# HELP! - Tweeter Hiss



## Danco1985 (Aug 30, 2011)

I just put in a system in my 2011 Jeep Grand Cherokee. It sounds great- but I have a hiss coming out of the tweeters. The hiss is a constant volume and pitch (not engine noise) and is there wether the volume is on or not. 

My gear:

HU: Stock
Processor: Lc8i
Fronts: Morel hybrid II 6 2way
Front Amp: Boston Acoustic GT-24
Rear fill/rear amp: stock
Sub: 12w6v2
Sub Amp: JBL MS-A500.1

Does anyone have any ideas on what this could be? I want to get a list of options to try before I take my car apart. All the amps and crossovers are hidden behind panels It will take me 45ish minutes to get to them so I really only want to do this once. 

Thank you in advance.


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## boogeyman (Jul 1, 2008)

Try lowering the gains on your front amp


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## Danco1985 (Aug 30, 2011)

It is not the gain. Even with gain all the way down and output on the lc8i all the way down the hiss is there. Any other ideas?


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## chad (Jun 30, 2005)

noisy amp.


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## Danco1985 (Aug 30, 2011)

What does that mean? The amp is broken or it is normal for this amp?


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## chad (Jun 30, 2005)

well, if the hiss is still there witht he amp turned all the way down, and/or the RCA's unplugged, then I'd say it's the nature of the amplifier.


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## dragonrage (Feb 14, 2007)

Hiss = poor SNR in some component along the way. If the amp gain knob doesn't change the hiss, then it's probably coming from the amp. If the gain knob does change it then it's at least partially coming from before the amp.


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## boogeyman (Jul 1, 2008)

What is the SNR of the amp?


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## ///Audience (Jan 31, 2007)

boogeyman said:


> What is the SNR of the amp?


SNR = Signal/Noise Ratio


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## azngotskills (Feb 24, 2006)

i have read that those audiocontrol pieces are notorious for noise problems....with the LC8i not plugged in, is there noise?


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## boogeyman (Jul 1, 2008)

BassBaller5 said:


> SNR = Signal/Noise Ratio


I know what it means I was asking the OP what the SNR was on his amps. 80 90 95 etc.


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## Danco1985 (Aug 30, 2011)

boogeyman said:


> What is the SNR of the amp?


>100db


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## Danco1985 (Aug 30, 2011)

Any other ideas? This hissing is making me want to rip out everything and go back to stock!


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## Grindcore (Dec 12, 2012)

Weird...I just replaced my Boston m1 tweets with some morel mt230...now I hear a hiss coming through the tweets when I def didn't before.i re adjusted the gains with an o-scope...still hear the hiss.the amp has a snr of 95.the old tweets were 8 Ohm these new ones are 6...is there anyway it could be a problem with their rating?? Didn't mean to hijack the thread but could the problem be a compatibility issue??


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## RNBRAD (Oct 30, 2012)

azngotskills said:


> i have read that those audiocontrol pieces are notorious for noise problems....with the LC8i not plugged in, is there noise?


What pieces are you talking about? Audio Control has always been the most transparent processors I have ever used. Extremely quiet!!!

It's usually a gain, level match problem somewhere though.


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## HIS4 (Oct 6, 2005)

You can try changing the ground isolation setting on the LC8 to see if that will help. Sometimes the wrong setting will cause noise.


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## ATOMICTECH62 (Jan 24, 2009)

The amp most likely has a defective op amp in the preamp stage.


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## LexusLover (Oct 14, 2017)

I'm having the same problem with an Audison 6 channel amp


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## gijoe (Mar 25, 2008)

You're amp is either terribly noisy, or just plain broken. An amp should never create hiss when there is no input signal to amplify.


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## Holmz (Jul 12, 2017)

gijoe said:


> Your amp is either terribly noisy, or just plain broken. An amp should never create hiss when there is no input signal to amplify.


Actually the SNR is the worst when there is no signal, as there is always noise added whether it is active components are even just a resistor. (Assuming that the temp is above 0-Kelvin.)

So usually one wants a lots of signal, so when a fixed amount of noise is added, then the SNR is maximised.
This is often somewhat jacked up as there is usually a fixed gain preamp stage and then the gain knob attenuates the signal down... better is to have the minimum amount of fixed gain - which is almost never done in car audio.

Whether the amp is just a noisy amp or actually broken requires someone who is knowledgable in servicing it.


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## Patrick Bateman (Sep 11, 2006)

LexusLover said:


> I'm having the same problem with an Audison 6 channel amp


It's a band-aid, but keep in mind that you can reduce hiss by simply wiring a resistor in-line.

Think about it this way:

Let's say that your tweeter has a constant hiss that's 70dB in level. If you wire a resistor in-line, and reduce that hiss by 10dB, that will make the problem way less annoying. It's true that you're throwing power away, but power is cheap.

Note that this works best if the hiss is constant. IE, if the level doesn't get louder as you crank up the volume.


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## Holmz (Jul 12, 2017)

Patrick Bateman said:


> It's a band-aid, but keep in mind that you can reduce hiss by simply wiring a resistor in-line.
> 
> Think about it this way:
> 
> ...


On the RCAs or on the speakers?
What size resister would one use?


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## JVD240 (Sep 7, 2009)

What head unit? Factory system configuration? Is it the Alpine system with centre channel?


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## Holmz (Jul 12, 2017)

JVD240 said:


> What head unit? Factory system configuration? Is it the Alpine system with centre channel?


The first post and then then this year's posts talks about gear.

Conceptually though, one may be better off understanding the source of the noise, rather than just chucking resistors in the direction of gear.


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## LexusLover (Oct 14, 2017)

I wish I knew the source of the noise. I thought I had pretty decent gear, but this hiss is making me think otherwise!


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## LexusLover (Oct 14, 2017)

I have the factory non mark Levenson head unit hooked up in my 2013 lexus es 350. It is hooked up by hi level speaker wire after the factory amp to a brand new audio control DM 608 DSP. Then the signal is fed to my 6 channel Audison Vrx 6.420.2 for my highs and mids which are a sundown SA-6.5 CS v.2 component set actively crossed over by the dsp. Also for my subs I have 2 12' sundown SA d4 rev 3 in a ported box tuned to 36hz pushed by an Audison Vrx 500.1. I am only getting a hiss thru the tweeters that does not go up with volume but does go up with gain. My gain is all the way down and still there. Also it doesn't matter which channel I have the tweeters hooked up to the hiss only follows the tweeters and not any other mid range speakers I hook to the other channels???


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## LexusLover (Oct 14, 2017)

It's the factory non mark Levenson head unit. I don't think it is an alpine but it does have a center channel.


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## LexusLover (Oct 14, 2017)

How much of a resistor? Do you know where I can find one?


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## Holmz (Jul 12, 2017)

LexusLover said:


> How much of a resistor? Do you know where I can find one?


If there is noise when the input is either disconnected or grounded, then it is coming from the amp.
If the amp is quiet with input RCAs grounded, then you need more gain before the input.

You do not need a resistor. A small cap could roll the highs off, which will mitigate some of the noise in addition to removing music.


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## DPGstereo (Jan 16, 2013)

Issue is most likely the Audio Control LC8.
I know they will talk about gains being off or ground jumper settings... never worked for me. 
I’ve used them several time, with different projects. While convent and inexpensive, they are noisy in the high frequencies. Always get tape-hiss from tweeters. Especially if high frequencies are boosted, at all. May try cutting high frequencies as much as you can live with. However, that kinda defeates the purpose...increase missing frequencies.


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## LexusLover (Oct 14, 2017)

It's actually the new DM 608 DSP not LC8I but I've heard the same thing about audio control and even some of the best DSP's like the Audison bit ones are suppose to be real bad. Not at all what you would expect when spending 500 to $1500 on something thats suppose to NOT drive me crazy! I've tried lowering the incoming signal, my gains are all the way down. Grounds are all to 1 distribution block and to one point on the chassis. Ive tried all the different grounding pin jumpers and tried different Rca's. I don't know what else to try?


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## DPGstereo (Jan 16, 2013)

LexusLover said:


> It's actually the new DM 608 DSP not LC8I but I've heard the same thing about audio control and even some of the best DSP's like the Audison bit ones are suppose to be real bad. Not at all what you would expect when spending 500 to $1500 on something thats suppose to NOT drive me crazy! I've tried lowering the incoming signal, my gains are all the way down. Grounds are all to 1 distribution block and to one point on the chassis. Ive tried all the different grounding pin jumpers and tried different Rca's. I don't know what else to try?


I've noticed that even with my Mosconi 8to12 Aerospace, if 8kHz and up are boosted much at all, you start hearing the dreaded "Hiss". 
Most SQ tunes, that I've seen, tend to roll-off 8kHz and higher. I wonder if this is why? Get a quite of sound as possible.
Of course, the higher your amp gains are set, the more it amplifies the noise.
And the closer you sit, physically, to the tweeter, the more noticeable it is.
The "dryer" the tune you can live with, the quieter the system will be, I've found.


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## LexusLover (Oct 14, 2017)

Did you have the same hiss with your Mosconi? And are you saying that you got relief from it by actually turning down the EQ on the bands above 8k?


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## Holmz (Jul 12, 2017)

LexusLover said:


> Did you have the same hiss with your Mosconi? And are you saying that you got relief from it by actually turning down the EQ on the bands above 8k?


Correct.
It may be easier to see which bands with a graph, but the noise is usually broad band.


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## LexusLover (Oct 14, 2017)

Ok cool! I might have some time to go mess with it today. I'll let you know my results. Thanks for your input.


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## LexusLover (Oct 14, 2017)

I was thinking about the whole resistor thing and wondered would a passive cross over count as a resistor in this situation? Or not enough of one to make a difference? Because the hiss was there with the tweeters both actively and passively crossed over. Not that I want to use that band aid of a fix with the resistor, but I was just curious to the logic if the passive cross over didn't even quiet it down a little.


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## Holmz (Jul 12, 2017)

LexusLover said:


> I was thinking about the whole resistor thing and wondered would a passive cross over count as a resistor in this situation? Or not enough of one to make a difference? Because the hiss was there with the tweeters both actively and passively crossed over. Not that I want to use that band aid of a fix with the resistor, but I was just curious to the logic if the passive cross over didn't even quiet it down a little.


No.

If the noise was from the preamp, then some attenuation (and hence more input signal to make up for it) could help.

Out the amp... then the tweeters are getting the same signals either directly or through the passive cross over.

What this really means is that you should try setting the EQ low and seeing if there is a difference... if there is no difference, then it means that the noise if from the amp itself.
So then set the EQ as high as possible, which should make a difference.
If the later is the case, then turning the head unit up and the amp gains down... (or the whole of the EQ bands up) should make the most of signal relative to noise.


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## DPGstereo (Jan 16, 2013)

LexusLover said:


> I was thinking about the whole resistor thing and wondered would a passive cross over count as a resistor in this situation? Or not enough of one to make a difference? Because the hiss was there with the tweeters both actively and passively crossed over. Not that I want to use that band aid of a fix with the resistor, but I was just curious to the logic if the passive cross over didn't even quiet it down a little.



I'd try..with everything connected and gains set to optimum settings...put EQ in by-pass mode. If less "Hiss" then you know that you can correct by lowering high frequencies settings. Usually above 8kHz. Re-engage EQ... for 6kHZ and above, try at flat position..0 boost.. or lower, if you can live with it. 

Using an in-line filter/resistor on a tweeter will simply lower it's volume.
You can accomplish, similar results by cutting/lowering frequencies with EQ.


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## Holmz (Jul 12, 2017)

DPGstereo said:


> I'd try..with everything connected and gains set to optimum settings...put EQ in by-pass mode. If less "Hiss" then you know that you can correct by lowering high frequencies settings. Usually above 8kHz. Re-engage EQ... for 6kHZ and above, try at flat position..0 boost.. or lower, if you can live with it.
> 
> Using an in-line filter/resistor on a tweeter will simply lower it's volume.
> You can accomplish, similar results by cutting/lowering frequencies with EQ.


A filter maybe, but a resistor alone will only make it worse.
If the noise is "in the amp" itself, then there will be little help by doing anything to the signal feeding into the amp.

If grounding the inputs still results in the hiss-noise being presents, then an amp with lower noise is needed if the goal is to have less of the hissy-noise.

Basically the OP needs to figure out if the noise if being fed into the amp, or if it is being created within the amp.


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## LexusLover (Oct 14, 2017)

What is the OP, is that me? I only get the hiss out of the tweeters, no matter what channel I power then off. The mids and/or sub don't get a hiss off any of the channels on the amp. Wtf! I'm starting to think it's the tweeters themselves, but how would that even be possible?


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## Holmz (Jul 12, 2017)

LexusLover said:


> What is the OP, is that me? I only get the hiss out of the tweeters, no matter what channel I power then off. The mids and/or sub don't get a hiss off any of the channels on the amp. Wtf! I'm starting to think it's the tweeters themselves, but how would that even be possible?


Yes, original poster == OP.

It is not the tweeters, unless those tweeters make noise even unplugged from the amp. Which they do not... as perpetual motion machines do not exist.

The noise is either white noise or pink. (I think it is white noise). So from a frequency perspective the noise is predominantly in the tweeter band.

Let us assume that the amp has noise coming out... then at the woofer and mid bass , those do not have great response at high frequency so the signal drives the speaker poorly being "out of the speakers band".
The only speakers that are optimised to play the noise is the tweeters.

However we have not proven it is the amp, unless you have actually powered the amp, without any input, to hear the hiss.

Of course a nice two little channel amp could power the tweeters and one could leave the other speakers on the noisy amp... if it even is the amp, which remains to be proven.


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## LexusLover (Oct 14, 2017)

Omg I just fixed it just now! It was a setting on the amp for the incoming signal. I had it set to accept 0.5 to 5 volts but I changed it to only 0.15 to 1.5 volts and the hiss was gone like a fart in the wind! Just in time too because I was gonna loose my mind! I am so relieved. Thanks to all for their inputs and thoughts.


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## Holmz (Jul 12, 2017)

LexusLover said:


> Omg I just fixed it just now! It was a setting on the amp for the incoming signal. I had it set to accept 0.5 to 5 volts but I changed it to only 0.15 to 1.5 volts and the hiss was gone like a fart in the wind! Just in time too because I was gonna loose my mind! I am so relieved. Thanks to all for their inputs and thoughts.


What's sort of song did you play?


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## LexusLover (Oct 14, 2017)

I played some classic rock and some rap. It didn't matter what type of music was played as far as that God awful hiss was concerned tho, as the hiss was always there even with the head unit turned off!


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## Holmz (Jul 12, 2017)

LexusLover said:


> I played some classic rock and some rap. It didn't matter what type of music was played as far as that God awful hiss was concerned tho, as the hiss was always there even with the head unit turned off!



It may have sounded good with this?


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## LexusLover (Oct 14, 2017)

The Doors sound pretty good for sure! Lol
I need to tweak some of my crossovers and could use a little more power now but I'm over all pretty pleased with my system now.


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## Holmz (Jul 12, 2017)

LexusLover said:


> The Doors sound pretty good for sure! Lol
> ...


Well the point was at the rain sound in that song should not be too affected by the hiss.


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## LexusLover (Oct 14, 2017)

The hiss is completely gone. Not even a trace of it anymore!


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## Holmz (Jul 12, 2017)

LexusLover said:


> The hiss is completely gone. Not even a trace of it anymore!


Maybe if you listen to the song "Riders on te storm", the humour of hiss not affecting it will come through... but many do not appreciate my sense of humour.


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## Jairow (Aug 22, 2017)

LexusLover said:


> Omg I just fixed it just now! It was a setting on the amp for the incoming signal. I had it set to accept 0.5 to 5 volts but I changed it to only 0.15 to 1.5 volts and the hiss was gone like a fart in the wind! Just in time too because I was gonna loose my mind! I am so relieved. Thanks to all for their inputs and thoughts.




Thank you for posting this! I was following this thread as I had the same thing. Switched from high level to rca on the amp for the heck of it after I read this post and that did the trick. Didn’t think it would work since I have high levels in to the MiniDSP and rca out to the amp from the dsp. 


Sent from my iPhone using Tapatalk


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## LexusLover (Oct 14, 2017)

Ok I get it now...im just a little slower than most lol


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## LexusLover (Oct 14, 2017)

I'm glad I could help you by figuring out what I had done. That hiss will drive you crazy and it's such a relief to have it gone forever. I was questioning every piece of equipment in my system as the culprit and come to find out it was just operater error!


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## JimmyDee (Mar 8, 2014)

Holmz said:


> Maybe if you listen to the song "Riders on te storm", the humour of hiss not affecting it will come through... but many do not appreciate my sense of humour.


I got your humour... right from the start.


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## 01LSi (Jul 27, 2012)

LexusLover said:


> Omg I just fixed it just now! It was a setting on the amp for the incoming signal. I had it set to accept 0.5 to 5 volts but I changed it to only 0.15 to 1.5 volts and the hiss was gone like a fart in the wind! Just in time too because I was gonna loose my mind! I am so relieved. Thanks to all for their inputs and thoughts.



Freaking thank you. This really bummed me out. Every time I got in my TLX it was depressing hearing this. Installers will all tell you "hiss and noise are normal". My ears are extremely sensitive to these sounds and noises alot of people don't hear in the same room as me and I've done it before without a high noise floor ...

I ran the stereo ground to share the same point with all other equipment. Have excellent quality cables. Running this all post factory amplifier and thought I'm going to have to live with it or revert to stock and take the hit.

I have an Alpine pdx-f4 and couldn't get rid of the hiss. Have this one from my last car

I have an Audison AV 5.1k and couldn't get rid of the hiss. I was using this on the system originally.

After reading this I risked buying a third damn amp that has a low level / high level sensitivity SWITCH. A JL HD 900/5. 

Hell wouldn't you know it. Problem solved.

PDX sensitivity wasn't adjustable. Audison required chopping the RCA's and I didn't wanna try chopping them or running another additional 8 conductor set from the front to back.

This has pissed me off so much. Thanks a damn million. 

On that note I have those two amps available for sale if anyone's interested. Audisons barely used.


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## LexusLover (Oct 14, 2017)

Try changing the setting on the amp for the hi/lo level input switch. I had the same problem and that took care of it. The hiss with return if I get my gains up too high still tho but I am able to keep my sanity for now!


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## LexusLover (Oct 14, 2017)

Sweet I'm glad I could help someone! It took me a while to figure it out but it was such a relief when I did!


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