jeffmeag wrote: Wed Apr 22, 2020 9:33 am
Yeah, it does seem I might be stuck. Would love to try the jl 7's but not much point in buying them just to see if they are any better. If there are no other suggestions that might help, this may be the end of it.
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Jeff
All 12 of your speakers are most likely wired in SERIES. This is because the number of speakers on your boat (12) exceeds the number of amplifier channels on your two amps (4 channels x 2 M400 Amps = 8 available channels for 12 speakers). In other words Cobalt is combining two speakers together (in SERIES) before running them to the amp.
So just adding amps won’t dramatically increase volume because you have to “unwire” the SERIES connected speakers from each other. (Which are most likely all of them).
EXPLANATION:
Most of the time speakers are wired in PARALLEL meaning the positive terminal of one speaker connects to the positive output channel of the amp. The negative terminal of that same speaker connects to the negative output channel of the amp. If you have a 4 Ohm speaker (which many cars and boats utilize) and a 100 Watt per channel amp @ 4 Ohms then you’ll push that relative amount to the speaker. Easy.
If you combine TWO speakers in PARALLEL to one amp output channel you’ll get even louder volume but it requires more current flow from the amp because the speaker impedance gets cut in half. 4 ohm / 2 speakers = 2 Ohms. (technically you multiply together each individual impedance (4x4), then divide the result by the sum of the impedances (4+4) but the results are the same here.) Most amps cannot handle two Ohm loads running two speakers in PARALLEL to each output channel. Believe it or not your M400 is rated to push 4 channels at 2 Ohms.
(JL Audio M400 Manual) This would really test that amps capabilities though!
So I believe Cobalt in its infinite wisdom decided to wire your speakers in SERIES. Like you mentioned earlier, this will dramatically cut down the volume. But this allows the amp to handle all 12 speakers easily. In a SERIES configuration the positive side wire of one speaker is connected to the positive channel output on the amp. The negative side of that same speaker is connected to the positive of the OTHER SPEAKER. Finally the negative of that other speaker is connected to the negative output channel on the amp. (Clear as mud?

see diagram below) This has the effect of doubling your Ohms so you now have a less efficient speaker (4 Ohm x 2 speakers = 8 Ohms). Again volume (technically sensitivity) will be reduced dramatically in a SERIES configuration.

(but your amp will more easily be able to keep up with the current flow required because of the increased resistance from the speaker(s).)
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SOLUTION:
Since it sounds like you’re not too concerned about “inside the boat” volume yet you want your “outside the boat”, Transom & Tower speakers louder, your goal is
two fold:
1a. Get rid of the SERIES speaker connection (which is the nest team Nauti tried to undo on their boat before just giving up and rewiring the entire boat)
on the speakers you want louder...the two on the Transom and the two on the Tower, so they can now be wired in a PARALLEL configuration.
2a. Using your existing second M400 with existing RCA connections; AND as long as your transom and tower speakers are at least 4 Ohms, try connecting these 4 speakers to your second M400 in a PARALLEL configuration by inserting both the tower speaker wires and the transom speaker wires into channel outputs 3 & 4.....again in a PARALLEL configuration as described above. This will require you to do a rewire from those particular speakers or use the existing wire and detach the SERIES connection between paired speakers. Use speaker output channel 3 for the left transom speaker & 4 for your right transom speaker. ...AND channel 3 for your left tower speaker and channel 4 for the right (yes you’re combining four speakers into two channels but this time in a PARALLEL configuration).
As you currently have it, use channels 1 & 2 to mono-bridge your sub.
Keep in mind that this will really task that 2nd M400 amp as it will need more current to keep up with this 2 ohm load, PARALLEL configuration on channels 3 & 4.
OR (what I would do to fix your problem)
1b same as 1a above.
2b. Like the Nautis mentioned you’ll need to ditch one JL M400 amp. It’s a great amp and you’ll be able to resell it to someone here or on Craigslist/ EBay. Keep your first M400 (the one in your pic showing your 8 in-boat speakers wired in Series and the one set of RCA inputs from the RF head unit). No need to touch that.
The other M400 showing the sub (gold wires) bridged will be taken out of the boat. It’s best to only run two amplifiers total vs three for reasons I will not go into.
Now pick up a
JL M800/8 (or JLMV800/8 if you want to incorporate DSP) 8 channel Amp. . I actually prefer the less expensive JL M800/8. It’s $764.99 on Creative Audio or Crutchfield. If you use Creative ask for James Taylor and mention my name from the PM’s you and I exchanged.

Then connect the 4 RCA’s (connected in a slightly different configuration mentioned below) from the RF head-unit that were originally connected to the old M400 to the M800 (again as mentioned in the recommendation below).
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Insert the labeled 1 & 2 (Subwoofer out) RCA’s (from your picture posted in your earlier post) into RCA inputs 1&2 on the M800 (pictured above)
Then insert your bridged subwoofer into output channels 1 & 2. Easy.
Take RCA's 3 & 4 (as labeled in your picture) from the head unit and insert those into RCA inputs 3 & 4 on the M800. Now in a PARALLEL configuration insert one of your transom speaker wires into the + and - sides of speaker channel output 3. Insert the other transom speaker wire into the + and - sides of speaker output 4..
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Use the Zone 2 Line out RCA from your
PMX-5 RF head unit (see diagram above) to connect your Tower speakers so you can control them separately with volume (or even turn them off at times if you desire (although BBP says he never does)) without affecting the rest of your in-boat speakers. Run the red and white RCA cable from this Zone 2 output to the M800 amp. Then add
two Y Splitters (single female to dual male) to this newly run RCA cable. This will now convert them to four line outs. Connect those four to inputs 5, 6, 7, 8 on the M800. Then connect your Tower speakers in a bridged mono configuration for max volume to your wakeboarders. The positive of one Tower speaker connects to the speaker output 5 positive terminal channel. The negative side of that same speaker connects to the negative speaker output on the number 6 channel. Do the same with the other Tower speaker using channels 7 & 8 in a bridged mono configuration.
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Finally set the JL Audio M800
input mode amp switch (pictured above) to 8 CH allowing all 8 inputs to power all 8 output channels. Then make sure each channel is set on
high pass (allowing higher frequencies to pass thru) on channels 3 thru 8. Set the filter frequency for each of those to 120 HZ allowing mostly higher frequencies on that spectrum to be directed to those higher range speakers.
Set channels 1 & 2 (your subwoofer) to
low pass allowing the lower bass frequencies only to pass thru to the subwoofer. Use 80Hz initially as per the
JL M800/8v2 Manual recommendation.
DONE
So for $750 ...minus what you get for your M400.... plus a little trial and error effort to eliminate series connected transom and tower speakers
your goal will be met. ....Louder transom speakers on channels 3 & 4....and.....Louder and more powerful tower speakers bridged on 5 thru 8 with separate volume on those as well.
Hope this helps.
Again feel free to PM me or even better call James Taylor (yes that’s his real name

) at Creative Audio who is the expert on this stuff. He will be happy to talk you thru it or may even have other options. Here’s the
link
Enjoy the music my friend



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