Remote Level Controls
Hi folks,
And Happy Holidays to those who will be observing Rosh HaShanah... "Peace to you!"
About a month ago I decided that I needed to
'Upgrade' the amp stack that drives the subs in my 2012 Limited. There was nothing wrong with the two
JL Audio HD-750/1 mono-blocks that I was using, I just got "THE ITCH" that some of us get when we need to continue the
'Never-ending' build that you've started some time ago! I decided to replace the JL's with a pair of
'Alpine' PDX M-12 mono-blocks. I know that I'm not the only one here that's running a
'Stand alone' Subwoofer System e.g., a system that is not dependent on, or akin to the truck's oem audio system. It has it's own power source, EQ, X-overs and needs only an audio signal from the HU to operate.
Anyway, I was having a problem with the
'Remote Subwoofer level Control'. It's mounted in the near proximity of the driver-seat and controls the remotely located power amps via a R-11 phone cable. The RLC that I had on the JL amps worked just fine, and I had hoped that I could use that control knob on the two
M-12's. Unfortunately the rheostats (potentiaometers) aren't with-in the same resistance range to run the OP-amps. So after finding that out, I removed the JL RLC, found a new location for the new Alpine RLC (RUX Knob) and installed it, only to find that it didn't work right either! The bass would go from zero to FULL GAIN within the first quarter (1/4) turn of the knob and then begin decreasing volume as the half turn mark approached... I'm telling you this because some of this stuff, you won't find in any books or online, nor will most professional audio system installers be able to help you when you run into this trouble... "Ask me how I know!"
After scratching my head for a while and cussin' a little, I put on my tech hat and started approaching this from another prospective! Because I'm running twin mono-blocks, I can't just use a single phone cord between the control knob and the amps. I need to split the signal using a combination of short (pig-tail) phone lines, a
'Y' adapter and the 15' phone wire that came with the RLC. I had never tested the 15 footer by itself, just ran it into the spliter that I had used on the JL's. So next I did run the 15' line directly from the control into one amp, and it worked fine. Now this is where you have to look very closely at all those phone cords.
I noticed that looking down from the top (latch, reading left to right), the 15 footer uses it's pin-out as
YELLOW, GREEN, RED, BLACK... BUT... the other end gets reversed going into the amp because
NEITHER port is inverted (upside-down). So the amp's port corrects the pins so that the pin-out will still read
YELLOW, GREEN, RED, BLACK. If the port wasn't correcting, the amp would see
BLACK, RED, GREEN, YELLOW. But by me adding the spliter and those two RJ-11 pigtails (which were designed to reverse the pins), the amps were seeing the pin-out order backwards! So here's what to watch out for:
"NON-REVERSED" RJ-11"
Above is the one I'm calling a
"NON REVERSED" RJ-11 (or straight) because inverting one latch on the cord will make the pin-out order read
"Y, G, R, B" from left to right on
Both ends.
"REVERSED RJ-11"
Above is the one I'm calling a
"REVERSED RJ-11" because
NOT inverting
One latch will cause the pin-out order (scanning from L to R) to read
"Y, G, R, B" on one end, and
"B, R, G, Y" on the other.
So if you ever have trouble with a remote level control and everything seems to be wired correctly but it's not working as it should, check all of your phone cords; RJ-11's come reversed (Standard) and in non-reversed (straight) orders.
'Happy Woofering'! :lookout:
Cheers!