what impendence am i acheiving that a 49-51 hz tone?

[SourDeez 10+ year member]

it's still dirty clipped power so still pointless. It's good if you wanna see smoke that's about it. It's also why some woofers take so long to blow and people claiming huge power from the socket and not blowing they are only using rated impedance not actual to figure out their power usage

Thought you were talking about powering the sub inside (amped) for some reason. Yeah hooking the sub straight to 120v would be crazy..and deadly. What tone would that even be producing?

 

[Moble Enclosurs 10+ year member]

Thought you were talking about powering the sub inside (amped) for some reason. Yeah hooking the sub straight to 120v would be crazy..and deadly. What tone would that even be producing?

It would not produce a tone because it is direct. What it will do is freeze the cone in a single motion and pass current through the coil without any means of cooling.

Now regarding the original question, it would depend on the enclosure, because there is a difference in electrical impedance and acoustical impedance and each are changed when a driver is loaded. So, as mentioned, the best way to know this is to test it. But it also can be figured for before a final design is completed. Usually, involving acoustical output, it will be (in a conventional design) around the tuning frequency, as it is with the resonance of a driver when tested free air, just this time when loaded, it is not related to Fs....but tuning, or low/high impedance. Some designs can exhibit more than one major impedance peak though, such as possibly 6th order designs, so again...very important to have it calculated first based on ALL factors of the design/driver, rather than a specific frequency of interest. If the idea is to match impedance for output, this would be the way.

 

[burprex]

It would not produce a tone because it is direct. What it will do is freeze the cone in a single motion and pass current through the coil without any means of cooling.

Wrong. Depending on what country/continent wall socket you hook the sub up to it could be any of the following *mind you there are deviations from this, but it's what is considered the norm*

220-240V - 60 Hz

220-240V - 50 Hz (Africa, Asia, Australia, Europe)

100-127V - 60 Hz (North America)

100-127V - 50 Hz

 

[Moble Enclosurs 10+ year member]

Wrong. Depending on what country/continent wall socket you hook the sub up to it could be any of the following *mind you there are deviations from this, but it's what is considered the norm*
220-240V - 60 Hz

220-240V - 50 Hz (Africa, Asia, Australia, Europe)

100-127V - 60 Hz (North America)

100-127V - 50 Hz

Interesting. I have never hooked a subwoofer up to a socket before, so I figured they were DC. Thank you for the graon as well by the way //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif it was deserved. Great catch! What I should have said is batteries will do this. Batteries are DC and wall sockets are AC. The wall socket will alternate from 120V back and forth from positive to negative. I was unaware that wall sockets were AC.

 

[burprex]

Interesting. I have never hooked a subwoofer up to a socket before, so I figured they were DC. Thank you for the graon as well by the way //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif it was deserved. Great catch! What I should have said is batteries will do this. Batteries are DC and wall sockets are AC. The wall socket will alternate from 120V back and forth from positive to negative. I was unaware that wall sockets were AC.

no problem just didn't want people getting the wrong impression then calling you out when they test it out for themselves.

 

[Moble Enclosurs 10+ year member]

no problem just didn't want people getting the wrong impression then calling you out when they test it out for themselves.

No worries. My specialty is more in acoustics rather than home electronics anyhow, so I have some learning in that field when it comes to circuits, but I assure you, anything car related or sound related in acoustical reproduction in car or home audio, watch out. Lol.

 

[Dirtrider4eva 10+ year member]

I peak at 49-51 in my car, im running a dvc 1.2ohm, and ita strapped on 2 aq1200s, I want to know If I could burp it when dropped to .6ohm, and only at my specific 49-51hz tones?.

because if the impedence at those specific tones are useable I would do that for comps..

 

[shizzzon 10+ year member]

DC only comes from power source if i am saying that right.

AC comes from "alternate" sources.

I'm probably saying it wrong.. just wikipedia it..

Basically, if it's a battery, it's DC, anything else is AC..

Chargers are DC output because they are charging... DC batteries.

Anyways, the reason why most people call box rise.. box rise is probably because these people do not know the difference between resistance and impedance. Therefore it was the unknowledgeable term used instead of calling it impedance curve.

 

[hispls 5,000+ posts]

I peak at 49-51 in my car, im running a dvc 1.2ohm, and ita strapped on 2 aq1200s, I want to know If I could burp it when dropped to .6ohm, and only at my specific 49-51hz tones?.because if the impedence at those specific tones are useable I would do that for comps..

You can also determine impedence at very low power. Use your test tone at very low volume and measure voltage, then measure current (a decent DMM should handle up to about 10A so if you do this in the neighborhood of 3 or 4 volts you should be safe.

Or as someone else mentioned buy or borrow Dayton WT3 to do an impedence sweep.

As Wen said, impedence will rise from other factors as well, but if you find impedence at low power it should give you an idea.

 

[shizzzon 10+ year member]

Impedance is higher at low volume..

The more you turn up the volume on the same frequency, the lower the impedance will go...

Eventually, cranking it too high will cause impedance to start going back up due to clipping, power compression, etc..

 

[Z1NONLY 10+ year member]

DC only comes from power source if i am saying that right.
AC comes from "alternate" sources.

I'm probably saying it wrong.. just wikipedia it..

Basically, if it's a battery, it's DC, anything else is AC..

Chargers are DC output because they are charging... DC batteries.

AC is alternating current. The source swings (alternates) from positive to negative and back. For home outlets, it does this @ ~60Hz.

DC is direct current. The current flows in one direction (unless something goes badly wrong) from negative to positive. (electron flow theory which I subscribe to) Or if you subscribe to "hole flow" theory, from positive to negative. Either way, current just flows in one direction.

 

[Z1NONLY 10+ year member]

Impedance is higher at low volume..
The more you turn up the volume on the same frequency, the lower the impedance will go...

Eventually, cranking it too high will cause impedance to start going back up due to clipping, power compression, etc..

Not too sure about this one. It's my understanding that coils have more resistance as frequencies increase. (Just as capacitors have more resistance as frequencies decrease.)

However, short of maybe heat soak or some other phenomenon, I'm unaware of impedance reacting to power alone.

Now, if you present a given source with different impedance loads, power will increase in response to lower impedance and decrease in response to higher impedance. (Unless said source has a fancy power supply/internal controls that changes/maintains output regardless of load, like JL's RIPS or something)

 

[shizzzon 10+ year member]

I did not say impedance goes down as frequency goes up.

I said if you increase power on the same frequency, the impedance will continue to drop to a point where it will eventually rise again.

I've done this clamp test many times in the past.

This is also why those who wish to find the resonance frequency of their vehicle may not find it properly at a low volume because the higher the volume, the more object's resonating frequency will change.

 

[Z1NONLY 10+ year member]

I assume you are talking about the effect a speaker enclosure has on impedance. (and the relationship between power and that effect)

I can't think of any reason the coil itself would change impedance, on the same frequency, just because of changes in power.

 

[shizzzon 10+ year member]

Yes i am talking about when it's in an enclosure.

OP stated he is using a box, I figured we were all talking about that and expanding...

I do not know the technical acoustics as to why it happens.. maybe Mobile Enclosure can tell us.