Car Audio Help needed

[WINNIPEGS_MOST_WANTED]

For the first time ever I am at a loss as to what my problem is...

A little background info:I'm not powering my speakers from the HeadUnit. They are powered by a separate amp; As are my subs. I ran all new wiring abandoning the stock stuff. A quick diagram to illustrate my setup



Last week I noticed my volume was substantially lower than it usually is. In short -- No sound is coming out of the rear speakers. I installed a new headunit two weeks ago.

First thing I checked were the fuses. No problems here.

I switched the front and rear channels post amp at which point in time I had sound out of the rears but not front.=> all 4 speakers are OK.=> front preouts from HU are OK.=> amp front channel is OK.

I swapped the front and rear channels pre-amp (after reverting previous change). Again sound out the rears but not front.=> amp rear channel is OK.=> logically, the problem must be in rear pre-outs from HU or wiring from those pre-outs to the amp.

Today I went back to the retailer I bought the HU from and got them to give me a new unit. I also purchased and installed new RCAs.

I connected everything and still no change. No sound from the rear speakers.

Out of frustration I swapped the amp and still get the same result.

So what I've deduced is the following:All 4 speakers are operating normally. The amp is not the problem.The wiring is not the problem.The Head Unit is not the problem.wtf...

I don't know what my next step is. :S !?

Should also mention that I tried measuring the voltage on the RCA's just before the amp with my multimeter (one terminal to the pin and the other to the sheild -- DC) but got no measurement. Am I doing this wrong?

Much thanks for any input/suggestions.

[W O T]

2 problems

It looks like your running one set of rcas for both your speaker amp, and then daisychaining it to your sub amp. Thats not good. Does your deck not have 2 outputs? I guarantee some speakers arent seeing frequencies they arent meant to be playing

Second,

if your front are working, and the rears are not, then you switch the front and rear connections at the amp and then the front dont work, and the rears do. 100% your amps output on that chanel is blown

OR, you have the switch on your amp flipped to 2 chanel (some amps have a 2 chanel 4 chanel switch)

I can help with this no problem as I deal with problems like this everyday. a pic of your sub/amp connections would help

[W O T]

Just noticed you put RCA 17ft X 2

Thats your problem, your deck has 2 outputs right? One is for your door speakers, and one is supposed to be for your sub. (they both give out different signals, so they should be labelled)

Use one set of rcas and run them to your speaker amp, then split those 2 connections with 2 of these (youll now have 4 connections for the speaker amp)

http://www.knukonceptz.com/pro...-1F2M

Then run the other rca output from your deck, straight to your sub amp, no daisychaining bulls***, thats how your gonna blow your equipment

Thats my guess, but you said this stuff was all working at one point when wired like you have pictured? Unless youre not telling me something

[WINNIPEGS_MOST_WANTED]

I'm not doing any daisy chaining.

The the deck has 2 pre outs. One is labelled as front; the other rear/sub. Both go to the 4 channel amp powering the door speakers. The 4 channel has a pre-out on it which provides a summed output of the inputs. This amp pre-out was designed to be used as I am using it.

[edit] Also I should add I've had this setup with a previous deck for 2 years without problems. The new deck was working properly for a week before I started seeing this problem. [/edit]
Modified by WINNIPEGS_MOST_WANTED at 6:19 PM 5/9/2009

[WINNIPEGS_MOST_WANTED]

A few pics before it gets dark:

[W O T]

That 4 chanels RCA outputs was NOT meant to be used as you have it.

It is meant to be used an as an output to other speaker amp.

Like I said, the high/front output rca should be run to the 4 chanel amp, then split with 2 y cables ( i highly suggest the kny klarity cables, there cheap and so is his canadian shipping )

And the rear/sub output should have its own dedicated rca

[W O T]

btw, I was more concerred on seeing where you have the chanel switch flipped to, youre sure its on 4 chanel? Try flipping it to the other settings if its is, Ive had a Boss amp be wired backwards before and functionned correctly when set on 2 chanel

[WINNIPEGS_MOST_WANTED]

Like I said, the high/front output rca should be run to the 4 chanel amp, then split with 2 y cables

I take it with this setup you lose the ability to fade from front/rear or left/right?

The manual states:Pre-Out JacksThese jacks provide a Front + Rear summed output(Non-fading). This is an ideal output for drivinga separate subwoofer amp. This output is fullrange,and is not affected by the crossover.
Modified by WINNIPEGS_MOST_WANTED at 11:49 PM 5/9/2009

[W O T]

No you still get full fading, and the voltage isnt decreased by splitting the cables either.

Its just that the deck has a dedicated sub output and you should use it for that.

If it isnt one of your 4 chanels rca outputs thats blown, itll will be your rear/subwoofer rca output on the deck thats blown. Quick way to tell if its your deck rca that blown is to take the 17ft rca thats plugged into the rear/sub output, and plug it directly into your sub amp. If your subs stop working, its your decks output

[WINNIPEGS_MOST_WANTED]

I'll give that a try this morning. How do you maintain the ability to fade F<->R and L<->R with only 2 channels sending signal to the amp though?

[WINNIPEGS_MOST_WANTED]

So it turns out i'm a complete idiot. The HU provides an option to switch the rear pre-outs from full range to sub. Everything sounds great and I still have to tweak my amps.

Thanks for the speedy responses WOT.

[slickroger]

Dont feel like an idiot.

its always the stupidest and least thought of problem.

very common

[fueler]

glad you figured it out. i had the same exact problem as you and went through the same exact steps.... turned out my RCA's had come undone under the rear seat (i have 2 rca's hooked together at that point)

problems like this always have a simple solution, the frustrating part is figuring it out !!

[fueler]

PS i used to have the same alpine mpr m350 amp for my JL 10w3.... Nice little powerhouse. Lasted me four years then fried. WHat kind of JL's you runnin, W0 or W3 ?

[WINNIPEGS_MOST_WANTED]

Those are older W3's. The amp is probably 7 years old; I swear it's indestructible

There's a better picture of my setup on cardomain:http://www.cardomain.com/ride/2551558/3
Modified by WINNIPEGS_MOST_WANTED at 7:31 PM 5/10/2009

[Empty V]

Those are older W3's. The amp is probably 7 years old; I swear it's indestructible

There's a better picture of my setup on cardomain:http://www.cardomain.com/ride/2551558/3

Modified by WINNIPEGS_MOST_WANTED at 7:31 PM 5/10/2009

Glad you figured it out, bummer you don't have dedicated front, rear and sub outputs. My Pioneer had some programming issues like that, just a weird choice in how they designed it.

Woot woot for JL!

Billy

[GFinger]

Your best setup for this amp/deck configuration is to conect the 4ch amp to the front output and the rear/sub to the sub amp. Having dedicated sub volume control is more useable than having fade control. There also shouldn't be a need for y-adapters. The alpine amp should have a 2/4ch input selector. Set it to 2ch, and all 4 outputs will use the 2ch input. your front-rear volume settigns will be set using the front and rear gain adjustments on the amp. (A side note, most radios will start to clip at 3/4 full volume, so when setting your gains, make sure that the radio is at 3/4 full volume at the loudest listening levels you want.) From your pictures, it doesn't look like the 4ch amp's crossovers are active. These should be set to 80hz high-pass and 80hz low-pass on the sub amp. If you plan on cranking it, set them to 100hz for less bass to the door speakers. Hope this helps.

[W O T]

His amp does not have a 2/4 rca input switch, so like I said he needs 2 Y cables. And yes a dedicated sub rca is optimal.

And im sure hes fine with his amps crossovers turned off, as hes probably controlling all of his crossover points on his headunit, and theres no "general rule" for an amp to give a clipped signal, it all depends on his RCA voltage, my gains are set to less than 1/4 and anymore it will clip with my 6v rca outs, was @ 2/3 gain with my old Kenwood 2v preout deck.

Measuring gain adjustment is done with a DMM, not a screwdriver

[fueler]

DMMs are for sissies! i measure gain with my ears.

[GFinger]

I wasn't talking about the amp gains, i was talking about the decks pre-outs. its safe to say that most will start clipping at 3/4 to full volume. The gains on the amp are set by ear in most cases.

As for the crossovers, If his deck does't have 3 pairs of RCA's it may not have a built in crossover. If it does, it will have only a few set points and may be a 6db per octave, so your better off using the amp's in my opinion, which i know is a 12db per octave.

[W O T]

His deck has a 12db/octave slope. Gains may normally be set by ear, but thats just because people dont know how to do it properly. You cant hear a clipped signal, so how can you set gain by ear? Sure with a 200watt amp you wont notice a difference and your subs wont even get stinky.

But when you start messin with anything over a true 500+rms, you can burn things up quickly, and get those subs smellin/blown in minutes with improper gain settings.

Most people listen for distortion, then back off a touch, clipping can occur before distortion though

Maybe Im just a stickler, but my amps are way to expensive to be taking shortcuts

[WINNIPEGS_MOST_WANTED]

His amp does not have a 2/4 rca input switch, so like I said he needs 2 Y cables. And yes a dedicated sub rca is optimal.

And im sure hes fine with his amps crossovers turned off, as hes probably controlling all of his crossover points on his headunit, and theres no "general rule" for an amp to give a clipped signal, it all depends on his RCA voltage, my gains are set to less than 1/4 and anymore it will clip with my 6v rca outs, was @ 2/3 gain with my old Kenwood 2v preout deck.

Measuring gain adjustment is done with a DMM, not a screwdriver

I turned all the crossovers filters and other crap off for diagnostic purposes. Properly tuned it after I figured out what the problem was.

[W O T]

Thats cool, I prefer to turn the amp crossovers off and do it all through my deck, but I guess not every deck has the eq mine does.

Everything sounds good now though?

[WINNIPEGS_MOST_WANTED]

Sounds great! Once again I can't hear the sirens right behind me