Calling Audio Gurus

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SoCal4Run

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So I recently had some audio equipment installed by a buddy. The following is what was installed:

- Alpine SPS-610c components in front and rear doors powered by JL Audio JX360/4 amp

- JL Audio 10wov3 Sub powered by JL JX500/1d amp.

So I was trying to fine tune things today. I set the gains using the multimeter procedure as detailed in the JL manual. However, it just doesn't seem right. There is a low buzz coming from the speakers with the music turned down low. Isn't there when I turn it up. Also, it seems like the speakers get too loud too fast and overpower the sub now.

So now I'm trying to figure out what to do. Do I just turn down the gains on the speakers until the buzz is gone? Any better way to set/check the gain?
 
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The buzz may be from a ground loop.
Are all the components grounded at the same spot?
Is the ground a good, clean one?
 
fourwd1 said:
The buzz may be from a ground loop.
Are all the components grounded at the same spot?
Is the ground a good, clean one?
Click to expand...

I guess I should say it's a buzz, but rather just some feedback. The amps are grounded in different spots, and i know the installer scraped away at the metal before placing the grounds.
 
must be using the hi leven input then? i would redo the gains, 0 on everything at the radio and also turn off asl if the radio has that, do you know where the radio volume starts to distort? how big of the number is the volume? 62 ? use like volume 46 and set the gains from there. i use another method now, but if you know anyone in the area that has a smd dd1 it does it much faster.
 
also set the gains with the amp filter to all pass, after your finish , turn the filter to hp at 80hz minumum, i always let the subs play lp 80hz and below.
 
riceandpho said:
also set the gains with the amp filter to all pass, after your finish , turn the filter to hp at 80hz minumum, i always let the subs play lp 80hz and below.
Click to expand...

I wonder if this is the issue. When I did the gain setting for the components, I did not set the filter to normal. It was still on HPF. Wondering if that's the issue.
 
Last edited:
When setting gains with filters on, it makes all the gain setting cranked up even more by a lil bit. I found that out on my build later on, then fixed that, I also gave up on jl amp to rockford fosgate .
 
Alright, so I'm still having issues tuning my system. Been through the process a few times now. Went back, turned off all the filters and set the gains with my dmm per JL'S recommendations. However, I still have hiss from tweeters. Got back behind the dash to look at LOC, and played with the gains on that. Turning it down made hiss go away, but also lowered the gain on the amp. So when I turn that back up, the hiss comes back.

So I don't know if it's because of the ground wire on the LOC not being grounded (I'm assuming the black wire in the pics below), or the ground of the amp itself. Any thoughts?

20150220_234613.jpg~original


20150220_220259.jpg~original
 
So I tried unplugging the rca's from the amp, and the hiss goes away. So I'm thinking it's something with the LOC or head unit causing the hissing. Any thoughts? Is there a special way I need to ground the oem Entune head unit?
 
from what i know, if its hissing, that means the gains are too high, if the loc gains are low,you dont get hiss right? and when its low, is the amp gain high?
since you know the speakers wires behind the radio, why not by pass the loc and use the high level input on the amp with those harness?
i think radio starts to distort at 57 with 1khz. use a ddm and set each rca output level to be around 3v if thats possible.
 
i did happen to retune my friend system, it had a audiocontrol lc7, amp gain was up, and it was hissing bad, also a rca cable was bad. so what i did was turn the amp gain all the way down and also changed the rca, measure where the factory unit clipped at the speaker level side, and set the audicontrol to match the output level of the rcas first, the output level was almost all the way up on the loc, the pointer was at the end of the max setting. after that, i disconnect the speaker leads and plug the rcas on the amp back, make sure to have everything turned off first. then i proceed to measure where it starts to distort and without touching the amp gain, its was distorting in the signal already, so after that, i went back on the audiocontrol output level and turn it down just a little, and it was clean again. so in the end the settings where like this, amp gains are all down, not even touched, and the output side of the loc is matched and adjusted accordingly. no more hiss. and the settings was a big difference from what he did before.
 
If I lower the gains on the LOC, then the gains on the amp need to get turned up. So I turned up the gains on the LOC so I could keep the gains on the amp turned down. And if I turn the gains down, then they don't achieve the voltage per JL'S specs.

So I'm assuming when I unplugged the rca's from the amp and the hiss went away, the issue lies in the LOC or the head unit. Been reading about some guys improving the ground of the stock head unit. Does this make sense?
 
i know you only use one of them, try the one on the input side only, and then if that doesnt help, use output side only. it can be a bad rca too, have any spares that you can play with?
 
riceandpho said:
i know you only use one of them, try the one on the input side only, and then if that doesnt help, use output side only. it can be a bad rca too, have any spares that you can play with?
Click to expand...

What do you mean by only use one of them?

I don't think it's a bad RCA, because I get it on both sides up front, and it goes away if I remove both sets of RCA's.
 
Well from what I read on that manual, the grounds are done internally, so u either ground the input or the output, also on the rca, if there's a bad connection on the outer part(neg side) it can cause noise too, middle of the rca is the pos side.
 
riceandpho said:
Well from what I read on that manual, the grounds are done internally, so u either ground the input or the output, also on the rca, if there's a bad connection on the outer part(neg side) it can cause noise too, middle of the rca is the pos side.
Click to expand...

If you are talking about the ground of the LOC, I tried stripping the black wire on each side and touching it to the head unit metal to ground, but that didn't make a difference, input or output side.
 
now im suspecing the loc might be the problem, anyway to swap it out for another one to test? might not be a bad idea to just get rid of that for a audiocontrol one, just saying, its a better unit, there might be other unit thats better.
 
riceandpho said:
now im suspecing the loc might be the problem, anyway to swap it out for another one to test? might not be a bad idea to just get rid of that for a audiocontrol one, just saying, its a better unit, there might be other unit thats better.
Click to expand...

One last thing I'm going to try. Someone was saying about turning the LOC gains all the way up and then setting gains on the amp. Right now, I sort of balanced them with gains on LOC set about midway. Make sense?
 
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