# Tweeters make constant "white noise" Help



## rnicolai (Jul 12, 2013)

I'm getting a constant "white noise - kshhhhh" sound from my tweeter when the system is turned on - happens when engine is off & also when running - acceleration or nothing else has any effect on the intensity of the noise whatsoever.

I have the tweets mounted in the a pillars hooked up in bridged mode to an Alpine KTP445-U (using RCA inputs).

Could this be a grounding issue with the amp, gain level issue, etc???


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## SkizeR (Apr 19, 2011)

it could be a gain or ground issue. first turn the car and head unit off, and unplug the rca cables from the amp. if the noise goes away, you know its something from before the amp. if thats the case, try grounding your head unit to where the amps are grounded to. if the noise is still there, either your gain is to high and you have a noisy amp, or you may have a questionable ground


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## gstokes (Apr 20, 2014)

That's sounds like an issue with signal ground and/or crappy Interconnects, if you're using unbalanced RCA's switch to Stinger 4000 Series..
You can also try running a chassis ground for the amplifier..
Keep us posted..


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## rnicolai (Jul 12, 2013)

Thanks - will try these steps when I get home.

Incidentally this alpine power pack amp does not require a separate hook up "kit." It actually hooks up inline to Head Unit. So with that being said, since the HU is grounded, should that also ground the amp, or do I need to separately ground the amp to chassis?


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## SkizeR (Apr 19, 2011)

rnicolai said:


> Thanks - will try these steps when I get home.
> 
> Incidentally this alpine power pack amp does not require a separate hook up "kit." It actually hooks up inline to Head Unit. So with that being said, since the HU is grounded, should that also ground the amp, or do I need to separately ground the amp to chassis?


you should be grounding both to chasis


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## gstokes (Apr 20, 2014)

rnicolai said:


> Thanks - will try these steps when I get home.
> 
> Incidentally this alpine power pack amp does not require a separate hook up "kit." It actually hooks up inline to Head Unit. So with that being said, since the HU is grounded, should that also ground the amp, or do I need to separately ground the amp to chassis?


A separate battery and/or chassis ground is not a bad idea, especially in your case where there is noise present in the system..


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## Patrick Bateman (Sep 11, 2006)

A 10ohm resistor won't fix the problem but it will make it basically inaudible. Basically you put a ten ohm resistor in front of the tweeter, and by doing so, you must send more power to the tweeter to get to the same SPL.

The net effect is that it drops the noise floor.

This only works if the noise in your system doesn't change when you turn up the volume. IE, there's a constant hiss.

I do this trick a lot because I use compression drivers, and compression drivers, due to their insane sensitivity, exacerbate noise problems.


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## SkizeR (Apr 19, 2011)

Patrick Bateman said:


> A 10ohm resistor won't fix the problem but it will make it basically inaudible. Basically you put a ten ohm resistor in front of the tweeter, and by doing so, you must send more power to the tweeter to get to the same SPL.
> 
> The net effect is that it drops the noise floor.
> 
> ...


or you can do it, ya know, the right way lol


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## Jepalan (Jun 27, 2013)

Random thoughts...

Turn the gain down. 

The input sensitivity of the KTU Power Pack is adjustable from 0.2 v to 4v. What source are you connecting it to? If you have a high voltage line source the gain better be close to minimum - otherwise you are amplifying the heck out of the source's noise floor.

If you are bridging the KTU power pack, make sure slide the input mode switch UP into the 2-CH mode and connect RCAs to the correct inputs (front R/L).


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## Kazuhiro (Apr 28, 2015)

Patrick Bateman said:


> A 10ohm resistor won't fix the problem but it will make it basically inaudible. Basically you put a ten ohm resistor in front of the tweeter, and by doing so, you must send more power to the tweeter to get to the same SPL.
> 
> The net effect is that it drops the noise floor.
> 
> ...



Neat trick. I might try this as my tweeters have a constant noise floor even with RCA's disconnected. I really dont want to run another ground, Im sure this one is fine. Might be that the amplifier is 26 years old haha.


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## SkizeR (Apr 19, 2011)

Kazuhiro said:


> Neat trick. I might try this as my tweeters have a constant noise floor even with RCA's disconnected. I really dont want to run another ground, Im sure this one is fine. Might be that the amplifier is 26 years old haha.


i wouldnt, because then your severely limiting the output of your tweeters


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## Kazuhiro (Apr 28, 2015)

It doesn't have to be 10 ohms, but worth a shot considering my gains are at zero at the moment. My tweets are three ohms so even a matched resistor would take the noise floor down by 6dB right? Being said that is only if the amp is the cause of the noise. 

Sent from my HTC_PO582 using Tapatalk


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## 14642 (May 19, 2008)

Hiss is almost NEVER a grounding issue. If you unplug the RCA inputs and it's still there, it's the amp. Instead of putting the resistors in there to limit the output power, how about just using two channels? That will also reduce the level by 6dB.


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## SkizeR (Apr 19, 2011)

Kazuhiro said:


> It doesn't have to be 10 ohms, but worth a shot considering my gains are at zero at the moment. My tweets are three ohms so even a matched resistor would take the noise floor down by 6dB right? Being said that is only if the amp is the cause of the noise.
> 
> Sent from my HTC_PO582 using Tapatalk


But then you have to turn gain up to compensate. Boom, noise introduced again

Sent from my SM-G920V using Tapatalk


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## Kazuhiro (Apr 28, 2015)

SkizeR said:


> But then you have to turn gain up to compensate. Boom, noise introduced again
> 
> Sent from my SM-G920V using Tapatalk


It is a noise floor that stays the same whether I am sending zero signal or loud music. If I turn gains up on the DSP, that shouldnt change this noise floor should it?


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## oabeieo (Feb 22, 2015)

rnicolai said:


> I'm getting a constant "white noise - kshhhhh" sound from my tweeter when the system is turned on - happens when engine is off & also when running - acceleration or nothing else has any effect on the intensity of the noise whatsoever.
> 
> I have the tweets mounted in the a pillars hooked up in bridged mode to an Alpine KTP445-U (using RCA inputs).
> 
> Could this be a grounding issue with the amp, gain level issue, etc???


The ktp445u is a inline amp. It's garbage ! I install those daily and they all have hiss and are noisy . If you want a keychain amp that is worth a darn I would look into the little arc amp. There's a few others , but the ktp sucks .


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## Patrick Bateman (Sep 11, 2006)

just made a double post, whoops


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## Kazuhiro (Apr 28, 2015)

Gave it a shot. Had a look through my toolbox, ended up settling for a parallel pair of 5.6ohm resistors with 10 watt ratings. The 10W concerns me as they will only be rated for 20w on each tweeter, although this should be enough for audible volumes. Might have to buy some larger ones. So 2.8ohm resistance on each.

Afterwards the hissy noise floor is much lower. I still have the amplifier gains at zero, but on the dsp I have changed the tweeter gain from 0.7 to 1.37. 

It has exposed another error which I believe is alternator whine, although it is very faint. One notable thing about it is that only the left channel is effected by it. It goes away with the RCAs unplugged, so first I will try grounding the RCA cables up the front.
I am still using the ground on the factory harness as I figured if I am not running a full head unit I probably wont be drawing as much current with just a BT receiver and DAC. If grounding the RCA doesn't work, I guess I'll have to make a new ground in there.

EDIT: Fixed the whine, ended up moving DAC to the trunk. 
If I put my ear right up to the tweeters, I can still hear a slight hiss. Will have to step up the resistance a bit I suppose.


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