N 800 D Crossover Phasing ?

[Horn Savant]

I'm fixing a movie theater & the dialog speaker (A7) has an N 800 D that does not have input, LF & HF speaker polarities indicated . Since I'm phasing this to L & R spkrs as well as Subwoofers, I'd like to get the polarities correct , so does anyone have the correct data ?

I think this X/O was made in the days of L1-L2 spkr terminal designations on earlier drivers which complicates it more I suppose.

[bfish]

Figure 20 on the page linked below shows the wiring for N800D and drivers in an A7;

http://www.lansingheritage.org/image...ign/page11.jpg

If you can't determine the overall phase from this or comparison to the L/R units, some testing may be needed. Could be as simple as a flashlight battery pulse while watching the LF cone(s).

[Horn Savant]

Thanks for schematic , L1= Neg on woofer and Pos on Tweeter ? Correct ?

Positive driver phase yielding forward motion of cone/diaphragm ?

[bfish]

Thanks for schematic , L1= Neg on woofer and Pos on Tweeter ? Correct ?

You're welcome.

For practical purposes and your application, yes.

The L1/L2 standard had ALL diaphragm/cone assemblies moving in the same direction in relation to the pole plate with the same polarity on the same terminals. When you consider that the HF diaphragm is behind the pole plate, and the LF cone is in front of it, the reversal makes sense in an application where the pole plates are aligned (vertically) as in the A7.

[whitebroncoii]

An old tech letter for the A7 discusses proper phasing as matching frequency arrival at crossover. This matching is independent of polarity because aligning the voice-coil does not align phase when dealing with a horn (and both the LF and HF of the A7 are horns).

The method described has the installer connect the HF driver polarity to obtain the most "dip" in response at the crossover frequency. Then the HF horn is physically moved forward or backward to really get the most "dip". Now flip the HF polarity and you have aligned the A7 phase.

This can be accomplished a couple ways . . .

1. Pink Noise and a 1/3rd octave analyzer
2. Input 800Hz and measure/listen for lowest output

This phase issue occurs in most loudspeaker systems and you will find the HF polarity inverted to obtain the best phase response. Examine most Altec Lansing internal crossovers and you will find the "hot" wire for the HF driver is actually ground or "-".

Gary