Cannot get sub to work with new amp after trying/ testing everything.

[Xeenic]

I'm going to try to give as much detail as possible so you can help me figure this out. I was given a Kenwood 350 watt max, 2 channel amp from a coworker. I have an upgraded factory sound system in my car that includes a 6 channel amplifier and a 10" Pioneer sub. I also have an aftermarket Pioneer Head unit. Everything has been working fine, including the sub. I decided to hook the Kenwood amp up to my stock sub.

My stock sub is a dual voice coil 2-ohms each coil. I redid the wiring of the sub in a series circuit, so that the total resistance would be 4-ohms. I tested this connection with a multi-meter and it works fine.

My amp has 2 channels that are min 2-ohm stable each, but can be bridged into a single channel that is 4-ohms stable. I went with the bridged connection, hence why I rewired my sub in a series circuit. I hooked up the power, ground, and power control (blue wire) and the amp turns on and off with my head unit. The power light comes on and stays on, there is about 12V current going through it when it's on (but also car engine is not running). So it appears to be working fine.

I tested the speaker output from the amp to the sub and no signal is going to my sub, which would explain why it is not producing any sound. My problem comes from I believe the output of the head unit to the RCA cables. I have tried testing the RCA cables and there is a barley noticeable signal coming from them, about .04 volts. I did a continuity test on the RCA cables themselves and it passed. I also did that test on my head units RCA outputs, by holding one probe of the volt meter to the outer shield of the RCA output, and the other probe to the metal case of the unit, and it passed as well.

On the head unit's settings, I have the subwoofer output turned on and I have tried maxing the subwoofer level and maxing the bass boost, still no signal. Also tried turning the gain on the amp all the way up. Could it be a problem with my head unit not outputting a strong enough signal through the RCA cable? How could I resolve this?

A side note: I tried testing the output on the amp to the sub with the multimeter on a very low DC volt setting (200mV) and while the numbers were very small, I noticed they seemed to go up significantly every time a bass note was played on the song.

What else could it be/ what could I try?

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[evilmonstertruk Premium Member]

I'm going to try to give as much detail as possible so you can help me figure this out. I was given a Kenwood 350 watt max, 2 channel amp from a coworker. I have an upgraded factory sound system in my car that includes a 6 channel amplifier and a 10" Pioneer sub. I also have an aftermarket Pioneer Head unit. Everything has been working fine, including the sub. I decided to hook the Kenwood amp up to my stock sub.
My stock sub is a dual voice coil 2-ohms each coil. I redid the wiring of the sub in a series circuit, so that the total resistance would be 4-ohms. I tested this connection with a multi-meter and it works fine.

My amp has 2 channels that are min 2-ohm stable each, but can be bridged into a single channel that is 4-ohms stable. I went with the bridged connection, hence why I rewired my sub in a series circuit. I hooked up the power, ground, and power control (blue wire) and the amp turns on and off with my head unit. The power light comes on and stays on, there is about 12V current going through it when it's on (but also car engine is not running). So it appears to be working fine.

I tested the speaker output from the amp to the sub and no signal is going to my sub, which would explain why it is not producing any sound. My problem comes from I believe the output of the head unit to the RCA cables. I have tried testing the RCA cables and there is a barley noticeable signal coming from them, about .04 volts. I did a continuity test on the RCA cables themselves and it passed. I also did that test on my head units RCA outputs, by holding one probe of the volt meter to the outer shield of the RCA output, and the other probe to the metal case of the unit, and it passed as well.

On the head unit's settings, I have the subwoofer output turned on and I have tried maxing the subwoofer level and maxing the bass boost, still no signal. Also tried turning the gain on the amp all the way up. Could it be a problem with my head unit not outputting a strong enough signal through the RCA cable? How could I resolve this?

A side note: I tried testing the output on the amp to the sub with the multimeter on a very low DC volt setting (200mV) and while the numbers were very small, I noticed they seemed to go up significantly every time a bass note was played on the song.

What else could it be/ what could I try?

Do you have two or three sets of preouts? What kind of stereo is it?

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[Jeffdachef 5,000+ posts]

Lets do another test to narrow it down

Try getting an aux to RCA Y splitter and test the amp straight from your phone to see if you get a proper signal. If it works then the amp is good and problem would lie within the head unit pre-outs or a bad RCA cable. If it doesnt work then its the amp. However i'm leaning more towards the head unit pre-out from your symptoms. Have you tried putting the head unit volume very high?

PS: I wish more people describe their problems with trouble shooting attempts like you. Its a breathe fresh air. Thank you. Compared to the typical " I get no soundz please halp!"

 

[Xeenic]

My head unit is a Pioneer DEH-X8500BS. It has 3 sets of preouts

Okay I went out and bought an AUX to RCA y splitter and hooked it up. I plugged it in and hit play and it didn't work at first, until I turned the volume way up on my phone I got lots of bass from the sub! So the amp and sub are working.

I have tried turning it up loud but I didn't want to blast my ear drums so not too loud. There is decent bass present from my door speakers and 6x9's, but it doesn't seem like the sub is making any bass.

PS: Well seeing as I've spent two days on this reading forums and how-to's, I know there's a lot that could go wrong and not providing details will not help figure the problem any better than all the threads I've read. And I've pretty much already tested everything I've read to try on the forums so it would help others to know what I've already tried. I really don't understand how people think someone can help them by just saying "WHY IT NO WORKE!" without any details lol

 

[Xeenic]

UPDATE: So I bought new RCA cables as well just to test those out. I was going to resort to using a line out converter to the amp instead of the RCA output on my head unit because my sub used to run off of the colored wiring from the head unit and that worked fine. Anyway, I plugged in the new RCA cables and got the same result, the bass in the speakers was really strong and rattles those little things, but there was no sub bass. BUT then I tried turning ON the loudness setting, which appears to raise the lows and the high but not the mids, and all the sudden there's some real bass! So the sub started working well at a higher volume.

I went ahead and went back to the original RCA cables and its still working. Here's the thing though: my input sensitivity on my amp was turned all the way up (to most sensitive), my bass boost was maxed, the subwoofer setting is turned on and the volume control turned all the way up (+6), and I was getting no or very little output from the sub. But all the sudden I turn on the loudness and it works?

Is there anyway to turn the bass down for just my other speakers but keep it up for the sub? I don't feel it is because the subwoofer setting is all the way up. I don't want to have my volume way up to get some bass, but if I just max all the bass boost and in the EQ the other speakers rattle and sound crappy (I might replace the door speakers soon).

 

[Boomin_tahoe 5,000+ posts]

Woah...bass boost maxed? Turn that down....you'll end up clipping pretty quick.

Also sounds like HU settings need adjusting.

 

[Xeenic]

Woah...bass boost maxed? Turn that down....you'll end up clipping pretty quick.
Also sounds like HU settings need adjusting.

Yeah... So the sub really only works with all the bass setting maxed and it's causing the other speakers to clip really bad and sounds horrible. Like I said, the subwoofer setting is turned ON and i turned it up +6 ( most it would go) and the sub is still getting very little or no power. Plugging in my phone to the amp the sub works fine so I don't believe it's a problem the amp or the sub.

The sub was much stronger with the stock system. My last thought is to use a Line Output Converter to take the original wiring out the back of the head unit and hook that to the amp, instead of using the RCA outputs on the back of the head unit. Do you think that could fix the problem? I've tried all the settings on the head unit and cannot get the sub to produce sound without serious distortion from the rest of the speakers.

Edit: If I turn the bass settings down a bit, so that I can turn the volume way up without it sounding like the speakers are about to blow, the sub still does not kick in when turning the volume all the way up on the head unit.