Adding a resistor for 4 ohm dash speakers=works!

[DavidN]

...
For the guy who swapped 2 ohm in the doors and 4 ohm in the dash... that would work. You basically cut the resistance in half through the whole system which keeps it in balance. However while cutting the resistance in half you’ve increased the loudness quite a bit which puts more stress on the stock amplifier in the radio. Since now the radio is putting out more watts that it wasn’t designed to do. I don’t recommend it as you can burn out the head unit prematurely...

I’m “that guy” and I kinda disagree with your statement. In fact I think the effect is quite the opposite. I decreased impedance throughout the whole system by 50%. So in my understanding the HU/amp has to work less hard to get the same sound output to the speakers than with the stock setup.
One observation that speaks for my “theory” here is, I exchanged the front door speakers first (rears a few weeks later) and when listening to music with the stock speakers in the rear and the JBL’s in the front, the front speakers were dominant and had significantly more output than the rears.
After swapping all the speakers, I never had to turn up the volume on my HU as high as with the stock speakers to achieve the same music output.

 

[blackbetty14]

I’m “that guy” and I kinda disagree with your statement. In fact I think the effect is quite the opposite. I decreased impedance throughout the whole system by 50%. So in my understanding the HU/amp has to work less hard to get the same sound output to the speakers than with the stock setup.
One observation that speaks for my “theory” here is, I exchanged the front door speakers first (rears a few weeks later) and when listening to music with the stock speakers in the rear and the JBL’s in the front, the front speakers were dominant and had significantly more output than the rears.
After swapping all the speakers, I never had to turn up the volume on my HU as high as with the stock speakers to achieve the same music output.

Sorry I was too lazy to go back and type your name in.

2 problems with what your saying....

1.) is that your stock amp in the radio is designed to run 4 ohm speakers. Your running at half the resistance and double the current. It’s like running a 4 ohm amp with 2ohm speakers when the amp isn’t designed for it.

2.) What you “think” isn’t fact and here’s is a brief description from Wiki. There’s a ton more info on the subject and how it could be worse or less worse depending on frequency and cone design yadda yadda. But essentially your asking your amp to work twice as hard. Dropping from 8ohm to 2 ohm is asking it to work 4x as hard.

From Wikipedia
Ohm’s law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship:

I (current; amps) = Voltage divided by Resistance (ohms)

At the risk of embarrassing myself, as resistance decreases the current required for a given voltage goes up.

As an example:
1 volt/8 ohms = 0.125 amps;
1 volt/6 ohms = 0.167 amps;
1 volt/4 ohms = 0.25 amps
1 volt/2 ohms = 0.5 amps

So, for a constant voltage, current requirements double going from 8 ohms to 4 ohms and quadruple going to 2 ohms.

 

[blackbetty14]

here is a quote from crutchfield which talks about what your doing and how it affects the amp in the radio.

Voice coil makes sound — amplifier pushes it
At the heart of every speaker and sub is a voice coil. This is the device that puts up the electrical resistance and performs the work. (The amplifier provides the power.) The resisting property of a coil is called its impedance and is measured in ohms. The lower a speaker's impedance, the easier it is for an amp to supply power to it. Problems arise when the amp's output meets very little resistance (low impedance) and it tries to put out more power than it was designed to produce. This leads to the amplifier overheating and then, hopefully, shutting down to protect itself from burning up.

 

[blackbetty14]

So since U’ve cut the resistance down by 1/2 your amp is supplying more power to the speaker as there is 1/2 the resistance. The problem is that you max out the amp and the range in which it was designed to work in thus affecting its longevity or the risk of burning out the amp and having to replace the entire radio.

You are correct that the speakers become easier to drive... but what I was saying is that the speaker isn’t the problem... it’s the stress put on the amp.


A good analogy could be an engine. Our hemis put out 400hp and everything is designed for that power rating. Increase the power to 800hp without increasing the engines ability to handle that power and ur put the whole short block at risk of destroying itself.

Your setup might work fine for a while or maybe not... just depends on a bunch of variables and when it decides to let go. I would prefer to match impediance to my system correctly like the rest of the world.

 

[DavidN]

Thanks for the explanation, @blackbetty14, really appreciate your detailed explanation(s)!

 

[2010 Infantry Vet]

I sill be running my JL audio 3.5" dash speakers off my radio, and amplifying the rockford components in the front and rear doors. Best solution i have found.

 

[Hemi395]

Read through this thread, my truck came with the 8.4A base audio system and the factory 3.5s have a 2.2uf 50v cap on one of the leads. I replaced them with Kicker KSC35s and put a 2.2uf 50v cap on each speaker. Sounds just like the factory speaker but obviously much clearer. Without those caps on them they were way too overpowering. I was originally going to go the resistor route but I didn't want to worry about them heating up. The caps don't heat up much at all.

Here's a pic of the factory base speaker with the cap what I put in it's place.

 

[JinxCanada]

Read through this thread, my truck came with the 8.4A base audio system and the factory 3.5s have a 2.2uf 50v cap on one of the leads. I replaced them with Kicker KSC35s and put a 2.2uf 50v cap on each speaker. Sounds just like the factory speaker but obviously much clearer. Without those caps on them they were way too overpowering. I was originally going to go the resistor route but I didn't want to worry about them heating up. The caps don't heat up much at all.

Here's a pic of the factory base speaker with the cap what I put in it's place.

if the 10w 4ohm resistors I have (not installed yet) don't work well or get hot then I might go this route as well. It's either that...or install a 4 or 6 channel amp and redo the whole system. as it stands now I'm still much happier with the speakers running on the head unit without amplification compared to the stock speakers. much happier with the sound. once I have the door panel rattle under control i'll be able to turn the bass back up and enjoy them even more....and if the resistor works as I expect then the 3.5" speakers on the dash won't be so in my face and overwhelming.

 

[blackbetty14]

Thanks for the explanation, @blackbetty14, really appreciate your detailed explanation(s)!

No problem! Hope it helps others as well.

 

[blackbetty14]

if the 10w 4ohm resistors I have (not installed yet) don't work well or get hot then I might go this route as well. It's either that...or install a 4 or 6 channel amp and redo the whole system. as it stands now I'm still much happier with the speakers running on the head unit without amplification compared to the stock speakers. much happier with the sound. once I have the door panel rattle under control i'll be able to turn the bass back up and enjoy them even more....and if the resistor works as I expect then the 3.5" speakers on the dash won't be so in my face and overwhelming.

They will work also I wouldn’t recommend turning up the bass with the stock location door speakers. Your better off doing a rear sub under one of the seats. The doors are too much of a PITA with sound deadoning and sealing and crap. Plus Ull get more bass out of even a single 8” or 10” over cranking up the 4 6x9s.

 

[JinxCanada]

They will work also I wouldn’t recommend turning up the bass with the stock location door speakers. Your better off doing a rear sub under one of the seats. The doors are too much of a PITA with sound deadoning and sealing and crap. Plus Ull get more bass out of even a single 8” or 10” over cranking up the 4 6x9s.

I am waiting for the weather to break...I have dual 10" Alpine Type S subs in a fibreglass Atrend box for under the rear seats matched with a 1200 watt RMS Pioneer GM-D9601 amplifier that will be running both at 1ohm to fill in the low end. I'm DYING to put them in...but we just keep getting hit with snow storms and freezing weather. My garage is filled with crap so there's no way fo rme to get my truck in there to do the work.

so...you think I should leave the bass setting low on the head unit and then just boost the bass signal in the amplifier/bass knob that came with the amp for the subs?

 

[blackbetty14]

I am waiting for the weather to break...I have dual 10" Alpine Type S subs in a fibreglass Atrend box for under the rear seats matched with a 1200 watt RMS Pioneer GM-D9601 amplifier that will be running both at 1ohm to fill in the low end. I'm DYING to put them in...but we just keep getting hit with snow storms and freezing weather. My garage is filled with crap so there's no way fo rme to get my truck in there to do the work.

so...you think I should leave the bass setting low on the head unit and then just boost the bass signal in the amplifier/bass knob that came with the amp for the subs?

Ull have to play with the settings but u will more than likely not have the bass cranked up that much with dual 10s and 1200w rms. I had a single 12” shallow pioneer with a 1400w or 340rms 4ohm amp and I ran it at 0 bass on the headunit. My current 18 I’ve upgraded the sub to the pioneer shallow and the rear doors and dash to JBL and I have the bass at 0 as well. The 8” hits cleaner than the 12 did but of course doesn’t have the level of bass with only 150w rms. But it rounds out the system enough for me to be ok with it and it’s louder and cleaner than the stock sub which was in the car for 3 days lol. I would swap it out for the 12” but I have the fold flat floors so my box won’t fit. But like I said it’s actually enough for me at the moment. It’s also stupid cold here and the freezing temps doesn’t make me wanna tear into the truck anymore lol.

When you install the subs your going to have to set the amp up correctly and set gain and headunit volume for no distortion and then you can play with the bass boost if you have the ability. But you should be impressed with the dual 10s and door rattles should be a thing of the past.

 

[JinxCanada]

Well I just wired in my 10w 4ohm resistors...and VOILA!!! my 3.5" Kicker CS speakers in the dash are back in line and sounding MUCH better!!!

 

[blackbetty14]

Told ya

 

[magician]

Read through this thread, my truck came with the 8.4A base audio system and the factory 3.5s have a 2.2uf 50v cap on one of the leads. I replaced them with Kicker KSC35s and put a 2.2uf 50v cap on each speaker. Sounds just like the factory speaker but obviously much clearer. Without those caps on them they were way too overpowering. I was originally going to go the resistor route but I didn't want to worry about them heating up. The caps don't heat up much at all.

Here's a pic of the factory base speaker with the cap what I put in it's place.

That's more in line with what should work best with the dash speakers and is in fact what the factory speakers have.

 

[JinxCanada]

The dash speakers are still somewhat bright...but much more in line with the rest of the system now.

 

[78Staff]

I found these, they are actually 1% offset which is great, but lack the ceramic glue/casing. Not sure how much heat a 10w resistor is really going to put out, but I'll probably just go with the ceramic 5% offset regardless.

https://www.ebay.com/itm/2-Vishay-D...340222?hash=item4b4a6f11be:g:RqUAAOSwySVZ8YFB

https://www.ebay.com/itm/2Pcs-Wirew...4b:m:m9VMsaA4wzjbtV9HbCq7Jow&var=641128389083

 

[PowrRam]

People need to remember this resistor mod is for the stock 6 speaker system, NOT the 9 speaker Alpine system.

If you think your replacement dash speakers are too bright and are overpowering the front door speakers, here's a simple test to try. (With the vehicle parked.) Play some music fairly loud. While it's playing duck your head a bit, at least below the top edge of the dashboard. Essentially you are somewhat neutralizing the prominence of the dash speakers. You should notice more bass and fuller sound coming from the front door speakers. The song instantly sounds better. I'm hoping when the resistors are installed they will bring the front door speakers more to the forefront.


Ordered these yesterday:

https://www.digikey.com/product-detail/en/yageo/SQP10AJB-3R9/3.9W-10-ND/18725

$.63 each, shipping was $3.95 via US Mail first class.

I forgot to buy heat shrinkable tubing. I could have gotten 6 feet for about a dollar from digikey.com. It's available locally but it's $3.99 for a dozen pieces about 3 inches long.

I also ordered another set of Metra wiring adapters for the dash speakers. The Metra 71-039C adapter for the dash speakers is no longer available. Apparently the adapter to get now is the Metra 72-7902.

I read through the whole thread. A couple of things. A 4 ohm, 20 watt resistor will dissipate heat better than a 4 ohm, 10 watt resistor. Either resistor will have the same effect on the sound level, after all they are both 4 ohm resistors. But the 20 watt is going to be physically larger and able to take away more heat. A wirewound resistor will dissipate heat better than a ceramic, molded resistor. Some resistors are wirewound and then encased in ceramic (like the one at the link I provided).

Once I get my resistors installed but before I put the dash grills back in place I will crank some tunes and see how hot the resistor gets.

 

[firebuff17]

How do you take the grill out/off from the standard 6 speaker dash speakers?

 

[PowrRam]

How do you take the grill out/off from the standard 6 speaker dash speakers?

I've got a plastic interior trim pry tool made for this purpose. However, a thin bladed screwdriver with the tip covered in masking tape (so as not to scratch the dash) would probably work. Any thin piece of plastic that will give you leverage should do as well. The tip of the cover piece that fits on the end of a Bic pen might work.