Sierra 2 measurements typo?

[N Boros]

Under measurements for the Sierra 2 we find:

41Hz -27kHz ± 3 dB (in room)

46Hz - 38kHz ± 3dB (anechoic)

Is this a typo? I don't understand why any ultrasonic frequencies would reduced this drastically in room. The anechoic measurements make sense when we look at the frequency response plots.

Now I realize that ultrasonic frequencies probably don't play too much of a role when we are listening, since most receivers filter them out, but the Sierra 2s seem like they can play them, if one can get everything else in the chain to do the same.

[davef]

Under measurements for the Sierra 2 we find:

41Hz -27kHz ± 3 dB (in room)

46Hz - 38kHz ± 3dB (anechoic)

Is this a typo? I don't understand why any ultrasonic frequencies would reduced this drastically in room. The anechoic measurements make sense when we look at the frequency response plots.

Now I realize that ultrasonic frequencies probably don't play too much of a role when we are listening, since most receivers filter them out, but the Sierra 2s seem like they can play them, if one can get everything else in the chain to do the same.

It's not a typo and it's not that they aren't there. When we measure an in-room response, we are looking at the response over a longer period of time, typically 30ms - this includes much of the room's effect on the sound. When we measure the anechoic response, we are looking at 6-7ms - which does not include the room's influence.

Such extreme high frequencies have very, very short wavelengths and as such, they are extremely directional and subject to an extreme amount of reflection and absorption due to the room.

Keep in mind the scale of the measurement at +/- 3dB The extreme highs are reduced, due to phase cancellation from reflection and room absorption, such that they simply drop off at a rate greater than 3dB - and fall off the specification's scale.

[N Boros]

It's not a typo and it's not that they aren't there. When we measure an in-room response, we are looking at the response over a longer period of time, typically 30ms - this includes much of the room's effect on the sound. When we measure the anechoic response, we are looking at 6-7ms - which does not include the room's influence.

Such extreme high frequencies have very, very short wavelengths and as such, they are extremely directional and subject to an extreme amount of reflection and absorption due to the room.

Keep in mind the scale of the measurement at +/- 3dB The extreme highs are reduced, due to phase cancellation from reflection and room absorption, such that they simply drop off at a rate greater than 3dB - and fall off the specification's scale.

Why does the Sierra tower, with the RAAL tweeter, not exhibit the same decrease in very high frequencies in room? The measurements are +/- 3 dB up to 32 kHz for anechoic chamber and in room measurements. I realize that the RAAL tweeter in the tower is different (larger). Is it because of the different driver, or something else?

[davef]

Why does the Sierra tower, with the RAAL tweeter, not exhibit the same decrease in very high frequencies in room? The measurements are +/- 3 dB up to 32 kHz for anechoic chamber and in room measurements. I realize that the RAAL tweeter in the tower is different (larger). Is it because of the different driver, or something else?

That could be a typo... I'll have to look into it.