Formula for Amp voltage(gain adjustment)

 

Silver Member
Username: Killerzracing71

Fredericksburg, Virginia United states

Post Number: 422
Registered: Aug-05
I have a mb qaurt raa-1000.....right no im running 1 15 @ 2ohms but plan on running both 15's @ 1ohm how do i calculate the voltage needed to properley adjusgt the gains
 

Silver Member
Username: Langless28

Post Number: 379
Registered: Dec-04
you set the gains on the amp according to the head units pre-out voltage.
 

Gold Member
Username: Theelfkeeper

Stockbridge, GA USA

Post Number: 1528
Registered: Feb-05
no real way to "calculate" the gain. suppose to match the Pre Out Voltage. just turn the HU 3/4 of the way up, then adjust up the gains until you start to hear distortion or you get as loud as you like. back off a little if you reach distortion.
 

Silver Member
Username: Killerzracing71

Fredericksburg, Virginia United states

Post Number: 425
Registered: Aug-05
Ok then Bassfishing.......then will u please come set my....Gains for me......Cuz i saying that it doesnt clearly say 4volt on that Knob or Killerzracing Gain voltage its kinda hard.......

and brandon i have done it that way too....sound decent...But.....I would like to use a vlotmeter to adjust it....That JL audio.tutorial...says to use a voltmeter n i would like. to try it so i can get it right....But 4 real i keep clipin the subs often.....

sum1 knows bout that JL audio gain tutorial.....
 

Silver Member
Username: Langless28

Post Number: 381
Registered: Dec-04
yeah the jl tutorial can be found at their website, all the amp pdfs have the tutorial in em, i know for a fact if u download the 300/4 manual it will have the procedure, but i think the numbers are for their amps only. i used jls method to set my 300/4 gain but i used brandons method for my xtant amp, and your right it has no numbers on it, i did it according to ear.
 

Silver Member
Username: Killerzracing71

Fredericksburg, Virginia United states

Post Number: 427
Registered: Aug-05
look i saw this formula somewhere.....it said
sqrt(ohm*watts) that waz its exact words.....I assume sqrt is Square Root.......

with my amp 1*1000=1000 sqrt of 1000 is 100v so i should read 100volts with a 50hz testone playing right
 

Gold Member
Username: Theelfkeeper

Stockbridge, GA USA

Post Number: 1546
Registered: Feb-05
Oscilloscope
 

Silver Member
Username: Lbeckner

Tulsa, Ok Usa

Post Number: 823
Registered: Oct-04
its voltage squared divided by two

if you were 100 volts output on amp then you would have 100*100=10000\2=5000watts
 

Silver Member
Username: Killerzracing71

Fredericksburg, Virginia United states

Post Number: 428
Registered: Aug-05
Lucas ur answer didnt help me much......Can u tell me how many volts i should be reading..100v did seem kinda high saying that the JL/1000 at 1.5ohms made 60 or 30 summin cant remeber for real....And brandon i dont have a Oscilloscope just laying around....LOL...


I Guess i did this right by going backward on your calc...I got 22.36v....

1000=2/x x=500
no wrong again did it by voltage squared divided by 2

now idid 40^2=1600 then divide by 2 =800 watts i got 1000 so im guessin alitle more volts like 40-45v

now is that AC or DC i assume AC
 

Silver Member
Username: Graphix1

Santa Rosa Heights, Arima Trinidad & T...

Post Number: 806
Registered: Oct-05
if ya dont wanna do it by ear just go out and buy an oscilliscope
 

Gold Member
Username: Rovin

Trinidad & T...

Post Number: 6929
Registered: Jul-05
i have that same amp on my 2 Rs & i don't have any fancy equipment 2 do it by the book so i turn my hu 3/4 up & play a hard hitting song & turn my gain just below clippin point , u can tell by the clipping indicator light - plays clean as a whistle with no problems ....
 

New member
Username: Spkrman

Chi town, IL U S A

Post Number: 5
Registered: Mar-06
just set it somewhere and use your sub level on teh deck to get it setup by ear.

Ive done it this way for years and never had any issues... you just have to listen for any sort of distortion.
 

Silver Member
Username: Solacedagony

New Jersey US

Post Number: 856
Registered: Oct-04
https://www.cs.tcd.ie/courses/baict/bac/jf/labs/scope/
From what I understand (which isn't much?) the oscilloscope is the most accurate way to set gains.
 

Silver Member
Username: Lbeckner

Tulsa, Ok Usa

Post Number: 829
Registered: Oct-04
if you have a digital volt meter then you can measure the voltage. make a cd with a 60hz sine wave tone on it and play it through your deck at 75-90% volume level and watch the voltage on the amp and increase the gain. you should see large jumps in the voltage as you turn up the gain. when you stop seeing voltage gains then you found the maximum voltage of your amp. you should turn the gain down a little from there to prevent clipping. i think this is what your asking but im not sure.
 

Silver Member
Username: Lbeckner

Tulsa, Ok Usa

Post Number: 830
Registered: Oct-04
this months car audio & electronicsmagazine had a simular question in the section where people write in and ask a question. go buy one and it will give more specific instructions. its like $3.99. but if not we will be more than glad to help more.
 

Gold Member
Username: B101

Queen City, NC USA

Post Number: 2114
Registered: Sep-05
http://mobile.jlaudio.com/support_pages.php?page_id=143
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