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/vbullet...read.php?t=278


Widget

[hjames]

Look at post #2 below:

http://www.audioheritage.org/vbullet...read.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/vbullet...read.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/crossov...itor-index.cfm

http://www.parts-express.com/wizards...AT&srchCat=196

http://www.parts-express.com/wizards...=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/Te...0Plus%20ts.pdf

or, since you've swapped UHFs from what the L88-Plus would use, maybe the N150 (1000Hz, 4,000Hz) here, 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