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Another pesky WS 420 question


dezul

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I am hearing a high pitched sound out of my Rev 10s every since I hooked up my 420. The high pitch is roughly in the 10-11k hertz range and does not increase with volume. The source of the audio doesn't matter. It happens on all sources inputted. I have the power and ground connected to the same power source as the amplifiers. The orange wire is ran off of the head unit's remote wire. I pulled the rca's connected to the tower amp and the noise went away. So that means I know it is either the amplifier or the rca output on the WS 420. I turned the gains all the way down on the amplifier and it helped a little but didn't eliminate the noise. The amp is a PPI 900.4 bridged into two channels. What are my other options? Should I get a ground loop isolator and see if that fixes the problem? Any ideas would be greatly appreciated.

Thanks,

Tim

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The the gains are accessible without removing cover. The older ones do hiss a little mire than the SQ. Hiwever, I still get a little hiss in my HLCDs even with the SQ. Not enough to be a big deal for me.

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Edited by bunji169
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A high pitch sound doesnt seem quite like the low volume white noise hiss that many got from the original 420 that was like 4 generations ago. Have you placed your ear real close to the in-boats just to see if you get some of that same noise. It may be there, just not as pronounced as it is from the larger more efficient HLCD's. Take a 3.5MM x RCA cable and go with to the tower amp with a media source. Have you swapped the in-boat RCAs with the tower RCA's at the EQ? This may be a little involved, but can you temporarily wire the tower speakers to a different amp and then bring the same RCA from the current tower amp to the temporary tower amp? This would 100% eliminate the

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A high pitch sound doesnt seem quite like the low volume white noise hiss that many got from the original 420 that was like 4 generations ago. Have you placed your ear real close to the in-boats just to see if you get some of that same noise. It may be there, just not as pronounced as it is from the larger more efficient HLCD's. Take a 3.5MM x RCA cable and go with to the tower amp with a media source. Have you swapped the in-boat RCAs with the tower RCA's at the EQ? This may be a little involved, but can you temporarily wire the tower speakers to a different amp and then bring the same RCA from the current tower amp to the temporary tower amp? This would 100% eliminate the

I will give the 3.5mm to rca a try. I had this exact same setup in my last boat, the only difference is I had ground loop isolators in the amps cause I couldn't find out where the engine noise was coming from. I was hoping to avoid using them this go around.

Sent from my SPH-L710 using Tapatalk

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I'm not getting clarity on what the exact noise is. Knowing more about the noise would help with understanding the cause and the fix.

10 to 11 kHz would be really high and shrill and possibly harder to hear as you rotate your head. More than twice the highest musical fundamental (like the smallest of wind instruments).

Alternator noise would remain the same regardless of the volume level, but would change in frequency/pitch as the engine rpm changes. It would only be there with the engine running. There are also other sources of very hf noise that are present with key on but the engine off.

Hiss can be described as a constant widespread noise like a distant waterfall. Certainly more so in the treble & high frequency range but not exclusive to ultra high frequencies.

A ground loop isolator is required in some applications (conflicts in power supplies or mixing AC and DC audio components). I wouldn't use them unless absolutely necessary as you are adding a bandaid and leaving the core problem intact.

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The noise is definitely 10-11k range. It is skrilling to my ears. The noise is with the engine off, parked in my driveway. I am hoping to test it a little more today when I go out on the lake. I don't think it is the hiss. I am use to the hiss and understand why it is there.

Sent from my SPH-L710 using Tapatalk

Edited by dezul
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I don't think the original EQ had the selectable ground reference feature.

Verify that the noise is there with the key completely off/out. This would totally eliminate the boat electronics as the source.

Certainly any in-boat coaxial will have more than enough hf response to reproduce that noise. An HLCD only has more treble, not more hf extension. So while it is possible, it would be rare that the EQ would produce a noise like this in one zone and not another.

You've got to take the isolation and substitution steps that MLA suggested, along with mine, to narrow it down to an internal EQ issue, internal amplifier issue, EQ-to-amplifier interface issue, or a boat engine management module issue. You have to isolate and substitute the tower speakers/harness, tower amplifier, and EQ zones. Also, I would unbridge that amplifier and try it one channel at a time.

A noise generated by an engine management module (key engaged), would sound like an extremely high pitch whine or sine wave. Very different sound than white noise or hiss. You also have a Class D tower amplifier which is analog switching somewhere in the area of 200 kHz, and not as high as better Class D products. A passive filter is used in the final amplifier stage to roll out that constant frequency. An artifact could show up in an ultra sensitive HLCD and would sound more random than a structured whine. Also, a harmonic from either the EQ or amplifier switching power supply would sound more like high pitched noise than a structured whine. There are a number of noise sources that could get into the signal path. Again, the isolation/substitution steps will help narrow the cause.

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The key is in the acc (turned counter clockwise) when I play the music. I did what MLA suggested and hooked up my phone through a 3.5mm to rca directly through the amp. I then turned the gain up on the amp a quarter turn. The hf noise was not present when I played music this way. I then reconnected the 420 rca to the tower speaker and the noise returned. What is my next step? Try a different pair of rca cables from the 420 to the amp? I will go try that and post up the results. Thanks for the help. Keep it coming.

Sent from my SPH-L710 using Tapatalk

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Ok. I tried several different solutions. Only one seemed to work.

I first tried a spare rca cable I had directly from the 420 to the amp. The noise still existed.

The one that worked and completely got rid of the high pitch was swapping the boat speaker rca at the 420 with the tower rca at the 420. It eliminated the high pitched noise and everything works fine. Does anyone have any guesses as why this is happened and how I can get by with this work-a-round. I don't want the boat knob controlling the tower speakers vice versa.

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If you reversed the zones coming out of the EQ, the noise could appear in the in-boat speakers although maybe not as aggressive since they are not HLCDs.

It would appear from your description that the most unlikely scenario is the case....that there is an internal problem in the tower zone only of the EQ. It could be related to water damage so look inside for any white residue. Sometimes you can clean this up with tuner wash. Or, since there are five stereo IC chips and complete EQ circuitry dedicated to the tower zone alone (this is two EQs in one chassis) you might have a bad component on just that side. And that would require a repair.

Do a complete reversal with both zones hooked up. See if you still have the issue moved into the other zone. If not then a reversal of the face nomenclature may be your only solution short of a repair. I would accept that before losing the dual zone EQ function.

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Oops. For a moment I forgot how the original EQ differs from the current model. A reversal would mean that the sub output would be with the tower zone rather than the in-boat zone. There is a so-so work-around for that if needed.

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