Low amp output even with gain at maximum. Running out of options

[b0r 10+ year member]

Something with the SOURCE or the output set to rear? We just did an install in my friends truck last night and everything hooked up was slamming in my car, but his was no where near what it needed to be coming from FM channels on the radio. When we switched the output to REAR instead of SUB it started to hit harder. The head unit had an output that said "REAR/SW" so we figured something was up. We loaded some music to a USB stick (his headunit is MP3 only, no cds) and it was hitting just fine. Strangely, with this music, the SUB option worked and the REAR didn't...???? I was just dumbfounded. Either way, it started working. It was strange because we turned the truck off with the REAR setting on and it hitting fine, but when we turned it back on with the new source as USB, the setting changed to SUB and was finally adjustable. GL!

 

[Side Show 10+ year member]

^^ so confusing.... headunits that have only two sets of rca's will almost always have one set that'll either be full range (rear) or sub (once sub is selected a lot of the audio settings change) this lets you set the lpf

 

[b0r 10+ year member]

^^ so confusing.... headunits that have only two sets of rca's will almost always have one set that'll either be full range (rear) or sub (once sub is selected a lot of the audio settings change) this lets you set the lpf

Yeah, tell me about it. I don't know if it's a JVC thing or what, but I have never used a JVC Headunit and I've also never experienced that issue before, but I do know that it sounded horrible until we switched it to rear even though it should've been on sub. And then it changed itself on the next start.

 

[Side Show 10+ year member]

you might have it wired wrong if it doesn't remember the settings/radio stations ect ect, most the lower range and mid range of pioneers are the same.

 

[ModifierMR]

get a new car?

Thinking about it. haha

 

[ModifierMR]

Something with the SOURCE or the output set to rear? We just did an install in my friends truck last night and everything hooked up was slamming in my car, but his was no where near what it needed to be coming from FM channels on the radio. When we switched the output to REAR instead of SUB it started to hit harder. The head unit had an output that said "REAR/SW" so we figured something was up. We loaded some music to a USB stick (his headunit is MP3 only, no cds) and it was hitting just fine. Strangely, with this music, the SUB option worked and the REAR didn't...???? I was just dumbfounded. Either way, it started working. It was strange because we turned the truck off with the REAR setting on and it hitting fine, but when we turned it back on with the new source as USB, the setting changed to SUB and was finally adjustable. GL!

Yea my Pioneer has a Sub/Rear preout. The settings to control it also work in conjunction with the high level outputs of the radio itself. So, if you set the settings as "Rear/SUB" It will allow the rear high level to output at full range, and the sub to operate and be adjustible. Now if you set it to "Sub/Sub", it only outputs to subs, and the rear stage is disabled (including high level). If you set it to Rear/Rear, then it acts as a full range rear output on the preout.

Think thats confusing? me too, as far as I have read from the instruction manual, you you have subwoofers attached then "Rear/Sub" option is the one I want.

I can adjust the sub level on the headunit, and low-pass cutoff, and slope. Even with the Sub level at +6 (highest setting) I cannot get the woofers to perform well at lower amp gain settings. Even when the gain on the amp is cranked it doesnt perform like it should.

Idk, these newer decks just dont seem to be as straightforward as the older ones. What ever happend to "Sub: yes/no"?

 

[Jepalan]

Here are some more guesses:

1) You have the sub amp bridged, but only the L or R input is working or connected. Try a Y-Cable from R only into amp, then try it from L only.

2) You have dual voice coils wired out of phase. (Check again, carefully, separately, from every speaker terminal to amp)

 

[Better-Action 10+ year member]

Are the subs moving pretty good but just have low sound output?

It sounds like your subs are wired out of phase to me. Unhook one and see how it sounds with just one.

 

[ModifierMR]

Here are some more guesses:
1) You have the sub amp bridged, but only the L or R input is working or connected. Try a Y-Cable from R only into amp, then try it from L only.

2) You have dual voice coils wired out of phase. (Check again, carefully, separately, from every speaker terminal to amp)

Both inputs are working correctly. I have tested them independently. The amp is a mono amp and does not have Left or Right output, its just a single output.

The woofers are SVC. Both woofers are wired in phase. There is a direct wire now running from woofer, straight into amp.

Are the subs moving pretty good but just have low sound output?
It sounds like your subs are wired out of phase to me. Unhook one and see how it sounds with just one.

Subs only move when the gain is jacked all the way up. Other then that, they are silent and motionless. And even with the gain cranked they are still not what they used to be.

 

[ModifierMR]

Here are some more guesses:
1) You have the sub amp bridged, but only the L or R input is working or connected. Try a Y-Cable from R only into amp, then try it from L only.

2) You have dual voice coils wired out of phase. (Check again, carefully, separately, from every speaker terminal to amp)

Both inputs are working correctly. I have tested them independently. The amp is a mono amp and does not have Left or Right output, its just a single output.

The woofers are SVC. Both woofers are wired in phase. There is a direct wire now running from woofer, straight into amp.

Are the subs moving pretty good but just have low sound output?
It sounds like your subs are wired out of phase to me. Unhook one and see how it sounds with just one.

Subs only move when the gain is jacked all the way up. Other then that, they are silent and motionless. And even with the gain cranked they are still not what they used to be.

 

[NIHL8ION]

If you're using the Sub pre-out on your HU, try turning the lpf on your amp off or all the way up and readjusting...

 

[Side Show 10+ year member]

think you old system isn't as good as you once thought. are both rca inputs being used on the amp?

 

[jrdnhsnbrg 10+ year member]

Solution: torch the car and start new.

 

[ModifierMR]

If you're using the Sub pre-out on your HU, try turning the lpf on your amp off or all the way up and readjusting...

I will try that, thanks

think you old system isn't as good as you once thought. are both rca inputs being used on the amp?

Both L+R RCA's are being used, plugged in, and receiving signal. I have yet to test how strong that signal from the HU is. I have an Oscilloscope, I may try using that to analyse the signal.

 

[ModifierMR]

UPDATE:

So i ended up buying another vehicle (not because of this problem lol) and I started off with a different, known working good deck. and a brand new amp wire kit. Bare metal, big seat bolt for a ground point.

Subs are a wee bit louder but no where near like they should be/used to be. Everything still checks out ok... im stumped lol. Maybe im cursed.

So far here is what I have checked/replaced

-Power wire and fuse holder

-Ground wire

-Metal on metal contact bolted to chassis grounding point

-RCA's are brand new

-Replaced MTX 600w amp with Alpine 1000w amp

-Tried 2 sets of woofers (two 12" MTX thunder and two older 15" Lighting audio) Both sealed, independent chambers

-I have tried 3 different Head units ranging from 2.0v to 8v pre out

-Voice coil impedance checks out ok

-Alternator (running) voltage is just under 14.0v

-power wires, gorund wires resistance check is OK