nrt/raal sierra tower preference?

[shinny]

Cost not a factor, I'd like to hear from any Sierra Towers owners out there that preferred and purchased NRT domes rather than Raals. I've got a big room, 26x26x16' high, open on one end and am thinking that the punchier nrt's with subs might be a better fit. I've heard some dome tweeters (upper end scan speak, I think) at shows that I may have liked as much or more than raal's but they weren't Ascends, as I've yet to hear the towers.

Steve

[swallan]

we have the towers with the nrt tweeter we are very happy with them, sometimes I think what if if we had the raals, but are very satisfied with what we have.we do have the horizon with the raal tweeter.

[RPM]

Just received NRT Towers a few weeks ago after having NRT Seirra 1's for a few years.
very happy with them!. I have only heard the RAAL in the 2's so never had a direct comparison but very happy with NRT.

[pierreterrier]

I have raals sierra towers. Never heard the nrt ones. Familiar with dome tweeters though. I only listen to music in stereo on my set up. My assessment is simple; if you like to sit in the sweet spot with the raals at or near ear level, they will provide the most unbelievable audiophile experience you probably will have ever heard. Their horizontal dispersion is excellent so you can sit left or right of the center and they still sound awesome. However they have a very poor vertical dispersion imo (a little over a foot up or down from 10-12 ft out if my memory serves me right), so if you lay down on the floor even at your sweet spot or stand up, you will lose a lot in clarity immediately. Meaning, if you like to walk around and do stuff while listening to music or if you throw parties with a bunch of people standing around, I definitely couldn't recommend the raals. The dome would be much better adapted for that kind of listening. And if you plan on doing some of both I believe the domes would be a more versatile option. I'm 60 and my party days are over, and I like to sit more nowadays than running around, so when I turn my system on it is simply to enjoy it from the sweetspot in a audiophile way, and the raals are the best thing I ever heard. In my case there is no contest, no way I could go back to domes. But I imagine that in multiple applications, more people would be happier all around with the domes than the raals. It's all about what your priorities are regarding how you like to listen to your music; passionately sitting in the sweetspot, go raals for certain, walking around doing other stuff, domes is your best bet. Anyway from experience that's how I strongly feel about it.

[shinny]

Thanks, P-terrior, this is the kind of info I'm interested in. Now that you bring it up, very little of our listening is "sweet spot" but more typically moving around the room, seated at the bar or in the adjacent kitchen. For example, a lot of laptop work and conversation happens at the high barstools, 14' away from the speakers putting ear height at almost 6ft. Based on what you are saying, maybe the raals wouldn't the best option in this application. I have good stereo separate components with/nice power and I can afford the extra $ for the raals. But then again, I don't want buy them if they're not well suited or going to make a positive difference for my use.

[pierreterrier]

This might help you further: Go in the tower discussion thread page 50 second entry from the bottom on 11-01-2013, davef posts a link to his chart about the recommended vertical listening window for 70mm raals.

[davef]

Just thought I would pop in here to provide a bit more detail and, perhaps, correct a few misconceptions.

Pierre, I am thrilled you are enjoying our Ribbon Towers!!

Regarding the statement:


they have a very poor vertical dispersion imo (a little over a foot up or down from 10-12 ft out if my memory serves me right), so if you lay down on the floor even at your sweet spot or stand up, you will lose a lot in clarity immediately.

The RAAL ribbons we use in the towers do not have "poor" vertical dispersion. Poor vertical dispersion would be defined as a very inconsistent and non-linear response at different vertical off-axis angles. Our ribbons actually roll-off very linearly off-axis and this continues the further you are off-axis (both vertically and horizontally). This is a feature you want in a transducer as it provides a much more consistent in-room response (also known as polar response, a critical characteristic to speaker performance)

Now, compared to a typical 1" dome tweeter, the ribbon in the tower offers more controlled vertical directivity, also referred to as more limited vertical dispersion. For a tower speaker, where the speaker will be placed on the floor and the tweeter will be at ear-level while you are seated, this is a very positive feature. Controlled vertical directivity helps reduce nasty high frequency reflections off the floor and ceiling, which enhance overall clarity within the room. It is one of the many reasons why our ribbon towers sound clearer than domes. It is also one of the reason why we positioned our midrange above the tweeter, which provides additional vertical directivity.

Vertical dispersion is described with a +/- angle. For our dome towers, which have less vertical directivity - vertical dispersion is +/- 15 degrees. For our ribbon towers, vertical dispersion is +/- 10 degrees. Outside of this "window" -- listeners may notice a slight drop-off of high frequencies - and the greater off-axis one is, the greater this drop-off becomes. There are other issues as well when one is vertically off-axis that have a greater effect than tweeter dispersion, but this would be the same between the ribbon and dome towers.

I will focus on just the tweeters.

Now for some math ... at 6 feet from the ribbon towers, the vertical listening window is ~ +/- 12.5 inches. The tweeter in the towers is positioned at ~ 35 inches off the floor. So at 6 feet distance, if your ear is between 22.5" - 47.5" off the floor, you will not hear a difference in the highs.

At 14 ft back, the vertical listening window is +/- 30" (which is huge), from 7.5" off the floor to 65" in height. It is a rare occasion that someone's ear would be this high, and in addition, a few inches here or there would be undetectable at these distances as the indirect sound would dominate what one hears (room reflections)

for the dome at the same distance, the vertical listening window is +/- 45".

The formula to calculate +/- vertical listening window would be your listening distance * tan ( +/- vertical dispersion angle)

Now, it is important to also understand that as the vertical listening window expands, so do nasty reflections. In large rooms, provided you will not have listeners very close to the speakers who will be sitting on the floor or standing, the ribbons are actually the better choice as they provide a wider and a more linear horizontal response and this translates to a more even response throughout the room as well as better imaging and clarity.

Please keep in mind that the ribbon towers actually have the larger sweet spot and the vast majority of our customers, who are using the towers in all sorts of rooms, prefer the ribbons by slightly over an 8-1 to ratio right now.

So, for large rooms like yours and based on the distances you mentioned – I actually strongly recommend going with the ribbons :)

Hope this makes sense!

[davef]

This might help you further: Go in the tower discussion thread page 50 second entry from the bottom on 11-01-2013, davef posts a link to his chart about the recommended vertical listening window for 70mm raals.

Thanks - I was wondering where that was :)

Here is the direct link: http://forum.ascendacoustics.com/images/ascenduploads/ribbon-listening-window.gif

[pierreterrier]

Thanks to you Dave for your always in depth explanations.

I sit 10 feet from either speaker and so for me there is a clear loss of clarity as soon as I get up and that's all I can go by, but I can see that if you are much further the dispersion would be much better, but yet if you walk around the room eventually you will get closer to the speakers and exit the ultimate listening window sort of speak. And yes I love my babies.

[pierreterrier]

The only way I would ever buy another set of speakers after my raals sierra towers is if Alexandr and you come up with raals providing an equal vertical dispersion as the horizontal one. I know from previous discussions that it is not feasible, but one can dream, that would be revolutionary in my mind.

[davef]

The only way I would ever buy another set of speakers after my raals sierra towers is if Alexandr and you come up with raals providing an equal vertical dispersion as the horizontal one. I know from previous discussions that it is not feasible, but one can dream, that would be revolutionary in my mind.

Thanks Pierre! The only way to have symmetrical dispersion would be if the ribbon were round. Dispersion is determined by the height (length) of the resonating diaphragm in that same plane. The shorter the length, the wider the dispersion. For example, to achieve wider vertical dispersion, the height of the ribbon would have to be shortened. The trade-off (there is always a trade-off), would be a decrease in radiating area and mass, which would lessen dynamic capabilities and require a higher crossover point. This is exactly what we did with the ribbon in the Sierra-2, as a bookshelf speaker (due to varying placement possibilities) should have wider vertical dispersion.

[S20]

For example, to achieve wider vertical dispersion, the height of the ribbon would have to be shortened. The trade-off (there is always a trade-off), would be a decrease in radiating area and mass, which would lessen dynamic capabilities and require a higher crossover point. This is exactly what we did with the ribbon in the Sierra-2, as a bookshelf speaker (due to varying placement possibilities) should have wider vertical dispersion.

Out of curiosity, what is the recommended vertical listening window for the Sierra-2?

Does the loss in radiating area and mass with the modified Sierra-2 ribbon make a significant difference in sound quality versus the ribbon in the towers?

[curtis]

Out of curiosity, what is the recommended vertical listening window for the Sierra-2?

Does the loss in radiating area and mass with the modified Sierra-2 ribbon make a significant difference in sound quality versus the ribbon in the towers?
I can answer the second with my experience. I could not tell the difference between the two ribbons as they are implemented in the Sierra-2 and Sierra Tower.

I own the second set of production Sierra-1's sold. I will be receiving my Sierra-2's on Tuesday, and I'll see/hear if there are any vertical dispersion issues in my room...I sit about 10' from the L/R speakers.

When hearing the Sierra-2's at Ascend, I didn't perceive any issues with vertical dispersion...the same goes with the Towers.

[davef]

Out of curiosity, what is the recommended vertical listening window for the Sierra-2?

Does the loss in radiating area and mass with the modified Sierra-2 ribbon make a significant difference in sound quality versus the ribbon in the towers?

The lesser radiating area simply means that this tweeter will not be able to provide the same level of dynamics that the tower ribbon is capable of. There is much discussion about this in the Sierra-2 development thread. The vertical listening window of the Sierra-2 tweeter is expanded by about 5 degrees, compared to the ribbon in the towers.