# Tweeters squealing when bass hits....



## rc10mike (Mar 27, 2008)

Yet another chapter in my noise problem book....

So I get my new AX3200D today. It sounds great and is a heck of a lot more efficient than my AX2000.

I was playing some 20hz stuff today just to test it out. I immediately noticed that the tweeters would squeal at high volumes.

This is the only clue so far,

"Don't connect all of your amplifier ground wires under one bolt. Contrary to belief, this is not required if the rest of the system is installed properly. If you do connect more than one power ground wire under a single bolt, you run the risk of amplifier ground modulation. This is caused by the current demands of, for example a woofer amp, modulating the power ground wire of a tweeter amp. This results in a squeaking noise that can be heard over the tweeters whenever bass notes hit."

Tonight I already tried moving the ground of the mid/high amp to 2 different spots..made no difference.

I tried muting the front speakers from the HU, no difference.
When I disconnect the rca's from the mid/high amp the noise goes away..


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## rc10mike (Mar 27, 2008)

Any ideas?


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## azngotskills (Feb 24, 2006)

tvrift said:


> When I disconnect the rca's from the mid/high amp the noise goes away..


try new RCAs


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## rc10mike (Mar 27, 2008)

azngotskills said:


> try new RCAs


Actually I did try that too


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## ChrisB (Jul 3, 2008)

So, if you disconnect your RCAs from the mids/highs amp while blasting some ultra low stuff through your subwoofer amp, the high pitch squealing goes away?  Does this happen with your other subwoofer amplifier?

Also, I see you have a Pioneer 800, be extremely careful with that unit. If you accidentally ground out the positive on your RCA while the HU is powered up, you can blow the internal pico fuse. A blown pico fuse will give you some weird noise in the system!


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## Bluto Blutarsky (Apr 1, 2007)

tvrift said:


> "Don't connect all of your amplifier ground wires under one bolt. Contrary to belief, this is not required if the rest of the system is installed properly. If you do connect more than one power ground wire under a single bolt, you run the risk of amplifier ground modulation. This is caused by the current demands of, for example a woofer amp, modulating the power ground wire of a tweeter amp. This results in a squeaking noise that can be heard over the tweeters whenever bass notes hit."


 Who said this?


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## t3sn4f2 (Jan 3, 2007)

Bluto Blutarsky said:


> Who said this?


Noise Prevention

It's from here. Dunno how valid it is though.


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## rc10mike (Mar 27, 2008)

06BLMUSTANGGT said:


> So, if you disconnect your RCAs from the mids/highs amp while blasting some ultra low stuff through your subwoofer amp, the high pitch squealing goes away? Does this happen with your other subwoofer amplifier?
> 
> Also, I see you have a Pioneer 800, be extremely careful with that unit. If you accidentally ground out the positive on your RCA while the HU is powered up, you can blow the internal pico fuse. A blown pico fuse will give you some weird noise in the system!


Yes, but not only with test tones, I can hear it while listening to bass heavy songs too. Also, I dont recall my last sub amp doing this, BUT I want to try and figure out what causes this noise before I say "bad sub amp"

Yes Im fully aware of the 800 problems, I already have the rcs gounded and currently I have 0 alt whine.

So how true is that termpro statement? Sounds like my exact problem, but that article is the only info I can find on it. I already tried re grounding the amps.


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## 60ndown (Feb 8, 2007)

i had some squealing once, it turned out it was a screw that was holding the speaker touching metal inside the door that it wasnt meant to be touching, try backing out 1 screw at a time (or all of them at once?) and see if the squealing stops.?

maybe when a big bass note hits (vba) its flexing a metal panel and making the screw touch?



tvrift said:


> Yet another chapter in my noise problem book....
> 
> So I get my new AX3200D today. It sounds great and is a heck of a lot more efficient than my AX2000.
> 
> ...


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## Bluto Blutarsky (Apr 1, 2007)

t3sn4f2 said:


> Noise Prevention
> 
> It's from here. Dunno how valid it is though.


 Couldn't we say everything in the car is grounded under one bolt? The one at the battery negative terminal?


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## LauZaIM (Feb 20, 2008)

What are you using to play the test tones? The head unit or an outside source? ie. laptop

Does it happen during music?


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## rc10mike (Mar 27, 2008)

LauZaIM said:


> What are you using to play the test tones? The head unit or an outside source? ie. laptop
> 
> Does it happen during music?


Ok I was using Bass Mekanik Power tools cd, actual copy not burned. I also heard it in bass heavy music.

While I was playing a 20hz tone, it sounded like the front speakers were producing a 20hz squeak. It starts at mid volume from where I normally listen.


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## Ziggy (Nov 29, 2007)

Is the "Loud" option on the 800 off?


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## t3sn4f2 (Jan 3, 2007)

Bluto Blutarsky said:


> Couldn't we say everything in the car is grounded under one bolt? The one at the battery negative terminal?


That's what I would think. They could mean that the bolt ground limits the current flow due to less surface area then a large lead lug on the battery. If that is why they say it then I don't see that as a possibility for any proper ground lug installed properly. They could say it as a precautionary recommendation assuming someone will be careless and just slap a bunch of terminals together half ass'ly on a thin bolt perhaps and not make direct contact with those lugs to the chassis. Just rely on the thin bolt to transfer the current.

Again, there could be an actual electrical reason to that recommendation that I don't know of.


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## Bluto Blutarsky (Apr 1, 2007)

t3sn4f2 said:


> That's what I would think. They could mean that the bolt ground limits the current flow due to less surface area then a large lead lug on the battery. If that is why they say it then I don't see that as a possibility for any proper ground lug installed properly. They could say it as a precautionary recommendation assuming someone will be careless and just slap a bunch of terminals together half ass'ly on a thin bolt perhaps and not make direct contact with those lugs to the chassis. Just rely on the thin bolt to transfer the current.
> 
> Again, there could be an actual electrical reason to that recommendation that I don't know of.


 I agree.
I would think if you had grounds all ganged up on a larger bolt, say a 3/8 (just like the size of a GM side post) you would be great. If you had them all ganged up on a #6 machine screw I would say it could be a problem.


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## rc10mike (Mar 27, 2008)

I hate my car/


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## rc10mike (Mar 27, 2008)

Any more ideas?


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## Ziggy (Nov 29, 2007)

Actually... I have same issue...but I turn my **** down when I hear it... I have alt whine on one channel too... 
But I'm drinkin and eatin hot wings rt now... Prolly gunna get busy with the g/f in a minute...
It's my birfday 2morrow... PARTY! 

Maybe ground your RCA's... Could be the inevitable pico... I'm there now...:blush: but i busy... drinktin


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## rc10mike (Mar 27, 2008)

Ziggy said:


> Actually... I have same issue...but I turn my **** down when I hear it... I have alt whine on one channel too...
> But I'm drinkin and eatin hot wings rt now... Prolly gunna get busy with the g/f in a minute...
> It's my birfday 2morrow... PARTY!
> 
> Maybe ground your RCA's... Could be the inevitable pico... I'm there now...:blush: but i busy... drinktin


Yep, already have the rca grounded to the HU chassis.


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## chad (Jun 30, 2005)

Bluto Blutarsky said:


> Couldn't we say everything in the car is grounded under one bolt? The one at the battery negative terminal?



I love the fact that the site has a section called "avoid ground loops" but does not condone star grounding


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## rc10mike (Mar 27, 2008)

chad said:


> I love the fact that the site has a section called "avoid ground loops" but does not condone star grounding


chad why am I getting this noise through my front speakers? You seem pretty smart, remember when you helped me fix that memphis amp on here a while back?


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## chad (Jun 30, 2005)

Something is oscillating, what kind of signal wiring, is it shielded, is it running along your sub wiring, and is indeed the shield grounded?


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## rc10mike (Mar 27, 2008)

chad said:


> Something is oscillating, what kind of signal wiring, is it shielded, is it running along your sub wiring, and is indeed the shield grounded?


Well, Im running the JL blue RCA's. Not really sure if they are shielded, but yes the shields are grounded, oh and they arent running along the sub wiring.


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## sqshoestring (Jun 19, 2007)

If you dump enough power into a ground, it could become not fully ground at some point. You could check voltage from battery ground to this ground under full power to see how much.

Most cars also have an engine to body ground as well so rarely is the battery to body the only body ground, but I don't know how much is too much for a given bolt. I have my amp on a bolt that holds the rear seatback in, it is just like the seatbelt bolts and very solid. But it is above the floor so less possible moisture issues there. Of course I only have about 700rms in the whole car.

I have to say I'd look at RCA type issues first, especially if it stops without the RCA. Makes me wonder if the new amp is back feeding noise into the HU though, not had that issue before just an idea.

Shielded RCA means and inside wire and shield of wire or foil covering it. Twisted pair is two wires twisted with no cover over them. Those are two major types of RCA I see out there.


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## JoshHefnerX (Jun 13, 2008)

tvrift said:


> Yet another chapter in my noise problem book....
> 
> So I get my new AX3200D today. It sounds great and is a heck of a lot more efficient than my AX2000.
> 
> ...


Your last sentence 1/2 answers yourself. If you're pulling the rca's from the amp, you either have a problem w/ the rca's or the deck. Try pulling the rca's from the HU and leaving them in the amp. If it's still silent, the you have a problem w/ the HU. If you hear it again, they something may be flexing and pinching/shorting the rca cable.

Josh


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