Pot vs L pad

[ironlake]

What is the difference between a pot and an l pad. At times reading here the two seem to get interchanged as the same. My experience in hifi would call the original volume controls on ar speakers tweeters and mid range, pots. My understanding of an lpad used to be a volume control that was always the same impediance no mater what the setting is. Thanks for any help understanding.

[Carlspeak]

Have you read the AR3a restoration document. It goes into detail about the use of rheostats and L-pads, what the differences are and how you can install each during a restoration.

[ironlake]

Yes I read it but it does not tell what the difference is except show a diagram of a wiper swiping two coils of resistance instead of one So what does that do. I appears all the ar volume controls are pots and not l pads

[RoyC]

Yes I read it but it does not tell what the difference is except show a diagram of a wiper swiping two coils of resistance instead of one So what does that do. I appears all the ar volume controls are pots and not l pads

AR speaker level controls were pots (potentiometers). Modern speakers use L-pads, variable or fixed.

In reference to speaker systems....

They both attenuate drivers by varying series and parallel resistance. The potentiometer does it with one resistor, and the L-pad does it with two. They each have a diffferent overall affect on the system impedance due to the differing approaches to attenuation. An L-pad can also be referred to as "fixed", consisting of a simple series and parallel resistor in the crossover...not an outboard control device.

This thread in the the AK forum shows how difficult it can be to explain...Post #5 provides excellent illustrations.

http://www.audiokarm...ad.php?t=285530

Roy

[Pete B]

How an L-pad works, that AK thread has mostly incorrect posts:

http://www.bcae1.com/lpad.htm

[Pete B]

Does anyone know if a pair of PE 50W L-pads will fit in a stock 3a or 5 mounting positions?

If not, how about one 50W for the mid and one 15W for the tweeter?

The 50W is physically larger.

[JKent]

OK. While we're on the subject....

Here's the L-pad diagram from PE. Over to the left it says "To amplifier or crossover." So does it matter where the L-pad is placed? In other words, is it OK to go from amp to L-pad and then to the crossover and finally to the driver? Or must the L-pad be placed AFTER the xo?

Thanks.

[Pete B]

An Lpad should go between the crossover and the driver in this type of application.

The intent is to properly load the XO even when there is attenuation.

[JKent]

4 hours ago, Pete B said:

An Lpad should go between the crossover and the driver in this type of application.

Thanks, Pete

[ra.ra]

Attached are the dimensions for the three versions of L-pads that are commonly available thru electronics suppliers. The 50-watt is the octagonal device. These are basically 40, 50, and 60 mm in width.

[RoyC]

12 hours ago, Pete B said:

Does anyone know if a pair of PE 50W L-pads will fit in a stock 3a or 5 mounting positions?

If not, how about one 50W for the mid and one 15W for the tweeter?

The 50W is physically larger.

Hey Pete,

50 watt L-pads won't fit....not even close. Two 15 watt L-pads just fit next to each other.

Roy

[Pete B]

Thanks Roy