I know this has been asked many times before, but there are many different answers and a lot of wrong information. Is the following correct or incorrect about series or parallel drivers?
If I connect 2 drivers in series:
1) 3db louder at the same wattage
2) half the current at the same voltage
3) twice the impedance
4) twice the wattage before distortion
5) twice the wattage before damage
If I connect 2 drivers in parallel:
1) 3db louder at the same wattage
2) twice the current at the same voltage
3) half the impedance
4) twice the wattage before distortion
5) twice the wattage before damage
The rules for connecting a set of drivers already wired in series or parallel are exactly the same as for connecting individual drivers.
If I connect 2 drivers in series:
1) 3db louder at the same wattage
2) half the current at the same voltage
3) twice the impedance
4) twice the wattage before distortion
5) twice the wattage before damage
If I connect 2 drivers in parallel:
1) 3db louder at the same wattage
2) twice the current at the same voltage
3) half the impedance
4) twice the wattage before distortion
5) twice the wattage before damage
The rules for connecting a set of drivers already wired in series or parallel are exactly the same as for connecting individual drivers.
Wattage is usually equated with efficiency, and voltage with sensitivity. See my alterations or comments above.
Later,
Wolf
2 woofers in series may not give you more output in terms of measured/calculated SPL
but if they are of smaller size it should give better power handling and lower distortion
and you might experience this as being more powerful, and louder
not multiway woofers, but I once in my youth connected two 6" fullrange drivers in series
and it sound better than when in paralel
somehow smoother
but it was common knowledge not to series connect drivers
so I didnt, even when it sounded like better
I guess that was a mistake
I also have some small Foster tweeter horn drivers
sounds like crap one by one
even worse in paralel
but connected in series they sound quite sweet really
but who wants two series connected tweeters
but if they are of smaller size it should give better power handling and lower distortion
and you might experience this as being more powerful, and louder
not multiway woofers, but I once in my youth connected two 6" fullrange drivers in series
and it sound better than when in paralel
somehow smoother
but it was common knowledge not to series connect drivers
so I didnt, even when it sounded like better
I guess that was a mistake
I also have some small Foster tweeter horn drivers
sounds like crap one by one
even worse in paralel
but connected in series they sound quite sweet really
but who wants two series connected tweeters
A driver will give a certain SPL for a watt of input.
Two drivers each with half a watt of input will give the same SPL.
Except, when the drivers comply with very rigorous conditions. Sometimes the SPL can be upto 3dB louder than the wattage predicts. This is due to the way the air loads the driver. Two drivers very close to each other relative to the frequency they are being asked to reproduce will affect the air loads of each other. When the frequency is low enough there is a full 3dB of extra output due to this air load interaction.
As the reproduced frequency rises the extra 3dB gradually falls off to nothing extra.
This all makes conclusion 1), in both sets, wrong for most conditions of operation.
Two drivers each with half a watt of input will give the same SPL.
Except, when the drivers comply with very rigorous conditions. Sometimes the SPL can be upto 3dB louder than the wattage predicts. This is due to the way the air loads the driver. Two drivers very close to each other relative to the frequency they are being asked to reproduce will affect the air loads of each other. When the frequency is low enough there is a full 3dB of extra output due to this air load interaction.
As the reproduced frequency rises the extra 3dB gradually falls off to nothing extra.
This all makes conclusion 1), in both sets, wrong for most conditions of operation.
Can you please define "efficiency" and "sensitivity" in the context of your comments? "3db louder at the same wattage" is well defined, as an SPL meter measure db and I can measure watts too. If you want to nitpick "3 more db at the same wattage" is a better way of wording what I wanted to say, as it is entirely objective.
Going by what I posted, at the same voltage, they won't.
I meant this as a theoretical question, 2 smaller woofers might or might not sound better than 1 large one, but that is outside the scope of what I wanted to ask.
This is why we need to understand the theoretical, instead of relying on other people's advice.
I also have some small Foster tweeter horn drivers
sounds like crap one by one
even worse in paralel
but connected in series they sound quite sweet really
but who wants two series connected tweeters
IMO comb filtering is more feared than it should be. Of course, this is something else people would benefit from understand the theoretical, instead of just going by standard practices "Never use multiple tweeters" or "Never more than 1/2 wavelength between drivers".
This is very interesting, do you have links to further information on this? Am I correct in saying everything I said is still correct as long as the drivers are far enough apart not to affect the air loads of each other?
What I am really surprised at is no one commented on 4) and 5), which were guesses on my part, and really important with something like a line array. Suppose I have 16 drivers that individual start distorting enough to sound bad at 20 watts and explode at 40. Using my logic above, the line array should handle up to 320 watts. Different logic can give wildly different power handling numbers, and unless this is well understood, line array builders will either blow all their drivers or never play them near full potential.
No !!!!
the drivers need to be VERY close together to get advantage from the coupling of Sd and this only applies at the low frequency end of the passband for that driver combination.
Sometimes the frequency is so low relative to the driver spacing that the +3dB effect is only available below the passband of the driver.
the drivers need to be VERY close together to get advantage from the coupling of Sd and this only applies at the low frequency end of the passband for that driver combination.
Sometimes the frequency is so low relative to the driver spacing that the +3dB effect is only available below the passband of the driver.
Distortion is related to excursion.
It takes 6 dB additional power to double excursion.
Going from one to four speakers increases efficiency by 6 dB (when the speakers are within 1/4 wavelength), so harmonic and IM distortion is also reduced by 6 dB for the same output level.
Power handling is determined by the individual driver, the total power handling is simply the single x the driver total, 16 x 20 is 320 peak.
Recently made some small driver line arrays:
http://www.diyaudio.com/forums/multi-way/236037-dirty-dozen-line-array.html
The drivers are rated for 10 watts, 20 watts max.
They hit over 10% distortion at 10 watts when run near Fs (191 Hz), but actually can hold up to 40 watts sine wave for a few seconds without burning the voice coil.
Even though the dozen speakers could handle short peaks of around 1200 watts, more than 120 watts will make them sound pretty distorted.
That said, the efficiency has gone from 83 dB one watt one meter to around 93 dB one watt one meter, so only 1/10th the power is needed for the same level of sound as a single driver.
10 dB sounds twice as loud to your ears, so you could also say that the line has only half the distortion at the same SPL as a single, while playing twice as loud using the same power.
Art
ehh, ofcourse I meant 2 woofers in series against one woofer of same type and size
or the calculation/theory would not make any sense at all
like you say yourself, two small woofers vs one bigger woofer is a hole different matter
I am using a line array with 12 Fountek Jp2.0 Ribbons, so fairly big guys with 6.5Ohm each.
Now, the big question is: Is there a difference in sound if for instance I choose to connect
- group four of them by connecting them in parallel first and than connect the three groups in series (equals 4.875 ohms)
vs.
- connect three of them in series and connect the resulting four groups in parallel (equals as well 4.875 ohms)
?
If all ribbons/individual system would be 100% the same, it should not matter I guess, but as in reality they are not and have tolerance, which setup would sound better ? Anyone tried ?
Now, the big question is: Is there a difference in sound if for instance I choose to connect
- group four of them by connecting them in parallel first and than connect the three groups in series (equals 4.875 ohms)
vs.
- connect three of them in series and connect the resulting four groups in parallel (equals as well 4.875 ohms)
?
If all ribbons/individual system would be 100% the same, it should not matter I guess, but as in reality they are not and have tolerance, which setup would sound better ? Anyone tried ?
I found this basically saying that the center to center distance, it couples below if that is 1/2 wavelength.
So a pair of 10" stacked (12" between centers, seperate boxes) would couple around 550hz and below.
If the drivers were wired in series, i'd see a droop above 500hz untill it catchs the tweeter.
Currently the b102 lines up perfectly for me with my morel.
So adding another woof in series would cause a depression in freq response.
Post #1
http://www.diyaudio.com/forums/subwoofers/52414-mutual-coupling-question.html#post585439
From ev "when 2 speaker systems are placed side by side, the woofer cones "mutually couple" causing the 2 systems to act as 1 system with twice the effective cone area at very low frequencies giving an additional 3db increase in maximum acoustic output. Mutual coupling will occur when the frequency is such that the center to center distance between the woofer manifolds is less than 1/2 wavelength."
So a pair of 10" stacked (12" between centers, seperate boxes) would couple around 550hz and below.
If the drivers were wired in series, i'd see a droop above 500hz untill it catchs the tweeter.
Currently the b102 lines up perfectly for me with my morel.
So adding another woof in series would cause a depression in freq response.
Post #1
http://www.diyaudio.com/forums/subwoofers/52414-mutual-coupling-question.html#post585439
From ev "when 2 speaker systems are placed side by side, the woofer cones "mutually couple" causing the 2 systems to act as 1 system with twice the effective cone area at very low frequencies giving an additional 3db increase in maximum acoustic output. Mutual coupling will occur when the frequency is such that the center to center distance between the woofer manifolds is less than 1/2 wavelength."
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