What I'm trying to design is 3-way speaker system, 1 tweeter 8 ohms, 1 mid 8 ohms, and 1 low 8 ohms, all passing through a Parts Express 3-way passive crossover. That load going to the amp is still going to be 8 ohms correct?
I'm getting hung up on whether or not I need to calculate anything between the speakers and the amp if I'm separating the signal to three separate frequency ranges with the cross over.
Help a newbie!! Thanks and Happy Holidays!
-Ben
I'm getting hung up on whether or not I need to calculate anything between the speakers and the amp if I'm separating the signal to three separate frequency ranges with the cross over.
Help a newbie!! Thanks and Happy Holidays!
-Ben
Right, outside of each driver's working range, the input impedance of that section as seen by the amplifier
goes way up. Then the sections all will combine when in parallel to around 8R, throughout the frequency range.
The impedance is only roughly "constant" though, and real speaker system impedance curves are usually
rather erratic. Take a look at these beauties. This can still work ok, because the amplifier is normally a
(low impedance) voltage source, and most speakers are designed to be driven by such a voltage source.
stereophile impedance - Google Search
goes way up. Then the sections all will combine when in parallel to around 8R, throughout the frequency range.
The impedance is only roughly "constant" though, and real speaker system impedance curves are usually
rather erratic. Take a look at these beauties. This can still work ok, because the amplifier is normally a
(low impedance) voltage source, and most speakers are designed to be driven by such a voltage source.
stereophile impedance - Google Search
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So stick with roughly 8 ohm amplifier for that design? I guess that is ultimately what I'm asking ......
I do plan on getting more into the science behind it all, right now I'm having fun putting systems together that work, and at least sound decent. This stuff is so complicated when you really get in the weeds.
-Ben
I do plan on getting more into the science behind it all, right now I'm having fun putting systems together that work, and at least sound decent. This stuff is so complicated when you really get in the weeds.
-Ben
Yes this will be 'nominally' 8 ohms.
In reality it will be as low as 6 in parts, but that's normal for an '8 ohm' speaker... but it's important, because if you are calculating crossover with 8 ohm book values they won't be quite right, because actual impedance is not 8 ohms.
I did my first speaker that way and it was 'okay' for someone not in the know, but clearly not correct once I learned more and knew what to listen for. Frequency response was measured once measurement equipment got within reach of Joe hobbyist, and you can easily see the crossover.
In reality it will be as low as 6 in parts, but that's normal for an '8 ohm' speaker... but it's important, because if you are calculating crossover with 8 ohm book values they won't be quite right, because actual impedance is not 8 ohms.
I did my first speaker that way and it was 'okay' for someone not in the know, but clearly not correct once I learned more and knew what to listen for. Frequency response was measured once measurement equipment got within reach of Joe hobbyist, and you can easily see the crossover.