Ive read alot of people talking about it some argue theres know such thing but...

what is rise?

how does it affect your system?

is there a way to couculate it? is there a free program to help factor it in?

i hope this dosnt cause any problems just wanting to learn

it's impedance curve, not rise and i guarantee you it exists.

There is the estimates way of measuring it-

Multimeter and Ammeter via AC obtains impedance minus phasingTrue RMS/

Vital Power and SPL-Lab both make devices used to measure these values if you want to keep them installed in your vehicle.

The SPL-Lab measures using TRUE RMS method.

But all in all, for daily driving, it's nothing to worry about.

What you're thinking of is impedance vs frequency. Impedance doesn't simply rise, but rather varies with the frequency.

Honestly there isn't any real good reason to even bother calculating it, or worrying about it for the average person. Though you can use a multi-meter and clamp meter to measure the amperage and voltage at a specific frequency to find the impedance. You would continue doing this at different frequencies to make a graph, or chart.

The enclosure alignment directly affects the impedance plot.

Here's an example of why people think it's important for them, but perhaps isn't:

Wired subs to 1ohm for max amp power (1000watts), so it's super loud.

In enclosure xxx at 40hz impedance is 3ohms, so instead of 1000watts the driver is only seeing ~250watts.

In enclosure yyy at 40hz impedance is 2.5ohms, so it's 400watts.

So enclosure yyy at 40hz has a lower impedance at 40hz, and more power. More power = louder, right? Not necessarily.

The green has a higher impedance from 30hz - ~50hz, so that means less power being received to the driver than blue, so blue must be better/louder right?

Here's SPL for each, and as you can see green has more output in the same range than blue, yet the driver is seeing less power.

The key point I'm making is people seem to underestimate the value of enclosure efficiency, and instead hype more power and or powering handling.

The above program is WinISD pro, and it's free to download.

okay so when people say there wired at 1.6ohm but after rise theyll be over 2ohm

what are the actually reading

When they say "they'll be over..." that's just to be expected because they have or have read what normally happens when measuring it.

Again, if this is for daily driving, do not attempt or expect to wire below the minimum advertised ohm load.

Doing so will require far more knowledge than just knowing what this topic is about.

okay so when people say there wired at 1.6ohm but after rise theyll be over 2ohm

what are the actually reading

Reread my first sentence, and look at the impedance vs frequency graph, and you'll understand.

okay so when people say there wired at 1.6ohm but after rise theyll be over 2ohm

what are the actually reading

Shizz and Stefan are correct, there's no such thing as "box rise". Impedance simply varies with frequency and while yes the enclosure does affect the shape of the impedance curve it's not the only factor. Impedance will vary with frequency due to the behavior of the driver, it will also increase as power is applied to the driver due to heat, etc.

Another thing people confuse is the difference between Re and nominal impedance. Re, also known as DCR or DC resistance, is the resistance of the coil with a DC signal. Re is one of the Thiele Small parameters listed by the manufacturer. It is typically a bit less than the rated nominal impedance of the coil. For example, a 2ohm voice coil might have a Re of 1.6ohm. So some uneducated fellow sees this and says his amplifier is wired to 1.6ohm and that "box rise" causes the impedance of the driver to be 2ohm. He would be wrong.

Since, as was mentioned, impedance varies due to several different factors over the entire audio bandwidth there is no one "impedance" to call a driver. A 4ohm driver isn't 4ohm at every frequency. Nominal impedance is basically an average value of the load presented to the amplifier over the intended operating bandwidth (outside of resonance, where there is a huge peak in impedance). Re and nominal impedance are not the same thing, and generally speaking when you hear someone say they are "wired" to odd values like .7, 1.6, etc it's because they don't understand the difference between Re and nominal impedance.

Nice posts guys! This thread should be stickied.

okay so when people say there wired at 1.6ohm but after rise theyll be over 2ohm

what are the actually reading

Since the rest is really been explained I'll point out one other quick thing. When people say that you should discount everything else they've said as they don't understand what is going on, nor should anything they think be followed. So usually what they are reading is SMD or some other forum full of misinformation.

As Stefan showed, EVERY enclosure will have a peak. Calling it a rise and planning for it without knowing what you are doing can get you in trouble.

okay so when people say there wired at 1.6ohm but after rise theyll be over 2ohm

what are the actually reading

Reread my first sentence, and look at the impedance vs frequency graph, and you'll understand.

sorry i was tring to scan through it and put together with what you were telling me now that i took time to read it carefully i understand the graphs better,

thanks to everyone who put info in i appreciate it

So usually what they are reading is SMD or some other forum full of misinformation.

So usually what they are reading is SMD or some other forum full of misinformation.

What are you doing here buddy? Are you spamming these threads or are you just a dumb fuck?

So usually what they are reading is SMD or some other forum full of misinformation.

What are you doing here buddy? Are you spamming these threads or are you just a dumb fuck?

Lol I was going to report it but figured it might be the latter.

I banned one last night for the same BS. We'll see how this goes.

So what about the people who wire down to .5 when their amp is 1 ohm stable expecting it to rise to 1? Is that totally unsafe or correct to a certain degree?

for quick burps, i do it all the time and suggest it for those who compete.

For daily, you would be better talking with the manufacturer to see how stout the current devices and layout of the board will except 50% more increase in current over the maximum rated ability.

Several amps exist now on the market that are wired to 0.5ohm daily and run just fine. I must stress 2 things though-

One, you need twice the battery power to do this compared to wiring at 1ohm for safety.

And 2- when i say to 0.5ohm daily, i mean 0.5ohm daily, not 0.35ohm daily which is common for many Dual 1ohm subs which have a DCR of 0.7.

I do not advise running 0.35ohms daily per amp as it puts a lot of stress on the amp itself regardless of it's build stature.

So what about the people who wire down to .5 when their amp is 1 ohm stable expecting it to rise to 1? Is that totally unsafe or correct to a certain degree?

Both.

If the sub is wired to a nominal .5ohm load then there will be frequencies where the actual load is higher than .5ohm and also frequencies where the load could be equal to or less than .5ohm. Along with this as the coil heats up the impedance of the coil is going to increase as well.

So, while it's true that the impedance could be 1ohm or higher at certain times, it's also possible for it to be .5ohm or less. How well the amplifier handles these lower impedance loads, the impedance curve of the system (driver + enclosure) and how well the coil dissipates heat to limit (or not limit) the rise in impedance with applied power are all going to factor in. The difference in power is not going to be audible while the additional strain to the amplifier and electrical system is going to be substantial, making it useless/pointless to do in a daily system.

As Shizz said, for competitors where every .1db matters and pushing equipment to their maximum is commonplace it can be beneficial. For a daily driver system it's completely unnecessary and pointless with no real benefit.

So what about the people who wire down to .5 when their amp is 1 ohm stable expecting it to rise to 1? Is that totally unsafe or correct to a certain degree?

You should not wire lower than is recommended for your amplifier and count on "rising to a safe level".

Gotcha! Thanks for the info guys.