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"Le This is the voice coil inductance measured in millihenries (mH). The industry standard is to measure inductance at 1,000 Hz. As frequencies get higher there will be a rise in impedance above Re. This is because the voice coil is acting as an inductor. Consequently, the impedance of a speaker is not a fixed resistance, but can be represented as a curve that changes as the input frequency changes. Maximum impedance (Zmax) occurs at Fs." I'm trying to implement a Zobel on a Trusonic FR80. I would like to find the TS's for this speaker. Thanks...Tre'
Re: How do I measure the Le of a speaker?
Measure the impedance of the speaker to find Le. It will be a complex impedance, having both reactance and resistance. You can use a Wheatstone bridge (inside a dedicated tester) or one of the measurement systems like Speaker Workshop to find impedance of your speaker.
Like from Parts Express. I use mine often for testing tolerence of caps and coils! Ron
Unfortunately, the effective Le and Re of the speaker's voice coil are going to change with increasing frequency. Fortunately, the Zobel circuits are not that sensitive so getting a Le and Re result at 1 kHz is good enough for sizing the Zobel. This is why there is typically a 25% factor in the rule of thumb equations for calculating the Zobel's capacitance and resistance. Martin
Thanks, but how do I measure inductance at 1K hz? Can I make a inductance bridge like a impedance bridge? I have an inductance meter but I don't know what freq. it uses. Tre'
I found it. Le=(sqrt(3)*Re)/(2*pi*fx) I have to find Re and fx first, but the article shows how to do that. Thanks...Tre' Speaker how to