Need advice on new receiver with Sierra1s

[catsAf]

12/8/2008

[curtis]

12/8/2008

I bet they are not 1st gen. Best to email the serial numbers to Ascend/Dave to check.

[catsAf]

Thanks! will do!

I appreciate your help very much! I am pumped now.! -D

[Mag_Neato]

The easiest way to tell if they are 1st gen, etc. is by removing the woofer and looking at the insulation. The 1st Gen were the only ones to use the fiberglass insulation in black mesh netting. The subsequent generation cabinets used white Dacron.

[davef]

My feeling on the matter: I think Cats you have a critical ear, and you might be especially sensitive to the slight dip the Sierra 1s have in the upper midrange frequency, around 3kHz. Your ADS speakers might even have a hump in this area, making the dip of the Sierra 1s all that much more noticeable when listening to certain kinds of music. If I was to bet, I'm guessing that this relative recess in the upper mids may take away somewhat from the 'open' sound you like. Given this is indeed the case, upgrading to the Sierra 2's - which is a very different beast - I'm sure will leave you grinning ear to ear!

Mark

The 2-3dB dip @ ~3kHz shown in the anechoic on-axis response of the Sierra-1 is caused by diffraction, where the output of the tweeter reaches the edges of the cabinet and diffracts. Minimal diffraction effects like this are inaudible in a typical listening environment. If you examine the horizontal off-axis response of the speaker, the dip disappears... This is because when perfectly on axis with the speaker, the diffraction effects caused by the cabinet edges will reach the microphone at exactly the same time and the frequencies slightly cancel each other causing the measured dip. Even slightly off-axis, the diffraction effects from both sides of the cabinet will reach the mic at different times and will no longer cancel each other.

When listening to a loudspeaker in a normal environment, we hear a combination of the direct sound of the loudspeaker and the indirect sound. In most listening rooms, the indirect sound fully dominates what we hear. Indirect sound is all of the reflected sound consisting of mostly the off-axis response of the speaker. This is one of the reasons why two loudspeakers can both have nearly perfectly flat on-axis response measurements, yet sound completely different from each other. While this diffraction artifact shows up on on-axis anechoic measurements, it would not show up in an in-room response where first reflections are not gated out.

In addition, even if it were not a diffraction artifact, actually hearing such a narrow bandwidth -3dB dip on an unsmoothed frequency response measurement would be quite a feat and I am doubtful that any human actually could. Our ears are generally sensitive enough to hear on a 1/3 octave scale. Here is what the response measurement of the Sierra-1 looks like on a 1/3 octave scale: http://www.ascendacoustics.com/image..._onaxis_sm.gif

That dip is now about -1dB at its worst.

What catsAf is hearing is not that dip in the response, but more than likely -- simply differences between the Sierra-1 and his older ADS speakers...

That being said, if catsAf is after cleaner and more detailed mids, the Sierra-2 would be nearly impossible to beat. However, if catsAf's old ADS speaker have pronounced mids and/or rolled off highs(something many of the old ADS speakers had), the Sierra-2 still might not sound right to him...

[markie]

Informative and fascinating, thank you David!
Mark