# JL HD-RLC mod question



## tophatjimmy (Dec 16, 2005)

So we've had some complaints at our store about how the HD-RLC works with the JL Audio HD and XD amps. Specifically that all the adjustment is in the last 1/4 turn.

According to JL, this is due to the knob having to play a dual purpose role; one is as a sub control on the amps, the other is as a volume control on the CL-RLC.

What would be the best way to determine what kind of potentiometer is being used in the HD-RLC, and is there an alternative pot that could be swapped that would allow a more "even" sweep for bass adjustment?


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## thehatedguy (May 4, 2007)

Probably first need to see if it is a linear or audio taper pot.

But I have the same complaint...it's either on or off it seems.


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## t3sn4f2 (Jan 3, 2007)

The rlc uses a potentiometer's resistance value or a digital encoder to control a digitally controlled solid state potentiometer. 

If it's considered a " master volume" pot, then it should be LOG (ie master volume type) not linear. You can tell if it's linear if it get really loud right away and then not so much as you turn the knob further.

In order for you to fine tune within a given range there would have to be preprogrammed detent values. I doubt it was implemented and just not being used. My guess is there was a fixed number of increments and they are all being used.

http://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/98476-circuit-details-how-jl-hd-amps-do-master-volume-control.html


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## Tommys (Jul 12, 2016)

tophatjimmy said:


> So we've had some complaints at our store about how the HD-RLC works with the JL Audio HD and XD amps. Specifically that all the adjustment is in the last 1/4 turn.


Did anyone ever get anywhere with this? I don't suppose JL made any alteration since?

I was about to order one of these, but not if the usable range is small and adjustments are much too sensitive.


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## What? (Jun 5, 2008)

JL did change how the knob works. I would contact tech for more info.


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## t3sn4f2 (Jan 3, 2007)

The change was for the xd line. I'm pretty sure they never change the HD since the change is not on the knob POT but the amps internal circuitry.


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