Installing a 3-prong attinuator?

**cradeldorf** · November 26th, 2012, 07:03 PM

Originally Posted by gortnipper

Yes, that makes more sense to me now. Sorry, I can be slow!

The reason I am asking this is because I have been mucking about with a L-pad wired onto (but after) my crossover as both a variable resistor and an L-pad in order to tune the GPA-IIIs horn to the cab/room better. I found that by using it as series-R instead of an L-pad, the sound was slightly better - a bit more "clear" is I guess is how I would characterize it, and I am trying to better understand why.

I might have to try that.

**gortnipper** · November 26th, 2012, 07:27 PM

Originally Posted by Old Guy

I just resign myself to some things I won't ever figure out...such as Redheads.

Dude - I am in the same boat. I have my own Redhead as well...

**gortnipper** · November 26th, 2012, 07:30 PM

Originally Posted by cradeldorf

I might have to try that.

I just used an alligator clip on the first leg - it makes it real easy to A/B.

**cradeldorf** · November 26th, 2012, 09:11 PM

If you think your hard at understanding... If you could regale me as to which of the 3 prongs your using I would be most appreciative. Are you leaving out the ground wire then? Which wire goes where? And if done that way shouldn't it be before the crossover?

**Alien_Shore** · November 26th, 2012, 10:44 PM

Lpads have two wirewound resistors in them. As OG said, one is in series with the input, while the other is parallel to ground.
If you use them as rheostats (as shown in the M19 examples above), the two rheostats act differently, so you can get different functions from them if you use pins 1/2 or 2/3. If you use the 1/2 rheostat, the resistance range is 0 - infinity (well, not really, but the min setting is no impedance, and the max setting is infinity - there's a "usable" maximum resistance in there before it goes to infinite resistance, depending on the wire that's in there, but usually around 3x the nominal rating of the LPad if I remember correctly). If you connect to the 2/3 rheostat, it acts quite differently. As OG said, the parallel resistance is reversed. So at the "min" setting, the connection across 2-3, will see the rated resistance value of the LPad (typically 8 ohms). As you crank up the setting, parallel resistance will move towards zero.

So put another way:

PINS - - - MIN - - - MAX
1/2 - - - zero - - - infinity
2/3 - - - 8 ohms - - zero

**cradeldorf** · November 27th, 2012, 02:57 AM

Originally Posted by Alien_Shore

Lpads have two wirewound resistors in them. As OG said, one is in series with the input, while the other is parallel to ground.
If you use them as rheostats (as shown in the M19 examples above), the two rheostats act differently, so you can get different functions from them if you use pins 1/2 or 2/3. If you use the 1/2 rheostat, the resistance range is 0 - infinity (well, not really, but the min setting is no impedance, and the max setting is infinity - there's a "usable" maximum resistance in there before it goes to infinite resistance, depending on the wire that's in there, but usually around 3x the nominal rating of the LPad if I remember correctly). If you connect to the 2/3 rheostat, it acts quite differently. As OG said, the parallel resistance is reversed. So at the "min" setting, the connection across 2-3, will see the rated resistance value of the LPad (typically 8 ohms). As you crank up the setting, parallel resistance will move towards zero.

So put another way:

PINS - - - MIN - - - MAX
1/2 - - - zero - - - infinity
2/3 - - - 8 ohms - - zero

Okay, I get it now, That was an awesome description. Thanks Mike.

Also found this,
http://www.bcae1.com/lpad.htm

**Old Guy** · November 27th, 2012, 09:36 AM

Originally Posted by gortnipper

Dude - I am in the same boat. I have my own Redhead as well...

The jury is still out, Redheads are either God's gift to man, or the female half of the race's revenge for everything males have ever done.

**gortnipper** · November 27th, 2012, 03:48 PM

Originally Posted by Old Guy

The jury is still out, Redheads are either God's gift to man, or the female half of the race's revenge for everything males have ever done.

It is a paradox that they can be both within nano-seconds of each other...

**gortnipper** · November 27th, 2012, 03:56 PM

Originally Posted by cradeldorf

If you think your hard at understanding... If you could regale me as to which of the 3 prongs your using I would be most appreciative. Are you leaving out the ground wire then? Which wire goes where? And if done that way shouldn't it be before the crossover?

I wired mine 2/3 on the positive leg after the xo.