Does ohm rise affect output of the amp

[n3w_3ra]

Lets say I have a 1 ohm stable amp and I buy a dual 1 ohm sub and run it at .5 ohms will my amp put out .5 ohms regardless of impedance rise? Or will the amp put out closer to one ohm?

I have a sax 1200d and looking at a good deal on a dual 1 just don't want to run the amp .5 daily

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[djprophet2012]

Judging by your question, In Order for you to run your Subs at .5 Ohms, You need an amplifer that is .5 Ohms Stable. If your amp is not stable at .5 Ohms you can risk over heating your amp and causing it to go into Protect Mode. The Sundown SAX-1200D specifications states that it is 1-Ohm Stable on their website. You can read more about this at SAX-1200D

If you need anything else inbox me!

 

[garychoffmann 10+ year member]

Many people run the sundowns at .5 main question is if you have the electrical to back that demand up. Why do you want to run at .5? So that with rise you're at 1 ohm? Most people accounting for rise in their systems are seriously invested into their cars and systems. Serious ground pounders or competitors.

 

[hispls 5,000+ posts]

If you have to ask this question you have no business running your amp below rated impedance.

 

[NASTY08IMPALA 5,000+ posts]

The saz series are the only ones id run at .5 ..the sae amd sax models are finicky down low

 

[Slo_Ride 5,000+ posts]

Judging by your question, In Order for you to run your Subs at .5 Ohms, You need an amplifer that is .5 Ohms Stable. If your amp is not stable at .5 Ohms you can risk over heating your amp and causing it to go into Protect Mode. The Sundown SAX-1200D specifications states that it is 1-Ohm Stable on their website. You can read more about this at SAX-1200D
If you need anything else inbox me!

this

 

[n3w_3ra]

If you have to ask this question you have no business running your amp below rated impedance.

I'm not asking if I can run my amp at .5 ohms, I'm asking if impedance rise = my amp ACTUALLY running at 1 ohm or higher. When Jacob tested the sax 1200 he tested it at .5 ohms at 1500 something at 11.8 volts with rise to 1.8 ohms or some shut so basically I realize running at .5 ohms can easily fry an amp but do not get if you account for rise as your final running ohms from the amp

Quote from initial clamp

Wired to 1 ohm nominal :

1170 Watts @ 12.5 volts

1.97 ohms after impedance rise

Wired to 0.5 ohm nominal :

1490 Watts @ 11.1 volts

0.85 ohms after impedance rise

---

Measured with my Extech True RMS power clamp meter several seconds into the tone @ 60 Hz -- this typically reads about ~15-16% less than a "dual peak hold" amp clamp test.

See I don't understand the rise to .85

 

[Slo_Ride 5,000+ posts]

I'm not asking if I can run my amp at .5 ohms, I'm asking if impedance rise = my amp ACTUALLY running at 1 ohm or higher. When Jacob tested the sax 1200 he tested it at .5 ohms at 1500 something at 11.8 volts with rise to 1.8 ohms or some shut so basically I realize running at .5 ohms can easily fry an amp but do not get if you account for rise as your final running ohms from the amp

Quote from initial clamp

Wired to 1 ohm nominal :

1170 Watts @ 12.5 volts

1.97 ohms after impedance rise

Wired to 0.5 ohm nominal :

1490 Watts @ 11.1 volts

0.85 ohms after impedance rise

---

Measured with my Extech True RMS power clamp meter several seconds into the tone @ 60 Hz -- this typically reads about ~15-16% less than a "dual peak hold" amp clamp test.

See I don't understand the rise to .85

i think you just answered your own question.

 

[Jeffdachef 5,000+ posts]

You'll get more power yes but how safe it would be would depend on your enclosure and many other factors, the only way you know your in the safe zone with impedance rise is with a clamp of your own inside your own vehicle with your whole setup.

 

[bbeljefe]

Amplifiers don't put out impedance, they react to impedance. Impedance fluctuates with every movement a voice coil makes and when they're in use, they're in constant motion, so the impedance is constantly changing.

As for "box rise", it doesn't exist. At least, no more so than the phrase "sun warm" exists to describe the effect the sun has on the Earth's surface when it rises. If you were to talk about "sun warm", most people would say DUH of course the sun warms the Earth when it rises. And that's pretty much what engineers think when people say box rise. Because... of course impedance rises when the coil is in motion. And on top of that, it rises whether the driver is in a box or not and it even rises when there is no amplifier connected whatever. That's just what happens and you can't blame it on anything other than physics.

So with that said, if an amp isn't .5Ω stable, you can assume that to mean that it doesn't like impedances below ~1.5Ω... because the people who designed it already know what the amp will actually see when connected to a given load. And they have to know that, otherwise they'd get fired or, go out of business. ;-)

Now... with all that said, just because a manufacturer doesn't say his amp is .5Ω stable, that doesn't mean the amp is not half ohm stable. Manufacturers have a vested interest in not telling people to run their equipment at its limits. Ladder manufacturers will tell you not to climb more than 6' high on their 8 ladders but that doesn't mean you can never climb to 8' on them and it doesn't mean you're certain to fall if you climb to 6'6". It just means they're protecting their interests and that you're responsible for your own safety.

So coming back to your question... yes, your amp will likely see a 1Ω or higher load if you run it at .5Ω. And Jacob Fuller knew that when he didn't tell people his amp could be run at a half ohm.

 

[SounDrive Pro Seller]

Impedance can drop as well as rise.. I never recommend using any amp below its rated impedance

 

[n3w_3ra]

Amplifiers don't put out impedance, they react to impedance. Impedance fluctuates with every movement a voice coil makes and when they're in use, they're in constant motion, so the impedance is constantly changing.
As for "box rise", it doesn't exist. At least, no more so than the phrase "sun warm" exists to describe the effect the sun has on the Earth's surface when it rises. If you were to talk about "sun warm", most people would say DUH of course the sun warms the Earth when it rises. And that's pretty much what engineers think when people say box rise. Because... of course impedance rises when the coil is in motion. And on top of that, it rises whether the driver is in a box or not and it even rises when there is no amplifier connected whatever. That's just what happens and you can't blame it on anything other than physics.

So with that said, if an amp isn't .5Ω stable, you can assume that to mean that it doesn't like impedances below ~1.5Ω... because the people who designed it already know what the amp will actually see when connected to a given load. And they have to know that, otherwise they'd get fired or, go out of business. ;-)

Now... with all that said, just because a manufacturer doesn't say his amp is .5Ω stable, that doesn't mean the amp is not half ohm stable. Manufacturers have a vested interest in not telling people to run their equipment at its limits. Ladder manufacturers will tell you not to climb more than 6' high on their 8 ladders but that doesn't mean you can never climb to 8' on them and it doesn't mean you're certain to fall if you climb to 6'6". It just means they're protecting their interests and that you're responsible for your own safety.

So coming back to your question... yes, your amp will likely see a 1Ω or higher load if you run it at .5Ω. And Jacob Fuller knew that when he didn't tell people his amp could be run at a half ohm.

Awesome answer exactly what I was looking for thanks man

 

[Mass Car Audio 10+ year member]

Amplifiers don't put out impedance, they react to impedance. Impedance fluctuates with every movement a voice coil makes and when they're in use, they're in constant motion, so the impedance is constantly changing.
As for "box rise", it doesn't exist. At least, no more so than the phrase "sun warm" exists to describe the effect the sun has on the Earth's surface when it rises. If you were to talk about "sun warm", most people would say DUH of course the sun warms the Earth when it rises. And that's pretty much what engineers think when people say box rise. Because... of course impedance rises when the coil is in motion. And on top of that, it rises whether the driver is in a box or not and it even rises when there is no amplifier connected whatever. That's just what happens and you can't blame it on anything other than physics.

So with that said, if an amp isn't .5Ω stable, you can assume that to mean that it doesn't like impedances below ~1.5Ω... because the people who designed it already know what the amp will actually see when connected to a given load. And they have to know that, otherwise they'd get fired or, go out of business. ;-)

Now... with all that said, just because a manufacturer doesn't say his amp is .5Ω stable, that doesn't mean the amp is not half ohm stable. Manufacturers have a vested interest in not telling people to run their equipment at its limits. Ladder manufacturers will tell you not to climb more than 6' high on their 8 ladders but that doesn't mean you can never climb to 8' on them and it doesn't mean you're certain to fall if you climb to 6'6". It just means they're protecting their interests and that you're responsible for your own safety.

So coming back to your question... yes, your amp will likely see a 1Ω or higher load if you run it at .5Ω. And Jacob Fuller knew that when he didn't tell people his amp could be run at a half ohm.

Excellent write up man. Good information for the newb's.