4 drivers in series/parallel louder?

[norman bates]

I think I've seen it written it is supposed to be 6db louder, but that doesn't make any sense to me. Think of them as resistors, now with 10 volts, each driver is seeing 1/4 of the power. So 4 drivers (8ohm drivers wired for a total load of 8ohms) to me would be the same db volume with the same voltage into 1 speaker.

Otherwise we could wire up a bazillion drivers in series/parallel and be 150db with say 8 volts rms going in (8volts into 8ohm = 1 amp = 8 watts).

Yes it would be cleaner, less cone movement for 4 drivers, but comb filtering isn't fun.


Am I right or wrong ??????

 

[xrk971]

Two in parallel is 6dB at same voltage (double the drivers is 3dB and double the current is 3dB more) but uses twice the power as current is doubled. Series parallel is just putting that 6dB in series so current is the same with double the output so it would have been 9dB. But since the voltage across each driver dropped by factor of two, power drops by 4x or -6dB. So now we have 9dB-6dB = 3dB net. However cone excursion is significantly reduced (half the movement but SPL doubled so distortion is a lot less ).

 

[sreten]

Hi,

Your wrong. 4 drivers are +6dB, 16 would be +12dB and 64 +18dB.
Its nothing to so with total power, which is the same, its all to do
with radiation efficiency, the 4 drivers each only drive a quarter
of the space the single driver does, giving the +6dB gain.

That gain comes at the cost of a 4 times bigger box, said box
could easily support a double diameter driver (4 x the area)
and for the same bass extension said driver will be +6dB.

rgds, sreten.

 

[sreten]

Two in parallel is 6dB at same voltage (double the drivers is 3dB and double
the current is 3dB more) but uses twice the power as current is doubled.
Series parallel is just putting that 6dB in series so current is the same with
double the output so it would have been 9dB. But since the voltage across
each driver dropped by factor of two, power drops by 4x or -6dB. So now we
have 9dB-6dB = 3dB net. However cone excursion is significantly reduced
(half the movement but SPL doubled so distortion is a lot less ).

Hi,

As an explanation that doesn't make any sense at all,
and is simply wrong. Simple fact is radiation efficiency
increases 3dB each time you double the number of drivers.
4 drivers wired series parallel are +6dB, same impedance.
(For both sensitivity and efficiency).

rgds, sreten.

Two drivers in parallel are +6dB sensitivity, but only
+3dB efficiency because of the half impedance.

Can you see the mistake for 4 drivers ?

Noting two drivers in series are the same senstivity
but +3dB more efficient due to doubled impedance.

 

[xrk971]

Guess I got that one wrong. 6dB does ring a bell now. What happens with 4 drivers all in series though?

I guess simple way is series parallel is same impedance so same current for given voltage but membrane area increased 4x or 6dB.

I made it too complicated.

4 drivers in series is 4x impedance or 1/4 current so sensitivity gain is 0dB.

 

[sreten]

Guess I got that one wrong. 6dB does ring a bell now.
What happens with 4 drivers all in series though?

Hi,

Sensitivity remains the same as the one driver,
The efficiency +6dB due to 4 times impedance.

rgds, sreten.