Gain Setting Tutorial

[fatryan 5,000+ posts]

ooooh, Sqrt = square root. i thought that was some technical term for something. im an idiot. ok, so my formula now works out to be 17.3V just like JL's site says, but is that per channel or for 2 channels? since i can only check 1 channel at a time, should i be looking for each channel to read 17.3V?

and also, where can i get a 1khz test tone like JL suggests? The link in this first post only goes up to 80hz.

 

[daillengineer]

Blah to JL and their tutorial. Get to someone that has (and knows how to use) an oscilloscope. The RMS calculation that everyone is doing isn't even 100% correct. The signal can still be clipping and you don't know it without seeing it. The ONLY way to set gains so that the amp is at its optimal performance level is to use the O-scope. You could be setting the gains lower than they should be with this voltage test you guys do. Every amp performs differently. You can have an amp that distorts more than another with the same exact specs. I would personally only trust my O-scope, and not the hand held scop, the test bench scope.

 

[Mikey Likes It 10+ year member]

i got an osilliscope, but dont know how to use it, anybody write a sticky on thst ish?

 

[fatryan 5,000+ posts]

well, sorry, but im not a millionaire. i cant afford an oscope and i also dont know any1 that has 1. ill stick to my DMM, but i just need my Q's answered.

 

[eFertLIS 10+ year member]

i got an osilliscope, but dont know how to use it, anybody write a sticky on thst ish?

Check this out -

http://www.resnet.trinity.edu/areynol1/gain.htm

 

[Meh! 10+ year member]

I have a Memphis pr300 amp that puts out 500rms bridged. Doing the calculations I get that my gain should be 44.7 volts. It is hooked to a Kicker comp Dual 2 ohm voice coil but it is wired in 4 ohm. I set it just how the thing shows and left my headunit how it always is but the sub is SOO quiet you can't even hardly hear it. It stinks horribly. All the bass goes to sub yet door speakers are putting out more bass than sub.

What did I do wrong does anyone have any idea? I KNOW the sub can surely take more than what its giving? The gain is only up like 1/4 of the way(44.7 volts), and my LP is turned on my amp at like whatever the notch between 45-250 is. When im adjusting gain what do I set the headunits built in sub crossover to?

Someone please guide me in the right direction.

 

[Meh! 10+ year member]

I have a Memphis pr300 amp that puts out 500rms bridged. Doing the calculations I get that my gain should be 44.7 volts. It is hooked to a Kicker comp Dual 2 ohm voice coil but it is wired in 4 ohm. I set it just how the thing shows and left my headunit how it always is but the sub is SOO quiet you can't even hardly hear it. It stinks horribly. All the bass goes to sub yet door speakers are putting out more bass than sub.
What did I do wrong does anyone have any idea? I KNOW the sub can surely take more than what its giving? The gain is only up like 1/4 of the way(44.7 volts), and my LP is turned on my amp at like whatever the notch between 45-250 is. When im adjusting gain what do I set the headunits built in sub crossover to?

Someone please guide me in the right direction.

Why do my posts go completely ignored? It seems like I have to BEG for help here. :-( What gives?

 

[geonfreaq 10+ year member]

Should you use a 50Hz. test tone nomatter what your box is tuned to, to set your gains properly?

 

[Acidburn 5,000+ posts]

for your sub amp, yes

 

[geonfreaq 10+ year member]

for your sub amp, yes

//content.invisioncic.com/y282845/emoticons/thumbsupwink.gif.129404938effda6ad9cca39e7f4b58a3.gif Tanks buddy!

 

[berettagtz 10+ year member]

What would be the gain amount in voltage for Mtx thunder 1501d hooked up to a swr 1521d sub (dual 2 ohm)??

And also, where would I find the sine wave cd???

 

[berettagtz 10+ year member]

Should I mess with the other two knobs, there are total of three, one is for gain and others are for frequencies and something else?

 

[95Prober 10+ year member]

can someone help me find out my voltage with that formula??

i got (4) 12inch DUAL 4 ohm subs, 500 RMS each for 2000watts and 2 JL500.1 amps. but i heard the amps put out 600+RMS watts or so. so do i use that number OR the 500 watt rating of the amps???

also, 2 subs PER amp. each pair will be wired in SERIES/PARALLEL for a 4 ohm load on each pair.

 

[tRiGgEr 5,000+ posts]

44.72v each amp. You use the RMS rating.

 

[95Prober 10+ year member]

44.72v each amp. You use the RMS rating.

thx man!!

so after i have that voltage number, what does that mean for me? what's the purpose of calculating this info??