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Discussion Starter · #1 ·
I don't have access to any fancy equipment, but do have a digital volt meter. can I play a test disk with various known frequencies and somehow measure the speaker output, plot it in excel and figure out my crossover points on my stock 2006 BMW 550?

Will the frequencies that are below the crossover point slowly have less output (at them same volume) as they move further away from the crossover point? Does the voltage of the speaker output increase/decrease with volume?
 

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Nope...

Your best be would to maybe play a test disk with a sine sweep (autosound 2000 maybe) and you may be able to figure it out by ear...

Otherwise you would want an RTA and some sort of sine sweep... then you could just watch the response..
 

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Hmm, interesting. I doubt that you could be too precise with it, but you might be on to something. You could probably narrow it down to a 500hz range.
 

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Discussion Starter · #5 ·
I guess I could get that cheap RadioShak sound meter and play various frequencies and just plot the output like that. I would think that there would be a voltage change with a change in output of the speaker though.

I thought about the PC route, but don't have a laptop, and the desktop ain't moving!
 

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I am not saying it is impossible, I don't know.

IMO though you could tune by ear and be just as close if not closer than trying to figure out how to do it with a DVM.
 

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I don't have access to any fancy equipment, but do have a digital volt meter. can I play a test disk with various known frequencies and somehow measure the speaker output, plot it in excel and figure out my crossover points on my stock 2006 BMW 550?

Will the frequencies that are below the crossover point slowly have less output (at them same volume) as they move further away from the crossover point? Does the voltage of the speaker output increase/decrease with volume?
Not only is this completely feasible but it's a standard electrical engineering lab experiment and is quite easy. Set your DVM on VAC and measure the input to the crossover and output (with load attached) at different frequencies. Compute the ratio out/in of these voltages. You can plot these on a log-log scale if you want but the crossover point is generally considered to be @ 3db down. If the crossover is symmetric that means the output of the high and low will be equal.
 

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Hmm, interesting. I doubt that you could be too precise with it, but you might be on to something. You could probably narrow it down to a 500hz range.
You can get way closer than that. Once you hit the crossover frequency on a 12db filter, the signal level starts a dramatic dive. At the crossover point, the voltage will have already decreased by 30% and the power by half. Another octave and the voltage will be quartered. If you can't get within 1% using this technique something is wrong with you or your DVM.
 

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Not only is this completely feasible but it's a standard electrical engineering lab experiment and is quite easy. Set your DVM on VAC and measure the input to the crossover and output (with load attached) at different frequencies. Compute the ratio out/in of these voltages. You can plot these on a log-log scale if you want but the crossover point is generally considered to be @ 3db down. If the crossover is symmetric that means the output of the high and low will be equal.

I stand corrected... :D I love when that happens... !:D
 

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Not only is this completely feasible but it's a standard electrical engineering lab experiment and is quite easy. Set your DVM on VAC and measure the input to the crossover and output (with load attached) at different frequencies. Compute the ratio out/in of these voltages. You can plot these on a log-log scale if you want but the crossover point is generally considered to be @ 3db down. If the crossover is symmetric that means the output of the high and low will be equal.
If you are measuring the crossover point, you have to be careful if you are talking 3dB down power-wise or voltage-wise. If you want to be 3dB down on power (what most crossover points are), you would have half of the power, but .707 of the voltage. If you want to be 3dB down on voltage, you would have .25 of the power.

I think the easy way is to find out which frequency causes output/input voltage to be .707. That would be 3dB down powerwise. So if you were putting out 10V at 1 kHz, and were putting out 7.07V at 1.5kHz, your crossover point would be 1.5kHz.

Edit: You have to be sure your DMM can still accurately register AC voltage at higher frequencies.
 

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You can try a Helix Xjust if you can find one hehe

I had two sold one and kept one. Unique piece of equipment
 

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sweep down pass voltage/2 is the -3dB point
So then -3dB crossover points are based on voltage, not power? I thought everything I came across was -3dB points were based on power. If you are -3dB down on voltage, you are -6dB (1/4 of the power!) down on power.

Just trying clarify...
 

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So then -3dB crossover points are based on voltage, not power? I thought everything I came across was -3dB points were based on power. If you are -3dB down on voltage, you are -6dB (1/4 of the power!) down on power.

Just trying clarify...
Ummmm, seriously man, think about that, I'll BRB gotta run out for a sec.

Edit, it took a long elevator trip to realize that I was VERY wrong and you are very right!
 

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Ummmm, seriously man, think about that, I'll BRB gotta run out for a sec.

Edit, it took a long elevator trip to realize that I was VERY wrong and you are very right!
Awesome, I'm not going crazy then :)

As long as the right info gets out there, that's all that matters!
 
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