Let’s Talk Speaker Impedance!

[KP Texan]

Bottom line, has the stock 4Runner speaker impedance caused issues for any of you running an aftermarket headunit?

Was thinking about this last night because I’m about to drop a Kenwood DMX905S in my dash, and will not be changing speakers for a bit.

The 4Runner stock configuration consists of two 4 ohm speakers in the front which are wired in parallel and gives a 2 ohm total load on each channel. This is below what any aftermarket receivers recommend, and could potentially overheat the internal amp.

Alternatively, the rear speakers are two 4 ohm speakers wired in series which give an 8 ohm total load for each channel. This is within aftermarket receiver specs even though it allows less output.

I’m wondering if it might be best to do a wiring change up front at the dash speakers. I have a 4 pin aftermarket harness to connect there, and by looking at the wiring diagrams I think this could be switched over to an 8 ohm load fairly easily by running the speakers in series.

Then when I do go to aftermarket speakers, I can deliberately chose low impedance models which could potentially give about a 6ohm total load on each channel.

Has anyone dealt with this? Thanks for any input!

 

[Superjet]

I see you have a Limited, are you bypassing the JBL amplifier?

 

[KP Texan]

I have the standard navigation without JBL, so no amp to contend with.

 

[Uncle Snake]

Crutchfield + Focal woof's and tweets. plug and play. You may loose a few db overall but the sound quality will more than make up for it. The shittier it sounds the louder you'll play it. 35yrs of car audio experience including competing. Stock system blows in '19 SR5p. Also, fading the sound forward 3/4 of the way will clean up the sound a fair amount if you're not ready to spend $$$$.

 

[KP Texan]

Crutchfield + Focal woof's and tweets. plug and play. You may loose a few db overall but the sound quality will more than make up for it. The shittier it sounds the louder you'll play it. 35yrs of car audio experience including competing. Stock system blows in '19 SR5p. Also, fading the sound forward 3/4 of the way will clean up the sound a fair amount if you're not ready to spend $$$$.

Did you even read my post, haha?

Anyway, back to impedance, I guess it’s not an issue for anybody’s aftermarket head unit? I can only assume the stock one is designed to handle a 2 ohm load on the front channels and an 8 ohm load on the rear. That being said, I don’t see how this dramatic of a mismatch would be a good thing. I would definitely bring the soundstage forward, but couldn’t I just accomplish this with fade?

 

[4Rums]

If you look up the specs of that radio it says 4-8 ohm speaker impedance. You will run the risk of frying it at 2 ohms.

 

[KP Texan]

If you look up the specs of that radio it says 4-8 ohm speaker impedance. You will run the risk of frying it at 2 ohms.

Almost every aftermarket radio is rated for 4-8 ohms as far as I can tell, yet I never hear mention of guys having problems on here with it.

That being said, I still think I might change the front speaker set over to series configuration for an 8 ohm load though.

 

[Superjet]

Changing the fronts to series would pass the crossover from the dash speaker onto the door speakers which you do not want.

 

[KP Texan]

Changing the fronts to series would pass the crossover from the dash speaker onto the door speakers which you do not want.

Very true... so I would have to use aftermarket fronts to get around that and still wouldn’t be able to use bass blockers on those little speakers.

What’s the solution then aside from going to an external amp? Is there no decent way to just use an aftermarket headunit in the 4Runner?

 

[4Rums]

Almost every aftermarket radio is rated for 4-8 ohms as far as I can tell, yet I never hear mention of guys having problems on here with it.

That being said, I still think I might change the front speaker set over to series configuration for an 8 ohm load though.

When you increase the volume, you are increasing the voltage across the speaker leads of the built-in amplifier. By Ohms Law, current (amperes) is inversely proportional to the resistance/impedance. So for a given voltage, the lower the impedance, the higher the current that said voltage will generate. As you increase the voltage (via the volume knob) on a lower that rated load, higher than designed for current will be generated. When too much current is generated, the amp will either go into protect mode, blow the fuse, overheat and fry, become unstable, or it wasn't simply tested for the lower load.

 

[KP Texan]

When you increase the volume, you are increasing the voltage across the speaker leads of the built-in amplifier. By Ohms Law, current (amperes) is inversely proportional to the resistance/impedance. So for a given voltage, the lower the impedance, the higher the current that said voltage will generate. As you increase the voltage (via the volume knob) on a lower that rated load, higher than designed for current will be generated. When too much current is generated, the amp will either go into protect mode, blow the fuse, overheat and fry, become unstable, or it wasn't simply tested for the lower load.

I understand basic circuits and know this quite well. That’s why I’m raising the question in the first place. I know tons of guys here have installed aftermarket headunits in their 4Runners, so I’m asking why it isn’t a prominent issue.

 

[Superjet]

Very true... so I would have to use aftermarket fronts to get around that and still wouldn’t be able to use bass blockers on those little speakers.

What’s the solution then aside from going to an external amp? Is there no decent way to just use an aftermarket headunit in the 4Runner?

Replacement speakers will still have a cap on them, you do not want them to play bass frequencies or you'll damage them.

I think you are over thinking this too much. Just install it and I doubt you'll have issues. If you do it will just put the deck into protect if it starts to overheat. Also keep in mind that the crossover on the dash speaker will also add resistance.

I would leave the wiring alone on fronts, disconnect rear tailgate speakers and jumper the wires that were leading to them bring the rear channel to 4ohm. Leave them in place if you like to tailgate (party mode).

 

[KP Texan]

Replacement speakers will still have a cap on them, you do not want them to play bass frequencies or you'll damage them.

I think you are over thinking this too much. Just install it and I doubt you'll have issues. If you do it will just put the deck into protect if it starts to overheat. Also keep in mind that the crossover on the dash speaker will also add resistance.

I would leave the wiring alone on fronts, disconnect rear tailgate speakers and jumper the wires that were leading to them bring the rear channel to 4ohm. Leave them in place if you like to tailgate (party mode).

Thank you; this is pretty much the straightforward type of answer I was looking for. I tend to overthink things like this.

 

[Uncle Snake]

Did you even read my post, haha?

Anyway, back to impedance, I guess it’s not an issue for anybody’s aftermarket head unit? I can only assume the stock one is designed to handle a 2 ohm load on the front channels and an 8 ohm load on the rear. That being said, I don’t see how this dramatic of a mismatch would be a good thing. I would definitely bring the soundstage forward, but couldn’t I just accomplish this with fade?

Let's try again. Upgrade the head unit all you want, with the tweeters in your dash and the shitty 6x9's in the front doors it will never get much better. It's just that simple. If you're looking for head unit features have at. If it's sound quality you're after you are just treading water......

Impedance wise you'll lose 3db for every time you double the impedance. Best of luck with this. An amp with a 4ohm impedance minimum will most often work with 2 ohm drivers until it overheats and goes into protection. Then it'll work again 19 minutes later.....

 

[Superjet]

Simply replacing the head unit will make a difference. The OEM has crossovers and bass roll off to avoid blowing the speakers and having warranty work done. The radio he is getting also has way more features to tune the system. Replacing the deck is a great starting point.

 

[4Rums]

Let's try again. Upgrade the head unit all you want, with the tweeters in your dash and the shitty 6x9's in the front doors it will never get much better. It's just that simple.

The OEM has crossovers and bass roll off to avoid blowing the speakers and having warranty work done. The radio he is getting also has way more features to tune the system.

 

[KP Texan]

As mentioned in my first post, I intend on replacing the speakers eventually. This still does not solve the impedance issue, and may make it worse given that many aftermarket speakers are less than 4 ohms.

The only other thing I could possibly do to solve this is to install a separate 2-ohm stable amp. I’d rather not go this route since car audio is not nearly the priority that it once was to me. I even used to design my own enclosures with WinISD, but I’m done with that stage of my life.

I simply want something that sounds decent and has CarPlay, but I don’t want to deal with adding a full complement of audio equipment.

 

[KP Texan]

OK, just as an update, I've decided to go with a compact amp under the driver's seat to fix this little issue. Those stock speakers might not be too happy before I get them changed out, haha.

 

[keyser_soze]

I've decided to go with a compact amp under the driver's seat to fix this little issue.

This is the best option, most headunits are not going to have enough power to properly drive a nice set of speakers at high volume. I suggest wiring your doors and tweeters separately, if you have a nice set of components you will be able to bi amp them and have better control.

 

[dangitzin]

The 4Runner stock configuration consists of two 4 ohm speakers in the front which are wired in parallel and gives a 2 ohm total load on each channel. This is below what any aftermarket receivers recommend, and could potentially overheat the internal amp.

Alternatively, the rear speakers are two 4 ohm speakers wired in series which give an 8 ohm total load for each channel. This is within aftermarket receiver specs even though it allows less output.

The fronts are actually 4 ohm and the rears are 8 ohm. I checked these when I hooked up a 5-channel amp because I wasn’t sure what the impedance the rears were since there are 4.

Anyways you’re fine installing your aftermarket hu.