I'd like to know the actual impedance of drivers I have but don't own or want to buy a microhpone, signal generator or sound card. So are there any calculators or crossover formulas online that can solve for driver impedance based on inputs of uF, mH and fc? And if so would results be meaningful?
thanks
thanks
This approach may or may not work out well, depending on how much you care about the end result. I mean in the 70s you just bought a woofer and tweeter, put a single cap in series with the tweeter, and called it good! So, sure, very basic stuff can work (for a boxed loudspeaker) to some degree. You will probably find that success is proportional to having a very good knowledge of what you are doing and vice versa.
I know that you recently inquired about an open baffle speaker in this forum. Keep in mind that a crossover for OB will require additional components to flatten out the driver responses. Most generic crossover design apps and so on assume a boxed loudspeaker and will lack these additional components.
To answer your question, if a driver is very well characterized by the manufacturer and you know the enclosure (box) size and type, then you probably can get a reasonably close estimate of the impedance vs frequency.
I know that you recently inquired about an open baffle speaker in this forum. Keep in mind that a crossover for OB will require additional components to flatten out the driver responses. Most generic crossover design apps and so on assume a boxed loudspeaker and will lack these additional components.
To answer your question, if a driver is very well characterized by the manufacturer and you know the enclosure (box) size and type, then you probably can get a reasonably close estimate of the impedance vs frequency.
A drivers impedance is not the same for different frequencies. This implies that there is not one value of C and L but it varies with frequency. There is also a component of R in the impedance which is frequency independent.
So a No to your question with the given input in post #1 but for sure a yes to if it is possible to calculate but it will contain an aspect of frequency but you don't have the ability apparently to supply that.
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So a No to your question with the given input in post #1 but for sure a yes to if it is possible to calculate but it will contain an aspect of frequency but you don't have the ability apparently to supply that.
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You don't need a microphone or signal generator to determine the impedance curve of a loudspeaker. A soundcard is useful though -- but chances are that you already have one. Does your computer play sounds? Does it have an audio input jack? If so, you've got all you need. Ok, a piece of software that will make use of the audio in/out is also needed, but there are a bunch of free programs out there (both kinds of "free": "free beer" and "free speech).
Are you saying you know the crossover component values and you want to work out the driver impedance they were designed for?
Just tell me what driver you want to impedance correct, and I can probably tell you by inspection.
I know how this stuff works.
Exact model please.
I know how this stuff works.
Exact model please.
That these values are also properties of a lone driver. But it doesnt change the premises - its a " no" go.
Why, because in order to do that one have to know the resulting speaker frequency response etc...
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Use your multimeter and measure resistance. We can tell you if they're 8 ohm or 4 ohm,
or
or
It won't be easy but we can make a guess if you tell us the values and the way they are connected.
I wouldn't think what driver it is is important and the maker doesn't provide driver impedances at crossover frequencies. The bottom line is I really like the sound of the speakers and just want to learn the impedance of the drivers at their crossover frequencies. The maker's spec. sheet just says 8ohms (minimum3.5ohms)
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I will measure impedance with my meter but the maker's document just says 8ohms (minumum 3.5 ohms).
XO is 150Hx and 3000Hz
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Henry,
The impedance is a complex valued quantity (amplitude and phase, combined into one number). For a loudspeaker as seen from its input terminals, or even just a driver alone, the impedance varies A LOT with frequency. You cannot just get one number for it, and you cannot back calculate it with any accuracy from the crossover diagram.
What I tried to explain to you before is that if you know a bunch of parameters for a DRIVER you can calculate ITS impedance as long as those parameters are very accurate and you know some things about enclosure that the driver is used in.
So you asked "are there any calculators or crossover formulas online that can solve for driver impedance based on inputs of uF, mH and fc" and the answer is no, not what you are envisioning.
1st order, L = ( 0.159 × Z ) / fx, where L = inductance of the coil in Henrys; fx = crossover frequency in hertz; Z = (actual) impedance of the speaker in ohms
re-arrange formula to solve for Z
re-arrange formula to solve for Z
The mid and woofer aren't really crossed. They are working together doing a kind of baffle step compensation. Based on assuming the mid is 8 ohms, it appears that it might be down a few more dB than wanted at the cross, which suggests it is more than 8 ohms there.. unless there is an upturn in the response. What size is this mid?
The tweeter also has some peaking relative to 8 ohms which suggests it is less then 8 ohms near the cross, or falls in response or is being EQed etc.
The tweeter also has some peaking relative to 8 ohms which suggests it is less then 8 ohms near the cross, or falls in response or is being EQed etc.