posted
is there a way to measure a speaker impedance throught a transformer (Accumatch to be specific) . My understanding is, that because the windings don't actually touch that I can't measure the impedance of a speaer thru it. any ideas?
-------------------- Zapco Studio 204 & 500 (2) JL Audio 15W6's Linear Power PA2R (other stuff) Full Air Suspension Posts: 63 | From: Fresno, CA | Registered: Oct 2000
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posted
yes you can do it. It's not any harder than just measuring impedance. Although there's no point in measuring the impedance of a sub through an impedance matching device.
So yeah, you can read it, but the answer will be different.
Posts: 768 | From: Ottawa, On, Canada | Registered: May 2000
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posted
so how can people verify that the transformer is working properly and isn't going to fry their amp? I found that trying to measure the speaker thru it was just measuring the accumatch's impedance. not the speaker
-------------------- Zapco Studio 204 & 500 (2) JL Audio 15W6's Linear Power PA2R (other stuff) Full Air Suspension Posts: 63 | From: Fresno, CA | Registered: Oct 2000
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posted
You can always measure voltage at the input and output. If we play a true sine tone at a steady level, we can easily compare impedances of the speaker and transformer load to amp.
ex: if our speaker is 1 ohm and the amp cannot handle anything lower than 4 ohm bridged, the voltage at the amp terminals will be higher than the voltage at the speaker terminals.
power in = power out power = v*v / r v*v/Rin = V*V/Rout Rin = 4 ohm Rout = 1 ohm we now have Vin^2 = 4* Vout^2 take the sqrt Vin = 2* Vout
general formula Vin = sqrt(amp load/speaker load) * Vout
If our x-fmr matches 1 to 2 ohm, we will get .707 volts on the output for every volt on the input.
In older times, impedance matching through transformers was common place, but no longer with the current solid state amps. In those times, the transformer had a common tap and then taps for 4 ohm, 8, 16, 32. the nice thing about it is that transformers can only pass AC, not DC signals.
Posts: 768 | From: Ottawa, On, Canada | Registered: May 2000
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