Just Wondering

[Paradoxx]

How about some caps on your power feeds? This is the most common source of noise, I find I get a fair bit with my iTrip plugged into the cigarette lighter...

[caspertt]

Thanks shockf6,

That really clears up basically what I wanted to know. Thanks for sharing your prowess.

Casper

[shockF6]

How about some caps on your power feeds? This is the most common source of noise, I find I get a fair bit with my iTrip plugged into the cigarette lighter...

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your sort of correct with your power feeds statement. the problem is actually an earth loop. that's why I can completely remove the whine with line isolation transformers.

There are a couple of otherways to combat earth loops that I will be trying out over the comming days as the isolation method cuts out some mid bass which is not ideal.

[Paradoxx]

Hmm

I hope I dont run into problems with my new deck

[81CJH]

Hey guys, I see this topic has been dormant for a while, but I'm curious as to the outcome.

I'm looking at setting up a DVD player using ASL's kit, and thought I might get a low level output kit while I'm at it, however if the low level output is REALLY low, then I'm not sure I'd bother.

Did anyone happen to try making a home brew solution for boosting the 0.4V ASL output?

...like maybe using an op amp?

This might even fix up some of the whine issues.

Come to think of it, you could use something like that for boosting up the AUX input as well.

[shockF6]

In relation to my fix for the 0.4V icc, im now up to my 5th board revision at getting this one right.

the problem is when you up the signal you also up the noise right along with it.

What ive got now is a line isolated pre amped board that is giving the amps around 8v ptp signals and there is next to no noise because of the line isolators in the circuit. Where im still fine tuning is because the isolators act like a high pass I need to rebuild the bottom end of the signal to keep is flat and sounding "normal".

This latest revision should be going into my car for testing on Saturday all being well.

Ill post up if I have success for anyone who is interested

[81CJH]

It's been a while since I did op amp theory, but would putting a buffer stage in at the start help out with the whine elimination? Or are they only impedance matching?

I guess a simple capacitive coupling on the input wouldn't work either, since the alternator whine you're dealing with is a valid A/C waveform as well, and it's not just a single frequency you can't notch out, since it moves with RPM.

Hmmm, I see your dilemma.

It's a ground loop that's the problem, right?

How about powering your box using a cheap, generic switch mode supply (eg. mobile phone charger) that's floating ground, or at least isolated through the switching process?

That would at least break the chain on the supply side, but I guess you still need a ground reference at some point.

Too hard basket. I hope your brain works better than mine when it comes to this kind of stuff...

Let's know how your experiment pans out.

[81CJH]

This might be worth reading...

http://www.termpro.com/articles/noise.html

Although most of it's pretty basic stuff, it might help uncover some basic flaws in the BA sound system.