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description: Audio advice and discussions with audiophiles and professionals. Free discussion forums, open to all and frequented by industry experts. Ask questions and get advice on stereos, speakers, hi-end amplifiers, pre-amps, home theater, tube hi-fi, turntables, vinyl, tweaks, music, films, video, DVDs and more.
items: Q. for Wayne - Spice Models
items: Determining mechanical reactance values for Spice models
items: Re: Determining mechanical reactance values for Spice models

Q. for Wayne - Spice Models
type: item
description: Wayne: How do you derive the LCR values for the mechanical reactances shown in the crossover document. I'd really like to be able to generate them for other drivers. Thanks, John B.
creator: John B.
date: 2001-12-31T11:17:43-00:00

Determining mechanical reactance values for Spice models
type: item
description: You can find equivalent circuit values by backsolving the formulas Fr = 1/2π√LC and Q = √LC/R using the impedance graph and/or Thiele/Small parameters. For example, if you know that impedance at resonance is 50 ohms and the resonant frequency is 40Hz with a Q of 5.0, then resistance must 50 ohms and inductive and capacitive reactances must be equal at 40Hz. A similar procedure is used to determine reactance values for the impedance peaks caused by horns, where the frequency and Q of resonant events is not expressely stated. In this case, the impedance graph is used to determine resonant frequency and Q values for each peak that is to be simulated with a corresponding tank circuit. Q is relatively easy to determine - it is resonance divided by bandwidth - so the frequency of each peak is divided by the width of each peak (at 70% amplitude) to determine its Q. This gives you resonant frequency, Q and amplitude, which is everything you need to know to express the reactive nature of a device.
creator: Wayne Parham
date: 2001-12-31T20:39:03-00:00

Re: Determining mechanical reactance values for Spice models
type: item
description: Wayne: Thanks, and a happy new year! John B.
creator: John B.
date: 2002-01-02T08:44:45-00:00