Rear speakers: no bass at all - Bypassing Amp entirely [Complete]

[jdlobb]

I've recently realized that neither of the rear speakers in my 1998 100-series have any base at all. They're putting out sound, but only high, and the sound is tinny and weak.

At first I thought it was the speakers, so I replaced them with brand new 6.5" JBL component speakers, but the problem persists.

I have a Pioneer AVH-2330 head unit, hooked into the factory amp, no bypass.

Is this likely a problem with the amp? I believe I've eliminated every problem through process of elimination. Head unit is hooked up correctly and speakers are brand new. Front speakers have full range of sound, plenty of base.

No amount of equalizer fiddling or bass boost at the head unit results in even the smallest amount of bass from the rear speakers.

Causes eliminated:

Wiring
Speaker operation

Solution:

Eliminating the factory amp entirely. Running new wire directly from HEAD UNIT to speakers.

 

[codertimt]

So...something that I feel I might can be helpful about...but then i saw you are running through the factory amp and that made me second guess myself...because I'm really not sure what might happen in the mystery sound circuit of that amp. First thing I was going to mention is that 103% of the time, if you replace factory speakers with aftermarket ones...you will lose bass response. It has to do with with efficiency of speakers...how much the cone moves with a certain amount of input voltage...etc. And generally your aftermarket speakers will sound better, but require more power to provide that low end fill you are looking for... However, after reading your post, I'm not sure that's what is going on or not. But I will go ahead and give some advice...it may or may not be the best advice...but it is advice. Ditch the factory amp. I don't know if you integrated into the amp or had it done by someone...but really and truly...the factory amp is not that nice.... Yes it is external to the head unit, but it really compares in no way to a good aftermarket amplifier. In fact it doesn't really compare that well to your aftermarket head unit. My suggestion is to find and follow the advice here on how to bypass the factory amp and run directly off the head unit. That way you know 106% nothing is going on between the output of your head unit and the input of your new speakers... Of course here are caveats...if you are still running the factory "sub" then you might lose some response you are wanting...but IMHO...the play would be to put an aftermarket amp on a set of good components up front before worrying about that...that "sub" really and truly isn't all that. Lots of ellipses in this post...I possibly need to find a new writing style...moving on. I run a set of decent components off a old school Punch 40 amp up front, run the rear coaxials off the head unit and have a 15" Sundown sub running off a decent amount of power...so...not apples to apples...but I can turn the sub off and still dial in some bass/midbass response from the components/coaxials... So eliminate the possible issues by bypassing the amp and go from there...

 

[ogsuv]

I agree with codertint, amp bypass is my recommendation also.

Also, in the mean time, I would flip the positive and negative speaker connections on one side only. Wherever it is easiest...at the head unit, amp or crossover. There is a chance that your speakers are out of phase (not both moving in the same direction) or if they are in phase, there is a chance you get more bass out of phase. whichever way sounds best is the correct way to leave it.

I have installed more speakers and subwoofer boxes than I can count and have heard my share of out of phase speakers and the difference is night and day, even with 1.21 jigawatts.

 

[jdlobb]

Thank's for the input so far. I think the easiest, or at least the least expensive, option for the time being is going to be to rewire to bypass the amp and run the speakers directly of the HU. Not really an issue, the factor subs have been shot for as long as I've owned the vehicle anyways.

Question for those in the know, before I go pulling things apart. Can I utilize the existing wiring from the head unit to the sub for the bypass? Is it a matter of just splicing different wires at the amp, or do I need to get new wiring to run from the HU to the location of the amp? I looked at some of the other threads on the bypass, and that was something I just couldn't readily tell.

 

[codertimt]

Yes, you can make the splices at the amp utilizing the existing wiring... Be aware that the head unit power on some variants(maybe all?) actually comes up from the amp wiring...just keep that in mind as you make the changes. The following link should cover the wiring for the most part...

Stereo Wiring: Land Cruiser / LX 470 (1998-02)

 

[jdlobb]

Update. On a hunch I remembered the "standard" vs "network" modes on the head unit and decided to see.

So it was in "standard" mode, with all the issues described above.

I reset the head unit to "network" mode, and now I have full range sound from the rear speakers, but nothing from the front. So I suspect there's something wrong with the wiring at the head unit. I'll need to pull it out and check all the wiring again. Now sure how it could be wired to cause this, but I will sort it out.

 

[codertimt]

Weird. Knowing nothing about the wiring and only glancing at a Pioneer manual to see what Network mode was, that would not be the result I would have expected either. Good luck with sorting it out...

 

[jdlobb]

Weird. Knowing nothing about the wiring and only glancing at a Pioneer manual to see what Network mode was, that would not be the result I would have expected either. Good luck with sorting it out...

yeah, doesn't make any sense to me either at a surface level, so my first step after work today will be to pull it all apart and re-check the wires.

 

[cornboy]

you know....it's all about that bass!

 

[Skidoo]

The factory amp has filters to send very low frequencies to sub-woofer and not to front and rear speakers. If those components have aged or failed it could be blocking more frequencies than it should.
The other thing to check is that your new head unit is sending all frequencies to front and rear speakers rather than to its subwoofer output which is probably not hooked to anything. When using factory amp it drives the subwoofers, not the head unit, so subwoofer section of head unit is not used. Buried in head unit's menus are all sorts of output configuration options.

 

[jdlobb]

Well. Triple checked all the wiring at the harness. nothing there wrong.

Waiting for a pack of connectors to show up so i can dive into rewiring everything to bypass the amp.

also just spent a over an hour fiddling with the parking break wire, which turned into a right PITA. Everything was super short and fragile, many problems.

 

[jdlobb]

well crap. i'm in the middle of this now, too late to turn back. I think I'm missing something, and I can't figure it out from the wiring diagrams.

There are only 5 speaker wires OUT from the HEAD UNIT, and 5 wires IN to the Amp on the smaller connector.

But on the larger connector OUT from the Amp there are 2 wires (+) and (-) for each speaker.

Do I need to run any additional wires from the head unit? or is something supposed to be spliced together? If I'm looking at this correctly, all 4 (-) wires at the HEAD UNIT run into 1 wire to the AMP.

I got all of the power wires to bypass the amp spliced correctly already, that was straight forward.

 

[codertimt]

Oh, I may have given you bad advice. I thought I had remembered there being enough wires to run everything, but now it dawns on me that I was only running my rear speakers from the head unit...so I stole some of the other wires to have enough (+)(-) combos for the rears. But from looking at the tlcfaq page, yes you will have to run some wires to have separate grounds for each speaker.

Sorry for the incorrect info...

 

[jdlobb]

well crap. It is what it is. Too late to turn back now. I'll have to run to Frys tomorrow I suppose.

 

[Skidoo]

I did not need to run extra wires to the amp, tied new head unit to wires in the dash. I am guessing the issue is with output setup of head unit, have you been through the menu options and understand what the settings do? The manuals are not clear and it took me several readings to decode the right setup.

 

[jdlobb]

I did not need to run extra wires to the amp, tied new head unit to wires in the dash. I am guessing the issue is with output setup of head unit, have you been through the menu options and understand what the settings do? The manuals are not clear and it took me several readings to decode the right setup.

So the problem is that the amp is toast, so I have to either replace it, or run the head unit straight to the speakers. If I were replacing the amp I suppose I wouldn't need any new wires. But because I'm running straight to the speakers I don't have enough wires.

No big deal, I think the new wires should just run down under the center console and come out under the passenger seat easy enough.
I already did the power bypass, and went ahead and sorted out the wires to the speakers, added bullet connectors, and tied the pairs together, so installing the new wiring tomorrow shouldn't take long at all.

I might run a set of RCA cables while I'm in there tomorrow, just to save a little time in the future if I install a better amp.

 

[Somebodyelse5]

So, did you decide to just bypass the amp yet? Cause after all the trouble of fiddling with that amp, everyone decide to just bypass it anyways. An aftermarket headunit and some new speakers sound better anyways. If you want base, get a small 10" sub in an enclosure... I wouldn't bother with getting anything reasonable out of the factory components

 

[ADVNZ]

So the problem is that the amp is toast, so I have to either replace it, or run the head unit straight to the speakers. If I were replacing the amp I suppose I wouldn't need any new wires. But because I'm running straight to the speakers I don't have enough wires.

No big deal, I think the new wires should just run down under the center console and come out under the passenger seat easy enough.
I already did the power bypass, and went ahead and sorted out the wires to the speakers, added bullet connectors, and tied the pairs together, so installing the new wiring tomorrow shouldn't take long at all.

View attachment 1674023

I might run a set of RCA cables while I'm in there tomorrow, just to save a little time in the future if I install a better amp.

I just did this upgrade today, I think the problem is that you are connecting via the 22 pin plug when you should be connecting to the speakers via the 14 pin plug.

On my pioneer unit I only needed to connect one wire from the head unit to enable sound and the bass is superb.

Check the diagram...you won't need RCA's....I tried that also:

See more details on this forum item: Pre-03 nav delete how-to

 

[jdlobb]

Shopping done, supplies bought.

Cut four 8-foot runs of 18g speaker wire, and prepped with bullet connectors and tags. Only thing left is to pull the harness and prep it as well. Don't remember white end of the bullet connectors I installed on it last night, so I may have to replace them. My amp will soon be completely vestigial.

Any advice on running the wires? Can I run them down the center console easy enough? How do I get them under the seat?

 

[jdlobb]

All done. Final installation was simple. My speaker runs were about 2 feet too long, 6-foot runs would have been exactly perfect.

Everything works great now. Full range of sound on all 4 speakers, tweeters still work.

There's a bit of distortion out of the RIGHT FRONT, I suspect the driver or the tweeter may be shot. The front speakers are almost 10 years ago, and cheaper than the new JBLs in the back. I'll probably swap them out in the near future and be done with it.