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Thread: Alternator whine and other noise problems.

  1. Back To Top    #11

    Re: Alternator whine and other noise problems.

    The noise floor with the engine off I believe is native to the dsp. I can get the master volume up to about 60/66 before i hear any noise with the engine off. With the engine running the alternator whine becomes audible about 38/66 on the master volume.

    If I open the circuit between the HU and the dsp the alternator whine goes away but the base system noise remains. the system hiss near max volume is something I can live with as I can get my spl up to where I want it around 52-55/66.

    I am starting to think I may have 2 bad HU's because I can disconnect the rcas from the HU and leave them connected to the dsp and the whine stops.

    I am using twisted pair type rcas which after doing some google fu last night may be the wrong type for my needs. I need to confirm what type of input the dayton dsp 408 uses. I suspect it is single ended and not differential.

    I am going to go digging through my boxes of odds and ends to see if I can dig up some shielded rcas to try as the ones I tested with yesterday were also a twisted pair design.

    I am also going to bug my brother to see if I can borrow his HU for a test. His is only a few months old and I know it does not have any noise issues in his car.

    Best case at this point is looking like a couple pairs of new rcas of a shielded type might solve the issue and worst case is I may need a new HU.

    I will report back as things develop as well as checking periodically to respond to other peoples posts.

    thank you all for the help and support. having other minds to bounce ideas off of is helping me keep my sanity as I work through this issue.

  2. Back To Top    #12

    Re: Alternator whine and other noise problems.

    Quote Originally Posted by Fernpatch View Post
    The noise floor with the engine off I believe is native to the dsp. I can get the master volume up to about 60/66 before i hear any noise with the engine off. With the engine running the alternator whine becomes audible about 38/66 on the master volume.

    If I open the circuit between the HU and the dsp the alternator whine goes away but the base system noise remains. the system hiss near max volume is something I can live with as I can get my spl up to where I want it around 52-55/66.

    I am starting to think I may have 2 bad HU's because I can disconnect the rcas from the HU and leave them connected to the dsp and the whine stops.

    I am using twisted pair type rcas which after doing some google fu last night may be the wrong type for my needs. I need to confirm what type of input the dayton dsp 408 uses. I suspect it is single ended and not differential.

    I am going to go digging through my boxes of odds and ends to see if I can dig up some shielded rcas to try as the ones I tested with yesterday were also a twisted pair design.

    I am also going to bug my brother to see if I can borrow his HU for a test. His is only a few months old and I know it does not have any noise issues in his car.

    Best case at this point is looking like a couple pairs of new rcas of a shielded type might solve the issue and worst case is I may need a new HU.

    I will report back as things develop as well as checking periodically to respond to other peoples posts.

    thank you all for the help and support. having other minds to bounce ideas off of is helping me keep my sanity as I work through this issue.
    YOU ARE NOT CRAZY, your HU's are NOT BAD, your RCA's aren't bad, your grounding isn't bad. Simplest way to verify if it's the DSP is run RCA from HU to amp. NO noise?(99.9999% you will say NOPE)

    So that leaves the DSP as the culprit. I am of the similar history with OLD equipment but ZERO NOISE.......swap in this DSP and UGGGH! I thought I had a bad unit, ordered another.......back ordered....waited a month.......NEW UNIT........SAME NOISE RESULTS. UGGG.

    Talking with Parts Direct where I bought it and their customer service team for months now. They said there is a prototype unit getting sent to them but who knows how long it will take to get to them for testing. So it's OBVIOUSLY a hardware or manufacturing issue.

    My only hope is that if I put the bluetooth USB in that I can feed the DSP music directly but unsure how I would control volume as it would likely not be from the radio. Might be able to get me by till the MFG gets their you know what together and fixes the issue.

    I agree that ACTIVE is WORLDS ahead of my old Clarion crossover that had NO NOISE for the past 21 years of use!(not kidding 21+ years actually) Using the same HU, same amps too!

    Stop killing yourself trying different HU's, ground points etc. The only fix MAYBE could be ground isolation of the RCA's but even then still might not be it. It's DEFINITELY NOT your wiring or shielded/unshielded RCA's.

    I signed onto this site just to post this so I may never get back here for anything other than to monitor this thread. If I find out anything new I will surely try and circle back around here to post it.

    Background on me. Started back in 1994 working at a stereo shop and have been a stereo fanatic ever since but I KNOW how to install things correctly! I am no engineer but the installation and diagnostics I got! Did basically the same..........AM I GOING CRAZY routine you did.

    Good luck!

  3. Back To Top    #13

    Re: Alternator whine and other noise problems.

    it's nice to know I am not the only one to go nuts over a noise issue like this. at this point i have a mostly functional work around in place by reworking my gain structure. the noise is still there but it is low enough in intensity that i can only hear it on quite passages.

    at this point I am waiting on doing anything until next month. if all goes well I will be ordering a measurement mic, some ground loop isolators, and some caps for tweeter protection duty after my next pay check. If i can't kill the whine with the addition of the isolators than I think my next step will be to contact tech support at Parts express and see if they have any other ideas.

    at this point the only thing I know for sure is that eventually this mis adventure will be behind me and that it will be worth it in the end. 20 years of playing with car audio and even in a minimally tuned state this is one of the best sounding systems I have ever built. I have no doubt that once i get it sorted and fine tuned it will be the best I have ever done.

    hopefully in about 2 weeks I will have all my needed tools to get this resolved and fully tuned.

  4. Back To Top    #14
    BURNED OUT Hillbilly SQ's Avatar
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    Re: Alternator whine and other noise problems.

    I agree with Pinky. If you had no noise without the dsp then noise with it it's the dsp. It's the only thing that has changed. I've been through this myself and had to quiet things down with gain structure trickery to mask it. If it weren't for the ground lift switch on my Helix I'd have ground noise right now.
    They might say "don't try this at home" but nothing about not trying it at your friend's house.

  5. Back To Top    #15

    Re: Alternator whine and other noise problems.

    I am not familiar with the Helix but I assume that "lifting the ground" with a switch performs a similar function as a ground lop isolator inline with the rcas would do? if so than hopefully the isolators I ordered last night are going to be my ticket to moving past this headache and getting on with fine tuning and loving my newly improved system.

  6. Back To Top    #16

    Re: Alternator whine and other noise problems.

    according to my tracking number my order from PE should be waiting for me when I get home from work today. Should have updates and hopefully a solution this weekend. next up is learn how to use REW and start taking base line measurements so I can dial in a tune with hard data instead of by ear. I am looking forward to learning some new skills soon.

  7. Back To Top    #17

    Re: Alternator whine and other noise problems.

    Wired in some protection caps for the tweeters and installed a set of ground loop isolators. my noise and my bass both vanished. Removed the isolator from my sub out and got my bass back. after a few test drives I have noticed on one brief instance where my whine started to come back briefly and than went away again. Long term I think I may need to look into a higher quality isolator device as the cheapies I bought have a few quirks.

    Overall I am happy that i no longer have a constant whine in the background any more. I am now changing my attention to getting set up for measurements. Hopefully I will be able to start a new tuning thread soon.

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