@atmasphere
atmasphere said - " a previous answer was incorrect.
Both speakers will move at EXACTLY the same time regardless of the hookup. "
Incorrect? Really? In theory, they move at EXACTLY the same time only when no capacitance exists in the circuit. Current through the coils is the same at any given time only when the circuit doesn’t have capacitance. We know this is not the case. All circuits have some level of capacitance and inductance. The question is whether or not the amount of capacitance in the circuit and how it interacts with the series inductance is readily detectable. In practice, it is not. However, because it is not readily detectable doesn’t mean it doesn’t exist. I stand by what I said above - there will in fact be a phase delay between the two loudspeaker drivers but it will be virtually undetectable.
If you had any experience designing or building amplifiers, you’d know that every energy storing element within a circuit contributes to phase lead or lag between voltage and current. Loudspeaker coils are no different. This becomes immediately apparent when trying to maintain a safe phase margin with a typical feedback amplifier. The frequency at which inadequate phase or gain margin results in oscillation might be well over 50khz - certainly much higher than any loudspeaker woofer can deal with - hence undetectable but still there nonetheless.
As for "obvious confusion" regarding efficiency and sensitivity, there was nothing inaccurate or "confused" about my explanation - which you essentially repeated until you said this:
"So if you have a 97 db 1 watt/1 meter 8 ohm driver, two in series will have the same efficiency (since each is absorbing 1/2 watt) while the sensitivity is 94 db. If you put the two drivers in parallel for a 4 ohm load, the efficiency is the same as 1/2 is absorbed by each driver if 1 watt is applied. However the sensitivity is now 100db. " - atmasphere
With that, you clearly blew it. Two identical drivers in series will draw half the current of one driver but acoustic output of the two drivers in series will be essentially the same as one driver - not 3db down or 94 db as you indicated. Their accoustical output will sum depending on the factors I noted in my original post. So acoustical efficiency is not the same as you indicated - but roughly double.
You try to draw a distinction between efficiency and sensitivity but clearly don’t understand the essence of the difference - you aren’t "applying a watt". The only thing you’re applying is voltage. The device(s) draws whatever current the resistance dictates. In the case of two 97db drivers in parallel, you’ll only get 100db output if a pair are in parallel and are drawing current sufficient for two watts - not 1 watt. Go back and read what you said. Two 8 ohm drivers in parallel that normally produce 97db at 2.83v drive level individually, will only produce 100db when they draw two watts in the parallel arrangement. In series, they will draw half the current but each device's acoustic output will sum to roughly 97db. Efficiency is doubled with the series arrangement and remains unchanged with the parallel arrangement.
Since your confidence level appears to be far ahead of your knowledge level, it might be a good idea to say " I THINK what the previous poster said might be incorrect". A little humility goes a long way and alleviates the need to on occasion eat crow.
atmasphere said - " a previous answer was incorrect.
Both speakers will move at EXACTLY the same time regardless of the hookup. "
Incorrect? Really? In theory, they move at EXACTLY the same time only when no capacitance exists in the circuit. Current through the coils is the same at any given time only when the circuit doesn’t have capacitance. We know this is not the case. All circuits have some level of capacitance and inductance. The question is whether or not the amount of capacitance in the circuit and how it interacts with the series inductance is readily detectable. In practice, it is not. However, because it is not readily detectable doesn’t mean it doesn’t exist. I stand by what I said above - there will in fact be a phase delay between the two loudspeaker drivers but it will be virtually undetectable.
If you had any experience designing or building amplifiers, you’d know that every energy storing element within a circuit contributes to phase lead or lag between voltage and current. Loudspeaker coils are no different. This becomes immediately apparent when trying to maintain a safe phase margin with a typical feedback amplifier. The frequency at which inadequate phase or gain margin results in oscillation might be well over 50khz - certainly much higher than any loudspeaker woofer can deal with - hence undetectable but still there nonetheless.
As for "obvious confusion" regarding efficiency and sensitivity, there was nothing inaccurate or "confused" about my explanation - which you essentially repeated until you said this:
"So if you have a 97 db 1 watt/1 meter 8 ohm driver, two in series will have the same efficiency (since each is absorbing 1/2 watt) while the sensitivity is 94 db. If you put the two drivers in parallel for a 4 ohm load, the efficiency is the same as 1/2 is absorbed by each driver if 1 watt is applied. However the sensitivity is now 100db. " - atmasphere
With that, you clearly blew it. Two identical drivers in series will draw half the current of one driver but acoustic output of the two drivers in series will be essentially the same as one driver - not 3db down or 94 db as you indicated. Their accoustical output will sum depending on the factors I noted in my original post. So acoustical efficiency is not the same as you indicated - but roughly double.
You try to draw a distinction between efficiency and sensitivity but clearly don’t understand the essence of the difference - you aren’t "applying a watt". The only thing you’re applying is voltage. The device(s) draws whatever current the resistance dictates. In the case of two 97db drivers in parallel, you’ll only get 100db output if a pair are in parallel and are drawing current sufficient for two watts - not 1 watt. Go back and read what you said. Two 8 ohm drivers in parallel that normally produce 97db at 2.83v drive level individually, will only produce 100db when they draw two watts in the parallel arrangement. In series, they will draw half the current but each device's acoustic output will sum to roughly 97db. Efficiency is doubled with the series arrangement and remains unchanged with the parallel arrangement.
Since your confidence level appears to be far ahead of your knowledge level, it might be a good idea to say " I THINK what the previous poster said might be incorrect". A little humility goes a long way and alleviates the need to on occasion eat crow.
