Ampliphier Voltage
50 Watt CAFz'r
Joined: Mar 2003
Posts: 359
Originally posted by Gmac:
Not realy it ignores inuctive reactince. Even if the coil had an inductance of 0.005 heneries it would take the impediance of the coil up to 4.512 ohms at 80HZ and then
1000 = v^2/4.512
4512=v^2
V=67
I assumed 0.005 heneries and wich could be way off, i have been looking through ampliphier design procedure and am just trying to work throught the ampliphication stage and am woundering the amplitude of the final wave and to determine that I need to have an idea of the inductance of the coil
Not realy it ignores inuctive reactince. Even if the coil had an inductance of 0.005 heneries it would take the impediance of the coil up to 4.512 ohms at 80HZ and then
1000 = v^2/4.512
4512=v^2
V=67
I assumed 0.005 heneries and wich could be way off, i have been looking through ampliphier design procedure and am just trying to work throught the ampliphication stage and am woundering the amplitude of the final wave and to determine that I need to have an idea of the inductance of the coil
amplifiers are considered voltage devices
the voltage remains the same
when the impedance increases current goes down
when current goes down so does power
Thread Starter
1000 Watt CAFz'r
Joined: Apr 2002
Posts: 1,089
Originally posted by Half Time Immortal:
Power is determined by your voltage
amplifiers are considered voltage devices
the voltage remains the same
when the impedance increases current goes down
when current goes down so does power
Power is determined by your voltage
amplifiers are considered voltage devices
the voltage remains the same
when the impedance increases current goes down
when current goes down so does power
Some one has to have an idea of what the inductance of a VC is on a sub.
1000 Watt CAFz'r
Joined: Oct 2003
Posts: 1,649
his current was at 1 ohm though... you're measuring 4 ohms.. current draw is proportional to the load resistance.. Current draw = Voltage/Resistance. Ahh, the joys of taking physics, makes all this stuff so much easier to understand [img]smile.gif[/img]
Guest
Posts: n/a
you voltage from the amp would stay at 44.7 volts no matter the impedance of the woofer , the current and therfore the power wouls drop
so if you were using the woofer example in your second post (4.512 ohms) on the same amp your power output would no longer be 1000 watts .......
so voltage and always stays the same, and you know your impedance
so your formula would have to be
44.7^2/4.15=power
power= 481 watts
if you wanna find out a woofers impedance at any given frequency you can play the tone you want and measure the speaker lead voltage and current (clamp on amp meter needed)
then you can calculate power and impedance with those 2 numbers
so if you were using the woofer example in your second post (4.512 ohms) on the same amp your power output would no longer be 1000 watts .......
so voltage and always stays the same, and you know your impedance
so your formula would have to be
44.7^2/4.15=power
power= 481 watts
if you wanna find out a woofers impedance at any given frequency you can play the tone you want and measure the speaker lead voltage and current (clamp on amp meter needed)
then you can calculate power and impedance with those 2 numbers
Thread Starter
1000 Watt CAFz'r
Joined: Apr 2002
Posts: 1,089
Originally posted by bigmike216:
his current was at 1 ohm though... you're measuring 4 ohms.. current draw is proportional to the load resistance.. Current draw = Voltage/Resistance. Ahh, the joys of taking physics, makes all this stuff so much easier to understand [img]smile.gif[/img]
his current was at 1 ohm though... you're measuring 4 ohms.. current draw is proportional to the load resistance.. Current draw = Voltage/Resistance. Ahh, the joys of taking physics, makes all this stuff so much easier to understand [img]smile.gif[/img]
Hey bigmike in physics have you covered the charging and discharing curves of inductors and capacitors when connected to a DC supply
[ March 31, 2004, 10:57 PM: Message edited by: Gmac ]
Thread Starter
1000 Watt CAFz'r
Joined: Apr 2002
Posts: 1,089
Originally posted by dodgeram:
you voltage from the amp would stay at 44.7 volts no matter the impedance of the woofer , the current and therfore the power wouls drop
so if you were using the woofer example in your second post (4.512 ohms) on the same amp your power output would no longer be 1000 watts .......
so voltage and always stays the same, and you know your impedance
so your formula would have to be
44.7^2/4.15=power
power= 481 watts
if you wanna find out a woofers impedance at any given frequency you can play the tone you want and measure the speaker lead voltage and current (clamp on amp meter needed)
then you can calculate power and impedance with those 2 numbers
you voltage from the amp would stay at 44.7 volts no matter the impedance of the woofer , the current and therfore the power wouls drop
so if you were using the woofer example in your second post (4.512 ohms) on the same amp your power output would no longer be 1000 watts .......
so voltage and always stays the same, and you know your impedance
so your formula would have to be
44.7^2/4.15=power
power= 481 watts
if you wanna find out a woofers impedance at any given frequency you can play the tone you want and measure the speaker lead voltage and current (clamp on amp meter needed)
then you can calculate power and impedance with those 2 numbers
Dodgeram you are most correct in the question I ha originaly asked because obviously it is assumed the power is rated at 2ohms.
Halftime
I now see what you were getting at
Sorry again I did not word my question correctly
Still does anyone know the approximate inductance of a VC on a sub?
Guest
Posts: n/a
there is no set inductance ........each woofer will have different inductance values wich not only change with frequency but also change depending on the enclosure they are in
if you want to know you have to start playing a bunch of different tones and measure the inductance at each frequency
if you want to know you have to start playing a bunch of different tones and measure the inductance at each frequency
1000 Watt CAFz'r
Joined: Oct 2003
Posts: 1,649
formula for inductive reactance - Xl = (2)(pi)(f)(L)
so if your coil had an inductance of 1.5 milihenries (0.0015 henries), and your frequency was 60Hz..
(2)(3.14)(60)(0.0015)
inductive reactance is .5652 ohms [img]smile.gif[/img]
Impedance and inductive reactance aren't the same thing.. formula for impedance:
(impedance)^2 = (resistance)^2 + (reactance)^2
or
Impedance = Sq Root of (resistance)^2 + (reactance)^2
or
Z = Sq Root of R^2 + X^2
so.. R = 2ohms
X = .5652 ohms
Z = Sq Root 2^2 + .5652^2
Z = 2.078
Z= your impedance at 60Hz [img]smile.gif[/img]
doesn't mean that's the number for your woofer.. but that would be the number if it had an inductance of 1.5 milihenries [img]smile.gif[/img]
[ April 01, 2004, 02:00 AM: Message edited by: bigmike216 ]
so if your coil had an inductance of 1.5 milihenries (0.0015 henries), and your frequency was 60Hz..
(2)(3.14)(60)(0.0015)
inductive reactance is .5652 ohms [img]smile.gif[/img]
Impedance and inductive reactance aren't the same thing.. formula for impedance:
(impedance)^2 = (resistance)^2 + (reactance)^2
or
Impedance = Sq Root of (resistance)^2 + (reactance)^2
or
Z = Sq Root of R^2 + X^2
so.. R = 2ohms
X = .5652 ohms
Z = Sq Root 2^2 + .5652^2
Z = 2.078
Z= your impedance at 60Hz [img]smile.gif[/img]
doesn't mean that's the number for your woofer.. but that would be the number if it had an inductance of 1.5 milihenries [img]smile.gif[/img]
[ April 01, 2004, 02:00 AM: Message edited by: bigmike216 ]
Guest
Posts: n/a
If all you want is a number I took 2mins and looked up the RF HX2 RFD2110 which is a dual 2 ohm coil and the inductance is 1.48mH: http://www.rockfordfosgate.com/scrip...ted=1065548252
Of course the RFD3118 has a larger diameter dual 2 ohm coil so it's inductance is 2.21mH: http://www.rockfordfosgate.com/scrip...ted=1065548255
Use the info how you think you need to.
Of course the RFD3118 has a larger diameter dual 2 ohm coil so it's inductance is 2.21mH: http://www.rockfordfosgate.com/scrip...ted=1065548255
Use the info how you think you need to.
Thread
Thread Starter
Forum
Replies
Last Post
