I just learned about impedance rise. HELP :(

[zoltman1991]

Alrighty.
Currently I have a JD1000/1 pushing a CompQ 12" (LC2i included).
I knew impedance rise was a thing, but I did not know how considerable of a rise this causes. I was told general rule of thumb is approximately 3x, which would effectively reduce my output by a significant amount.

Several questions:
-this is determined by box and trunk specs, correct? This is independent of the amp.
-If I clamp my current system, and get the impedance and wattage, this will allow me to determine my impedance rise for my subwoofer/box/trunk?
-If so, can I use this information to better match my next amp? - for instance, If it does show a rise of 3x, should I target an amp that produces 3000w rms at 2 ohms to account for this rise?

How come we're always told to match amp with subs? No one accounts for impedance rise when selecting systems (at least I never did and never experienced this).

Click to read more...

 

[1aespinoza Premium Member]

How come we're always told to match amp with subs? No one accounts for impedance rise when selecting systems (at least I never did and never experienced this).

I think you are overthinking it. I am sure amplifier manufacturers have taken all this into account when designing the circuitry. From what little I know about "box rise", I assume that it actually helps your amp from too low of an impedance and going into protect or worse. Many use the rule of thumb to have an oversized amplifier but the reason is so it will function effortless and not overtax the charging system. I myself have always used a smaller or matching RMS amplifier. I do not recall ever having an issue with the amp's power level choking due to impedance rise. I think impedance rise only comes into play with heavy power users. I think us in the 2k and under should not need to consider it.

 

[spokey9 5,000+ posts]

I wouldn't focus on it much unless you're trying to hit a number on a meter. You'd be surprised how little power your subs actually see when playing music

 

[Jimi77 Premium Member]

Alrighty.
Currently I have a JD1000/1 pushing a CompQ 12" (LC2i included).
I knew impedance rise was a thing, but I did not know how considerable of a rise this causes. I was told general rule of thumb is approximately 3x, which would effectively reduce my output by a significant amount.

Several questions:
-this is determined by box and trunk specs, correct? This is independent of the amp.
-If I clamp my current system, and get the impedance and wattage, this will allow me to determine my impedance rise for my subwoofer/box/trunk?
-If so, can I use this information to better match my next amp? - for instance, If it does show a rise of 3x, should I target an amp that produces 3000w rms at 2 ohms to account for this rise?

How come we're always told to match amp with subs? No one accounts for impedance rise when selecting systems (at least I never did and never experienced this).

Some people do account for impedance rise - they're called SPL competitors. For the rest of us, we can ignore impedance rise.

 

[metalheadjoe 10+ year member]

I also just learned about impedance rise, and most people here don't understand it.

 

[shredder1 10+ year member]

Alrighty.
Currently I have a JD1000/1 pushing a CompQ 12" (LC2i included).
I knew impedance rise was a thing, but I did not know how considerable of a rise this causes. I was told general rule of thumb is approximately 3x, which would effectively reduce my output by a significant amount.

Several questions:
-this is determined by box and trunk specs, correct? This is independent of the amp.
-If I clamp my current system, and get the impedance and wattage, this will allow me to determine my impedance rise for my subwoofer/box/trunk?
-If so, can I use this information to better match my next amp? - for instance, If it does show a rise of 3x, should I target an amp that produces 3000w rms at 2 ohms to account for this rise?

How come we're always told to match amp with subs? No one accounts for impedance rise when selecting systems (at least I never did and never experienced this).

Impedance rise is either helpful or can become a thing to be fought depending on your goals. I've found a well designed enclosure negates all the effort tying to grab more power for a daily setup. Now if you know that 47hz is your cabin frequency and your box peaks about the same while trying to hit max #'s sizing/tuning the enclosure correctly can let you accurately predict output if all factors are known thru testing. I thought I was one of the last geeks to test, test and test again till max output was delivered. Once the cabin becomes a real thing then throw out the frequency you started with and rinse and repeat... it never ends.
Just tune for your musical tastes and bolt the thing down to be sure that rise is under control... otherwise open a can of crazy (like I did) chasing numbers.