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Multi-Way Conventional loudspeakers with crossovers

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Old 23rd August 2005, 01:01 PM   #1
Brown is offline Brown  United Kingdom
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Default audio calculations - please help

The diagram shows part of a signal path in a sound reproduction system




------------> +6dBu ----> +8dBW ----------> 1m
crossover amplifier loudspeaker


The active crossover unit has a dynamic range 90dBu up to +18dBu
The amplifier has a dynamic range of 75dBW up to +24dBw
The loudspeaker has a cone diameter of 38cm, a nominal rated input impedance of 8 ohms and a sensitivity of 100dB/W/m
The listening room has a noise floor of 40dB

Calculate

a)The spl generated at a distance of 1metre from the loudspeaker

b)The voltage gain of the amplifier under the condition shown

c)The maximum and minimum rms voltage output from the crossover

d)The maximum amplifier output in Watts

e)The peak voltage (vpk) on the loudspeaker cable when the amplifier is producing maximum output

f)The lowest frequency capable of being reproduced by the loudspeaker drive unit in the absence of a baffle or a cabinet

g)The lowest frequency that is capable of being reproduced when the loudspeaker is mounted in the centre of a circular baffle 4 metres diameter

h)The octave range of the reproduced sound if the highest input frequency is 16 khz and the loudspeaker is mounted on the baffle described in part g

i)The dynamic range of the system



please please help if you can. im well stuck
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Old 23rd August 2005, 01:20 PM   #2
Did it Himself
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I'm not doing your homework for you You only joined today as well

You can't do it without knowing the input signal magnitude anyway. Unless that's the +6dBu figure in your diagram?
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Old 24th August 2005, 07:24 AM   #3
Svante is offline Svante  Sweden
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Default Re: audio calculations - please help

Quote:
Originally posted by Brown
f)The lowest frequency capable of being reproduced by the loudspeaker drive unit in the absence of a baffle or a cabinet

g)The lowest frequency that is capable of being reproduced when the loudspeaker is mounted in the centre of a circular baffle 4 metres diameter
Yes, this sounds like a home exam or something, so I won't do the job. However, I'm wondering a bit about the person who wrote the exam. The two questions above don't make sense. There will be a cutoff frequency, for sure, but there will still be sound coming out of the speaker below that cutoff, just a bit weaker. So the correct answer would be: "anything above DC".
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