Calibrating a sound level pressure meter
 

Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to for
light load and less than 22.5V , seems to work adequately on 15V , I intend
using 2xPP3 , 18V

Calibrating a sound level pressure meter
 

On Sep 27, 7:40*am, "N_Cook" wrote:
Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to for
light load and less than 22.5V , seems to work adequately on 15V , I intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

Calibrating a sound level pressure meter
 

nesesu wrote in message
...
On Sep 27, 7:40 am, "N_Cook" wrote:
Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz 3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

Calibrating a sound level pressure meter
 

On Oct 1, 9:17*am, "N_Cook" wrote:
nesesu wrote in message

...
On Sep 27, 7:40 am, "N_Cook" wrote:

Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , *the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz *3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

To measure SPL, A-weighted, it would have to cover 200 to 20000 Hz. No
acoustical standard covers 300 to 3000 Hz.

http://en.wikipedia.org/wiki/A-weighting

Calibrating a sound level pressure meter
 

spamtrap1888 wrote in message
...
On Oct 1, 9:17 am, "N_Cook" wrote:
nesesu wrote in message

...
On Sep 27, 7:40 am, "N_Cook" wrote:

Other than the B battery test mark on the scale for running off the
1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz 3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

To measure SPL, A-weighted, it would have to cover 200 to 20000 Hz. No
acoustical standard covers 300 to 3000 Hz.

http://en.wikipedia.org/wiki/A-weighting

+++

It is very basic one probably intended for schools use, no A or C wightings
just 40 to 120 dB att sw and slow/fast response sw (470uF across the meter)
and battery sw, but there is a calibration pot externally accessible.
I will use the calibrator preset via ps variation and the B mark to reset
the meter to deemed 15.5V and 24.5V B and 100 percent of the meter

Calibrating a sound level pressure meter
 

On Sat, 1 Oct 2011 20:18:30 -0700 (PDT), spamtrap1888
wrote:

On Oct 1, 9:17*am, "N_Cook" wrote:
nesesu wrote in message

...
On Sep 27, 7:40 am, "N_Cook" wrote:

Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , *the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz *3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

To measure SPL, A-weighted, it would have to cover 200 to 20000 Hz. No
acoustical standard covers 300 to 3000 Hz.

http://en.wikipedia.org/wiki/A-weighting

I am not all that comfortable with your declaration of NO standard covers
300 to 3000 Hz as that range is very commonly used in radio and telephony
measurement.

?-(

Calibrating a sound level pressure meter
 

On Oct 2, 5:02*pm, josephkk wrote:
On Sat, 1 Oct 2011 20:18:30 -0700 (PDT), spamtrap1888









wrote:
On Oct 1, 9:17*am, "N_Cook" wrote:
nesesu wrote in message

....
On Sep 27, 7:40 am, "N_Cook" wrote:

Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , *the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz *3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

To measure SPL, A-weighted, it would have to cover 200 to 20000 Hz. No
acoustical standard covers 300 to 3000 Hz.

http://en.wikipedia.org/wiki/A-weighting

I am not all that comfortable with your declaration of NO standard covers
300 to 3000 Hz as that range is very commonly used in radio and telephony
measurement.

?-(

If the only sound sources were telephone receivers, then a sound level
meter that covered only the voice channel range (originally limited by
the frequency response of the carbon granule "transmitter") would have
some value. But real sound sources cover more of the 20-20000 Hz audio
range.

Calibrating a sound level pressure meter
 

If I get back to this meter. I cannot make sense of the B indicator , the
resistor chain suggests 100mV fsd but reassembled and largely functioning
meter fsd is more of order 1V.
2 db ranges 60 and 70dB are stuck together . But for good posistions
switching between ranges for differing 1KHz sine signal in, consistent "0"
dB and +6.7 dB switching betweeen adjascent ranges. Don't know if that 6.7
instead of 10 is due to sine rather than noise source, will have to try
again with an attenuateable noise signal

Calibrating a sound level pressure meter
 

On Mon, 3 Oct 2011 00:00:55 -0700 (PDT), spamtrap1888
wrote:

On Oct 2, 5:02*pm, josephkk wrote:
On Sat, 1 Oct 2011 20:18:30 -0700 (PDT), spamtrap1888









wrote:
On Oct 1, 9:17*am, "N_Cook" wrote:
nesesu wrote in message

....
On Sep 27, 7:40 am, "N_Cook" wrote:

Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , *the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz *3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

To measure SPL, A-weighted, it would have to cover 200 to 20000 Hz. No
acoustical standard covers 300 to 3000 Hz.

http://en.wikipedia.org/wiki/A-weighting

I am not all that comfortable with your declaration of NO standard covers
300 to 3000 Hz as that range is very commonly used in radio and telephony
measurement.

?-(

If the only sound sources were telephone receivers, then a sound level
meter that covered only the voice channel range (originally limited by
the frequency response of the carbon granule "transmitter") would have
some value. But real sound sources cover more of the 20-20000 Hz audio
range.

Whoosh much? No other cases ever occurred, and were measured?

?-)

Calibrating a sound level pressure meter
 

On Oct 3, 9:27*pm, josephkk wrote:
On Mon, 3 Oct 2011 00:00:55 -0700 (PDT), spamtrap1888









wrote:
On Oct 2, 5:02*pm, josephkk wrote:
On Sat, 1 Oct 2011 20:18:30 -0700 (PDT), spamtrap1888

wrote:
On Oct 1, 9:17*am, "N_Cook" wrote:
nesesu wrote in message

...
On Sep 27, 7:40 am, "N_Cook" wrote:

Other than the B battery test mark on the scale for running off the 1960s
B122
type 22.5V battery . But of course no standard for what the B equates to
for
light load and less than 22.5V , seems to work adequately on 15V , I
intend
using 2xPP3 , 18V

With nominal batery voltage [22.5V] applied from a bench supply, where
does the meter pointer fall relative to the 'battery' markings on the
scale?
If the pointer is in the 'good' area just above the minimum battery
mark then the meter deflection is in the right ball park, not as far
out as your first post would suggest.
My B&K came with a calibrator source that fits over the mic and emits
a tone of about 1kHz to tweak the calibration if needed.

Neil S.

++++++

I'll go with your suggestion and leave as I found ignoring the new
suspension ribbon and a replaced intermittant B-E transistor
Looks as though Dawe bought in these Sifam ribbon suspension meters , *the
original label saying 1.45V and mention of an external pcb. I suspect Dawe
removed that pcb and the movement itself is 100mV. Battery test is simple
chain of resistors , protect diode and rest switched out. So if 100mV fsd
then for a new B122 battery 100 percent fsd would correxpond to 24.5V and
the B marker correspond to 15.5V which seems reasonable. As the mic is
capacitive , about 300 to 3KHz *3dB bandwidth , not electret, not worth
going to any effort calibrating this SPL.
B mark is 64 degrees of 90 degree arc of meter swing, 71 percent fsd

To measure SPL, A-weighted, it would have to cover 200 to 20000 Hz. No
acoustical standard covers 300 to 3000 Hz.

http://en.wikipedia.org/wiki/A-weighting

I am not all that comfortable with your declaration of NO standard covers
300 to 3000 Hz as that range is very commonly used in radio and telephony
measurement.

?-(

If the only sound sources were telephone receivers, then a sound level
meter that covered only the voice channel range (originally limited by
the frequency response of the carbon granule "transmitter") would have
some value. But real sound sources cover more of the 20-20000 Hz audio
range.

Whoosh much?

Troll much?

* No other cases ever occurred, and were measured?

?-)

Start he

http://en.wikipedia.org/wiki/Sound_level_meter