How to calculate ohm rise and drop in a system?

[Mr.meyhem 10+ year member]

i have an apsm 1300 and an oa 15 d2. I'm wired to 1 ohm right now. on stock electrical. 80a alt. big 3 done. I've heard the froze thrown around. "after ohm rise ill being doing this not this"

my apsm 1300 is suppose to do 1k w at 1 ohm. but i don't think it is really doing this. so i have my gains set wrong. in order to set my gains correctly i need to know how many watts I'm actually running due to ohm rise?

thanks

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[RangerDangerV2 5,000+ posts]

stick a dmm in the terminals on your 15.... their is box rise but that varies with different frequencies and I suspect that you are not burping....

 

[Mr.meyhem 10+ year member]

stick a dmm in the terminals on your 15.... their is box rise but that varies with different frequencies and I suspect that you are not burping....

not for burps. for daily driver. and this ohm load will tell me what? say its like 2.1 ohms off the sub. and its a dual 2 ohm so do i just put a + in one side and a - in the other?

 

[rebelfromva 10+ year member]

Believe he means at the amp

 

[RangerDangerV2 5,000+ posts]

well a d2 wired in series will be more like 3.28 ohms not 4....

 

[Mr.meyhem 10+ year member]

okay so what do i need to do to measure on the sub or amp to find out what i should set my gains to. using the formula: rms watts of amp x ohm load. then square root. cuz i have it set for 1000w. 31.4 v but the amp isn't doing that so I'm clipping.

 

[Mr.meyhem 10+ year member]

question has really not been answered....

 

[IonRL205 10+ year member]

Just set the amp for the RMS that it's supposed to do at the ohm load. Since you will rise, your amp will put out less power so you shouldn't be clipping, unless you already have the gain set too high.

For daily driving, just set it how you normally would and don't worry about the box rise.

 

[brynm 10+ year member]

This explains it perfectly

Let me google that for you

 

[Falcons 5,000+ posts]

ohm loads change with each given frequency. so if your playing a dynamic song that goes from 25 hertz to 80 hertz, your ohm load is going to change like crazy, so there is no reasonable way to calculate box rise for a daily driver.

 

[TaylorFade 10+ year member]

i have an apsm 1300 and an oa 15 d2. I'm wired to 1 ohm right now. on stock electrical. 80a alt. big 3 done. I've heard the froze thrown around. "after ohm rise ill being doing this not this"
my apsm 1300 is suppose to do 1k w at 1 ohm. but i don't think it is really doing this. so i have my gains set wrong. in order to set my gains correctly i need to know how many watts I'm actually running due to ohm rise?

thanks

And this surprises you?

 

[CAT MAN 5,000+ posts]

And this surprises you?

ohai tay........i lolerskated

 

[Flex68 10+ year member]

I've heard the froze thrown around. "after ohm rise ill being doing this not this"

Far enough north that English is second language...?

 

[sexy 10+ year member]

Setting gains with a dmm is not very accurate to begin with. Setting gains with an oscope is very accurate but still it is only accurate if done with test tones by someone who knows what they are doing.

A lot of people use the velleman oscopes for about $100 you can’t go wrong. You just set it on auto with a test tone and you have an accurate answer.

 

[duanebro 10+ year member]

This can be measured with a impedance measuring program. I have had good luck with a program called LIMP. It is part of a package called ARTA. You will need a very simple jig. Generally you don't need to do this though. Setting you gains with a mutlimeter will be close enough.