Ground Loop help

[bradl79 10+ year member]

hello, i am getting a whine from my tweets (only when off crossover when trying to go active) so i am trying to figure out where my issues is and how to fix, 1st i have my battery grounded with stock and 1/0ga wire to stock ground (bare metal) and engine block to stock ground (bare metal) also with stock wire and 1/0ga. Now for the amps and ms-8, this is where i may have an issues. i have a 4ga (2ft) wire going from seat belt bolt sanded to bare metal no paint and wire going to Distro block, from distro block having 4ga wire to amp1 and 4ga wire to amp2 and 12ga wire going to MS-8, could the distro block be the issue? it is a Memphis multi output distro block. thank you.

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[yogegoy]

Try grounding one of your output RCA's negative jacket to bare metal. If that doesn't work you can upgrade your MS-8 to a Bit One and go optical, it only transmits light pulses through the fiber optic cable and zero electricity. That's the easy way but it surely works, although my HU became obsolete when I switched to iphone docked using Pure i-20 for 100% optical.

 

[bradl79 10+ year member]

i'd love to go Optical but i have an Android i could not find an optical option for Android

 

[yogegoy]

Are you certain you don't have any docks for Andriod? Just asking since I use the i-20, it's a sure fire way getting rid of electrical mechanical noise.

 

[Jepalan]

Your ground loop may have nothing to do with the power grounds on your devices - it may have more to do with your signal (RCA) connections. OR it could be a gain issue.

Are you running only a single set of RCAs from the Clarion to the MS-8. Double-check the RCAs between the MS-8 and the amp - try grounding the RCA ring to chassis ans see if it helps. How are you setting the amp gain in the tweeter path from MS-8 to tweets when attempting active?

 

[bradl79 10+ year member]

Your ground loop may have nothing to do with the power grounds on your devices - it may have more to do with your signal (RCA) connections. OR it could be a gain issue. Are you running only a single set of RCAs from the Clarion to the MS-8. Double-check the RCAs between the MS-8 and the amp - try grounding the RCA ring to chassis ans see if it helps. How are you setting the amp gain in the tweeter path from MS-8 to tweets when attempting active?

I set all my gains with an Oscope so no clipping, I do have just one set of RCA's going from HU to MS-8, I am using an AUX port so i am wondering if that could be it too, i need to test that. I will also try to ground the RCA ring to chassis also and see if that works. thank you guys for some suggestions.

 

[trumpet 5,000+ posts]

I set all my gains with an Oscope so no clipping

Turn your gains down and recalibrate MS-8. If all of your speakers are on separate amplifiers try putting the gains at minimum(the highest voltage marks on the amps). If the gains are too high you can get a variety of issues, especially an unusually loud noise floor. It can also make your system sound worse than it really should sound.

 

[bradl79 10+ year member]

Turn your gains down and recalibrate MS-8. If all of your speakers are on separate amplifiers try putting the gains at minimum(the highest voltage marks on the amps). If the gains are too high you can get a variety of issues, especially an unusually loud noise floor. It can also make your system sound worse than it really should sound.

So on my amps i will turn the gains all the way down, recalibrate the MS-8 (normal Calibration Setup)? then will i use an oscope again to set the gains on the amps using test tones like i normally would?

 

[trumpet 5,000+ posts]

So on my amps i will turn the gains all the way down, recalibrate the MS-8 (normal Calibration Setup)? then will i use an oscope again to set the gains on the amps using test tones like i normally would?

No. Skip the o-scope. I haven't once used my oscilloscope to set up my MS-8 or for others. When you're taking the measurements while wearing the mics the sweeps should be about as loud as someone talking in the passenger seat at a normal volume. The subwoofer sweep can be almost inaudible. The mics will still be able to measure the bass.

If this results in your music not sounding as loud as it should when you're done calibrating and you've set the volume on MS-8 to -6 like you should, then you can bump up the gains with the 2V mark as your maximum target. Turn up the gains the same amount on each amp.

 

[blazian87 10+ year member]

So on my amps i will turn the gains all the way down, recalibrate the MS-8 (normal Calibration Setup)? then will i use an oscope again to set the gains on the amps using test tones like i normally would?

When you attempt to go active, you don't really need to use oscope to set gains because it should be wayyy below the clipping point.. I would recommend putting the tweeter gain absolutely to the lowest, and try to match mids from there.. Should be plenty loud..

 

[drockstar 10+ year member]

Can you try changing your RCA cable for your tweets to the one being used for your mids or subs? If the issue goes away, replace the cable. Keep in mind it may be before or after the MS8. I had the issue with my 360.3 and it turned out to be a set between the HU and processor.

 

[trumpet 5,000+ posts]

When you attempt to go active, you don't really need to use oscope to set gains because it should be wayyy below the clipping point.. I would recommend putting the tweeter gain absolutely to the lowest, and try to match mids from there.. Should be plenty loud..

The gain setting tips I mentioned are specific to tuning with MS-8. MS-8 attempts to set all levels automatically by boosting output voltage to certain channels as needed.

 

[bradl79 10+ year member]

thank you u all, i will try that out trumpet, but when i have my gains all the way down on the amps and set the MS-8 to about 8 or 10 after calibration, its still very low and i have to turn my HU to about 28/40 when i usually use 20. also i am getting a low noise from tweets even when the rca's are off the amp, would that mean its coming the MS-8.

drockstar these are brand new RCA'S and i even tried an old pair coming from MS-8 to amp for tweets.

Thank you guys for all ur help and suggestions.

 

[trumpet 5,000+ posts]

-6 on MS-8 is the standard "safe" volume level when you're using an aftermarket head unit and you have not boosted any bands on the graphic EQ. 28/40 is not bad, don't be afraid to turn up the HU volume. I used to run a Clarion NX603 up to 1 click below maximum if needed.

Regarding the tweeter hiss, you need to be absolutely sure you do not have a ground loop. I don't make a habit of doing this, but you can try running a small gauge wire between the head unit ground and your MS-8/amplifier ground.

 

[bradl79 10+ year member]

Should I run grounds to the same point or is using a distro block ok?