Quote:
Originally Posted by
NathanJ
...Doubling the number of speakers gains 6 dB [ 20 log (2) ]
No. Radiation in space obeys inverse square law, but radiatiing area is simple addition. 2 cones in close proximity are +3dB
Quote:
Doubling the speakers halves the wattage to each speaker which looses 3 dB [ 10 log (.5) ]...
Also no. Load varies, depending if you use parallel (+3dB) or series (-3dB) wiring, the only two options available.
Quote:
This means that 4 x 4ohm speakers can be wired at 4ohm for a 6dB sensitivity increase.
Am I right?
Ironically, yes.
MTMs are the simple example.
- two 8-Ohm drivers in parallel are 4 Ohm load, draw twice the power (+3dB) and have twice the area (+3dB) so the total
voltage sensitivity is +6dB.
- two 4-ohm drivers in series are an 8 Ohm load, draws half the power (-3dB) and still have twice the area (+3dB), so there is no change (0dB) in total voltage sensitivity.
In the 4-driver case, I assume series/parallel wiring to achieve a 4 Ohm load. Two 4-Ohm drivers in parallel are a 2 Ohm load, and a +6dB sensitivity. Two of the 2-ohm loads in series are back to 4 Ohms, but as we saw above, with no net add in sensitivity.
Example of 8-ohm drivers in parallel:
Aviatrix
Example of 4-Ohm drivers in series:
TriTrix
Have fun,
Frank