Basic Electronics and 21

7/27/2019 Basic Electronics and 21

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AS APPLIED TO ELECTRONIC MUSICAL

PRODUCTION AND PERFORMANCE

Part One Basic training

JIM DuBARR INSTRUCTOR

MICHAEL FUSON COURSE CONSULTANT

CREATED BYJIM DuBARR ENTERTAINMENT. ALL RIGHTS RESERVED. USE OF ALL MATERIALS CONTAINED HERIN ISAUTHOIZED TO ALL MEMBERS OF THE SAINT JOSEPH MUSIC FOUNDATION FOR PURPOSES OF EDUCATION ONLY.


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DEFINITIONS OHMS LAW SOLVING EQUATIONS USING OHMS LAWWHAT IS FREQUENCY MORE ABOUT FREQUENCY THE FREQUENCY SPECTRUM SPEAKER CONSTRUCTION

FREQUENCY AND SPEAKERS CROSSOVERS EQUALIZERS


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IMPEDANCE

IMPEDANCE MATCHING

SERIES AND PARALLEL CONNECTIONS

POWER HANDLING CAPABILITIES RMS vs. PEAK WATTAGE

TOTAL HARMONIC DISTORTION

READING SIMPLE SPECIFICATION SHEETS(Specs)


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CURRENTThe flow of electrons

within an electroniccircuit.

Measured in Amperes

Electronic symbol I

Also known as amps.

RESISTANCEOpposition to the flow of

electrons in an electroniccircuit.

Measured in Ohms

Electronic symbol R

Also represented byOmega


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VOLTAGEThe potential, or pushing

power, of electricityavailable to a circuit.

Measured in Volts

Electronic symbol E

Also symbolized as V

POWERThe measure of the ability

of an electronic circuit toaccomplish a task.

Measured in Watts

Electronic symbol P

Also symbolized as W


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CURRENT AMPS - I

VOLTAGE VOLTS - E

RESISTANCE OHMS - R

POWER WATTS - W

E

I R


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With any two variables, the third may be found by usingthe following simple formulas;

E (Voltage) = I (Current) x R (Resistance)

I (Current) = E (Voltage)

R (Resistance)

R (Resistance) = E (Voltage)

I (Current)


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Frequency is the essence of Sound

Frequency is defined as the time between the reoccurrence ofthe same event

Sound waves create pressure waves in the air that vibrate theear drum, causing us to hear. These sound waves are

sinuodal, or modulate from zero to a positive level, then toan equal negative level, then back to zero again. The

period of time it takes for this cycle to occur is called thefrequency. In electronics, this is measured by what is

called a sine wave, which resembles a sideways S.Frequency is measured in units called Hertz, abbreviated

as Hz, also called Cycles per Second.


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LOW FREQUENCY

Low frequency sound

waves are long, andrepeat less frequently.Low frequency sounds ,

like that of a bass, vibrate

the ear drum less often,so we hear low sounds.

HIGH FREQUENCY

High frequency sound

waves are short, andrepeat more often. Highfrequency sounds, such

as lead guitar, vibrate the

ear drums more often, sowe hear a higher sound.


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Low Frequencies

20 Hz to 250 Hz

Midrange Frequencies250 Hz to 2 kHz (2000 Hz)

High Frequencies

Above 2 kHz to extent of hearing capabilities.


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PLACEHOLDER FOR PICTURE OF SPEAKER


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Low Frequency

Larger magnets and coils arenecessary to produce lowfrequencies.

More power is necessary toenergize these large coils,

which are actually resistors bynature.

Power is measured in watts,low frequency speakersrequire more wattage toproduce sound.

High Frequency

Smaller magnets and coils areneeded to produce highfrequency sound waves.

Less power is needed toenergize the smaller coils ofthese speakers, consequentlythere is less resistance in thiscircuit.

Less wattage is necessary topower these speakers, asmaller Power amp can beused.


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Crossovers are adjustable frequency dividers which allowselected frequencies to pass, or be blocked from passing, tospeakers.

In simple terms, crossovers provide a means of allowing

only lower frequencies access to larger bass speakers whileblocking higher frequencies. At the same time they allowonly higher frequencies to pass through to the smallerspeakers and horns, while blocking the lower frequencies,

which could damage the smaller speakers.

Crossovers can be two way, or three way which additionallyallows control over frequency distribution to Midrangespeakers .


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Equalizers allow the user to control the volume ofindividual frequencies distributed to speakers.

Equalizers allow for fine tuning of the force of soundwaves produced by the speaker for each of the

adjustable frequency ranges by providing resistance tothe chosen frequency being adjusted.

Using Ohms Law, we can see that more resistancemeans less voltage.

Understanding speaker construction, the speaker willvibrate less, producing less powerful sound waves inthe adjusted frequency range.


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Typical 32 Band Equalizer

Two-Way Crossover


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Please take this time to jot down any questions you may have.

This presentation will be available online through the Foundations website. Acomprehensive five part course is available through the Foundation as well. There

is no cost for these services, however donations to the Foundation will beaccepted. Questions (and possibly tutoring) can be addressed to the following

links after tonights presentation. Thank you for attending!

Jim DuBarr [email protected] Fuson [email protected]
mailto:[email protected]:[email protected]


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Impedance is simply the combined resistance of allcomponents of any given circuit.

Since it is resistance, it is measured in ohms.

Multiple speaker enclosures usually contain an internalcrossover to separate frequencies between the different size

speakers in the cabinet.

The resistance of this crossover, combined with the resistanceof the speakers themselves, represents the impedance.


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To insure proper operation of speakers and poweramplifiers, it is important to match the impedance of thespeakers to the output of the power amplifier used.

Failure to insure proper impedance matching may damage

speakers and power amplifiers, and at a minimum willshorten the useful life of the items.

Most matching can be done easily by either choosing thecorresponding output on the power amplifier, or in somecases setting a control on the power amplifier for the

correct output impedance. Many power amplifiers matchimpedance automatically through sensing circuits.

Most speaker enclosures are 4, 8 or 16 ohm impedance.


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How you connect multiple speakers together can havean effect on total impedance of the circuit.

SERIES one cable connects the power amplifier tothe first speakers input. The second speaker is

connected from the first speakers output to the inputof the second speaker. In this scenario, if the firstspeakers impedance is 4 ohms, and the second is 4ohms, the total impedance of the circuit is 8 ohms.

PARALLEL separate cables connect each speaker to aseparate output of the power amplifier. Each speakermaintains its own impedance rating.


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Because there are no universally accepted standards, most professional loudspeakermanufacturers use different test methods to arrive at a power handling specification.

This rating does not necessarily correspond to the best amplifier size to use nor is it ameasure of the "safe" amplifier size to use under actual operating conditions.

There are three separate and very distinct issues regarding selecting amplifier power forloudspeakers.

1. LOUDSPEAKER POWER HANDLING RATING2. SELECTING AN APPROPRIATE AMPLIFIER SIZE

3. PREVENTING LOUDSPEAKER DAMAGE

If an audio system is operated improperly, damage to or failure of a loudspeaker can occureven with an amplifier sized well below the loudspeakers power rating.

Contrarily, if an audio system is operated properly, damage to or failure of a loudspeakercan be avoided even with an amplifier sized well in excess of the loudspeakerscontinuous (or RMS, average, etc.) power rating.


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RMS, or Root Mean Standard, describes the point in asignal, or frequency when distortion begins to occur.

This can be heard by turning a radio up to full volume andlistening. Once the volume is decreased, you hear less

unnatural noise other than the sound itself. RMS is 70.7% of the peak Wattage.

Example: 100 watts peak=70.7 watts RMS. Above 70.7watts, distortion will increase proportionally to the

maximum allowed by the design of the circuit. Simply put,a volume knob incremented 1-10 will begin to producedistortion of the signal when turned to 8 or above.


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Music is made up of both Fundamental and HarmonicFrequencies.

A note produced by a musical instrument, A for example, isproducing a fundamental frequency of 440Hz or cycles persecond. It is also reproducing harmonics of that frequency that

are multiples of the fundamental frequency, such as 880Hz,1220Hz, 1760Hz and so on.

Each of the harmonic frequencies is lower in level or volumethan the fundamental, but they serve to give each instrument itsunique sound.

When the total harmonic distortion of an amplifier is measured,the difference in the level of the harmonics at the output stage ofthe amp is compared to the level of the harmonics at the inputstage, and the difference is the extent of the distortion.


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Behringer B212XL SYSTEM DATA

High-performance woofer

B212XL: 12" (305 mm)

B215XL: 15" (381 mm)

Tweeter compression driver

B212XL and B215XL: 1.75" (44 mm)

Frequency range

B212XL: 65 Hz to 18 kHz

B215XL: 55 Hz to 20 kHz

Power rating

B212XL: 800 W Peak Power

200 W Continuous Power

(IEC 60268-5)

B215XL: 1000 W Peak Power

250 W Continuous Power

(IEC 60268-5)

Impedance

B212XL and B215XL: 8

Sensitivity (1 W @ 1 m)

B212XL: 95 dB (Full Space)

B215XL: 96 dB (Full Space)

Dispersion

B212XL: 90 x 60

B215XL: 70 x 40

Crossover frequency

B212XL: 1.9 kHz B215XL: 2.0 kHz

DIMENSIONS/WEIGHT

Dimensions (HxWxD)

B212XL: approx. 21 23" x 13 58" x 10 58"

(approx. 550 mm x 345 mm x 270 mm)

B215XL: approx. 27 13" x 17 13" x 13 116" (approx. 695 mm x 440 mm x 335 mm)

Weight

B212XL: 24.0 lb / 10.9 kg

B215XL: 38.7 lb / 17.6 kg

Documents

Basic Electronics and 21