If a 4ohm/20w speaker is connected in series with a 4ohm/40w speaker, and the amp is capable of 60w, how would the power distribute?
If those same speakers were connected in parallel?
Replies (15)
trunkisloud on 08/8/2007 23:03:33
im thinkin it will divide it evenly.....paralell would mean 2ohms i believe....same division..
gearhead on 08/8/2007 23:43:28
So both speakers would get 30w, right?
OK, If a 2ohm/40w speaker is connected in series with a 4ohm/40w speaker, and the amp is capable of 80w, would both speakers get 40w?
If those speakers were connected in parallel?
swez on 08/9/2007 01:21:44
If both speakers are 4 ohms and in parallel, they get the same power... 30 watts and that is usually safe for both speakers. (The amp sees a net 2 ohms)
If one speaker is 2 ohms and the other is 4 ohms and are in parallel, the 2 ohm speaker will get 2x power the 4 ohm speaker gets. The net ohmic load here at the amp is 1.33 ohms. If the amp is not 1ohm stable, you'll see amp issues. (Thermal heat, low ohmic shut off)
It would be be safe to wire both speaker in series for a net 6 ohms and get a safe load to the amp. The low ohmic speaker will get more power.
This calculator may help:
http://www.1728.com/resistrs.htm
Swez
PS You say the amp is rated at 80 watts? (At what ohmic load is that 80 watts available?) 2 ,4 or 8 ohms?
gearhead on 08/9/2007 02:18:38
I'm just talking hypothetically right now (trying to learn a little).
swez on 08/9/2007 10:15:28
Good question and worth asking too. But now you you know the answers and can make an informed decission.
Keep asking, we're here to help...
Swez
gearhead on 08/9/2007 22:43:53
Another "learning" question.
A 2ch amp is not 1ohm mono stable (but it is 1ohm stereo stable), and it is rated for 600wrms @2ohm mono. If I connect a 1.6ohm load that will only need to draw 250wrms, will it be detrimental to the amp? Will it cause any other problems?
swez on 08/10/2007 08:40:00
In 2 channel mode, you should be OK if the amp mentioned is indeed 1 ohm stable in stereo mode.
If you did bridge the amp MONO and it is not pushed too hard, it will probably work at 1.6 ohms. (If the amp gets hot or shuts off, then you'll know it's not a good fit) The protection circuits should keep most amps from internal melt-downs. I would monitor this carefully if you try it. If the amp heats up a lot under normal listening, avoid this option if possible.
FYI: If there are complex passive crossover networks on the speakers you intend to use, they often have impedance loads that tend to "fix the load" the amp will actually see. It's not just the speaker ohmic rating the amp sees, but also impedance loads from the passive filters as well. (Inductive and Capacitive loads + Zobel network matching resistors are common in better passive networks)
Most passive networks make it difficult to measure resistance values with an Ohmeter. However, we can calculate "Z-nominal" by Ohm's Law if we know Voltage, Wattage, Current or resistance in a given circuit. (If we know 2 of these parameters, we can deduce the remaining 2 parameters w/ Ohm's Law )
Do you have an Ohm's Law pie chart?
http://www.installer.com/tech/ohmslaw.html
Swez
gearhead on 08/10/2007 09:01:39
"FYI: If there are complex passive crossover networks on the speakers you intend to use, they often have impedance loads that tend to "fix the load" the amp will actually see. It's not just the speaker ohmic rating the amp sees, but also impedance loads from the passive filters as well. (Inductive and Capacitive loads + Zobel network matching resistors are common in better passive networks) "
If 2 passive crossovers (that measure 4ohm with an ohmeter) are wired in parallel, will that provide a 2ohm load? I understand that impedence isn't the same thing as resistance, but that measuring the resistance of a speaker will give a rough estimate of it's impedece. Are you saying that if a passive crossover measures 4ohms with an ohmeter (with the woofer & tweeter connected to it), then that is what the amp will actually see?
swez on 08/10/2007 10:00:54
When we test a speaker, passive crossover network or both with a simple DMM Ohmeter and no audio, we get a static ohmic load reading that is fixed in value. (In this case, yes... 2 ohms) Most portable DMM's are DC voltage based. Caps block DC voltage to a major degree or entirely. The Zobel compensation resistor is actually what is being measured. (4/8 ohm resistor ect.)
However, when we play music through the speakers and crossovers, the dynamic impedance changes dramatically with the frequency of audio passing through both the speaker and crossovers. A Zobel compensation network helps smooth out the actual load the amp sees, but beyond the "fixed load resistor", impedance values of the filters and speaker coils react a lot based on frequency. (HP, LP and BP filters are common in complex passive networks)
There is actually a very complex set of variables to work with and that is why a quality set of Component speakers are so expensive. They tend to use better crossover parts and designs and many components too. (It takes years of study to become a good filter network designer/engineer) I don't have that level of background. (If I did, I would not have much interest ot time for this site) hehe
In a nutshell, a quality passive crossover network is complex and there are non-degreed designers that have mastered this deeply as a hobby. But it takes a lot of time, electronics theory studies and expensive equipment to proof out a given design. It's not rocket science, but pretty close to it in its own right. That's why these guys make big bucks.
Swez
gearhead on 08/10/2007 10:20:32
300w x 2@ 1ohm stereo = 150w x 2@2ohm stereo (theoretically), correct? And THANKS for putting up with so many off the wall questions. The old grey matter doesn't comprehend as well as it did 30yrs ago.
swez on 08/10/2007 10:53:28
Theoretically, yes that's about how it comes out on paper, but in the real world of dynamic audio, speakers loads change with frequency. We can even plot them with an AC volt meter to see just how much things change.
If voltage goes up, impedance is going down
If voltage is coming down, impedance is going up
This test assumes a variable tone generator is used and we measure the AC voltage at the speaker, (Not the amp)
Ahhh, you're gray matter is just fine. I have lots of gray matter these days. Most of it is on top the dome and not inside anymore. I guess it leaks out as we age.... LOL
Good and reasonble questions BTW... just hard to answer at times in a way that others can digest and use it later. If confused, ask for claification.
Swez
gearhead on 08/10/2007 22:18:16
Are higher end passive crossover networks designed for a particular speaker based on T/S parameters? What happens if, oh say, an MB Quart crossover is used for Blaupunkt components?
swez on 08/11/2007 00:45:30
Absolutely the case... expensive speakers often use complex crossover networks to get the best performance from their total package.
Some network designs are more generic and easy to use other speakers off another brand. However, in a case like Diamond, Focal, MBQ and other high end Comps, the crossovers are designed very specific to the speaker parameters and quirks.
Yes, the T/S is part of the equation for sure! But also to compensate for speaker matching, crossover points, minimal phase issues and lots more things are considered. As I said earlier, passive networks can be very complex in design and function. These Mfg's will test the livin' hell out of a quality Comp design to insure the best possible results.
In your situation, there's only one way to tell how well the MBQ passives mate to the Blau's... complex wave form testing with a tone generator, AC meter and O-Scope. Yes, we can get a general feel by ear, but this is not very reliable if we don't know the full features of the network and each speaker used. (Very complex issues at hand here)
Swez
PS An example might be... the tweeter used has a usable frequency range of 2.5KHz and up. It may not be 4 ohms either. (It could be 6-8 ohms) If we use another brand of speakers and the tweeter is rated at 5.0 KHz and up and has a different resistance value range, feeding it a 2.5KHz signal will destroy the tweeter in time. (See what I mean?)
gearhead on 08/12/2007 11:42:02
Can a crossover be used as a bandpass filter? Example: connect a midbass driver to the woofer terminals, and connect a 50w/4ohm resistor to the tweeter terminals.
swez on 08/12/2007 15:04:29
It's a lot more complex than that. "BP filters" or "Notch filters" are common in very high quality crossover networks and have 3 main functions:
1. Blocks deep bass to MB drivers
2. Blocks highs that should go to MR/TW drivers
3. May have impedance matching load resistor to level out the load resistance amp sees
To make one that works properly, you'll have to find a notch filter handbook or crossover guide reference.
Basically, we are working with a 2-3 stage filter network. The number and values of each component, (Coil,Cap, resistor) are determined by the drivers' ohmic load and the upper and lower bands with need to be attenuated.
This link shows simple 6dB/octave filters. That is, a single Cap or Coil is used for filtering. These are wide slope filters and may not be adequate for MD/Notch filtering. (12dB/oct. Butterworth filters are much better)
http://www.bcae1.com/passxovr.htm
http://www.carstereo.com/help/Articles.cfm?id=9 (A better calculator)
FYI, if an amp is powering only MB and a horn tweeter, we can use the amps HP filter setting to block lows and only require an upper band filter LPF for the MB driver and a HPF for the MR/TW driver.
In a nutshell, BP filters are a bit more complex and require a fair amount of study time to build them right the first time out.
Swez
PS Quote: "It's a jungle out there".
http://www.maxim-ic.com/appnotes.cfm/an_pk/1795
The esteemed value of a skilled filter design engineer is nothing short of a math wizzard or god-like maven! (Swez)
"A small tribe, in the dense wilderness, is much sought after by head hunters from the surrounding plains. Known throughout the land for their esoteric expertise, this is the tribe of the Analog Engineers, who live in the farthest regions of the left half Plains, past the jungles of Laplace.
The guru of analog engineers is the Analog Filter Designer, who sits on the throne of his kingdom and imparts wisdom. You never get to see him, even with an appointment, and you call him "Sir."
The countless pages of equations found in most books on filter design can frighten small dogs, and digital designers. This article clears a path through the brush for the practical engineer and unravels the mystery of filter design, enabling you to design continuous-time analog filters quickly and with a minimum of mathematics."
A little deep huh? Wait until you start looking at design formulae... MEGO, (My Eyes Glaze Over) sets in rapidly.
PS Did we just open up a fresh can of worms or what? Let's go fishing and forget all this stuff for a day. LOL I'm going fishin'! CLAP
If those same speakers were connected in parallel?
Replies (15)
trunkisloud on 08/8/2007 23:03:33
im thinkin it will divide it evenly.....paralell would mean 2ohms i believe....same division..
gearhead on 08/8/2007 23:43:28
So both speakers would get 30w, right?
OK, If a 2ohm/40w speaker is connected in series with a 4ohm/40w speaker, and the amp is capable of 80w, would both speakers get 40w?
If those speakers were connected in parallel?
swez on 08/9/2007 01:21:44
If both speakers are 4 ohms and in parallel, they get the same power... 30 watts and that is usually safe for both speakers. (The amp sees a net 2 ohms)
If one speaker is 2 ohms and the other is 4 ohms and are in parallel, the 2 ohm speaker will get 2x power the 4 ohm speaker gets. The net ohmic load here at the amp is 1.33 ohms. If the amp is not 1ohm stable, you'll see amp issues. (Thermal heat, low ohmic shut off)
It would be be safe to wire both speaker in series for a net 6 ohms and get a safe load to the amp. The low ohmic speaker will get more power.
This calculator may help:
http://www.1728.com/resistrs.htm
Swez
PS You say the amp is rated at 80 watts? (At what ohmic load is that 80 watts available?) 2 ,4 or 8 ohms?
gearhead on 08/9/2007 02:18:38
I'm just talking hypothetically right now (trying to learn a little).
swez on 08/9/2007 10:15:28
Good question and worth asking too. But now you you know the answers and can make an informed decission.
Keep asking, we're here to help...
Swez
gearhead on 08/9/2007 22:43:53
Another "learning" question.
A 2ch amp is not 1ohm mono stable (but it is 1ohm stereo stable), and it is rated for 600wrms @2ohm mono. If I connect a 1.6ohm load that will only need to draw 250wrms, will it be detrimental to the amp? Will it cause any other problems?
swez on 08/10/2007 08:40:00
In 2 channel mode, you should be OK if the amp mentioned is indeed 1 ohm stable in stereo mode.
If you did bridge the amp MONO and it is not pushed too hard, it will probably work at 1.6 ohms. (If the amp gets hot or shuts off, then you'll know it's not a good fit) The protection circuits should keep most amps from internal melt-downs. I would monitor this carefully if you try it. If the amp heats up a lot under normal listening, avoid this option if possible.
FYI: If there are complex passive crossover networks on the speakers you intend to use, they often have impedance loads that tend to "fix the load" the amp will actually see. It's not just the speaker ohmic rating the amp sees, but also impedance loads from the passive filters as well. (Inductive and Capacitive loads + Zobel network matching resistors are common in better passive networks)
Most passive networks make it difficult to measure resistance values with an Ohmeter. However, we can calculate "Z-nominal" by Ohm's Law if we know Voltage, Wattage, Current or resistance in a given circuit. (If we know 2 of these parameters, we can deduce the remaining 2 parameters w/ Ohm's Law )
Do you have an Ohm's Law pie chart?
http://www.installer.com/tech/ohmslaw.html
Swez
gearhead on 08/10/2007 09:01:39
"FYI: If there are complex passive crossover networks on the speakers you intend to use, they often have impedance loads that tend to "fix the load" the amp will actually see. It's not just the speaker ohmic rating the amp sees, but also impedance loads from the passive filters as well. (Inductive and Capacitive loads + Zobel network matching resistors are common in better passive networks) "
If 2 passive crossovers (that measure 4ohm with an ohmeter) are wired in parallel, will that provide a 2ohm load? I understand that impedence isn't the same thing as resistance, but that measuring the resistance of a speaker will give a rough estimate of it's impedece. Are you saying that if a passive crossover measures 4ohms with an ohmeter (with the woofer & tweeter connected to it), then that is what the amp will actually see?
swez on 08/10/2007 10:00:54
When we test a speaker, passive crossover network or both with a simple DMM Ohmeter and no audio, we get a static ohmic load reading that is fixed in value. (In this case, yes... 2 ohms) Most portable DMM's are DC voltage based. Caps block DC voltage to a major degree or entirely. The Zobel compensation resistor is actually what is being measured. (4/8 ohm resistor ect.)
However, when we play music through the speakers and crossovers, the dynamic impedance changes dramatically with the frequency of audio passing through both the speaker and crossovers. A Zobel compensation network helps smooth out the actual load the amp sees, but beyond the "fixed load resistor", impedance values of the filters and speaker coils react a lot based on frequency. (HP, LP and BP filters are common in complex passive networks)
There is actually a very complex set of variables to work with and that is why a quality set of Component speakers are so expensive. They tend to use better crossover parts and designs and many components too. (It takes years of study to become a good filter network designer/engineer) I don't have that level of background. (If I did, I would not have much interest ot time for this site) hehe
In a nutshell, a quality passive crossover network is complex and there are non-degreed designers that have mastered this deeply as a hobby. But it takes a lot of time, electronics theory studies and expensive equipment to proof out a given design. It's not rocket science, but pretty close to it in its own right. That's why these guys make big bucks.
Swez
gearhead on 08/10/2007 10:20:32
300w x 2@ 1ohm stereo = 150w x 2@2ohm stereo (theoretically), correct? And THANKS for putting up with so many off the wall questions. The old grey matter doesn't comprehend as well as it did 30yrs ago.
swez on 08/10/2007 10:53:28
Theoretically, yes that's about how it comes out on paper, but in the real world of dynamic audio, speakers loads change with frequency. We can even plot them with an AC volt meter to see just how much things change.
If voltage goes up, impedance is going down
If voltage is coming down, impedance is going up
This test assumes a variable tone generator is used and we measure the AC voltage at the speaker, (Not the amp)
Ahhh, you're gray matter is just fine. I have lots of gray matter these days. Most of it is on top the dome and not inside anymore. I guess it leaks out as we age.... LOL
Good and reasonble questions BTW... just hard to answer at times in a way that others can digest and use it later. If confused, ask for claification.
Swez
gearhead on 08/10/2007 22:18:16
Are higher end passive crossover networks designed for a particular speaker based on T/S parameters? What happens if, oh say, an MB Quart crossover is used for Blaupunkt components?
swez on 08/11/2007 00:45:30
Absolutely the case... expensive speakers often use complex crossover networks to get the best performance from their total package.
Some network designs are more generic and easy to use other speakers off another brand. However, in a case like Diamond, Focal, MBQ and other high end Comps, the crossovers are designed very specific to the speaker parameters and quirks.
Yes, the T/S is part of the equation for sure! But also to compensate for speaker matching, crossover points, minimal phase issues and lots more things are considered. As I said earlier, passive networks can be very complex in design and function. These Mfg's will test the livin' hell out of a quality Comp design to insure the best possible results.
In your situation, there's only one way to tell how well the MBQ passives mate to the Blau's... complex wave form testing with a tone generator, AC meter and O-Scope. Yes, we can get a general feel by ear, but this is not very reliable if we don't know the full features of the network and each speaker used. (Very complex issues at hand here)
Swez
PS An example might be... the tweeter used has a usable frequency range of 2.5KHz and up. It may not be 4 ohms either. (It could be 6-8 ohms) If we use another brand of speakers and the tweeter is rated at 5.0 KHz and up and has a different resistance value range, feeding it a 2.5KHz signal will destroy the tweeter in time. (See what I mean?)
gearhead on 08/12/2007 11:42:02
Can a crossover be used as a bandpass filter? Example: connect a midbass driver to the woofer terminals, and connect a 50w/4ohm resistor to the tweeter terminals.
swez on 08/12/2007 15:04:29
It's a lot more complex than that. "BP filters" or "Notch filters" are common in very high quality crossover networks and have 3 main functions:
1. Blocks deep bass to MB drivers
2. Blocks highs that should go to MR/TW drivers
3. May have impedance matching load resistor to level out the load resistance amp sees
To make one that works properly, you'll have to find a notch filter handbook or crossover guide reference.
Basically, we are working with a 2-3 stage filter network. The number and values of each component, (Coil,Cap, resistor) are determined by the drivers' ohmic load and the upper and lower bands with need to be attenuated.
This link shows simple 6dB/octave filters. That is, a single Cap or Coil is used for filtering. These are wide slope filters and may not be adequate for MD/Notch filtering. (12dB/oct. Butterworth filters are much better)
http://www.bcae1.com/passxovr.htm
http://www.carstereo.com/help/Articles.cfm?id=9 (A better calculator)
FYI, if an amp is powering only MB and a horn tweeter, we can use the amps HP filter setting to block lows and only require an upper band filter LPF for the MB driver and a HPF for the MR/TW driver.
In a nutshell, BP filters are a bit more complex and require a fair amount of study time to build them right the first time out.
Swez
PS Quote: "It's a jungle out there".
http://www.maxim-ic.com/appnotes.cfm/an_pk/1795
The esteemed value of a skilled filter design engineer is nothing short of a math wizzard or god-like maven! (Swez)
"A small tribe, in the dense wilderness, is much sought after by head hunters from the surrounding plains. Known throughout the land for their esoteric expertise, this is the tribe of the Analog Engineers, who live in the farthest regions of the left half Plains, past the jungles of Laplace.
The guru of analog engineers is the Analog Filter Designer, who sits on the throne of his kingdom and imparts wisdom. You never get to see him, even with an appointment, and you call him "Sir."
The countless pages of equations found in most books on filter design can frighten small dogs, and digital designers. This article clears a path through the brush for the practical engineer and unravels the mystery of filter design, enabling you to design continuous-time analog filters quickly and with a minimum of mathematics."
A little deep huh? Wait until you start looking at design formulae... MEGO, (My Eyes Glaze Over) sets in rapidly.
PS Did we just open up a fresh can of worms or what? Let's go fishing and forget all this stuff for a day. LOL I'm going fishin'! CLAP
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