Sensitivity @ 1m/2.83V
96dB


Westlake gave this as a sensitivity spec on one of their speakers. i
don't know what it means, or what a good number would be. i know a
frequency response of 20-20khz +/- 0.1db is a good spec for a preamp,
but i don't know how to read a monitor sensitivity spec.

in article , xy at
wrote on 12/2/03 10:11 PM:

Sensitivity @ 1m/2.83V
96dB


Westlake gave this as a sensitivity spec on one of their speakers. i
don't know what it means, or what a good number would be. i know a
frequency response of 20-20khz +/- 0.1db is a good spec for a preamp,
but i don't know how to read a monitor sensitivity spec.

2.83V refers to the voltage input to these speakers which generates 1 watt
of power.
96dB at 1 meter distance in free space with 1 watt of applied power is a
fairly efficient speaker system. What this spec doesn't tell is across what
bandwidth this efficiency is measured.

xy wrote:
Sensitivity @ 1m/2.83V
96dB

Westlake gave this as a sensitivity spec on one of their speakers. i
don't know what it means, or what a good number would be. i know a
frequency response of 20-20khz +/- 0.1db is a good spec for a preamp,
but i don't know how to read a monitor sensitivity spec.

That means if you put 2.83V into them, at one meter distance you will get
96 dB SPL of output.

Normally speakers are measured in dB SPL at one meter with one watt.
Since W=V^2/R, you know that 2.83V is the voltage you get with one watt
going into an eight-ohm load. So if you assume the speaker really is
eight ohms at the frequency they measured it at, you can use this for
comparison purposes.

This tells you how big an amp you need to get a given output level.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

umbriaco wrote in news:BBF2CAFF.425A3%
:

in article , xy at
wrote on 12/2/03 10:11 PM:

Sensitivity @ 1m/2.83V
96dB


Westlake gave this as a sensitivity spec on one of their speakers. i
don't know what it means, or what a good number would be. i know a
frequency response of 20-20khz +/- 0.1db is a good spec for a preamp,
but i don't know how to read a monitor sensitivity spec.

2.83V refers to the voltage input to these speakers which generates 1
watt
of power.
96dB at 1 meter distance in free space with 1 watt of applied power is a
fairly efficient speaker system. What this spec doesn't tell is across
what
bandwidth this efficiency is measured.



Actually 2.83 volts into a speaker with an impedance of 8 ohms equates to
1 watt. If the speaker has a 4 ohm impedance, 2.83 volts is 2 watts of
power.

Assuming the speaker has an impedance of 4 ohms, the sensitivity is really
93 db at 1 watt, 1 meter away.

If it is a 8 ohm speaker, then the sensitivity is 96 db at 1 watt, 1 meter
away.

Sensitivity is yet another way of determining how much power you will need
for a particular SPL.

r



--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.

Scott Dorsey wrote:

xy wrote:
Sensitivity @ 1m/2.83V
96dB

Westlake gave this as a sensitivity spec on one of their speakers. i
don't know what it means, or what a good number would be. i know a
frequency response of 20-20khz +/- 0.1db is a good spec for a preamp,
but i don't know how to read a monitor sensitivity spec.

That means if you put 2.83V into them, at one meter distance you will get
96 dB SPL of output.

Normally speakers are measured in dB SPL at one meter with one watt.
Since W=V^2/R, you know that 2.83V is the voltage you get with one watt
going into an eight-ohm load. So if you assume the speaker really is
eight ohms at the frequency they measured it at, you can use this for
comparison purposes.

This tells you how big an amp you need to get a given output level.

Since someone has brought this subject up, may I ask if anyone can confirm
what I recently heard.

Sure, speaker sensitivity has traditionally been measured @ 1W @ 1m. Which is
indeed 2.83V for an 8 ohm load.

Of course, speakers don't have constant impedance, it's a nominal figure. So
it made sense to actually say 2.83V rather than 1W, at least when referring to
8 Ohm nominal cabinets / units, as speakers are voltage driven.

Lately I heard that some unscrupulous manufacturers were using the 2.83V
'standard' also when measuring 4 ohm units, thereby gaining artifically an
extra 3dB on the sensitivity figure.

Any comments ?


Graham

Lately I heard that some unscrupulous manufacturers were using the 2.83V
'standard' also when measuring 4 ohm units, thereby gaining artifically an
extra 3dB on the sensitivity figure.

Any comments?

I don't see what's unscrupulous about it; the data this spec yields are useful.
If I have two speakers, one 4 ohms and one 8 ohms, both rated at the same
sensitivity (say 92dB at 1 meter, 2.82 V), then they'll play at the same volume
for a given setting of the control room pot. That's useful to know.

It's also useful for the consumer to notice that this is the equivalent of 2W
(well, more or less, since the impedance isn't constant) and do your amp-needed
calculations accordingly.

Peace,
Paul

Pooh Bear wrote:
Since someone has brought this subject up, may I ask if anyone can confirm
what I recently heard.

Sure, speaker sensitivity has traditionally been measured @ 1W @ 1m. Which is
indeed 2.83V for an 8 ohm load.

Of course, speakers don't have constant impedance, it's a nominal figure. So
it made sense to actually say 2.83V rather than 1W, at least when referring to
8 Ohm nominal cabinets / units, as speakers are voltage driven.

Right. And we usually tend to make sensitivity measurements at 1 KC, and
most 8 ohm nominal systems tend to be around 8 ohms at 1 KC, so that seems
respectable.

Lately I heard that some unscrupulous manufacturers were using the 2.83V
'standard' also when measuring 4 ohm units, thereby gaining artifically an
extra 3dB on the sensitivity figure.

Any comments ?

I haven't seen that yet, but I wouldn't put it past anyone. There is an
amazing amount of specsmanship that goes on in the consumer audio world.

Ever seen a data sheet with a waterfall plot? You won't.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."