[Raiz]

So I took out the factory speakers and added in some Infinity Kappa 6.5 components. The woofers sound great, and the tweeters do too, BUT, there is a hiss coming from them. When I put the factory tweeter back in, the HISS is gone, but it sounds like a wet towel is covering it.... which is the reason they were replaced.

I tried to get rid of the hiss by adding various resistors and capacitors, but none of them seem to do much to get rid of it. They do have an effect on the volume of the tweeter though.

Please help!

 

[Raiz]

Maybe try moving the ground. Is this running off factory power or aftermarket amp/hu?

It's running off of factory power. I just did a direct replacements of the factory speakers with the Infinity Kappa components. It does not get louder when the car is running or when I rev it up. It's there when the car is off and just running from battery power. It has to be that the aftermarket tweeters are more sensitive than the factory tweeters.

Any ideas what my next steps to get rid of it should be?

 

[Raiz]

Probably ground loop.

I've been doing all the tests with the car off. I turned it on and pressed the gas a few times. The hiss stayed exactly the same. It didn't get louder or quieter. That's the easiest way I know to test for a group loop.
I really think we are dealing with a sensitivity issue on the tweeter.

 

[Raiz]

If the tweeter is quite a bit more sensitive than the old one, I would expect it to play louder too.

You could build some L pads from resistors, there are online calculators..

Thanks. I'll see if I can google a good guide.

 

[Raiz]

Yes, this is because the new tweeter is more sensitive. the noise was there before it was just below the audible threshold... just like @bnae38 said.. you need an L pad to attenuate the output before it reaches the tweeter so you will not hear the hiss when your volume is turned down.. its a PITA i do everything possible to keep my system from doing it.. i cannot stand any humm or hiss.

Exactly what I'm thinking. I have several different resistors and capacitors (kits from Amazon).

I have tried all of the following:

1. Adding a resistor on the positive line of values: 1.2, 2, 3.3, and 4.3 Ohms.
2. Adding a capacitor on the positive line of values 2.2uF, 4.7uF, 10uF, 22uF, and 47uF.

The volume changed whenever I added in the resistors/caps, but the hissing remained throughout. I tried each of these 1 at a time in series on the positive line going to the tweeter.

 

[Raiz]

y the loc simply can't knock down 20 dB of boost at 30k.

So..... how do I fix it? It's a brand new 2021 VW Tiguan R-Line if that helps at all.

 

[Raiz]

The cap would need to go between + and -, (not inline).




Turning the gain down.
Using the resister line does that to an extent… maybe a cap brethren the +/- ,Then a larger resistor to the speaker after that… or visa—versa.




No Argument with the last part. But it still deserves some work to understand if it is the source/amp.
if there were RCAs from the HU, then it would make lifer easier.

Sweet! These are the answers I'm looking for. Being a noob to all this I guess I figured it needed to be in series with the woofer, not in parallel. I'll give it a try!

 

[Raiz]

Without a dsp there is not much you can do.
You could add an inductor in in line and lowpass the tweeter around 20k you would need a 0.03 inductor in line with the positive wire.

If the cap across the tweeter doesn't fix it when I try it tomorrow, I'm down to move to the next step. If that's a DSP, give me a recommendation for an inexpensive yet decent one!

 

[Raiz]

Stop wasting your time man.
What car is this? Make year model

2021 Volkswagen Tiguan R-Line

 

[Raiz]

I tried placing several different value capacitors across the + and - leads. It didn't seem to help at all. The factory tweeter has a 5.6uF cap soldered into it. I desoldered it and tried that on the new tweeter as well but it had no effect.

The hiss is still present.

 

[Raiz]

While it would be nice to go our an spend $1500 on an amp, I'm kind of having fun troubleshooting this issue.

My next plan is to create a low pass filter and start knocking off the higher end frequencies until the hiss disappears. After some reading, a resistor in series and a capacitor in parallel with the tweeter should create the filter.

I'm going to start with a 1ohm resistor and a 14uF capacitor, which will knock off anything above 10khz.... if the web calculators are correct. Should be a good starting point.

 

[Raiz]

More updates.
The stock speakers DO have the hiss, it's just much more minimal. This confirms that it's just a crappy signal from the head unit. The reason it's so minimal on the stock tweeters is because they constantly sound like they have a pillow over them, so the hiss is hard to hear unless you put your ear up to them.

I created a few low pass filters and didn't have great results. Adding the resistor in series definitely lowers the overall volume of the tweeters (as it should), but the capacitor in parallel doesn't appear to do anything. It should be cutting out the high frequencies as I increase the size of the cap, but it isnt... or at least it doesn't sound like it to my ears. I'm simply jumping a bipolar cap it across the + and - lines going to the tweeter. Am I doing something wrong here?

 

[Raiz]

Some diagrams show the capacitor running to ground instead of the negative side. Something to try in my next attempt I guess.

 

[Raiz]

A cap will not filter any high frequency from the signal path.
You will need an inductor. At 4 ohm the value is 0.03 millihenrys.
A cap will not filter high frequencies.

Thanks for the reply. My reading has shown that a low pass RC filter should filter out high frequencies using a resistor in series and a capacitor in parallel with the signal. Could you further explain why a cap won't filter high frequencies? It's not that I don't believe you, but rather I just want to understand.

 

[Raiz]

The ultimate solution, as some of you have pointed out, is to find a way to clean up the signal from the factory head unit before it even gets to the speakers.

Given that I have plenty of volume coming from the speakers, I assume I don't need an amp at all. I just need a way to clean up the signal to the speakers.

 

[Raiz]

Well, I gave up.

Couldn't get rid of the hiss no matter which way I hooked it up. The only fix would be an aftermarket DSP with an equalizer built in so I could find the afflicted frequency and drown it out.... but then I'd need a amp... the cost keeps going up and it's more than I want to spend on this project, so I installed it as is. If you're driving or the AC is blowing, you can't hear the hiss, but I will always know it's there and it will bother me.

 

[Raiz]

You maybe need to figure out where the hiss is coming from? (Otherwise we are back to post #21 and the concept of throwing solutions at a problem)

99% certain it's coming from the head unit. I hear the hiss on the stock tweeter as well as the aftermarket tweeter, it's just a bit more noticeable on the aftermarket tweeter (because it's more sensitive). The aftermarket tweeter is still much better than the stock, so it's an upgrade, but I don't have the time or money to make it sound like I want to.

 

[Raiz]

Yes, I want to keep the highs. We are on a road trip now and the sound out of the new tweeters is much more clear and open compared to the stock.

I need to keep the OEM head unit for navigation, various sensors, car warnings etc.

EDIT: I measured resistance across the tweeters as 4ohm. Unless the crossover combines the woofer and tweeter resistance to make the overall system 2ohm.

 

[Raiz]

in this instance i would consider a helix dsp with a dedicated dap or phone digital input so you can then set the vw hu as a main input and have it switch over for a set time if it senses signal on the main in, but you will get high quality digital audio from the dap

So the fix is to completely bypass the OEM head unit... 😕

 

[Raiz]

In case I missed it, in a quick scroll....
I'm just curious how high you are having to turn your gains up ??? I had a Kenwood HU, that had issues, and I had to really crank up my gains, especially with my mono subwoofer amp, and that led to a lot of ugly hiss.
Ended up getting a sweet new Pioneer and immediately I was able to turn my gains down to less than half. Hiss immediately went away 🙂👍

I'm not. I'm using direct replacement speakers on a factory head unit. No amp is installed. The hiss is present on both the factor tweeters and the aftermarket tweeter, but it is more pronounced on the aftermarket tweeter because it is more sensitive. This is all because the signal coming from the factory head unit is crap and needs to be corrected somehow.