the sa build is finally done! I thought.....whining from subs.


devin171moto

CarAudio.com Regular
Feb 29, 2020
181
32
Gilbert, AZ
hey guys its your favorite obsessive compulsive question asker.

the 2 sa 12 build in the 03 envoy is done!
big 3 with a northstar agm stock alt. holding 14.6 volts running.
i set the amp with a voltmeter to 1000w rms while i test things as i dont have an oscilloscope and this amp can put out twice the rms rating of the subs
taramps smart 3 on a generic amazon inline rca bass knob. box sounds great. props to shredder2!

my problem..
the subs whine when the system is on but music isnt playing
hard to describe the sound. almost like when you sit in a passenger jet and the sound the plane makes right beforre the turbines spool up.
when the bass knob is all the way down theres no noise (because the subs are basically off)
as i turn the bass knob up, without music playing, i start to hear the wine getting loud as i turn the knob up.
once i turn the knob past id say about 3/4 of the way up, the sound gets quieter and quiter untill i reach max on the bass knob.
bass knob all the way up its still there. but barely audible.
(its pretty damn loud when the bass knob is half way, like normal conversation volume) a consistent tone.
 

devin171moto

CarAudio.com Regular
Feb 29, 2020
181
32
Gilbert, AZ
  • Thread Starter Thread Starter
  • #2
im thinking its just a shitty bass knob. low quality resister in the knob are creating a resonant frequency in the rcas of some sort. gonna try wiring dirrectly to radio to see if that stops it.
then i'll check if different rcas work.
i'd appreciate any other ideas in the mean time. the smart 3 has 1 input so i just plugged the left in at the amp. and the bass knob has left and right rcas hoocked at both ends. maybe that?
 

shredder2

CarAudio.com Elite VIP
Nov 19, 2017
2,905
544
Az
Sounds like a ground loop issue... is it alternator whine that changes with Rpm? I'm assuming your using a second amp for your highs? I've heard subs motorboat but whine?
 

shredder2

CarAudio.com Elite VIP
Nov 19, 2017
2,905
544
Az
hey guys its your favorite obsessive compulsive question asker.

the 2 sa 12 build in the 03 envoy is done!
big 3 with a northstar agm stock alt. holding 14.6 volts running.
i set the amp with a voltmeter to 1000w rms while i test things as i dont have an oscilloscope and this amp can put out twice the rms rating of the subs
taramps smart 3 on a generic amazon inline rca bass knob. box sounds great. props to shredder2!

my problem..
the subs whine when the system is on but music isnt playing
hard to describe the sound. almost like when you sit in a passenger jet and the sound the plane makes right beforre the turbines spool up.
when the bass knob is all the way down theres no noise (because the subs are basically off)
as i turn the bass knob up, without music playing, i start to hear the wine getting loud as i turn the knob up.
once i turn the knob past id say about 3/4 of the way up, the sound gets quieter and quiter untill i reach max on the bass knob.
bass knob all the way up its still there. but barely audible.
(its pretty damn loud when the bass knob is half way, like normal conversation volume) a consistent tone.
Any pics of everything installed?.. sometimes that can help
 

devin171moto

CarAudio.com Regular
Feb 29, 2020
181
32
Gilbert, AZ
  • Thread Starter Thread Starter
  • #8
Sounds like a ground loop issue... is it alternator whine that changes with Rpm? I'm assuming your using a second amp for your highs? I've heard subs motorboat but whine?
I tried bringing the rpm up and couldn't really hear a change in pitch.
I haven't put in my mid amp yet. currently running high sensitivity JBLs off head unit.
just one 0 gauge run from battery. voltage reads 14.6 at the amp running.
Then I have one 0 gauge ground to a post that bolts the seat in. **** it here i'll take pictures i have a flashlight lol
 
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shredder2

CarAudio.com Elite VIP
Nov 19, 2017
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I tried bringing the rpm up and couldn't really hear a change in pitch.
I haven't put in my mid amp yet. currently running high sensitivity JBLs off head unit.
just one 0 gauge run from battery. voltage reads 14.6 at the amp running.
Then I have one 0 gauge ground to a post that bolts the seat in. **** it here i'll take pictures i have a flashlight lol
Ground location?.. signal source?.. could be a bunch of things including amplifier. Probably easier to diagnose in person I'd say without hearing it. R U sure it's not the amp fan?.. lol
 

devin171moto

CarAudio.com Regular
Feb 29, 2020
181
32
Gilbert, AZ
  • Thread Starter Thread Starter
  • #11
Ground location?.. signal source?.. could be a bunch of things including amplifier. Probably easier to diagnose in person I'd say without hearing it. R U sure it's not the amp fan?.. lol
lol absolutely not the amp fan. thats what i thought it was at first. but when the bass knob is all the way up i can hear a slight tone and when i put my finger on the sub its vibrating
its too late to test but rca and removing the bass knob are my first try's tomorrow
 

devin171moto

CarAudio.com Regular
Feb 29, 2020
181
32
Gilbert, AZ
  • Thread Starter Thread Starter
  • #12
Ground location?.. signal source?.. could be a bunch of things including amplifier. Probably easier to diagnose in person I'd say without hearing it. R U sure it's not the amp fan?.. lol
my rockfords didn't do this. but i did ground my volt meter to my receivers ground. thats coming from the power wire at the amp. and the rcas are coming from the radio so maybe that?
 

shredder2

CarAudio.com Elite VIP
Nov 19, 2017
2,905
544
Az
Too many sources/paths can cause noise... simplify the wiring and you might find the solution.
Jmo... a 2v deck in my situation stomps on a 2v deck with 6v+ line-driver/eq... quieter and more/better signal. I just reset levels.
 

devin171moto

CarAudio.com Regular
Feb 29, 2020
181
32
Gilbert, AZ
  • Thread Starter Thread Starter
  • #15
Have you tried unplugging the Bass knob to see if it's still there?
yeah was gonna wait to do that but i just ran to circle k so took it off and tested the noise is gone. its way louder than i expected. set the gain to approx 1500rms at 50 volume and turned it up fast at a stoplight and got a little disoriented lol
 
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shredder2

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Nov 19, 2017
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yeah was gonna wait to do that but i just ran to circle k so took it off and tested the noise is gone. its way louder than i expected. set the gain to approx 1500rms at 50 volume and turned it up fast at a stoplight and got a little disoriented lol
Now I'd like to hear it... setting gains can be a "B" and best set by feel/ear if a DD1/oscope is not available. Doing it with a multimeter is pissing in the wind imo. Get something and find your decks clipping point then set levels along with filters.
 

Bobbytwonames

Trigger Man!
Aug 28, 2018
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Now I'd like to hear it... setting gains can be a "B" and best set by feel/ear if a DD1/oscope is not available. Doing it with a multimeter is pissing in the wind imo. Get something and find your decks clipping point then set levels along with filters.
So, should a bass knob be a last addition? It seems all too often that these bass knobs cause problems.
 

shredder2

CarAudio.com Elite VIP
Nov 19, 2017
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So, should a bass knob be a last addition? It seems all too often that these bass knobs cause problems.
A passive rca knob is the shit... my amp has temp, voltage and clip right on the knob so I use it but previously i almost never used the factory supplied knob.
I'd say features, type of gain and quality determine what I'd use.
 

Bobbytwonames

Trigger Man!
Aug 28, 2018
4,422
177
Vegas
A passive rca knob is the shit... my amp has temp, voltage and clip right on the knob so I use it but previously i almost never used the factory supplied knob.
I'd say features, type of gain and quality determine what I'd use.
What knob would you suggest for a MD3K?
 

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