In Reply to: Re: Are all screw-on piezo -thanx Motorola sheet - using piezo w. tube posted by freddyi on March 30, 2001 at 17:33:55:
In this case, a capacitive load, series resistance will act as a low pass filter since the motor's impedance at high frequencies is so much lower than it is at low frequencies. In the top octave, the tweeter's impedance gets smaller and smaller, so the voltage divider becomes more and more proportioned towards the series resistance. Still, if the series resistance is small enough, it won't adversely affect performance and will protect the system from very high frequency oscillation.I used to connect 1 ohm, 1/4 watt resistors in series - just for this purpose. It acted as a fuse. And I think two ohms is just as appropriate as one. I don't install this component anymore, but there is no harm in it - and it most certainly does provide protection from UHF oscillation. The only reason I stopped is that I've never blown a quartz tweeter, nor have I ever found an amp that oscillated because of one. But that doesn't mean they can't be blown or that a person can't find an amp that will oscillate from this load. And the tiny added resistance may improve such a situation.
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