L Pad Polarity --help Me Please!

[charminator777]

Hi an AK member recently told me that i needed L PADS to attenuate my horns -big altec set up --realizing that my horns were way louder than my drivers i went ahead and ordered 2 of these contraptions from PARTS EXPRESS--part number 260-262
being a woman the first thing i noticed when they came was THERE IS NO KNOB!! ok i let that slide but now i am lookin at these little guys thinking NOW WHAT??
so -who is the L PAD expert in here?? there is a schematic on the side of the box but it does not help me one bit

for one thing there are no polarity markings on the units themselves -and of course i am thinking that i need to install these in line with my horn wires which i have TWO of but the L PADS have THREE terminals ! the schematic has numbers on it and includes AMP -
I AM LOST HERE PEOPLE AND I DO not want to blow any thing up today --lookin straight at these dealy boppers from left to right i have 3 terminals that can take soder or spade connectors-their approximate position like on a clock goin clockwise would be 11 12 and 1 oclock
so if you give me directions please refer to the terminals in that respect this will make it easier for me
i need to know exactly where they go and how to hook them up !!??
what i am hookin up is some big cabinets -ea has a 12 altec driver in them and an electrovoice crossover and the altec horns and their drivers

one more thing
i now have those altec bi flexes and i think i am goin to just keep em -long story -but they are 12 inchers and can only do about 20 watts -i do not over drive my systems -
i was thinkin of putting these guys eventually in some cabinets which i found at the flea market this weekend -they are some pretty big SEARS ROBUCK cabinets -about 3 feet tall and 14 inches wide and oh about 10 inches or more deep -i havent measured-they ea have one port at the bottom and a tweeter and a midrange-ah--i would of course rewire them including the terminals and get new and better tweeters and midranges for them
oh -they ea have a big fat 12 in em already--so only paid 6 bucks ea for these-the grills are bad but thats no prob
my question is -would that be a good enough enclosure for my bi flexes -they are pretty sturdily made
thank you very much
charmaine

[rek50]

I think it might work like this: The "Amp" wires are the two wires that go to the driver, from the crossover. Run the + wire to #1 and back to + on the driver (notice the dot/connection on the box schematic). Run the - wire to #3, and another wire from #2 to the - on the driver.

[JBL/NHT Fan]

An L-pad is a specialized potentiometer (fancy name for volume control) it's just a very low resistance usually high wattage pot (abbrev. for potentiometer) It's a resistance device, so has no real "polarity" If you're familiar with the schematic of a pot, the L-pad is the same.

It's a resistor with a moveable tap. On every one I've ever seen, the left and right terminals are the two ends of the fixed resistor, and the center is the wipe (moving contact) I would expect the amp positive to feed in one side and amp negative to feed the other. This gives an 8 ohm load to the amp and keeps it happy (I know it'll change when you connect the speaker, but I'm trying to keep this simple) The center terminal is the one that changes as you rotate the shaft. This will give you a volume control when you connect the spkr hot side to it. the spkr neg lead should connect back to whichever side of the pot has the amp neg lead.

[GordonW]

I just drew this up- here's a very basic L-pad wiring diagram. This should apply to any 3-pin L-pad.

Also, your Altec horn drivers should either have a RED and a BLACK terminal, or a terminal labelled "1" and a terminal labelled "2". If it's red or labelled "1", it's a positive (+) terminal, if it's black or labelled "2", it's a negative (-) terminal as far as the diagram below is concerned.

As far as positive and negative are concerned- as long as you keep polarity from the crossover to the speaker, it doesn't matter which way the L-pad is oriented vs. the negative and positive speaker wires. Of the two wires going to the horn driver from the crossover, just "arbitrarily" define one of them to be (+) and the other (-), and splice in the L-pad according to the diagram, making sure you maintain the SAME way on the input and output...

Gordon.

[JBL/NHT Fan]

Gordon drew exactly what I was trying to describe.

[GordonW]

Just noticed the second question... it depends on how big the Sears speaker cabinets are. Those Altec 12" drivers would need, I'd think, at least 2.5 cubic feet, so if the cabinet are 36x10x14 or close, then they should, at least in theory, work. You might find that blocking the port may improve the sound... these BiFlex drivers are sometimes "high-Q", which means they have a pronounced resonance peak... those drivers sometimes will get too "boomy" in a ported box, unless it's REALLY big (as in, 5 cubic feet, possibly more).

As for mids and tweeters... those Altec drivers are made to be run "close" to full-range, so you'd probably only need a tweeter to supplement them. Something that can do the treble range, from say 3000 Hz and up, should be a good complement. Just block off the existing tweeter hole, and put whatever new tweeter you find, into the MIDRANGE hole... that'll get it closer to the woofer, which will make it sound better at wider listening angles (when you're off to the side from the speaker).

Regards,
Gordon.

[DaWoofer]

Thanks for the diagram Gordon, Ive been wondering about that for a long time. I need new ones for my H-223 Jensen's. Im anxious to hear them in a proper cabinet. I will find out what all the fuss is about driver alignment, time, speed and all that since these have the radial tweet right in the center of the woofer. I have the cabinets all set to go, just a little more solder work and I can report on these old drivers.

[kcollins4]

Thanks for asking that question Charminator. I'm getting ready to replace some pots too, and I'm making hard copies of these responses. Good info for the electronics challenged Thanks to everyone

[charminator777]

ok you guys--thanx so much- i will run this by my son -ORION -he is helpin me out here--and he also talked to parts express
so hopefully this will all work then i can have those horns balanced and run the z9s and all the altecs in here
and thank you gordon for the schematic and the info on the cabinets -will be a while before i get to that but i will let you all know what happens
=-really appreciate all i learn here and the great comradery on this site with all yu vintage maniacs
-another vintage maniac
charmaine

[rek50]

Yes, Thanks Gordon, a picture IS worth more than a 1000 words.