A couple of additional questions:

Would you recommend this as a long-term solution? Or is it meant to simply test your theory about the capacitively coupled output on the HK?

If I did use this, would it get rid of the noise all by itself, or would I still need to use the GLI filter?

I could probably wire this myself if I had a detailed circuit diagram (including the caps and battery hookup).

Thanks!

 

It would be a good test, but also useful if built well
It fixes the (possible) impedance mismatch of your system with the GLI. It sits between them. Its the GLI filter that fixes the noise.
That's why I suggested a techie friend. The web site I linked to had information, but a little sketchy. Here's another Op Amp reference:

http://www.talkingelectronics.com/Pr.../OP-AMP-2.html
Good Luck, JeffD

 

OK - I am resurrecting this thread again...

The speculation that the output of the HK drive+play is capacitively coupled makes me wonder...

Why would HK do this in the first place? Is it meant to prevent ground loop issues (or DC from going out on the output)?

What would happen if I took it apart and looked to see if there was a capacitor in there (and I shorted it out)? Could this solve my problem? I am at my wits end here with this - I just want it to work.

Thanks!

 

Blocking DC is the usual reason. You may be able to find a schematic diagram for the HK and check if the capacitor is there.
If I was correct and there is a capacitor, don't short it out. Put a larger capacitor (get one that is significantly higher value -in microfarads, has at least the same voltage rating, and if polarized - better if non-polarized - but more expensive, across the original (in parallel, oriented in the same direction).
Increasing the capacitance should improve your low frequency response when the noise filter is installed after the HK (If I was correct in the first place).

I took a look at the manual for your HK. Do you still get the noise problem when using it through your FM radio (I assume that your are presently connecting directly through audio cables)?
Good luck.
JeffD

 

Good question. I will have to try that again. I tried the FM transmitter once upon a time and noticed that it had very poor reception, so I can't recall if the noise was there. I want to say that it wasn't present, but that there was a lot of static.

 

Jeff,

According to the manual (see page 5) there is an antenna output. You could attach an FM antenna to this output to boost the signal received at the radio, especially if you run a cable to the vicinity of the existing antenna. You could also try various FM frequencies (see page 9).

JeffD

 

I tried several FM channels - they were very hit or miss.

The antenna output is for an optional wired FM modulator. You feed this output to the external modulator, and then you put the modulator in series with the antenna cable that feeds into the back of your radio's head unit.

I don't have the modulator, and I don't want to tear into the dash of my car unless I really have to.

 

Update:

I tried the FM transmitter again, and there is no "whine" (this is to be expected, since it bypasses the output jack of the HK). It is very staticky, and doesn't sound very good, though.

I also tried hooking up the iPod directly to the aux input (via the headphone output on the ipod), and this produces no noise. I tried plugging the iPod connector from the HK into the ipod while using the headphone jack, and as soon as the metal part of the connector (the outer metal shell - not the pins) comes in contact with the ipod connector, the noise starts.

I am about ready to dissect the HK and check it out.

One other question though. If this is a ground loop, would it make sense to connect the "ground" of the aux input (behind the accessory box in the Camry) to the ground of the Aux power adapter? I don't think I dare try this, but could this remove the ground loop? Just wondering...

Thanks!

 

spiff72 — The ground loop problem is because you already have a double ground connection, forming a loop. Any voltage difference between different points around this loop (caused by wiring resistance, radio-frequency interference, etc.) injects the interference signal into the audio circuitry — the latter can't distinguish between the "real" audio and the interference being injected into its input. The solution is really to eliminate the ground loop. This can be difficult, even for experts. Joining the grounds together as you suggest may help, and it can't do any harm, but it may make things worse. The car's wiring diagram shows that the AUX socket's shield is connected at both the radio end and at the AUX adapter end, and this connection probably should not be broken since it serves as the audio's intended return path. The trouble is really that the auxiliary devices you're using are connected to both the 12-V power ground and the audio ground, and they are connecting these two together inside their internal circuitry in the wrong way. What would be worth trying, I think, would be to try joining the power ground and the audio ground together at the point where they enter the auxiliary device — in this case the H/K device. You would probably have to open the device to do this. One other thing to try would be to disconnect the shield of the audio cable from the connector at one end only, leaving the power ground to act as the audio ground return, and see if this cures the problem. You should probably try this first, as it's easier to do. But, you may get a very loud noise if you plug the audio lead in without the power lead being connected already, since the audio signal would then have no ground return at all!

Stan

 

Thanks for the suggestions, Stan.

I forgot I had these wiring diagrams - so I just pulled them up here. The "Stereo Jack Adapter" appears to have 4 wires - one of which is labeled "VA-" and the another labeled ADPG (these are the labels on the Nav Receiver Side). I assume the latter means "adapter ground"? What function does this serve if the VA- appears to be the return path for the audio?

I am curious why this Camry seems to have such a strong tendency toward these ground loop problems (assuming it is a ground loop). Is it poor design? Or could it actually be a defect? I know that I am not alone with these problems!

Thanks!