Yamaha White Paper (Installation Series Speakers) User's Guide download pdf (Page 4)

A White Paper Of The Installation Series Loudspeakers

1) About phase characteristics between

drivers

Even a single speaker system may have the out-

of-phase problem (for example, between HF and

LF drivers of a 2-way speaker system).

Figure 4 shows the phase response of a 2-way

speaker system. The cutoff frequency is 1.5 kHz

for both the HPF (18 dB/oct, BW) and LPF (18

dB/oct, BW).

Let's focus on 1.5 kHz frequency now.

From the graph of the amplitude response, you can

see that 1.5 kHz frequency sound is reproduced

both by the HF and LF drivers. From the graph of

the phase response, you can see that the phase

difference between HF and LF is 180 degrees.

Both signal levels are equal so both cancel each

other and in result, the dip is created in the

amplitude characteristics. Also in the overall

phase response graph, you can see that the phase

suddenly changes between 1 kHz and 2 kHz. In

result, the speaker system has a bad phase

characteristics around the crossover point.

Figure 5 shows the phase response of the same 2-

way speaker system as Figure 4, however, the

speaker system is adjusted for reducing the phase

difference in the range between 1 kHz and 2 kHz

within 90 degrees. The slope of the phase

characteristics is constant over the whole range,

so the bad influence to the amplitude

characteristics is minimized.

The "installation" series has smooth phase

response that has the constant slope over the

whole range.

<Figure 4: Influence of the phase difference to the

amplitude response>

100 1000 10000

Frequency [Hz]

Relative S.P.L. [dB]

Low

High

Low+High

10dB

-180

-150

-120

-90

-60

-30

120

150

180

100 1000 10000

Frequency [Hz]

Phase [Degree]

Low

High

Low+High

<Figure 5: Response of a speaker system that has in-phase

units>

100 1000 10000

Frequency [Hz]

Relative S.P.L. [dB]

Low

High

Low+High

10dB

-180

-150

-120

-90

-60

-30

120

150

180

100 1000 10000

Frequency [Hz]

Phase [Degree]

Low

High

Low+High

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Yamaha White Paper (Installation Series Speakers) User's Guide Page 4

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