weird noises.. I think I damaged some equipment - tl;dr

[alfisti 10+ year member]

Hi community. Something went wrong.. again lol I am so sad and tired. (kinda long post, appreciate your help)

97 VW polo (90amp alt, big3 pending)

0ga power&ground amp wire, 150a fuse

pioneer 6600bt, focal er5 RCA, dls comp (no amp)

kicker zx1500.1 - alpine type-r 10" (1000rms) - custom enclosure tuned ~36hz

Problems: A low volume hiss from sub. You have to literally stick your ear to the cone to hear it. A jet turbine like noise, something pitchy like a -digital- high rpm sound. It's tone goes up and down randomly. Engine on or off, RCA's plugged in or not, it doesn't matter.. it is there. If it is harmless to equipments, I don't care. Local shops said this sound is normal from amps.. i don't think so. Plus there is a tiny pop from sub when amp powers up.

My main concern is when RCAs are plugged to amp AND engine running, sub makes a little vibration(+little noise mentioned above) Engine off & rcas plugged: only humming. And it seems like sq went to sh*t gradually.. like every note is same. -Maybe this is placebo-

When gain setting with a dmm I noticed **** volts fluctuates (ex: 44.5 - 46.7 - 45.2 ...) bought a bad amp? //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

+ and maybe installer damaged my HU rca outputs?

some extra info:

set gain conservatively with help of dmm & no dimming

almost never pushed the system too hard (i hope)

50hz 0db test tone, HU %75 max volume used

signal - power wires from different sides of vehicle

amp ground is good but i will make it better

Rca cables: triple shielded, remote wire is pointlessly kinda big lol.. noise from there possible?

Bad batt ground & bad HU ground can cause amp to generate noise even when RCAs are unplugged?

Thanks a lot!

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[alfisti 10+ year member]

Thanks for nothing //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[alfisti 10+ year member]

Update

when everything is running, that little sub vibration(@zero volume) disappears if I set amp's crossover to 50hz. It starts again around mid way (125hz I guess?) there is no crossover OFF option at my HU.. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

pitchy digital high rpm like sound from sub is so low that IF it is harmless and doesn't disrupt sq at full tilt.. I don't care it. what do you think?

 

[chevyaddict83 10+ year member]

Bad grounds are the devil. Did you unplug rcas while everything was powered up?

 

[hispls 5,000+ posts]

Many low priced head units are noisy with enough amplification. Like you'd never notice with a 300W amp, but when you get 1500W you'd notice.

If it's noisy with no RCA's plugged in that's rather suspicious. I don't suppose you have another amp you can swap in to test with?

 

[alfisti 10+ year member]

I have a hifonics 1208d. Will test now.. and I think I will find out that I bought a bad amp. today is a sad day //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

lil vibration at zero volume only starts if amp's LPF is set to 125hz or higher, regardless of rcas connected or not

 

[alfisti 10+ year member]

well I tested with hifonics and same things happen.. but much more hard to hear. Whine noise is there but noticeably less than kicker, especially when no RCAs connected.

hifonics xover increases noise&volts too.. interesting, I didn't knew it had such effect. So I had to set HU lpf 200hz -24db and amp lpf ~80hz -24db is it o.k.? //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

my new problem is cone gets warm even though I set everything conservatively. I guess bad enclosure design

 

[alfisti 10+ year member]

ZX1000.1 Signal to Noise Ratio -62dB

ZX1500.1 Signal to Noise Ratio -55dB

ZX2500.1 Signal to Noise Ratio -65dB

maybe noisy by nature ?