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Amp tuning

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Old 09-14-2010, 10:40 AM
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Amp tuning

Hey guys . So im tuning my amp and sub today and just have a few issues. Now i have alpine pdx 1.000 amp and alpine type x 10 inch subwoofer. I know to match the input gain with my headunits output of 2.5 volts but when i set it to this i get nothing but when i set it to the .1-1 volt setting it works??? Also what should i be setting the low pass lp filter too. My subs range is 26-200hz.

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Old 09-14-2010, 11:08 AM
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simple gain setting:

1. turn your amps gains down (highest voltage input meaning the amp is least sensitive)
2. get your favourite cd with the type of music you listen to the most with ample bass response.
3. turn your head unit volume up to about 80-90% of max volume.
4. turn the gain control towards a lower voltage setting until you hear distortion (it should get very loud) and then turn the gain back slightly
5. your gains for that amp are set and good for daily listening.

Don't worry about where the dial on the amp ends up as head unit output and amp input are not always measured the same way and don't necessarily correlate to equivalent numbers. Use your ears to tell you what sounds right.

what you don't want to do is to set the gains really high (low voltage setting) so that you get max volume at 1/3-1/2 of your volume control as this will eventually lead to you turning it up further and clipping your amp and potentially damaging your equipment.

cross over setting:
start at 100hz lp at 6db/oct slope and adjust slope (if available) up from there and the frequency down from there. This setting can take some time and listening to finally get where you want it as all cars are different (you may have a bass hump or dip at a certain freq. range), your components or front speakers may be able or less able to blend at lower settings etc...so this one will require patience.

Last edited by veeman; 09-14-2010 at 11:16 AM.
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Old 09-14-2010, 12:49 PM
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Originally Posted by veeman
simple gain setting:

1. turn your amps gains down (highest voltage input meaning the amp is least sensitive)
2. get your favourite cd with the type of music you listen to the most with ample bass response.
3. turn your head unit volume up to about 80-90% of max volume.
4. turn the gain control towards a lower voltage setting until you hear distortion (it should get very loud) and then turn the gain back slightly
5. your gains for that amp are set and good for daily listening.

Don't worry about where the dial on the amp ends up as head unit output and amp input are not always measured the same way and don't necessarily correlate to equivalent numbers. Use your ears to tell you what sounds right.

what you don't want to do is to set the gains really high (low voltage setting) so that you get max volume at 1/3-1/2 of your volume control as this will eventually lead to you turning it up further and clipping your amp and potentially damaging your equipment.

cross over setting:
start at 100hz lp at 6db/oct slope and adjust slope (if available) up from there and the frequency down from there. This setting can take some time and listening to finally get where you want it as all cars are different (you may have a bass hump or dip at a certain freq. range), your components or front speakers may be able or less able to blend at lower settings etc...so this one will require patience.
One thing I would like to add to # 3, turn your HU volume to about 75-90% ONLY if it still sounds clear. If you start to hear distortion or it starts to sound bad back up until it is perfectly clear again and set it there. Remember the volume you used as you can NEVER turn it past that without some risk of damage. Some HUs start to distort anywhere above 75% volume.
Nick
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Old 09-14-2010, 01:08 PM
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easier is to just crank the gains up
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Old 09-25-2010, 06:15 PM
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?

no offence but if you just crank the gains up you probably don't know too much about tuning, more is not always better, especially if you understand ho0w it works, i bet your system sounds like crap
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Old 09-25-2010, 06:22 PM
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Originally Posted by DR T2
no offence but if you just crank the gains up you probably don't know too much about tuning, more is not always better, especially if you understand ho0w it works, i bet your system sounds like crap
yuli is christ.
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Old 09-25-2010, 06:49 PM
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Yuli helped me set my gains at they're all the way up, and my system sounds amazing
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Old 09-25-2010, 07:50 PM
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its not right

ask any professional installer, it's either it's distorting, possibly the rca out from the deck is at too low of a voltage meaning the amp is probably not pumping to it's fullest or you have a way under-powered amp. you should have room for improvement.

think of it as redlining your engine every time you hit the gas, im not saying its always loud, it might gradually go up as you turn up the volume, but it's just not effecient that way, but w/e tickles your ears..
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Old 09-25-2010, 08:18 PM
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OP: i sell and install alpine at the shop i work for.. The advise veeman gave you is really accurate.. Just Make sure you adjust your subsonic filter for protection if your in a ported box.
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Old 09-27-2010, 02:50 PM
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Originally Posted by DR T2
no offence but if you just crank the gains up you probably don't know too much about tuning, more is not always better, especially if you understand ho0w it works, i bet your system sounds like crap
If you only knew LOL

OP, veeman's approach (with BigRedGuy's added note) is what I would have posted. I'll also mention something Dukk said a while ago that makes this even easier... See if you can locate a 1000Hz tone (sine wave). You'll hear the tone go flat when either the deck or the amp "clips". It is much easier to tell when the tone is distorted than music, and makes the gain setting more accurate. Unless you have access to an oscilloscope and know how to use it, the prementioned method is best

EDIT: Also, I should add that your deck's output voltage is NOT constant. In fact, 2.5 volts is a mathematical answer to what the deck can produce. It is literally what the deck could put out if there were no losses between the battery and output stage, and the deck was forced to constantly run directly off it's voltage rails. This is of course impossible and very destructive. The .1-1 is most likely the accurate setting, as a result

Last edited by RomanticMoments; 09-27-2010 at 02:53 PM.
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