Just a few basic (possibly stupid) questions.
What is the difference in the construction of 2 and 4 ohm voice coils? Is more/less copper used or something?
Another sub construction question. How do the two voice coils on a DVC speaker function together? Can a DVC sub be harmed if each voice coil is wired to a a different channel and there is big differences in what each channel is making?
I know what crossovers are for, but how do they do it?
I have too much time to think lately, and not enough beer in the house to prevent that. LOL
Replies (10)
jamesp on 03/25/2007 15:25:26
Shoota, the "General Car Audio Hellp" tutorial on this site explains all of this in detail. The link below is for crossovers. After looking at it , then just go to the section that explains resistors, then capacitors( which make up the crossovers)...
Chapter 30 deals with electronic crossovers. There are over 125 web pages within this tutorial and it should be required reading for anyone with no formal electrical training that is serious about audio.(IMNOSO)....A few minutes spent browsing that site looking at the charts used to demonstrate how the rolloff slope is affected by the parameters that can be set with equalization made it clear to me how a crossover at 12dB/octave differs from a 24 dB/octave crossover slope. This is great resource to help understand what does what and why.
http://www.bcae1.com/
cplkittle on 03/25/2007 16:48:32
As far as the difference in coils, alot of it is determined by the resistance of the copper. Think of it as being different grades or purity. They will probably have identical coils as far as size of wire, layers and length, but use a different resistance. There is no quality difference in the sound though.. just different wiring options.
If you connect a DVC sub to a 2 channel amplifier or 2 seperate amplifiers, you could run into a number of problems.
Both outputs need to be identical. Not that hard to do with a 2 channel, just put it into mono, or feed it a mono signal. With 2 identical amplifiers feeding 2 coils on the same speaker, it is a little harder. Even though the amplifiers are supposed to be identical, the interior components are made by the lowest bidder (they used to tell us that when I was in Iraq.. don't put too much faith in your gear, it was made by the lowest bidder).
The potentiometers or rotary knobs made for gain are not the same. This is where checking the outputs with a voltmeter is critical. One gain may be at 1/2 while the other is at 5/8, and the output is the same.
Why is this important?
If both coils are not fed a mono identical signal, they work against each other. This reduces output for one, but more importantly, it reduces the movement of the cone. Reduced cone movement results in poor cooling of the voice coils. This will cause the coils to heat up and warp. With the coils heating up, the resistance increases as well, speeding up the heating process even more. The rate of speaker self destruction is very fast once the coil begins to heat up, all the factors multiply upon themselves.
If the sub is given a stereo signal, how the song is recorded will determine whether or not the sub recieves unbalanced signals. Alot of songs use left to right fade for a little color in the music. If any bass notes are included in this fade they will just appear weaker becasue the signal goes from both coils to only one. But only for a short period of time.
ShootuhMcBustaCap on 03/25/2007 23:37:20
Word I figured as much with the coils damaging each other, since hooking up only one coil will kill a sub with the quickness. Had to ask though, thats while I said they might be stupid.
cplkittle on 03/26/2007 00:25:34
don't sweat the basic questions dude. I was asking the same things when I first got here.
ShootuhMcBustaCap on 03/26/2007 09:22:33
Thanks for the info on the ohmage especialy, I have been wondering about that ever since I first heard of ohmage
jamesp on 03/26/2007 13:52:35
The reason that you can not match the measurement of the resistance of your voice coils precisly with the rated resistance is that the ratings are nominal. Since it varies considerably with frequency we see 2 Ohm or 4Ohm voice coils generally reading less on our DVOM equipment.
You can get the desired impedence by using either the length and size of the wire alone or in combination with a resistor in the voice coil circuit. I dont know if speakers generally use both but it seems logical to do so.
When I put the meter on my single 12" Alpine 4 Ohm DVC type R wired in parrallel for a 2 Ohm load it read 1.79 Ohms.
ShootuhMcBustaCap on 03/27/2007 09:31:49
That much I knew, but it was more the raw cunstruction I was wondering about the most. I just couldnt get how two things that were pretty much exactly the same could be so different. I figured it was the copper, but really didn't know. I lose sleep thinking about stupid stuff like this.
jamesp on 03/28/2007 08:03:58
With voice coils you have both a resistive and inductive load. The resistive part, a length of wire with or without resistors, is easily measured with a ohmmeter. The inductive load is non linear and increases with frequency and not easily measured except as a range.
ShootuhMcBustaCap on 03/28/2007 08:55:00
That I didn't know. Thanks!
cplkittle on 03/29/2007 00:43:44
hook up an ohm meter to a sub and push the cone in and let it go, you will see the meter go from 3.6 to 40something, back to 3.6.
What is the difference in the construction of 2 and 4 ohm voice coils? Is more/less copper used or something?
Another sub construction question. How do the two voice coils on a DVC speaker function together? Can a DVC sub be harmed if each voice coil is wired to a a different channel and there is big differences in what each channel is making?
I know what crossovers are for, but how do they do it?
I have too much time to think lately, and not enough beer in the house to prevent that. LOL
Replies (10)
jamesp on 03/25/2007 15:25:26
Shoota, the "General Car Audio Hellp" tutorial on this site explains all of this in detail. The link below is for crossovers. After looking at it , then just go to the section that explains resistors, then capacitors( which make up the crossovers)...
Chapter 30 deals with electronic crossovers. There are over 125 web pages within this tutorial and it should be required reading for anyone with no formal electrical training that is serious about audio.(IMNOSO)....A few minutes spent browsing that site looking at the charts used to demonstrate how the rolloff slope is affected by the parameters that can be set with equalization made it clear to me how a crossover at 12dB/octave differs from a 24 dB/octave crossover slope. This is great resource to help understand what does what and why.
http://www.bcae1.com/
cplkittle on 03/25/2007 16:48:32
As far as the difference in coils, alot of it is determined by the resistance of the copper. Think of it as being different grades or purity. They will probably have identical coils as far as size of wire, layers and length, but use a different resistance. There is no quality difference in the sound though.. just different wiring options.
If you connect a DVC sub to a 2 channel amplifier or 2 seperate amplifiers, you could run into a number of problems.
Both outputs need to be identical. Not that hard to do with a 2 channel, just put it into mono, or feed it a mono signal. With 2 identical amplifiers feeding 2 coils on the same speaker, it is a little harder. Even though the amplifiers are supposed to be identical, the interior components are made by the lowest bidder (they used to tell us that when I was in Iraq.. don't put too much faith in your gear, it was made by the lowest bidder).
The potentiometers or rotary knobs made for gain are not the same. This is where checking the outputs with a voltmeter is critical. One gain may be at 1/2 while the other is at 5/8, and the output is the same.
Why is this important?
If both coils are not fed a mono identical signal, they work against each other. This reduces output for one, but more importantly, it reduces the movement of the cone. Reduced cone movement results in poor cooling of the voice coils. This will cause the coils to heat up and warp. With the coils heating up, the resistance increases as well, speeding up the heating process even more. The rate of speaker self destruction is very fast once the coil begins to heat up, all the factors multiply upon themselves.
If the sub is given a stereo signal, how the song is recorded will determine whether or not the sub recieves unbalanced signals. Alot of songs use left to right fade for a little color in the music. If any bass notes are included in this fade they will just appear weaker becasue the signal goes from both coils to only one. But only for a short period of time.
ShootuhMcBustaCap on 03/25/2007 23:37:20
Word I figured as much with the coils damaging each other, since hooking up only one coil will kill a sub with the quickness. Had to ask though, thats while I said they might be stupid.
cplkittle on 03/26/2007 00:25:34
don't sweat the basic questions dude. I was asking the same things when I first got here.
ShootuhMcBustaCap on 03/26/2007 09:22:33
Thanks for the info on the ohmage especialy, I have been wondering about that ever since I first heard of ohmage
jamesp on 03/26/2007 13:52:35
The reason that you can not match the measurement of the resistance of your voice coils precisly with the rated resistance is that the ratings are nominal. Since it varies considerably with frequency we see 2 Ohm or 4Ohm voice coils generally reading less on our DVOM equipment.
You can get the desired impedence by using either the length and size of the wire alone or in combination with a resistor in the voice coil circuit. I dont know if speakers generally use both but it seems logical to do so.
When I put the meter on my single 12" Alpine 4 Ohm DVC type R wired in parrallel for a 2 Ohm load it read 1.79 Ohms.
ShootuhMcBustaCap on 03/27/2007 09:31:49
That much I knew, but it was more the raw cunstruction I was wondering about the most. I just couldnt get how two things that were pretty much exactly the same could be so different. I figured it was the copper, but really didn't know. I lose sleep thinking about stupid stuff like this.
jamesp on 03/28/2007 08:03:58
With voice coils you have both a resistive and inductive load. The resistive part, a length of wire with or without resistors, is easily measured with a ohmmeter. The inductive load is non linear and increases with frequency and not easily measured except as a range.
ShootuhMcBustaCap on 03/28/2007 08:55:00
That I didn't know. Thanks!
cplkittle on 03/29/2007 00:43:44
hook up an ohm meter to a sub and push the cone in and let it go, you will see the meter go from 3.6 to 40something, back to 3.6.
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