242 stock speaker wiring

[ChrisP]

I upgraded my stereo this winter. In the process I learned a few things about the stock wiring that I figured I should share. I found out that the rear channel is running the cockpit speakers and the swim step speakers and the front runs the bow speakers and the tower tweeters. Well anyone who has played with the fader would have figured this out but what you may not know is that the rear speakers are wired in series. Meaning they are drawing an 8 ohm load. I assume this is to protect the head unit which is not 2 ohm stable. Oddly enough the front channel is only drawing a 4 ohm load. I only figured this out after adding a set of speakers in the cockpit. I wired them up parallel with the fronts and before I removed the tweeters from the equation I pulled out the multimeter to verify the ohm load. It was at 2ohms. Not sure how the bow speakers and tower tweeters are wired to accomplish a 4 ohm load but it works for me. So I checked the rear channel and they were at 8 ohms. I rewired the rear speakers parallel, they are now at a 2 ohm load and are way loader off the same amp.

Anyway hope this is helpful for anyone planning to add an amp using the stock wiring.

 

[David Decker]

Thank you, @ChrisP - this info will help me. I'm about to add a Polk 5-channel amp and a sub. I would not have guessed that the speakers would be wired in series, but I guess it does make sense.
Since the tower tweeters are connected via a crossover (a high-pass filter that presumably blocks DC which your DMM may be using to measure resistance), this might explain your measurement of 4 ohms up front.
The DC resistance may be 4 ohms up front, but the impedance is a more complicated function involving the frequency of the signal.

I think I am going to pull new wires for the bow and cockpit speakers to connect to the new amp.

 

[BoaterGuy]

@ChrisP is your new HU 2ohm stable? If not, you risk sending voltage to the speaker coils and blowing them.

 

[David Decker]

@ChrisP I'm assuming you added an external amp and kept the Polk head unit integrated with your Connext system?

 

[ChrisP]

@ChrisP I'm assuming you added an external amp and kept the Polk head unit integrated with your Connext system?

Yes I added a 4 channel amp for the 2 ways and an amp for the sub. The HU is not powering any speakers. The decision I have now is if I need another amp to run the 8" 2 ways I added or if running them parallel with the front speakers will work. If what you are saying is true and my meter is not reading the resistance properly than I would be truely having a 1 ohn load on the front which could blow the amp. On the other hand if the rears were wired in series, maybe so is the front? They could be at an 8 ohm load? What would it do if I paralleled an 8 ohm load and a 4 ohm load? Does anyone have access to a speaker diagram for the 242? I could not find one.

 

[David Decker]

We really could use a wiring diagram.

Maybe the impedance of those crossover boxes depends on frequency. For low frequencies (including DC), the crossover may look like an open circuit (it just blocks low frequencies from reaching the tweeters). As frequency increases beyond the cutoff for the crossover, the impedance would begin to drop -- the amp would start seeing some load and the tweeters start doing useful work.

I think that if the bow speakers and tweeter crossovers were in series, the crossovers would block bass from reaching the bow speakers?

4 ohms and 8 ohms in parallel is 1/(1/4+1/8) = 2.667 ohms.

 

[shane hric]

Guys, I have no idea what your talking about but since I'm going to be installing a new system come spring, I will be reaching out for advise...please!

 

[ChrisP]

We really could use a wiring diagram.

Maybe the impedance of those crossover boxes depends on frequency. For low frequencies (including DC), the crossover may look like an open circuit (it just blocks low frequencies from reaching the tweeters). As frequency increases beyond the cutoff for the crossover, the impedance would begin to drop -- the amp would start seeing some load and the tweeters start doing useful work.

I think that if the bow speakers and tweeter crossovers were in series, the crossovers would block bass from reaching the bow speakers?

4 ohms and 8 ohms in parallel is 1/(1/4+1/8) = 2.667 ohms.

Definitely need a wiring diagram!! I will reach out to my dealer. I will share if I come up with one.

For now I will try to run the tweeters with the front 2 ways unhooked. This should tell me if they are wired together in series or parallel as they will not work if they are in series.

 

[Rodney Findley]

Head unit power is never as clean as amplifier power. One reason is the signal-to-noise ratio are better on the amps, and more importantly (to me) is "headroom". As a former car audio competitor, this was a major deal that we used in our stable. You gain this be using a higher power amplifier but only using 20-30% gain, also keeping the ohm load closer to the RMS mark (which is usually 4-ohm on a class A/B amp) will make for better sound, lower current draw, and reduced heat. ramble, ramble.......
With installing the amp you should alleviate the strange configuration and should would improve by 100% with the design of the new 5-channel amps nowadays!

Also, regarding an earlier comment on achieving a 4 ohm load with (4) 4 ohm speakers, you can series-parallel them and stay at 4 ohm. I had to do this back in the day with a 2-channel stereo amp on (4) SVC 4 ohm subs.

maybe I was totally of topic but I guess I felt the need to type!

 

[ChrisP]

Head unit power is never as clean as amplifier power. One reason is the signal-to-noise ratio are better on the amps, and more importantly (to me) is "headroom". As a former car audio competitor, this was a major deal that we used in our stable. You gain this be using a higher power amplifier but only using 20-30% gain, also keeping the ohm load closer to the RMS mark (which is usually 4-ohm on a class A/B amp) will make for better sound, lower current draw, and reduced heat. ramble, ramble.......
With installing the amp you should alleviate the strange configuration and should would improve by 100% with the design of the new 5-channel amps nowadays!

Also, regarding an earlier comment on achieving a 4 ohm load with (4) 4 ohm speakers, you can series-parallel them and stay at 4 ohm. I had to do this back in the day with a 2-channel stereo amp on (4) SVC 4 ohm subs.

maybe I was totally of topic but I guess I felt the need to type!

Appreciate the input but the question was more on getting 4 ohms from ( 2 ) 4 ohm speakers. Not sure if it is even possible?

 

[JEvanoff]

Definitely need a wiring diagram!! I will reach out to my dealer. I will share if I come up with one.

For now I will try to run the tweeters with the front 2 ways unhooked. This should tell me if they are wired together in series or parallel as they will not work if they are in series.

This isn't a wiring diagram but it is a lot more info. that came with my 2015 242. Hope this helps...

 

[David Decker]

Appreciate the input but the question was more on getting 4 ohms from ( 2 ) 4 ohm speakers. Not sure if it is even possible?

As far as I know it wouldn't be possible without the use of some other component(s), like a crossover. If you put the two in series, you get 8 ohms and if in parallel you get 2. I'll post back what I find out once I tackle this project next weekend.

 

[ChrisP]

As far as I know it wouldn't be possible without the use of some other component(s), like a crossover. If you put the two in series, you get 8 ohms and if in parallel you get 2. I'll post back what I find out once I tackle this project next weekend.

The fronts and tweeters are run in parallel. I am going to run the fronts, added cockpit speakers, and the tweeters off one channel of my amp. I talked to a guy at my local stereo shop and he said that the load will only be increased at signals above the crossover setting and it should work fine. I guys when the weather gets better and I get some long run time on the stereo I will find out. I will keep an eye on the amp to make sure that it is not over heating or anything weird. Worst case I unhook the tweeters........not sure I need them with the added 8" 2 ways anyway..........

I wonder if there is a way to test your actual running load on the amp?? Does anyone know?

 

[David Decker]

@ChrisP - I know it is possible to measure speaker impedance, but the math is a little complicated.
There is some PC-based software to calculate it - see these links:

http://www.bcae1.com/resvsimp.htm
http://www.linearx.com/downloads/DownloadUpdatesTop.htm

 

[Flower]

I upgraded my stereo this winter. In the process I learned a few things about the stock wiring that I figured I should share. I found out that the rear channel is running the cockpit speakers and the swim step speakers and the front runs the bow speakers and the tower tweeters. Well anyone who has played with the fader would have figured this out but what you may not know is that the rear speakers are wired in series. Meaning they are drawing an 8 ohm load. I assume this is to protect the head unit which is not 2 ohm stable. Oddly enough the front channel is only drawing a 4 ohm load. I only figured this out after adding a set of speakers in the cockpit. I wired them up parallel with the fronts and before I removed the tweeters from the equation I pulled out the multimeter to verify the ohm load. It was at 2ohms. Not sure how the bow speakers and tower tweeters are wired to accomplish a 4 ohm load but it works for me. So I checked the rear channel and they were at 8 ohms. I rewired the rear speakers parallel, they are now at a 2 ohm load and are way loader off the same amp.

Anyway hope this is helpful for anyone planning to add an amp using the stock wiring.

Just learned this also. I only have the stock speakers. Can the front and rear channel play at the same time? Like you said, i adjusted the fade to the rear and no sound?