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AR-2ax Level Controls. Originals: 16 Ohm Rheostats. Replace with?????

Speaker Level Controls.

I am a big fan of level controls on speakers, and fully intend to keep them on the AR-2ax Speakers I just bought as a reaction to the discussion here

 

(this forum has cost me a heckofa lot of money over the last 2 years)!

...........................................

It seems the originals are 16 ohm rheostats, which vary current. ranging from +/- 15 ohms to +/- 7 ohms if this eBay listing is correct.

 

choices:

a. 16 ohm rheostats (2 contacts, control current) (clean original if salvageable) or new

b. 16 ohm potentiometer (3 contacts, control voltage)

c. L-Pads, like I just replaced in my main speakers with drivers from 1958.

I understand an advantage of L-Pads is that they always show the same impedance to the crossover. AR chose 16 ohm rheostats in the 60's, L-Pads existed, they did not use them. 

IF change to L-Pad, would you use 16 or 8 ohm L-Pads for these speakers?

Specs say: Minimum 8 ohms (not nominal)

thanks as always for your help

Elliott

elliottbnewcombjr
elliottbnewcombjr OP
5,388 posts
 

this shows original corroded rheostats

https://people.ohio.edu/postr/bapix/AR_2ax.htm

 

elliottbnewcombjr OP
5,388 posts
 

Crossovers

they are on a Masonite board inside the cabinet, look like these (not mine)

 

 

Oddly: The speakers were designed with 3 terminals and an external jumper, so that they could be used ’woofers only’ with the jumper removed.

Parts: Parts Express, $90. delivered

a. Four 16 ohm L-Pads (same as recently used for my main speakers)

b. Five Pack small knobs for 1/4" dia L-Pad Shafts

c. Two 6uf caps (use two x 3 uf parallel) for the midranges

d. Two 4uf caps for the tweeters

e. existing 1.88 mH Inductors

 

 

elliottbnewcombjr OP
5,388 posts
 

The new L-Pads were TOOOOO big. A pair cannot get close enough together for the shafts to fit thru the existing holes in the crossover board (1-3/4" c/c). Returned for full refund to Parts Express.

It turned out that my existing Level Controls needed very minor cleaning, good to go. Lucky, some are in terrible shape. Thus the new parts were quite inexpensive.

New capacitors, bullet connectors crimped on, duct seal from home depot, polyfil from walmart, done.

I put project photos here

 

audiokinesis
2,737 posts
 

"The new [16-ohm] L-Pads were TOOOOO big. The new L-Pads were TOOOOO big. A pair cannot get close enough together for the shafts to fit thru the existing holes in the crossover board (1-3/4" c/c). Returned for full refund to Parts Express."

One of their dual-8-ohm L-pads can be configured as a 16-ohm potentiometer, with a sufficiently small footprint.

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