[Holmz]

Probably ground loop.

If it is white noise and the engine is off, then priably not a ground loop??

 

[Holmz]

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.

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

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

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.

... Otherwise the OP needs a new source/amp.

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.

 

[Holmz]

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!

An amp with a high damping factor will need a resistor in-line before the capacitor.

If it is the amplifier that is hissing like a pit of vipers, then a DSP will not help.

ideally one probably wants to understand what is happening before just throwing a buchacci of solutions at the problem hoping one of them sticks to it.

 

[Holmz]

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.

An inductor would also do it well, or a bigger cap across the +/-.

A used amplifier with a low noise floor should be easy if the HU had RCA outputs.

 

[Holmz]

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)

 

[Holmz]

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.

If it is coming out of the HU then how do you explain this:

… The only fix would be an aftermarket DSP with an equalizer built in so I could find the afflicted frequency and drown it out...
…

However the other fix could be a HU with less noise.

but,… we sort of need a way to work out whether either cure is reasonable.

 

[Holmz]

A cap across the tweeter pod and neg won’t reduce high freqs, it will load the radio down more as in theory at some freqs it could be a dead short, but it certainly won’t reduce voltage at the tweeter or the current through the tweeter, sorry but that is a waste of time
…

yeah it would require a resistor in front of it, otherwise the amp would just keep adding more high freq.

 

[Holmz]

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

If you are completely bypassing the HU then you could do that kid you have an amplifier.
But I lost track of whether or not you have an amplifier between the HU and the speakers???

If you do, then just get an iPhone to RCA and plug it in and see how that sounds.
That 8 to $15 should probably come before shipping for DSPs.

If not then you probably need the amp at some point anyhow and it will let you have some way to determine if the speakers are OK or not.

 

[Holmz]

But what does a cap do across the speaker terminals? A resistor will reduce levels regardless of a cap being present, I don’t get what the cap even does apart from present a potential short circuit at some freqs?

in a first order circuit when the cap is playing well above the crossover point it is effectively not there, ie a short… so the speaker plays whatever it does. So for example a 4 ohm tweeter with a crossover point of 3.5khz at 6khz the cap will add no resistance to the circuit and therefore the driver can play 6khz as loud as it coul were the cap not there

Now put that same cap over the + and negative terminals and at some freq it will become a dead short, how does that achieve anything? Do anything functional?

The OP wanted to try resistors, etc.

The cap across the +/- should short the high freqs, but only if there is a resistor before it, otherwise the amp will just drive it harder.

But yes an inductor is probably better.

 

[Holmz]

You guys are probably right.
(Because I think that OP still had it hissing.)

 

[Holmz]

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 pronounces 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.

You cannot remove the noise without removing the signal along with it.
So without a lower noise amplifier, and using the existing HU, there is not a lot of options left.

The only thing I believe that you could do is put something like 4 or 8 ohm resistor in series, and then a 4 ohm in parallel with the speaker +/-.

• That will attenuate the new speakers by 1/3rd using 2x 4 ohm resistors… so ~4-5 dB.
• And using the 8 ohm, in series, and the 4-ohm in parallel, will attenuate it by 1/5th or ~7dB.
• Using a single 4 ohm in series, with no parallel resistor, will give 1/2 or 3dB of attenuation.

You could probably get by with maybe using 1W resistors if you are not cranking it up too much… it should still get into the 95-100dB range which is usually enough for many people.

It may not sound great, but it should hiss less.