Where's the base port and Lpads?

[Zilch]

Yep, more like that. Where's the bass port and Lpads?Here, maybe?

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4412LR.pdf

What product(s) other than L150 used 033?

[4313B]

L40, L110, L150

[midlife]

Here, maybe?

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4412LR.pdf

What product(s) other than L150 used 033?
Will installing the bass tube on the cabinet "back wall" make any difference?

[Mr. Widget]

Will installing the bass tube on the cabinet "back wall" make any difference?Not if you keep the speaker out away from the wall.

As for Zilch's suggestion to follow the 4412 design, based on my photo, I don't think there is enough room with the large bezel on that 033.

Since you plan on using the 033, I would suggest you use the mid and HF sections of the N150 network (additional info below). I would also use the LE5-10 or it's equivalents see matrix below:

http://www.audioheritage.org/vbulletin/showthread.php?t=5706

http://www.audioheritage.org/vbulletin/showthread.php?t=1747


Widget

(There is no way I could have pulled together this information without the previous generous support of Giskard/Techbot. I only bring this up now because I don't usually mess around with these types of projects, but for anyone attempting them, there is a ton of available info that he has posted over the years on how to do it right. Obviously it does help if you know which questions to ask.)

[Zilch]

L40, L110, L150Thank you.

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L40%20ts.pdf

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L110%20ts.pdf



Will installing the bass tube on the cabinet "back wall" make any difference?Closed box is an option, actually.


As for Zilch's suggestion to follow the 4412 design, based on my photo, I don't think there is enough room with the large bezel on that 033.My intent was rather larger in scope; I'll think about how to express it, perhaps later today....