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...or atleast let me know what you think is best.

My friend who used to be an installer and I have been talking about how to set up my system through e-mail. I respect his opinion, but I have a feeling that he may be not correct on this. He claims that it is better to have the gain on my amps higher and keep my line drivers on my x-over low. However, I think the oppisite...I think that the gain should be low on the amps and the gain on the x-over should be high.

Someone clarify this for me and explain why one is better then the other.

FYI...I currently have both amps with the gain about 1/4 of the way up, and the gain on both outputs from the x-over is at about the max. I have gotten mild hiss when the radio is all the way down since I got the x-over, but nothing horrible...but the hiss seems constant no matter where I keep the gain on the x-over.

Thx

 
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i have done mine like yours.

Injen

 
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Try checking the grounds on all your audio equipment to track-down the hiss. . . could be engine noise. . . unless it's happening when the engine's not on.

I'd try turning DOWN your line level output a bit and turning the gain on your amp(s) up to about 1/2. Never hurts to experiment a bit, but you don't want your amps' gains maxed-out. . . it's just not a good idea.

 
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Ok, thanks for the input guys. I did some experimenting when i got home from work today.

First i tried turning down the gain from the max on the x-over, and the hiss went down (the amp's gain was at a lil less then 1/4)...but the radio was ofcoarse not loud enough.

Second I tried turning doen the x-over gain to 1/2 way and I turned the amps gain to about 1/2 way...and the hiss was horrible!!!! So there goes my friends theory! There has to be something else wrong I guess.

No matter what, the hiss occured while the engine was off at the same degree for both ways.
I have never had substancial hiss before, but I have gotten engine noise before if the RCAs were facing a certain way behind the radio...but I made sure before I installed the x-over not to have any clicking or alternator type noises.


What are the typical causes of hiss when both the car is on and off? Could changing the ground jumper on the crossover make a difference with this type of hiss?


Is it bad to have the x-over grouded to the same spot as the radio?? I have them both mounted to a screw under the dash.


I can't even desribe how hard it is to get to my gain on my highs amp though because it is behind the panel on the side of the back seat...so basically I have to use a 2" mirror and a screw driver head

 
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well, naturally whatever sounds best is ideal, no matter what the settings! however, talking purely theory, he is right.

turning up the gain on yoru line driver will boost the signal to the amplifier itself, so there is no need to have it as high. so that theoretically works.

something else to consider also is radio volume. using the line driver as the main signal booster, youll bost up all the signal problems the radio puts out, if there are any!

so ideally, you want the signal (and this is just theory, here) as large as it can be as close to the actual media as possible. ever compare gain high volume low versus gain low volume high? you see what i mean!

now you throw a line driver in there, and its a bloody mess how to tune! just takes time. its the fun part of the hobby!

 
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Indeed. . . and the sound quality will be only as good as the source unit (head unit)

Which head unit are you running, Fonto? It's possible you'll need to upgrade. Hopefully not. Although if you do, that would certainly explain the hiss since it's NOT engine noise.

 
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I have a Kenwood Excelon X549...or a number close to that. Kenwood says it has 4.5v output.

 
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werd...but i do hate having to press my face against my back window to try and get my fingers in there to adjust the gains

 
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i say about mid on both

 
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That sounds like something to try.

A question for those of you who have worked with Audio control x-overs: does having the gain on the x-over all the way down mean that it is at the HU output voltage, or does having the gain on the notch in the middle mean that the the voltage is at what the HU puts out...I am just curious about that.

 
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shoot, i never checked that, i guess i should have! my pioneer puts out 2.2 volts playing a 0dB tone with the volume maxed out. maxing out my 6xs with that 2.2 volt maxed signal put out 12 volts from the crossover. so that was my max....

but i never took the time to measure minimums, unfortunately, i have no idea!

 
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I called audio control to ask this question earlier today. The person I spoke to said it was basically a potimeter (sp) with no cut, only increase. The reason why I was curious about this is because I was looking through the audiocontrol pruducts and one of their products (The Matrix, I think) can be cut by 12 dbs and can be increased by 24 dbs.

The person I spoke with told me that the contol on the 6xs can increase the output by 12 dbs on the front and rear outputs, and by 18 dbs on the sub output. In order for the 6xs not to increase the voltage, and to keep the HUs stadard voltage, he said it should be left at the minimum setting (completely counter clockwise).

Anywayz, all this means that I am prolly putting out to much voltage to my amps if I have the x-over gains maxxed. Prolly if I turned the gain on the x-overs down to halfway it will prolly sound pretty much the same but will less hiss. i will have to try that after work.

 
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on my 2x3 it SEEMED to be actual gain at the notch, and drop the gain down lower. also try playing with the ground isolation jumper inside of it.

 
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Yeah, I was thinking about trying this. I just wanted to jusitfy in my head how moving the ground iso jumper would get rid of hiss...but what the heck, I will give it a shot when I get the chance. The only other thing is to try turning the gain on the x-over all the way down and just put the gain on the amps to their normal positions...but if I do this, and there is hiss, I will be pissed

Could grounding have anything to do with hiss?

 
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hiss, im not sure, but definitely alternator whine, so the ground jumper can definitely affect that! try it and see!

 
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So I tried a few more things today. I moved that jumper to all 3 positions and one made the nastiest alternator whine ever...and the 3rd one kept the hiss with just a lil bit of whine...so i set it back to the original position and went back to just the hiss

One thing I realized is that the nasty whine that i got while adjusting the jumper was probably because when I recently rewired my RCAs to the trunk I put them trough the lil hole in the bump just behind the back seat...but I also have my grounds to that metal piece and I have my power wire going through the hole on the other end of that metal part I didn't realize that this metal piece is prolly carrying current through it and may be messing with my RCAs...but I dunno if that causes hiss.

anyway, random vent

 
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Your gain should be as low as possible and you should use more voume from your head unit or line driver. this keeps the signal voltage high and the noise low. the gain is there to match the input sensitivity to the output voltage from your headunit. On Rockford amps you will get full output if the gain is all the way down with 6.5V of input and full output from the amp is the gain is at full and 0.5V of input. if your gain is high and your input signal is high you can over drive the input stage of the amp causing a clipped signal, engine noise or even overheat the amp. the lower you can keep the gain the better.

 
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Lord, I have tried everything and the hiss is bad. I even sat in my wifes car to compare what it sound like and ofcoarse she gets hiss, but much quiter.

This is what I have tried:

-rechecked all my grounds to make sure all are tight (amps, x-over, HU)
-re-ran my RCA to my high's amp
-moved the jumper on th x-over.
-ran the gains in almost every way possible....currently I have the gain on the amp just barely turned (about an 1/8 of the way up) and I put the line driver between half and 3/4s of the way, but the hiss remains the same no matter where i put it.

Any other ideas on what I should check?

One thing that I was thinkin was that I have my x-over screwed in under my seat. Could the problem (hiss, with both car on and off) be caused because I have metal screws touching both the chasis of the x-over and the chasis of the car? Is so, should I use screw made of a different material? What kinda srews should I use?

 
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have you tried moving your grounds, rather htan just checking them? if you have a noisy ground, the cleanest ground connection isnt gonna remove the loop!

 
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I will try that next...I currently have both the HU and the x-over grounded to the same bolt behind the power socket (where the cigarette lighter would be).

 
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you might have to live with it, thats always the risk of adding powered circuits in yrou signal path, adding noise.

ive found through tuning you cna minimise it, then overpower it through volume (road noise anyways, there will always be crap in there) but i have yet to hear 100% noise free stereo in a car...

 
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well I am not giving up yet...still have a few more things to try

I am going to try regrounding. If that doesn't work, I am going to try moving the jumpers on my x-over back to 0dbs because I recently moved it to -1.5dbs, and see if that does anything