L1/L2 VS. +/-

[mungkiman]

I am using University midrange drivers with Altec 511B horns in my Khorn project. The driver terminals are labeled L1 and L2, rather than + and -. Can someone tell me how to wire them properly? All help is appreciated. Thanks in advance,

Chris

[WMcD]

My immediate thought was that L1 is plus and L2 is minus. Then I realized I didn't have a single piece of paper to back that up.

All I can find is an old EV spec sheet showing woofers labeled as T1 being plu and T2 as being minus.

I'm pretty sure the above is correct.

Gil

[artto]

Briefly hook up a 1.5 volt flashlight battery to the speaker (C or D cell should be fine). If the speaker moves "out" (positive direction), then the positive battery terminal is connected to the positive speaker terminal.

Followup: sorry, I didn't realize you were talking about a compression driver. Might be kind of difficult to see the diaphram. But I'd say Gil's assumption is correct. L1=+ L2=- Try it. I doubt it will hurt anything.

[mungkiman]

Thanks to you both!

[WMcD]

It occurs to me that L might stand for "Lug" in the Altec vocablulary. In the EV vocabulary, T may stand for "terminal."

Yeah, the fact that this is a midrange driver makes it impossible to see the diaphragm.

I've not tried it, but let me suggest the following along the lines of the battery test.

It is pretty much univerally true (I believe) that when positive voltage is applied to the positive lead to the driver, the diaphragm moves toward the throat. It produces sudden increase in pressure at the throat (pipe end) of the driver.

You might be able to detect a positive accoustic pulse (actually a step funtion up). This will require placing the driver on it's butt end with the pipe end facing up. Then place a small piece of paper on the pipe end. I'll assume it is one inch or so in diameter and you cut a piece of paper the size to cover it. Maybe trace the circle with a quarter dollar coin.

Then apply the battery voltage and hold the voltage applied (plus on the battery to L1 and negative to L2, to thus cause the diaphragm to move forward. It might blow the piece of paper off.

If the battery polarity is reversed, the negative voltage step may suck the paper on tightly.

Again, I've not done it. Yet it seems a valid test you can do at home. It might require buying some allegator test leads at RS. I'm sure you can tinker together the wiring.

Gil

[Trey Cannon]

Gill has a good idea...BUT remember that a driver is an electric motor. It is ment to run with Alternating current not Direct current (like in a battery)

If you leave the battery connected to long, it will heat up the voice coil and can burn it out. The smaller the coil the more quickly this happens.

I suggest a small mod in the test. The setup is the same; only connect the battery in "Morris code" fashion. This will limit the time the coil has DC applied to it and should protect it from harm.

[djk]

The 1, 2, terminology refers to which wire goes into the magnetic field first.

On a woofer #1 is positive, on a compression driver it depends on the location of the phase plug and magnet. WE 594, Altec 802, 288, JBL 375, 175 type construction #1 is negative. On Atlas, University, EV(except the DH1, 1012) #1 is positive.