High / low impedance power amplifiers

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High / low impedance power amplifiers

High impedance

Low impedance

Outline

The speaker system can be run with with less current compared to low impedance, and the distance between the amplifier and the speaker is long, and it is used when running many speakers.
In the case of high impedance connection, the amplifier side operates with the output voltage of 100V or 70V.

Generally, one speaker system is connected to one channel.
When transmitting electrical signals from the amplifier to the speaker, a low impedance connection is advantageous for sound quality because the loss due to cable resistance is small in the case of short distances.

Speaker

High impedance speaker

Low impedance speaker

Impedance

Several hundred Ω to several kΩ

2 to 16 Ω

Merits

One power amplifier can drive multiple speakers
Allows long distance transmission not affected by cable resistance
Easy to add or remove speakers
A mixture of speakers with different rated inputs can be used

Favorable in sound quality
Easy connections
Does not require a speaker transformer

Demerits

It is inferior to low impedance in sound quality.

The number of speakers that can be connected is limited.
In the case of long distance, transmission loss occurs.

Use place

It is inferior to low impedance in sound quality.

Live events with emphasis on sound quality

Speaker,
how to choose an amplifier

Power amplifier
rated output

≥

Total W value of speakers

Example) Up to 100 1W speakers for 100W amplifier, 20 for 5W speakers

Speaker's
Maximum Allowable input

Power amplifier
rated output

Example) 8 Ω 600 W (PGM) 、8Ω　speaker, 8 Ω 340 W power amplifier

100V and 70V lines of high impedance power amplifiers PT. 1

The output voltage of the high impedance power amplifier is mainly divided into 100V and 70V.
The connection point of the speaker output terminal differs depending on whether the speaker is designed for 100V or 70V.
It is also called 100 series and 70 series.
A 100V line with less voltage drop than a 70V line is better for long distance transmission.

100V and 70V lines of high impedance power amplifiers PT. 2

The input power (W) to the speaker is different for 100V lines and 70V lines.
For speakers of the same impedance, the input power at the 100V line is twice that of the 70V line.

Therefore, if you go from 100V line to 70V line, the volume will be lower, but you can connect twice as many speakers.

Speaker impedance	100V line	70V line
10k	1W	0.5W
5k	2W	1W
3.3k	3W	1.5W
2k	5W	2.5W
1k	10W	5W
670	15W	7.5W
500	20W	10W
333	30W	15W