Rep Power: 312

As some of you know, i have my laptop ran into the aux input of my clarion DXZ855MP and i'm getting amp hiss....bad....i don't think it's a preamp problem cuz when i turn the sensitivity up on the aux inputs, the hiss goes up with it...so i'm thinking it an impedence miss-match. My laptop is 50mWa and 20Ohm, but i cant find what the input levels are on this freaking deck. I went to clarion's website site and it told me that an aux input was to "accept input from an external device" the world is getting way to dumb these days. any idea what it would be or where i could find it?

 
Rep Power: 0

you could always try giving tech support a call, you'll be escalated to a level 5 tech before getting information that classified

 
Rep Power: 0

you need a better RCA cable. but the real problem is your using mini RCA that Y splits into regular left right channel RCA cable... if you understand that... its your reason for the hissing

 
Rep Power: 334

 
Rep Power: 312

it's not that it's the deck itself....even when i have nothing hooked up it hisses, i just went and bought impedence converters and wired it into the deck. I'm thinking i might get an ipod adapter and use that for the input...any other ideas?

 
Rep Power: 289

its a groudning issue. run find a metal ground on your laptop.. a screw the goes in. or inside the battery pack maybe. and ground your lappy to your car close to the decks ground.

should solve your problem toot sweet

et me knwo if that works. it did for me with my xbox. which is a pc in th general sense with the same rpoblem on my clarion

 
Rep Power: 312

i just went and bought a ground loop isolator and it helped sound clarity but the hiss is still there, it's something in the deck itself...i'll have nothing hooked up to it at all and the hiss is still coming through, i do have i little altenator whine so i'm thinkin it might be a ground problem....but i dont hear it on cds or radio...i'm confuzed

 
Rep Power: 289

it is a ground problem.. groudn yoru lappy like i said and plug her in.. and youll see its gone.. as for a hiss when laptop isnt plugged in. its picking up interference fromt he cables and so forth crap. same problem has no where to groudn that to so it lets u hear it hehe..

umm try this
if you know enough about rca cables. the outside metals ring is ground. see if u can hack into each cable. create a comon ground and run that to the chasis of the car.

you have a ground issue cause even though people install the rca's there designed for incar things. I.E. dvd player. which is designed to ground itelf incar. things like a lappy, pc, xbox so such arnt designed to ground them selves properly. hence why they mostly use two prong a/c plugs isntead of groudned 3 prong


****
do as i said. ground your laptop. pop open the batter area. find a case screw toushin metal. lift it slide a wire in there and groudn the wire. see if it kills the hiss with the laptop installed. if it does great im pretty sure it will. as for unplugged u need to either detach the cables. or find a proper way t groudnt hem to the casis when not in use.

simply decks are designed to have rca in but not designed properly

i have a high end clarion i get the same thing. its luck fo the draw

 
Rep Power: 312

I'll try that but the laptop also has a crappy sound card so tonight i built a preamp for it to clean the sound up, i used a dual-gain style with a ne5532an dual op-amp coupled with a ne5534an's for each channel...I just smoked one of the ne5532an's cuz of a "wiring issue" (aka me getting +18v and -18v mixed up). even without grounding the laptop the one channel of it that worx sounds sooooooooo much better.

for those of you that dont know what the hell i just said i just made myself a purty new preamp that doubles the input volume of my laptop with only one **** up....


I'm still going to try the grounding of the rcas but i dont think it'll help cuz when i disconnect the rcas from the back of the deck the hiss is still there...i think that i'm just overdriving the inputs on the deck itself by sending this chincy laptop signal too it. I'll still do it though, it wont do anthing but help it; and plus it'll be easy to do when i hook up the preamp, only one more wire, so y not?

 
Rep Power: 335

so you are telling me that you are using your laptop with rca input of the deck...

well the hiss is coming from the ground loop...let me elaborate

your car has battery voltage with reference to the GND or chassis ground….12V to the chassis
Also your laptop has ground with respect to the laptop battery….your pc battery voltage to the ground….

The problem occurs these two ground are not relative to each other…I am saying that these two grounds are totally different grounds…

Your deck will see through RCA some voltage(signal) from your laptop….but this signal coming into the RCA will have a reference of car battery ground…
Also the signal from the laptop will have a signal...

------- this is your signal from laptop


------- this is your (laptop or car) ground..
------- this is your (car or laptop) ground..

-------- this is the absolute ground or earth ground…

when you measure against earth ground, there is a difference…between laptop and car grounds...

but you know all this since you are capable of building an amp….
if you were close to me, i would be able to figure out using equipments from work...

 
Rep Power: 360

I had this once by mistake. Some metal part of the unit is directly touching metal connected to the chassis of the car. Most likely its the end of one of the RCA input/output jacks coming out of the unit. I had that problem. Just tape over the rca jacks you aren't using and move them off metal.

And Devani, even if the reference ground for each device is different, I have seen this done before and work well. Also I highly doubt that the difference is that big, as they are both 12V batteries (right?). So the difference should be minimal. If it really is the ground difference making, then we can all discover the beauty of op-amps.

 
Rep Power: 335

that metal part touching chassis of the car could be problem...although it never happened to me tho...
Dell inspiron uses 14.8V and Hitachi old one uses 12V thinkpad 1417 uses 9.6V....i have them....idk about all the others...all laptops are different...

ground difference should be minimal like you said...
only way to make sure is to actually see it on a scope...

 
Rep Power: 312

I dont mean to sound dumb but even with absolutely nothing plugged into the deck it still hisses....but it still a grounding problem with the laptop?

 
Rep Power: 360

Its either the unit is improperly grounded, check that wire, or a metal part of the unit is grounded which is no supposed to be, check the other wires.

 
Rep Power: 312

this i will do today i just ran out of daylight to do it last night, the reason y i'm sceptical about grounding the laptop is i built all this so it'd be removeable.

 
Rep Power: 360

Well, just look at your ground and all your signal wires. If you have RCA terminals not being used make sure to tape over them with like electrical tape or cover them with the caps the HU came with (but they fall off so I suggest tape.)
If you do tape over them, just make it so that if you have to take it off, it will come off easily later, but won't fall off on it's own

 
Rep Power: 312

as long as the laptop comes out and the mount i have folds down i'm happy...hopefully once i take care of this hiss it'll sound better than cd quality, this preamp sounded pretty damn good (for the channel that worked)

well i taped everything off, and put in a new ground and the hiss is still there....only thing i can think to do at this point is swap out the NE5532AN with a opa2228 on my preamp so it has ALOT more gain than it did before, so i have the deck at a lower volume and hear less hiss

 
Rep Power: 0

the preamp you built sounds interesting, any schematics??

 
Rep Power: 312

I've got the schematics of the chips, but the caps and the resistors came on the board...

 
Rep Power: 360

this hiss is probably alternator wine. search that and see if you can find some other fixes for it. They make those ground loop isolators and sell them at radioshack, but search around here to find what worked for other people.
sorry i cant reply more but I have tons of homework to do for my math and electrical engineering class right now!

 
Rep Power: 312

here's a pic of the preamp i just built\installed:

it made a HUGE difference in clarity and volume....i cant find a good place for a ground really...i'm using the metal behind thefuse box right now. I was wondering if i should just screw into the metal brackets around the center console or what?

 
Rep Power: 360

ground on any chassis metal as long as you sand off the area first. that way you get the best contact possible.
good idea too, glad you are electronics literate.

 
Rep Power: 312

I'll try that and see how that works...any ideas if that doesn't work?