Other than the obvious change of impedence when wiring dual voicecoils in series, are there any other effects that should be taken into consideration?
I assume that the sensitivity will be affected (lower)?
Anything else?
There is nothing wrong with wiring a dual voice coil subwoofer's 2 coils in series. That's the whole point of DVC subwoofers, they give you many wiring options.
It won't have any negative effects of the sub, it just changes the impedance seen by the amplifier.
I'm almost sure that sensitivity at 1W/1M will be the same... electricpower to acoustic power... linear function with the DRIVER efficiency factored in.
BUT at 2.83V the system's sensitivity will change respectively depending on how much power is derived from 2.83V at varoius impedances.
Chad
Quote:
Originally Posted by bikinpunk
Mark's an up late kinda dude. His neighbor has a horse.
I'm almost sure that sensitivity at 1W/1M will be the same... electricpower to acoustic power... linear function with the DRIVER efficiency factored in.
BUT at 2.83V the system's sensitivity will change respectively depending on how much power is derived from 2.83V at varoius impedances.
Chad
Which actually raises my second question (hijacking my own thread lol!)
An amplifier which has a rating of 200w@4 X2, 300w@2 X2, 600w@4 x1(bridged)
Would it be safe to assume that it SHOULD produce 400@8 X1 (bridged) ???
Please note that when wiring multiple drivers it is recommended that series connections between drivers be avoided at all costs. This does not include series connections made between voice coils on the same driver. For more information, please consult our dual voice coil tutorial.
Please note that when wiring multiple drivers it is recommended that series connections between drivers be avoided at all costs. This does not include series connections made between voice coils on the same driver. For more information, please consult our dual voice coil tutorial.
double the per channel rating at 4 (double voltage) then divide in half for doubling the impedance.
Chad
I follow that Chad...and it makes sense...
The thing that confuses me is how they arrive at 600w at 4 ohms bridged then?
(300 at 2 ohms X2)
That is the logic I used to come up with 400w bridged at 8 ohms...double the power of the single channel rating at half the impedence of the bridged load (if that makes sense)
Please note that when wiring multiple drivers it is recommended that series connections between drivers be avoided at all costs. This does not include series connections made between voice coils on the same driver. For more information, please consult our dual voice coil tutorial.
It is far less desirable to make subwoofer to subwoofer connections in series. Because of slight and unavoidable differences between speakers and because of the high likelihood of uneven loading between different speakers in a car, there will be slight differences in the mechanical behavior of the two speakers in series. These differences in movement result in induced voltage (called back EMF) being created by the speakers across the series connection. This effect causes a problem when two speakers which behave differently are connected in series because the speakers can modulate each other (cause each other to move), resulting in distortion. The problem becomes more serious as more speakers are connected in series.
A good experiment to show the effect of back EMF is the following: connect four speakers in series and short the positive and negative input leads of the series circuit. Push down on one cone with your hand; you will notice that the three other speakers will move in the opposite direction of the one you are pushing. Now, reconnect the speakers in parallel, short the inputs and push down on one cone. The speakers will not modulate each other because each one is shorted directly.
Back EMF modulation is not a concern when the voice coils of a dual voice coil speaker are wired in series to each other because the coils are physically coupled on one moving mass. Therefore, they cannot possibly modulate each other because they cannot move independently.
Ugh. First of all, I hate that it's become commonplace to refer to motion EMF as "back EMF". I know a lot of people do it, but it bugs me anyway. "Back EMF" was a phrase that was born before speakers came into existence, and describes something else entirely. Just because motional EMF is EMF that can affect things upstream (ie. back) doesn't make it back EMF! [/rant]
Anyway, if your speakers are so different that any perceived effect results, then it's time to buy some new speakers. Thing is, even if these electrical differences between subwoofers are already present, they'll STILL manifest themselves as differences in output whether because of back EMF or not.
I also don't agree with their final paragraph. Yes, motional EMF can affect speakers that are wired in parallel. A lot of study has been devoted to just that problem. That's part of the reason the outputs of good amplifiers have junk in series and parallel with the speaker. [the other reason is to make capacitive loads less of a problem, which isn't an entirely different issue...]
The thing that confuses me is how they arrive at 600w at 4 ohms bridged then?
(300 at 2 ohms X2)
That is the logic I used to come up with 400w bridged at 8 ohms...double the power of the single channel rating at half the impedence of the bridged load (if that makes sense)
Fuzzy math in the marketing department
Quote:
Originally Posted by bikinpunk
Mark's an up late kinda dude. His neighbor has a horse.
The thing that confuses me is how they arrive at 600w at 4 ohms bridged then?
(300 at 2 ohms X2)
That is the logic I used to come up with 400w bridged at 8 ohms...double the power of the single channel rating at half the impedence of the bridged load (if that makes sense)
There are losses associated with throwing more current through the thing. Your output won't exactly double when you cut the impedance in half. The amount of loss will depend on the particular amplifier. But if you know the 2 ohm rating, then you can assume the 4 ohm bridged rating will just be the sum of the outputs of the 2 ohm rating since the same amount of current is being drawn in both cases (except for some exotic designs).
to add to Mark's post, put them in a common volume of air. This way "human error" in box design wil not cause issues and causes many mechanical differences in drivers to "average out"
Quote:
Originally Posted by bikinpunk
Mark's an up late kinda dude. His neighbor has a horse.
There are losses associated with throwing more current through the thing. Your output won't exactly double when you cut the impedance in half. The amount of loss will depend on the particular amplifier. But if you know the 2 ohm rating, then you can assume the 4 ohm bridged rating will just be the sum of the outputs of the 2 ohm rating since the same amount of current is being drawn in both cases (except for some exotic designs).
That is what I meant...why wouldn't the 8 ohm bridged rating be the sum of the 4 ohm per channel output rating...I think Chad's formula is to figure current..which should be the same however the voltage is now doubled, so wouldn't the power be double the single channel rating at half the impedance?
Start thinking volts, not watts. When you bridge an amp you double the voltage (with losses), that's what happens V+V, Then plug and chug numbers
Chad
That is actually what I did...and figuring volts divided by impedance (ohms) the current stays the same (8 ohms bridged VS 4ohm stereo)
so to figure wattage or "P" you can take volts times current E x I = P
Correct?
I am asking...trying to figure this out
That is what I meant...why wouldn't the 8 ohm bridged rating be the sum of the 4 ohm per channel output rating...I think Chad's formula is to figure current..which should be the same however the voltage is now doubled, so wouldn't the power be double the single channel rating at half the impedance?
It would be. If the amp does 200 watts per channel x 2 into 4 ohms, it should do 400 watts x 1 at 8 ohms.
The problem comes from ratings such as the rating of my PPI A600.2 and many other amps, it says 150 watts x 2 into 4 ohms, 300 watts X 2 into 2 ohms and 600 X 1 into 4 ohms bridged. I don't believe it's really possible to completely double the power when the impedance is cut in half.
In reality, according to CA&E's test of the A600.2, it did 174 watts x 2 into 4 ohms, 304 watts x 2 into 2 ohms and 608 bridged x 1 into 4 ohms.
So...yes, the amp will double it's power bridged into twice the impedance of the 2 channel rating, but no amp doubles it's power when the impedance is cut in half. Those ratings are marketing.
In other words PPI rated their A600.2 like this:
150W x 2 @ 4 ohms
300W x 2 @ 2 ohms
600W x 1 @ 4 ohms
But if accurately rated, it would be more like this:
175W x 2 @ 4 ohms
300W x 2 @ 2 ohms
600W x 1 @ 4 ohms.
Dual voice coils in series...effects
Linear Mode
