--> The Victor Orthophonic System:

The Maxfield-Harrison Electro-Mechanical Model (simplified)

Maxfield-Harrison Electro-Mechanical Table of Correspondences

 Force (dynes) Velocity (cm/Second) Displacement (cm) Impedance (dyne sec/cm) Resistance (dyne sec/cm) (or mechanical ohms) Reactance (dyne sec/cm) (or mechanical ohms) Mass (gms) Compliance (cm/dyne) Electromotive Force (volts) Current (amperes) Charge (coulombs) Impedance (ohms) Resistance (ohms)   Reactance (ohms)   Inductance (henries) Capacity (farads) Figure 1

Compliance between two moving elements in direct connection is represented as a shunt capacity; compliance between a moving element and a fixed or rigid element in direct connection as a series capacity. Figure 2

Simplified diagram of equivalents

Here are the two equations upon which the whole theory of design are based: when................... The record surface is to be considered an approximate equivalent of a constant current electrical generator of infinite impedance.

fc = transmission system cut-off frequency in cycles per second

C = shunt compliance per section in cm/dynes

M = series mass per section

zo = characteristic impedance over the largest portion of the band range.

(Confused yet?)

The value of M is a diaphragm of 13.5 cm sup 2 with a mass of .186 gms.

Cut-off frequency chose was 5,000 hz after which surface noise becomes a real nuisance.

In this particular example, the characteristic impedance is calculated @ 2920 mechanical ohms.

Maxfield and Harrison ultimately settled upon a final design that resulted in a characteristic impedance of about 4500 mechanical ohms to produce acceptable volume.

The lever-transformer ratio of 4500/2920 was determined as necessary to produce the required resistance in the system.

(Ive talked to several engineers concerning the whole subject as it pertains to the Orthophonic system and all of them said it is tantamount to a bunch of engineering voodoo and marketing mumbo-jumbo for the most part.)

Page Created: 4 August 2003