Would it be possible to go back to the original question? This thread contains lots of great information,
but I am still struggling with the basics. I apologize for this “newbie” request, but I'm clearly misunderstanding something and would be grateful for some help!
All other
things being equal (PLEASE SEE full caveats note at bottom), I thought the following were generally true:
- If
you double an amp’s wattage, you increase your potential spl by 3db. Thus, an amp which doubles its watts
when the speaker load is halved (not all amps truly do this) driving an 8 ohm
speaker with a sensitivity of 90db would generally have essentially the same
spl potential driving a 4 ohm speaker with a sensitivity of 87db.
- In
general, the higher you turn up the volume of your amp to the same set of speakers, the harder it has to
work. All the way up is relatively hard work (and
may cause clipping, etc.), barely on should not be much work.
- Theoretically,
if the same speaker system could be made in an 8 ohm version and a 4 ohm
version with the same sensitivity rating (let’s say 90db), then the same amp
driving the 4 ohm version would need less “signal” or a lower volume setting to
attain the same spl in the same room as the 8 ohm version.
If the above are basically right, I don’t understand why an
amp would need to work harder with a 4 ohm load than an 8 ohm load to put out the
same spl in the same room. If the above are not correct, where did I go wrong?
THE HOSE ANALOGY: I’ve
heard the previously referenced analogy of water going through a hose many
times, and each time it sounds backwards to me.
It seems to me that if the flow of water – or amount of water moving
through space over time – is to remain constant, a larger diameter pipe, or
lower impedance, would make it easier for a pump (or amp) to push that water. If the flow remains constant, then as the hose
diameter decreases, the pressure increases and the pump would need to work harder. Why is this not correct?
Clearly, I must misunderstand some fundamental concepts! I’m not an engineer or science “type” so may
need some baby steps.
PLEASE NOTE: in order
to try to understand the basics, all of the above is based on simplistic
and theoretical situations, with all other things such as speaker
configuration and design, other components, room size, etc. being equal AND
with all components properly matched. I
understand that real world implementations may vary.
