Looking to the speakerHeads for help/suggestions! !

[Farny]

@Farny @jocolo21 @Daddy Fat Sacs OK, I don't know if I'm just not reading the specs right, or I'm looking at something completely different. Everything is set up and I want to tune the amps, but I can't find the voltage settings. ?‍

MA704 - 4 ch @ 4ohms

MA4505 - 2 ch bridged at 4ohms, sub at 2ohms

Sepec sheet for both:
JBL Marine Amplifier Specs

@Daddy Fat Sacs has got the science going on. My tuning skills are pretty basic. Turn up gain until clipping then back off a bit. I defer on this one. How were the results?

 

[jocolo21]

i use these videos last month when setting mine

 

[TXtraumaRN]

@Daddy Fat Sacs has got the science going on. My tuning skills are pretty basic. Turn up gain until clipping then back off a bit. I defer on this one. How were the results?

@Daddy Fat Sacs was spot on with his calculations. Got her on the water today to test everything out and it sounds awesome. The upgrade to the 2ohm sub made a night and day difference too! Definitely getting closer to the sound I'm looking for. Two problems tho...
1. One of the channels (front right) on the 704 Amp (for the cabin speakers) is very weak. I've hooked different speakers up and get the same result, but those speakers on a different channel sound fine. It literally sounds like I'm just playing a song on my phone (I thought it was at first). All four speakers on their own channel, nothing bridged. Could it be a bad channel? All speaker wire is the OEM runs (14awg) spliced with RCA's and 12awg wire.

2. The main Amp (4505) running the towers and sub overheats really fast (only 5 min of play time) and goes into "protect" mode and shuts down. Each tower speaker (2) is 4ohms on a bridged channel (front and rear). The sub is 2ohms on its own unbridged channel. Am I drawing too much power? Is the gain set too high even though there's no distortion? I'm running 2awg cables for +/- into a fuse panel (3 ft run) with 4awg going from the fuse panel to the amp (less than 18 inches long). All speaker wire is 12 awg.



(oh and don't even get me started on the remote wire. Freaking useless. ?)

 

[Adrian @ JB Solutions]

1. Swap RCAs at the amp to see if changes anything.

2. Check voltage at amp while playing. Double check resistance at each input with DMM. If those are all within spec then back off gain and see how it performs, though it takes some serious clipping to put an amp in protect that quickly. Usually it’s voltage or too low of resistance.

 

[Johnboat]

Ok here goes so the formula you want to be using is
V = the square root of RMS power x Speaker ohm

So for your 704 is 70w rms x 4ohm = 280. square root of 280 =16.73 your desired voltage

The 4505
Towers are 130w x 4ohm = 520. Square root of 520 = 22.8

Sub is 500w x 2ohm = 1000. Square root of 1000 = 31.62

Remeber it is imperative that you disconnect ALL speakers while tuning. Turn your head unit up to 75% volume. Turn off any bass boost, trebble, mids, bass all need to be set at 0. You will want to ensure that your amps to high level sensitivity switch for your mids/highs and of course to a low level sensitivity for your sub. I also would set your frequency on your mids/highs around the 120hz and your sub around 60 to start. You can always adjust these once your amps are tuned for better quality of sound on your preference. Start with the gains all the way down, plug your multimeter into each terminal respectively and start to slowly turn up the gain as you watch the multimeter. Once you have your gains set, turn down the volume all the way, TURN OFF batteries, reconnect all speaker wires accordingly, turn batteries back on and enjoy!!

For your towers and other coaxial speakers you want to use the 1khz track and the 50hz track for the sub.

Both tracks can be found here

https://jlaudio.zendesk.com/hc/en-us/articles/235503327-Audio-Files

Thanks for posting this info. I just installed a JBL amp in my kids truck and have two new amps "Delivered yesterday" to install in my boat. I will be using this method to tune all. Much appreciated!

 

[RobbieO]

I've been following this thread for awhile. I'm pretty good with automotive electrical systems, so I told myself, I can do this. But after watching the different posts about tuning amps, gains, crossovers etc. I'm just going to have an audio shop do my upgrade. You audio geeks are pretty amazing. For me, I have a freaking headache.

 

[jocolo21]

How many tower speakers? If only 2 why dont you try setting it up as a 2 ch amp instead of bridging.

 

[TXtraumaRN]

Not sure what you mean, unless I've got the terminology wrong, I thought bridging turned 4 channels into 2 channels? Off this Amp I'm running 2 tower speakers and a sub.
I thought this was the best way to optimize power for the speakers I'm using.

 

[Adrian @ JB Solutions]

Yes keep it bridged.

 

[jocolo21]

Was trying to say if 4 tower speakers wire them on 2ch at 2 ohm. I wire my 4jl 8.8 to a wdt sounds syn dx2 @2hms but toned it down to 260w per can.

 

[212s]

1. One of the channels (front right) on the 704 Amp (for the cabin speakers) is very weak.

Check that your +/- are correct - if one speaker is wired backwards, it'll be out of phase with the others and sound weak.

2. The main Amp (4505) running the towers and sub overheats really fast (only 5 min of play time) and goes into "protect" mode and shuts down.

Sounds like you're simply maxing the amp and it's not able to keep up or keep cool enough. Does it only happen when you've got it cranked up loud or all the time? If it's only when cranked up loud, then turn the gain down a notch to keep it from running so hot.

 

[Farny]

Not sure what you mean, unless I've got the terminology wrong, I thought bridging turned 4 channels into 2 channels? Off this Amp I'm running 2 tower speakers and a sub.
I thought this was the best way to optimize power for the speakers I'm using.

View attachment 173209

Nice neat wire work!! Clean

 

[TXtraumaRN]

Soooo.. Bad news. 3 of my 4 brand new JBL cabin speakers are blown. Don't know when or how it happened as I was still getting volume from them when I took the boat off the water. Went out to work on it today and couldn't get anything. Checked all the wiring and was only getting resistance on one line, so I pulled all the cabin speakers. All but one has zero resistance at the Coil. I don't know if something shorted and ran DC through the lines or what, but I'll be putting the wet sounds speakers back in for now. (already checked the amp and there's no DC output).

 

[Adrian @ JB Solutions]

Do they scratch when you push down on them? Do they smell at all?

 

[TXtraumaRN]

Do they scratch when you push down on them? Do they smell at all?

No, I get nothing out of them at all. No smell either.

 

[Adrian @ JB Solutions]

No, I get nothing out of them at all. No smell either.

Strange, if you set the gains too high they should smell a little from burning up the voice coil. Speakers blow a few ways but 99% of the time it’s a burnt coil.

Try hooking up a 9v battery to them and see if they pop. Sometimes weird shit happens that doesn’t make sense.

 

[TXtraumaRN]

I've been following this thread for awhile. I'm pretty good with automotive electrical systems, so I told myself, I can do this. But after watching the different posts about tuning amps, gains, crossovers etc. I'm just going to have an audio shop do my upgrade. You audio geeks are pretty amazing. For me, I have a freaking headache.

It's been a learning curve for sure. And while I dabbled in car audio as a kid, this isn't much different except that you have to understand that you're not going to get the same type of sound as you do in an enclosed car. If anything it's taught me that I really didn't know as much as I thought I did. For an untrained ear (like myself), it would be difficult to do the "tried and true" adjusting til you get distortion. If you know how to use a multi meter and can do the calculations (i.e. use a calculator) it's actually pretty simple. The problems I've been having are my own doing. I initially tried to tune it by ear, but when I eventually admitted I didn't know what I was doing and put a meter on things I found the gain was over double what it should have been on almost all channels. Thankfully I didn't blow my $1200 tower speakers. ?

 

[TXtraumaRN]

Strange, if you set the gains too high they should smell a little from burning up the voice coil. Speakers blow a few ways but 99% of the time it’s a burnt coil.

Try hooking up a 9v battery to them and see if they pop. Sometimes weird shit happens that doesn’t make sense.

My father who has been in electronics all of his life said the same thing, and also recommended the 9v test. I'm going to give that a shot tomorrow.

 

[212s]

I initially tried to tune it by ear, but when I eventually admitted I didn't know what I was doing and put a meter on things I found the gain was over double what it should have been on almost all channels.

Speakers are simple devices mechanically - a moving voicecoil is a wound wire electromagnetic field tube operating around a magnetic pole. Apply an AC sinewave signal (music) to the voicecoil and it pushes the speaker element back and forth duplicating the recorded music.

Clipping distortion is about the worst thing for speakers - when the amp is over-driven, it clips the top/bottom of the AC sinewave signal which is essentially DC into the speaker's voicecoil. AC is transient and brief heat production which the speaker can dissipate, but DC is full power constant current to the voicecoil leading to quick overheating and damage to the voicecoil. Once the voicecoil overheats to the point of breaking the wound wire connection, the speaker is dead as it can no longer generate an electromagnetic field.

The 9v battery trick will let you know for sure if the speaker is damaged and dead: tap the +/- briefly on the 9v battery and if there is no movement of the woofer cone, it's dead. A multimeter will also show some continuity, but if none, the speaker is dead.

Most likely what happened was you played it too loud on the water and the voicecoils melted a bit. Once they cooled and you tried them again, the wiring popped.

 

[TXtraumaRN]

Install is finally complete with sound test and everything sounds awesome (already got the JBL cabins replaced)! ?
I'll post an install thread with sound test later this week. Thanks to everyone who walked me through it and helped me realize I didn't know what the F I was doing.