Various measurements on audio equipment. by jimmy67music. A classic reprint of the famous Norman Crowhurst book that is a complete compendium of measurement and testing techniques for audio equipment including. AUDIO MEASUREMENTS. by Crowhurst, Norman H. Edition: First Edition; First Printing. Book Description. New York: Gernsback Library, Inc.. First Edition .

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Tube Literature

Instead, the screen supply is usually derived from the plate supply, using either a series resistor or a voltage divider. Although this two-stage arrangement can never get as far as causing oscillation, it can cause a peak in the frequency response. Explain the advantages and limitations of coaxial lines.

Hence, with the same magnetic heldy the high-impedance circuit gives a margin of 80 db 10, In industry, in academic education, and particularly in working with graduates from college, this need is evident.

Consequently, the mismatch problems met in making the diaphragm of the microphone or loudspeaker act uniformly over a wide range of frequencies are not present. The grooves can be cut two ways: Then, although minute currents may flow between the cathode and heater wiring, there will be no audio voltage corresponding to them. An input resistor ofohms is across the basic amplifier input inside the feedback loop.

Each of these receptors, however, does not transmit its individual frequency to the brain.

Comments and remarks are always welcome! The only changing voltages in the tube are the grid and plate potentials. As the complete circuit from ground to the live side of the input at the audip consists of the entire line out to the microphone and back, the total voltage induced by the magnetic field will cancel out giving zero resultant induction.

Inevitably such a change of approach will mean a change of stress. The internal ampli- fier gain A is the part that changes with frequency and produces the phase shift. When the push-pull stage is operated class AB, the plate currents in the tubes change appreciably during different parts of the waveform.

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What is the maximum loop gain that can be used with positive feedback without causing oscillation? First, on 6 October, will be Burning Amp in They were, unfortunately, ignored. Hence we need further smoothing action to get an adequately smooth or steady d-c and to avoid producing hum in aueio amplifier.


As the wave dips back toward zero, the capacitor will maintain the output current by discharging into the load, thereby keeping the voltage nearly constant between peaks. This change takes time. The control for the high-frequency end is called a treble control, for audio purposes, and onrman for the low-frequency end is called a bass control.

All kinds of power components and circuits radiate at power frequencies mostly 60 and cycles. By continuing to use our website you are agreeing to our use of cookies. Although mesaurements book deals with the equipment of the day, largely it based on vacuum tubes, much of that equipment is still available at bargainbasement prices.

Assuming a recording from 20 cycles to 20, measureemnts, this would mean the magnitude of movement to give the same output at 20 cycles would be times what it is at 20, cycles.

Doubling the frequency must halve the amplitude, so that the maximum rate at which the stylus moves at the different frequencies will be constant.

Why is a capacitor necessary with a screen supply circuit? Electromagnetic shielding meaaurements not use a magnetic material, but rather one that conducts electric current well, such as copper or aluminum.

Audio Measurements by Norman Crowhurst dwnld

If the cur- rent should drop to 0. It must not warble up and down, or flutter up and down. If, on the other hand, the surface is connected by a low-resistance path to ground, the charges will leak away rapidly with- out causing this interference.

This book or any parts thereof may not be reproduced in any form or in any language without permission of the publisher. The opposite is true with electric induction.


Usually this happens at a very low frequency and at a very high frequency, due to ultimate loss in the coupling capacitors at the low-frequency end and stray capacitance between stages at the high- frequency end.

Akdio is the approximate source resistance as a multiple or fraction of load impedance with feedback connected? The other is an accentuation or boost of some frequencies compared with the rest. An amplifier uses overall feedback, voltage derived at the output, and series injected at the input. The difference between the input and output waveforms, which represents the distortion component, acts to reduce the amount of the distortion.

In this way the extra 5 milliamperes flowing in the volt- age divider helps considerably in maintaining a steady screen potential. Now assume that the ohm load is connected to the amplifier, still with 2 millivolts at the input. Using an acoustic re- sistance consisting of a large number of holes that allow the air to pass through but offer resistance to its passage achieves an intermediate condi- tion that damps the diaphragm properly.

He was prolific in a way that few writers are, but more importandy he explained his subjects in a way that almost anyone, novice or expert, could understand. For this reason, the positive-feedback oscillator produces considerably more harmonic distortion than either of the other types. The subject of concern in audio is called electro-acoustics, because it deals with the combination of electronic and acoustic effects.

Automagically notify you when someone responds. How should it be listened to, and what happens if such a recording is played over a more conventional system?