how do you calculate impedance rise?

[headbussaboi 10+ year member]

Like the title states. Does it require professional equipment?

Click to read more...

 

[Immacomputer 10+ year member]

Calculate or measure?

 

[headbussaboi 10+ year member]

Calculate or measure?

Well alot of people talk about how they have rise after installing their sub so the amp will never so X.XX ohms. I want to know how to see exactly what kind of load you are sitting at after the rise. Did that make sence?

 

[IgnoreMe 5,000+ posts]

V x A = W

V / A = R

r= impedance

w= watts

v= voltage

a = amperage

 

[squeak9798 5,000+ posts]

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=2690

 

[Immacomputer 10+ year member]

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=2690

There is a lot of misinformation thrown around in that thread. Sealed enclosures don't cause an impedance rise??? Aperiodic membranes having the flattest curves? Driver impedance peaking at tuning?

 

[casper97ta 10+ year member]

pi = mc^2/e + 36 - srt90

You're an idiot

 

[Lance 10+ year member]

varies per box, frequency played etc,

No set way to calculate it, but you could measure it with a Clamp Ammeter and a MM.

 

[thch 10+ year member]

T/S specs can be used a bit. These show how energy is transfered across the gap. This also explains why a loudspeaker's impedance is not just defined by the coil resistance and inductance -- the magnetic field and moving coil allows energy to be transformed from electrical to mechanical and back. Thus the mechanical system affects the impedance of the speaker!

of course, the model doens't include some of the high-power effects, and other non-linear effects.

 

[headbussaboi 10+ year member]

So there isn't anyway to guestimate that a 1 ohm load, for example, will generally see a X ohm load after rise?

 

[IgnoreMe 5,000+ posts]

i made a thread about this a couple weeks back...

the answer came out to "no, you just gotta build and test, then rebuild, and retest". lets just say build a box, and hope that the impedance rise isnt terrible.

 

[thch 10+ year member]

So there isn't anyway to guestimate that a 1 ohm load, for example, will generally see a X ohm load after rise?

there is, as i've mentioned. but because impedance rise is not important to most users there is no need.

For the SPL competitors that might use information about impedance, the other effects might be significant

a program like winisd will give you an estimate if you think it matters.

 

[Lance 10+ year member]

i remember lloyd Big bass man, said once he can design boxes to yield low impedence rises,

Haven't seen him around much though.

 

[Immacomputer 10+ year member]

So there isn't anyway to guestimate that a 1 ohm load, for example, will generally see a X ohm load after rise?

It will vary over frequency and yes, many modeling programs can give you a rough estimate but it doesn't mean a whole lot.

It's really not a big deal for daily driving seeing that the point of high impedance still has the same output as other frequencies outside of the rise.

There is much more to output than just power and system resonance has a lot to do with it. Guess where there is usually an impedance spike?

 

[fwb_1234 10+ year member]

Where?