Whats the deal with FRACTION OHMS?

[krisfnbz 10+ year member]

Ok so I was a noob a while back, still probably am to most of you guys. I know the basics on ohms and resistance and etc, however sooner or later im going to be upgrading the stuff. I see alot of high end amps that people are saying on this forum do .3 ohms and .5 ohm and .7 ohm. What the **** is that?

I was looking to get a couple BTL 18's loaded with 2 orion 2500d's

Click to read more...

 

[Showrides]

Ok so I was a noob a while back, still probably am to most of you guys. I know the basics on ohms and resistance and etc, however sooner or later im going to be upgrading the stuff. I see alot of high end amps that people are saying on this forum do .3 ohms and .5 ohm and .7 ohm. What the **** is that?
I was looking to get a couple BTL 18's loaded with 2 orion 2500d's

.5 = 1/2 of an ohm of resistance. It it is just very little resistance, and if you understand the basic of ohms that is all you need to know.

 

[bdawson72 5,000+ posts]

Itsjust the low impeadences (ohm loads) that an amp can hadle.

Different Voice coil configurations yield different impeadences. Thus. the different numbers.

 

[Twistid 5,000+ posts]

the lower your amp goes the bigger your e-penis is //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[fwb_1234 10+ year member]

ok first off. most of those ohm ratings are close approximations. Like a DVC 4ohm does not have 4.000ohm resistance per coil.

When you wire some thing in series you add the resistances. (That would be wiring that 4ohm DVC sub to 8 ohms.)

The other method of wiring is in parallel. To get this total resistance its the inverse of the inverses of the other values.

Ex: solving for X, using the 4ohm DVC sub

1/X = 1/4 + 1/4

1/X = 1/2

X = 2ohms.

Like that.

The really akward ones like .7 come from wiring subs in parallel (probably 2 1.4ohm coils).

SeanDub has a "quad 2" which really means a quad ~2.5 ish. So he's running just around .7ohms.

 

[darkist240sx 10+ year member]

^^^ deff what he said. go sundown or IA and you should be packing like a horse.//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[01xtreme 10+ year member]

The .7 and 1.4 are the actual resistance of the RE/Fi 1 and 2 ohm coils...is it not?

 

[skadude016 5,000+ posts]

The .7 and 1.4 are the actual resistance of the RE/Fi 1 and 2 ohm coils...is it not?

yup

 

[XanderMoser 10+ year member]

When you measure the DC resistance of a coil with a multimeter, that number is only an approximation of what the amp will see. Because the resistance of the coil will change based on the frequency that it is playing, this is called impedance. Impedance is basically the resistance at a specific frequency. A 4 ohm voice coil will be about 3.5 ohms DC resistance, but could vary greatly from 4 ohms when playing various frequencies.

 

[JonJT 10+ year member]

When you measure the DC resistance of a coil with a multimeter, that number is only an approximation of what the amp will see. Because the resistance of the coil will change based on the frequency that it is playing, this is called impedance. Impedance is basically the resistance at a specific frequency. A 4 ohm voice coil will be about 3.5 ohms DC resistance, but could vary greatly from 4 ohms when playing various frequencies.

The impedance the amp sees will also depend on the alignment the woofer is in. Impedance can vary from 1 ohm all the way to 30+ depending on the number of woofers and the box.

 

[ngsm13 5,000+ posts]

When you measure the DC resistance of a coil with a multimeter, that number is only an approximation of what the amp will see. Because the resistance of the coil will change based on the frequency that it is playing, this is called impedance. Impedance is basically the resistance at a specific frequency. A 4 ohm voice coil will be about 3.5 ohms DC resistance, but could vary greatly from 4 ohms when playing various frequencies.

The impedance the amp sees will also depend on the alignment the woofer is in. Impedance can vary from 1 ohm all the way to 30+ depending on the number of woofers and the box.

INdeed to both!

Also, when put into an enclosure... you will deal with impedance rise as well.

nG

 

[JonJT 10+ year member]

The .7 and 1.4 are the actual resistance of the RE/Fi 1 and 2 ohm coils...is it not?

Actual DC resistance

 

[DejaWiz 5,000+ posts]

Something else to keep in mind....

T/S Re = actual VC DCR. Almost never what is advertized as the nominal impedance.

Example: Sub X is marketed as a DVC 4 Ohm nominal impedance, but will have an actual Re of 3.5 Ohms per VC. Wired in parallel, the overall DCR is 1.75 Ohms, not 2 Ohms.

Fractional Ohms is going to depend on the manufacturer of a given sub. Say you have a DVC 3 Ohm sub wired in parallel. Final nominal impedance = 1.5 Ohms

 

[ngsm13 5,000+ posts]

I don't see the difficulty in why people can't understand DirectCurrentResistance...

nG