Impedance Rise TREATMENT. HOW TO ?

[MasterOfAllBass 10+ year member]

well the ohms are always changing wile you play "your shit" But my 4 15 hdc315-a D2 wired down to .5 in a 15cb foot box after diss with 240sq inchs of port i saw 1.3 - 1.4 ohms after imp

 

[Engine_hp 10+ year member]

how did u measure imp ?

using a DMM wile it cracked full load ?

 

[tsupra98 10+ year member]

how did u measure imp ?
using a DMM wile it cracked full load ?

you can't use your dmm to measure ohms while there's power. but i am also curious as to how you measure imp rise

 

[zfrerichs 10+ year member]

You take the ac voltage and clamp the power then I think it's ac voltage divided by ac amperage

 

[S.B.C. 10+ year member]

I dont think it does, dont know a thing about that. I know its mosfets bite the dust in the 10's
Been repaired twice

Because their garbage //content.invisioncic.com/y282845/emoticons/veryhappy.gif.fec4fed33b4a1279cf10bdd45a039dae.gif

 

[lowriderram_95 10+ year member]

You take the ac voltage and clamp the power then I think it's ac voltage divided by ac amperage

care to explain a bit more? I don't know shit about usin a dmm

 

[tsupra98 10+ year member]

You take the ac voltage and clamp the power then I think it's ac voltage divided by ac amperage

oh duh of course it's just using the power wheel to figure it all out i wasn't even thinking about that i was just thinking only measuring not calculating //content.invisioncic.com/y282845/emoticons/redface.gif.62fdbfe1a101588a808c4cff71bcb942.gif

 

[Engine_hp 10+ year member]

you can't use your dmm to measure ohms while there's power. but i am also curious as to how you measure imp rise

and why is that ?

 

[James Bang 5,000+ posts]

not caring helps.

 

[DonH 5,000+ posts]

you do know many things such as wire size, heat, fluctuating power, etc. all have to do with impedance rise right?

best way around it is get an amp that can overpower a woofer by about 2-300 rms and set the gain correctly! overpowering>clipping

 

[Engine_hp 10+ year member]

not caring helps.

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[Immacomputer 10+ year member]

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Seriously, it does. Worrying about your impedance rise is is pretty useless. Also, your understanding of it seems pretty far off. That "nominal impedance" value given with your drivers is roughly the normal impedance AFTER rise has taken place. There will be spikes around resonance point and those can only be changed by the enclosure. And the only thing that will really change is the frequency at which these occur.

You know that DCR value that is lower than what you think your drivers are rated at? Like 3.2 ohms instead of 4 or 1.4 ohms instead of 2? That is the DC resistance BEFORE impedance rise and the new figure will be the nominal impedance after rise.

Go read a few posts about impedance rise:

http://www.caraudio.com/forum/search.php?searchid=5787471

 

[pawn man 10+ year member]

imp rise is most critical in spl comps. for daily it is not an issue. as imp rises the power goes down. so you get lower #s. to minimize imp rise cut down on sharp corners. some folks put wedges of wood in all cornors of the box so as no right angles in the box. ( coat the inside of box with resin can also help. i run my subs in 12" pvc pipe. no sharp angles so lower imp rise.

 

[Engine_hp 10+ year member]

^^^ what do u usually coat the inside with ?

what dose DCR stands for

 

[pawn man 10+ year member]

fiberglass resin