Simple question, looking for simple answer.

[Karkov]

Only looking for answers from those that have tested this and can actually say one way or the other, no pissing matches.

A million variables go into impedance rise (box/ohm/impedance rise) and every build/box/vehicle is unique to itself of course.

One question: Does it help keep impedance rise minimal by having 1-2 amps per subwoofer as opposed to 6-12+ subwoofers per amplifier?

Different angle: Is impedance rise worse the more subs you have hooked to a single amplifier or does it play no role at all how many amplifiers and/or subs are being used? Is quantity of subs to amp or amps to subs not one of the variables??

[tboorn]

i dont have an answer, but i also have a question similar to yours that ive often wondered, i just havent gotten around to testing.

is the amount of rise you have consistent over different ohm loads, given the same sub/box/amp combo.

heres where the question derives from for me, ive noticed people say they have 3.4x impedence rise (not that exact number just rise as a constant variable), but usually theyve only tested at a single ohm load. say 1 ohm nominal would rise to 3.4ohm. i recognize rise is different at different frequencies lets just say we're speaking strictly peak hz. If i want to know if i can wire lower, say going from 1ohm nominal to .25ohm nominal, is rise a constant variable. so .25ohm would rise to .84ohm? or does it change given the nominal load.

[Karkov]

Anyone?

[mrd6]

i dont have an answer, but i also have a question similar to yours that ive often wondered, i just havent gotten around to testing.

is the amount of rise you have consistent over different ohm loads, given the same sub/box/amp combo.

heres where the question derives from for me, ive noticed people say they have 3.4x impedence rise (not that exact number just rise as a constant variable), but usually theyve only tested at a single ohm load. say 1 ohm nominal would rise to 3.4ohm. i recognize rise is different at different frequencies lets just say we're speaking strictly peak hz. If i want to know if i can wire lower, say going from 1ohm nominal to .25ohm nominal, is rise a constant variable. so .25ohm would rise to .84ohm? or does it change given the nominal load.

For the purpose you are thinking, yes, you can assume rise scales linearly.

If you are wired to 2 ohm and rise to 4, you could drop to .5 and expect to rise to 1 ohm. Technically, your rise may be slightly different depending on the actual power applied to the sub at 2 ohm vs .5 when going full tilt but 99.9% of the time it isn't going to matter.

As to the original question, it doesn't matter. Depending how you are wired you may see a higher dc resistance component at the amp terminals if you use one amp with a large number of subs, than one sub with one amp, but the impedance rise is unrelated.

[ChevyBoy95]

In my build, regardless of amplifier count, rise has been constant. (CT 7k vs. 2 RD D9's) Both rose from 1 ohm to 3.6 ohms at peak freq.

[reedal]

i dont have an answer, but i also have a question similar to yours that ive often wondered, i just havent gotten around to testing.

is the amount of rise you have consistent over different ohm loads, given the same sub/box/amp combo.

heres where the question derives from for me, ive noticed people say they have 3.4x impedence rise (not that exact number just rise as a constant variable), but usually theyve only tested at a single ohm load. say 1 ohm nominal would rise to 3.4ohm. i recognize rise is different at different frequencies lets just say we're speaking strictly peak hz. If i want to know if i can wire lower, say going from 1ohm nominal to .25ohm nominal, is rise a constant variable. so .25ohm would rise to .84ohm? or does it change given the nominal load.

For the purpose you are thinking, yes, you can assume rise scales linearly.

If you are wired to 2 ohm and rise to 4, you could drop to .5 and expect to rise to 1 ohm. Technically, your rise may be slightly different depending on the actual power applied to the sub at 2 ohm vs .5 when going full tilt but 99.9% of the time it isn't going to matter.

But the rise wouldn't remain linear with a change in DCR. As the DCR changed, so would the power applied. More power = more heat. As the amount of heat applied to the coil changes, so would the impedance rise, correct? The only way to keep it linear would be to ensure that the applied power over the given bandwidth didn't change either.

Edit: after Chevy's post, maybe I'm wrong?

[ShadeTreeMechanic]

Coil heat causes power compression. The impedance rise that is also called "box rise" is a factor of sub, box and cabin.

[mrd6]

i dont have an answer, but i also have a question similar to yours that ive often wondered, i just havent gotten around to testing.

is the amount of rise you have consistent over different ohm loads, given the same sub/box/amp combo.

heres where the question derives from for me, ive noticed people say they have 3.4x impedence rise (not that exact number just rise as a constant variable), but usually theyve only tested at a single ohm load. say 1 ohm nominal would rise to 3.4ohm. i recognize rise is different at different frequencies lets just say we're speaking strictly peak hz. If i want to know if i can wire lower, say going from 1ohm nominal to .25ohm nominal, is rise a constant variable. so .25ohm would rise to .84ohm? or does it change given the nominal load.

For the purpose you are thinking, yes, you can assume rise scales linearly.

If you are wired to 2 ohm and rise to 4, you could drop to .5 and expect to rise to 1 ohm. Technically, your rise may be slightly different depending on the actual power applied to the sub at 2 ohm vs .5 when going full tilt but 99.9% of the time it isn't going to matter.

But the rise wouldn't remain linear with a change in DCR. As the DCR changed, so would the power applied. More power = more heat. As the amount of heat applied to the coil changes, so would the impedance rise, correct? The only way to keep it linear would be to ensure that the applied power over the given bandwidth didn't change either.

Edit: after Chevy's post, maybe I'm wrong?

Yep, you're totally right. Thats part of what I was referring to in my last sentence^. Another thing that often changes with power applied and additional suspension travel is the sub's FS which will change the FR and affect rise.

The thing is, that change in DCR usually ends up being negligible in the real world. Hence, Chevy's post. Also, In my build I had all 4 subs on a 5k amp wired at .5. Then switched to 4 3.5K amps at .5 each (one per sub). I saw the same rise either way.

Plus, I wouldn't really consider a change in power due to DCR to be part of rise. Rise is the imaginary component of your system impedance that is frequency dependent.

[Karkov]

i dont have an answer, but i also have a question similar to yours that ive often wondered, i just havent gotten around to testing.

is the amount of rise you have consistent over different ohm loads, given the same sub/box/amp combo.

heres where the question derives from for me, ive noticed people say they have 3.4x impedence rise (not that exact number just rise as a constant variable), but usually theyve only tested at a single ohm load. say 1 ohm nominal would rise to 3.4ohm. i recognize rise is different at different frequencies lets just say we're speaking strictly peak hz. If i want to know if i can wire lower, say going from 1ohm nominal to .25ohm nominal, is rise a constant variable. so .25ohm would rise to .84ohm? or does it change given the nominal load.

For the purpose you are thinking, yes, you can assume rise scales linearly.

If you are wired to 2 ohm and rise to 4, you could drop to .5 and expect to rise to 1 ohm. Technically, your rise may be slightly different depending on the actual power applied to the sub at 2 ohm vs .5 when going full tilt but 99.9% of the time it isn't going to matter.

But the rise wouldn't remain linear with a change in DCR. As the DCR changed, so would the power applied. More power = more heat. As the amount of heat applied to the coil changes, so would the impedance rise, correct? The only way to keep it linear would be to ensure that the applied power over the given bandwidth didn't change either.

Edit: after Chevy's post, maybe I'm wrong?

Yep, you're totally right. Thats part of what I was referring to in my last sentence^. Another thing that often changes with power applied and additional suspension travel is the sub's FS which will change the FR and affect rise.

The thing is, that change in DCR usually ends up being negligible in the real world. Hence, Chevy's post. Also, In my build I had all 4 subs on a 5k amp wired at .5. Then switched to 4 3.5K amps at .5 each (one per sub). I saw the same rise either way.

This is mostly what I was wondering, I have seen people go from 4 subs with one amp to same 4 subs with 4 amps and claim it helps with rise. I didn't know for sure but started to believe it. I thought if we had a way to combat rise I would go that route but if it's always the same then meh

I am too simple minded to attempt to figure out the reasons why some builds have more rise than other and what those factors are.

Thanks all!!!!!!!!!!!!!!!!!!!!!!!

[reedal]

i dont have an answer, but i also have a question similar to yours that ive often wondered, i just havent gotten around to testing.

is the amount of rise you have consistent over different ohm loads, given the same sub/box/amp combo.

heres where the question derives from for me, ive noticed people say they have 3.4x impedence rise (not that exact number just rise as a constant variable), but usually theyve only tested at a single ohm load. say 1 ohm nominal would rise to 3.4ohm. i recognize rise is different at different frequencies lets just say we're speaking strictly peak hz. If i want to know if i can wire lower, say going from 1ohm nominal to .25ohm nominal, is rise a constant variable. so .25ohm would rise to .84ohm? or does it change given the nominal load.

For the purpose you are thinking, yes, you can assume rise scales linearly.

If you are wired to 2 ohm and rise to 4, you could drop to .5 and expect to rise to 1 ohm. Technically, your rise may be slightly different depending on the actual power applied to the sub at 2 ohm vs .5 when going full tilt but 99.9% of the time it isn't going to matter.

But the rise wouldn't remain linear with a change in DCR. As the DCR changed, so would the power applied. More power = more heat. As the amount of heat applied to the coil changes, so would the impedance rise, correct? The only way to keep it linear would be to ensure that the applied power over the given bandwidth didn't change either.

Edit: after Chevy's post, maybe I'm wrong?

Yep, you're totally right. Thats part of what I was referring to in my last sentence^. Another thing that often changes with power applied and additional suspension travel is the sub's FS which will change the FR and affect rise.

The thing is, that change in DCR usually ends up being negligible in the real world. Hence, Chevy's post. Also, In my build I had all 4 subs on a 5k amp wired at .5. Then switched to 4 3.5K amps at .5 each (one per sub). I saw the same rise either way.

Wow, I must have spaced on where you mentioned power the first time. My bad.

Sorry for the derailment Karkov.