gain setting tutorial question

[billybrown66 10+ year member]

i read the first two and last pages of the gain setting tutorial thread, its kinda long so forgive me if this question is answered. i'm going to set my gain through this jl tutorial, however one thing i noticed i'm still confused about. on the spreadsheet in the jl tutorialit shows JL amps and their target voltage. IE the 250/1@2ohm targets voltage at 22.4V, at 4ohms targets 31.6V, so to me this means that higher the ohms more voltage.

now i dont have a jl amp, so i have use this forumla:

square root(resistance*power)

but wouldnt this forumla give the same voltage for all different ohm setting for an amp? IE. an amp that gives out 250 watts@4ohms would give out 500 watts@2ohms so the setting for both of these ohms for the same amp would be 31.6V, but on the jl tutorial the higher the ohms the higher the voltage? and for that matter what about mono sub amps that put out 250 watts@4ohms and 1000watts@1ohm, would the gains be set higher for a 4 ohm setting?

any help would be appreciated.

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[thch 10+ year member]

higher voltage = more power

higher impedance (ohm) = less power

so to get equal power, a 4ohm load needs a higher voltage then a 2ohm load.

if should give equal voltages for all ratings on the amp. halving impedance should double power.

JL amps use an interesting design to detect the impedance attached, then change the supply voltages. for this type of amp, the voltage ouput would change.

 

[billybrown66 10+ year member]

alright so i'll use my amps for example

i have mb quart raa4200 operating at 100watts@4ohms. sqrt(400) = 20 Volts

my mb quart raa1000 is operating at 1000watts@1ohm. sqrt(1000) = 31.6 Volts

but what if i get a subwoofer that is a 2ohm speaker, would i still run my raa1000 at 31.6 volts? i mean it wouldnt make any sense too, but 500*2 = 1000 , sqrt(1000)= 31.6

 

[billybrown66 10+ year member]

ahhh, if i only knew that. thanks.