Testing
When
you have finished your repair, and have fitted the driver
back into its cabinet, taking care to connect it correctly.
It's worth giving it a gentle test. Below are some sounds
and tones, which can help.
Caution
Some of these tones may not be audible for several reasons.
So it is very important not to 'over drive' your amplifier
and speaker. Do not over power the driver outside of the cabinet,
as it can lead to excessive cone movement and damage the driver.
Tones
1.
440Hz - 'Middle
A' on a musical instrument. This should be heard and give
a good central image between a like pair of speakers, if not
something's wrong.
2.
50Hz - A low frequency,
you should be able to see the bass cone just moving. Not too
loud. Check for air leaks around the cones, by running your
hand around over the drivers you have removed and refitted.
Take care not to touch the cones or diaphragms.
3.
30Hz - A very
low frequency, may not be heard, depending on the speaker
and the size of your room.
4.
Pink Noise in Mono
- This sound is a form of noise that theoretically contains
all frequencies. It should sound a bit like static you get
when tuning between radio stations. Pink noise is defined
as having equal energy per octave and it's an important signal
for loudspeaker testing if you have loudspeaker measurement
equipment. When playing this sound, and your loudspeakers
are in phase, the sound should appear to come from the middle
of each loudspeaker when listened to individually, and give
a good central image when played on a stereo pair of loudspeakers.
5.
Pink Noise
out of Phase - This is the same sound as above, but recorded
with one channel out of phase, reversed. Here the sound should
appear to come from the left or right loudspeakers individually,
and not give a good central image.
If
you have a fault?
Go over your connections, to the loudspeaker cabinet and inside
the loudspeaker from the crossover to the drivers. Check
fuses. Do not change the polarity of any drivers you have
not removed, or you can end up in a terrible mess.
-o0o-
Here
are some more tones to help set up your system, recorded at
-3db in .wav format.
20Hz
- 25Hz - 31.5Hz
- 40Hz - 50Hz
- 63Hz - 80Hz
- 100Hz - 125Hz
- 160Hz - 200Hz
- 250Hz - 315Hz
- 400Hz - 500Hz
- 630Hz - 800Hz
- 1kHz - 1.25kHz
- 1.6kHz - 2kHz
- 2.5kHz - 3.15kHz
- 4kHz - 5kHz
- 6.3kHz - 8kHz
- 10kHz - 12.5kHz
- 16kHz - 17kHz
- 20kHz
Tip,
if your computer is not connected to your hi-fi, use your
'burner' to make a CD of the tones, If you need help? Let
me know and for £1.50 I'll pop a CD in the post.
Greg
greg@speaker-repairs.co.uk
21-Oct-2007
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