PowrRam
Senior Member
- Joined
- May 12, 2018
- Posts
- 767
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- Location
- Minneapolis
- Ram Year
- 2018 Big Horn
- Engine
- 3.6L V6
Installation of Resistors on 4 ohm Dash Speakers
This Modification Applies To Non-Alpine Dash Speakers
The Setup
I have a 2018 Ram 1500 with the stock 6 speaker stereo system and 8.4 Uconnect. I replaced the stock dash speakers with Polk DB351’s. These are 4 ohm speakers; the stock 3.5” speakers were 8 ohm speakers.
The Problem
The result is the Polk dash speakers play louder than designed and tend to overpower the 6”X9” front door speakers. (I have replaced the front door speakers with Pioneer TS-A6966R) Because the dash speakers are now 4 ohms instead of 8 ohms they draw more current and play louder. They seem excessively bright as well. Others have said their Kicker 3.5" speakers are too bright. I suspect any speaker of less than 8 ohms will seem louder and "take over" the sound in the front half of the vehicle.
The Solution
Short term solution was to severely turn down the treble on the stereo’s equalizer. I also cranked up the bass setting and tapped the fader one spot toward the rear speakers. This made the dash speakers less prominent and made the songs played from my USB stick sound acceptable but it was not a long term solution.
Long term solution as described by some here has been to wire a 4 ohm resistor into the positive lead of the aftermarket dash speakers to bring the resistance the 8.4 Uconnect “sees” from the dash speakers back up to 8 ohms. This will tamp down the loudness of my Polk dash speakers, reduce the brightness, and hopefully get my equalizer settings back to some semblance of normalcy.
The Parts
To complete the project I bought 2 resistors, 2 Metra wiring adapters and some heat shrink tubing.
I purchased two 3.9 ohm resistors rated at 10 watts from DigiKey. The cost was $.63 each. Shipping was by US first class mail and was $3.95.
https://www.digikey.com/product-detail/en/yageo/SQP10AJB-3R9/3.9W-10-ND/18725
The Polk 3.5” speakers had been installed in my 2015 Big Horn so I already had the Metra wiring adapters, part# 71-039C. I decided I might as well get another set to install the resistors. Then I would have one set with resistors, one set without resistors. However, the 71-039C are no longer available. The replacement Metra is part# 72-7902. These are identical to the 71-039C. I have read somewhere about “reversing the polarity” of these 72-7902 adapters, but no need to do this since they are the exact same part as the 71-039C.
I bought them here:
https://www.thewireszone.com/p-9366...s-for-select-chrysler-dodge-hyundai-pair.aspx
Less expensive than Crutchfield and a comment in the reviews from 2 months ago said, “worked perfect for my 2014 Ram 1500.” I was sold.
I bought 1/8” diameter heat shrink tubing. I ended up buying a package of ten 12” long sections for $2.50 from an electronics surplus store in town. I subsequently found that Microcenter has 3 foot lengths for $1.29. I ended up using a total of about 3 inches of this tubing.
The Procedure
I gathered the tools I’d need—small wire cutter, small needle-nose pliers, wire stripper, soldering iron, and solder.
1. Cut a section out of the positive lead of the Metra adapter. (The positive lead is the white wire.) I decided to cut a section a tad bit shorter than the equivalent length of the resistor. That way, the finished assembly would have both wires the same length. Using the wire cutter I made the cut about 1” from the connector that hooks into the Ram wiring harness.
2. Strip about 3/8” of insulation off the positive lead wire. I used the small needle-nose pliers to clamp onto the wire about midway between the (now) small section of the positive wire in order to securely hold onto the wire. If you try to strip the insulation by holding onto the connector itself you might rip the wire out of the connector. I then used the wire stripper to strip off the insulation. Twist the strands of wire tightly together.
Place a ¾” section of heat shrink tubing onto the positive wire and slide it up to butt up against the connector.
3. Using the small needle-nose pliers form a “hook” in the exposed copper wire. Using the soldering iron and a small amount of solder, tin the wire hook. You will want to use the small needle-nose pliers to hold onto the wire just ahead of the heat shrink tubing. Doing this provides stability and also the pliers acts as a heat sink so the heat shrink tubing doesn’t shrink from the heat imparted from the soldering gun.
4. Cut most of the resistor lead off, leaving about 3/8” length remaining. Tin the resistor lead with solder. Use the needle-nose plier to form a hook in the resistor lead. Interlock the hook in the resistor lead into the hook in the wire adapter.
5. Use the soldering iron to solder the hooks together. Use minimum amount of solder as the heat shrink tubing will need to slide over the solder joint. Turn the assembly over and make sure you have a solid solder joint. If not, touch it up with the soldering iron and a tad more solder.
6. Gently slide the heat shrink tubing over the soldered joint. I had to wiggle it a little bit to get it to slide over the joint.
7. Use a lighter to shrink the heat shrink tubing into place. Hold the lighter’s flame about 3 inches below the heat shrink tubing. Twirl the wire on its axis to evenly heat the tubing until it shrinks tightly around the solder joint.
(Continued in next post)
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