Ascend Sierra Luna Duo Center/Main Speaker Review

[Dennis Murphy]

https://audioxpress.com/article/test-bench-bozhen-new-audio-lab-cq66-ribbon-tweeter

Surely just a big ass ribbon?

No--"The CQ66 utilizes a 65 mm × 15 mm pleated aluminum diaphragm (the CQ76’s diaphragm is 80 mm × 20 mm). The pleats are mechanically connected to a section of the voice coil (see Figure 1). T" Pure ribbons don't have voice coils. That's why their moving mass is lower than other tweeter designs. It's not an AMT either, because there aren't any vertical pleats that squeeze the sound waves out.

 

[GimeDsp]

Surely someone with these speakers and a mic can do a normal in room measurment and gate the results to see what it shows.

I would hope Ascend knows how to do either of the 2 common nearfild measurement techniques to combine port, woofer, and tweeter for what has been called an accurate response to within 1DB of anechoic.


I am trying to be positive
I hope there is a good reason for these issues and that Ascend can chime in and maybe learn and grow from this.

 

[ctrl]

This tells me that they’re doing the typical measurement method of gating and merging. If so, their measurement method simply doesn’t have the resolution to show narrow midrange resonances. A window of at least 20Hz accuracy would be needed to show these kind of resonances because the Q is so high. Windowing just glosses over these things. It’s the downside to the often used quasi-anechoic method.

One cannot leave the slightest room for excuses.
As soon as you have prepared the near field measurements of the drivers and ports for merging with the gated measurements, you will notice the resonances - by the way, only a two-channel measurement guarantees a clear phase relationship between the different measurements.

For a poorly designed small bookshelf loudspeaker this would look like this:

The pink curve is the frequency response of the BR port, with a nasty resonance around 1.2kHz (the sound pressure was corrected according to the BR port area).
In yellow is the frequency response of the driver and in red the resulting total frequency response of the speaker.
A baffle-step correction was also made so that the FR corresponds quite well to the reality of a free field measurement (like the NFS does).

You can immediately see how (with very high probability) the BR-Port resonance will affect the overall frequency response of the loudspeaker - the overall frequency response of near-field measurements only reliably represents reality up to about 300-400Hz, but can still be used for a quantitative estimation of the effect of the BR-Port resonance.

Either Ascend is not able to perform, calculate and interpret such near-field measurements or it ignores their results knowingly - understandable for a DIY beginner with little knowledge, but unforgivable for a company that makes money with its products.

 

[617]

One cannot leave the slightest room for excuses.
As soon as you have prepared the near field measurements of the drivers and ports for merging with the gated measurements, you will notice the resonances - by the way, only a two-channel measurement guarantees a clear phase relationship between the different measurements.

For a poorly designed small bookshelf loudspeaker this would look like this:
View attachment 91417
The pink curve is the frequency response of the BR port, with a nasty resonance around 1.2kHz (the sound pressure was corrected according to the BR port area).
In yellow is the frequency response of the driver and in red the resulting total frequency response of the speaker.
A baffle-step correction was also made so that the FR corresponds quite well to the reality of a free field measurement.

You can immediately see how (with very high probability) the BR-Port resonance will affect the overall frequency response of the loudspeaker - the overall frequency response of near-field measurements only reliably represents reality up to about 300-400Hz, but can still be used for a quantitative estimation of the effect of the BR-Port resonance.

Either Ascend is not able to perform, calculate and interpret such near-field measurements or it ignores their results knowingly - understandable for a DIY beginner with little knowledge, but unforgivable for a company that makes money with its products.

To add onto this, the choice of a small slot port is really unusual and suspect here. I haven't built many slot ports but I wouldn't load them with a midrange driver if I did. The repeated resonances are reminiscent of an undamped transmission line.

Ascend uses the MLSSA system which is sold on a website which hasn't been updated in 11 years. I strongly suspect the designer is not designing these speakers with full, high resolution off axis data but is rather sticking to the methodology favored by designers in the past. Pure speculation of course.

Generating a complete fr plot from near and far field measurements is difficult and prone to error, but the issues we are speaking would show up in any nearfield measurement of the port/woofer.

My personal opinion is that the designer knows about these issues but believes they are not significant.

 

[GimeDsp]

One cannot leave the slightest room for excuses.
As soon as you have prepared the near field measurements of the drivers and ports for merging with the gated measurements, you will notice the resonances - by the way, only a two-channel measurement guarantees a clear phase relationship between the different measurements.

For a poorly designed small bookshelf loudspeaker this would look like this:
View attachment 91417
The pink curve is the frequency response of the BR port, with a nasty resonance around 1.2kHz (the sound pressure was corrected according to the BR port area).
In yellow is the frequency response of the driver and in red the resulting total frequency response of the speaker.
A baffle-step correction was also made so that the FR corresponds quite well to the reality of a free field measurement (like the NFS does).

You can immediately see how (with very high probability) the BR-Port resonance will affect the overall frequency response of the loudspeaker - the overall frequency response of near-field measurements only reliably represents reality up to about 300-400Hz, but can still be used for a quantitative estimation of the effect of the BR-Port resonance.

Either Ascend is not able to perform, calculate and interpret such near-field measurements or it ignores their results knowingly - understandable for a DIY beginner with little knowledge, but unforgivable for a company that makes money with its products.

WOW, that is a nasty looking peak.
I just did a quick sweep of the port in my cheap , front ported insignias and it has a batman curve but well below the tuning frequency.

Is it true that a simple nearfiled of only the port would show enough of the the problems all by itself?

 

[Ricardojoa]

I understand that. My current made in USA purshases.

Audiocontrol measurment mic---cam with a VERY bad cal file and the company was unrespnsive.
Schitt Loki EQ--- Both units they sent me had channel drop outs on start up and after and sounded very

Why should people support USA companies when there is dishonestry and extreme lack of QC.
I want to support USA companies but I can only spend so much time and money on failed and bad products.

It is disappointing to see something like this from AA. But to me there is more than just amir measurements . It is hard to believe that Dave is aware of the issue and still insist to putting out the product. It could have easyly gone to another design. Also Dave is well aware that his product could be easily be tested from third party review.
At least i know the sierra line speakers are very nicely built, as far as QC i dont think AA is skimping on this.

 

[Ricardojoa]

On another note, im suprised that amir did not bother to do a measure with the port sealed since this could be the main cause of the poor measurements we see.

 

[3125b]

In that case, the manufacturer shouldn't have put the port there in the first place.
The speaker performs fairly poorly as is and hence should be changed, no more no less.
Figuring out the how is up to the manufacturer.

 

[YSC]

On another note, im suprised that amir did not bother to do a measure with the port sealed since this could be the main cause of the poor measurements we see.

Interesting to test if it didn’t take hours. If that’s the solution even maybe sacrificing more bass ascend should do that right in the first place

 

[Ricardojoa]

Interesting to test if it didn’t take hours. If that’s the solution even maybe sacrificing more bass ascend should do that right in the first place

Well keep in mind AA doesn’t have the same measuring equipment like amir, so it could very well be a design flaw that could not be tested from AA. Amir have tested other 3 AA speakers that were rear port and didn’t exhibit these issues.
And to me , just like the wow1 from Salk that had issue with the FR, if salk was aware they wouldn’t have introduced to the market.

 

[SimpleTheater]

I can not in any form or fashion recommend the Ascend Sierra Luna Duo.

Got it boss. Going out and buying the Ascend Sierra Luna Single.

 

[anmpr1]

BTW, how do members feel when their stuff tests badly?

Why would it matter? Unless someone purchased sight unheard and had no idea about it in the first place. Loudspeakers are the only component that allows for subjective sonic taste (other than fringe stuff like record players and cartridges). Either you like it, or you don't. Or you have mixed thoughts over it. If you like it, then how can a measurement change that? Possibly one would like something better that measured closer to 'the ideal'-- I guess one could argue that. But the only way with loudspeakers is to live with them in your living room for a couple of weeks, get used to the sound, and then make a determination.

The problem anymore is that there are fewer and fewer local dealers with a selection for in-store comparison, and then allow in-home trials for a week or two. Typically, at least today and for many brands, one must buy something mail order, have it shipped to them, and if they want their money back they must pay return freight, which with loudspeakers can be a sizable expense.

If you are looking for a small two-way 'monitor' speaker it's usually easier, because most 'guitar stores' have a dozen brands you can go listen to, take home and audition. For 'high end' type home loudspeakers it's difficult.

The problem as I see it is dealing with these smaller 'boutique' makers. My guess is that no one has any idea what they sound like before they purchase. Most audiofools at least have a general idea what a B&W, JBL, Klipsch, Polk, or other established manufacturer's speakers sound like. You get into Ascend Lunar Module territory and how would you even begin to know?

 

[richard12511]

If you like it, then how can a measurement change that?

Psychoacoustics. Perhaps there was expectation bias or placebo helping you to enjoy it before you knew it measured terribly. Ascend is an ID company that sells many speakers based on the fact that they publish superb looking measurements. I could definitely see where expectation bias(based on the published measurements) could trick one's brain into enjoying a sound that they don't actually enjoy based on pressure waves alone. Once that placebo is removed(by ASR), the sub-optimal pressure waves take over the brain's impression.

 

[RichB]

The problem as I see it is dealing with these smaller 'boutique' makers. My guess is that no one has any idea what they sound like before they purchase. Most audiofools at least have a general idea what a B&W, JBL, Klipsch, Polk, or other established manufacturer's speakers sound like. You get into Ascend Lunar Module territory and how would you even begin to know?

I am not following why the term "audiofools" is used to describe folks who like major brands. Not all products from these companies are bad, some are excellent, namely JBL.

Ascend seemed to have embraced the design methodology of good on axis and off-axis performance and provided measurements to verify performance. These are good things. Hopefully, there will be some follow up from the manufacturer to explain the discrepancies.

- Rich

 

[anmpr1]

I am not following why term "audiofools" is used...

I use it in jest. Don't take it personally or too seriously. I consider myself an audiofool. Or at least at times I've been one. In fact, anyone who has participated in this hobby for a long time has likely joined in on the foolishness.

 

[napilopez]

I see their website specifically mentions “quasi-anechoic” as well as a note to ignore response below 250Hz. This tells me that they’re doing the typical measurement method of gating and merging. If so, their measurement method simply doesn’t have the resolution to show narrow midrange resonances. A window of at least 20Hz accuracy would be needed to show these kind of resonances because the Q is so high. Windowing just glosses over these things. It’s the downside to the often used quasi-anechoic method. These can be done pretty easily in a large parking lot, street or driveway with no obstructions, though.





http://www.ascendacoustics.com/pages/products/speakers/duo/duomeas.html

Well keep in mind AA doesn’t have the same measuring equipment like amir, so it could very well be a design flaw that could not be tested from AA. Amir have tested other 3 AA speakers that were rear port and didn’t exhibit these issues.
And to me , just like the wow1 from Salk that had issue with the FR, if salk was aware they wouldn’t have introduced to the market.

Yes, quasi-anechoic measurements like those used by ascend and me lack lower midrange resolution, but as @ctrl alluded to earlier, that only really explains why the port errors don't show up in the presentation of the final measurements, not how they could have made it through the design process.

When you do quasi anechoic measurements, you have to either perform nearfield measurements and sum the outputs of all bass sources, or you have to perform ground plane measurements. In both cases, these port problems should be obvious. Well, I've never used ground plane myself, but from what I've seen from @hardisj, the method should be accurate beyond 1kHz if done properly. In nearfield measurements a port's issues are all laid bare, it's the summation that can be a bit tricky. But even if your summation is not completely accurate, such problems should be in full view.

I believe ascend uses ground plane based on some old posts, but not sure if that was the case here.

So that makes me wonder if something went off with manufacturing at some point. I don't know. I still don't think ascend is intentionally decieving anyone - no point in posting such extensive measurements if they can be debunked by anyone with a microphone that has a slight sense of what they're doing.

 

[hardisj]

Well, I've never used ground plane myself, but from what I've seen from @hardisj, the method should be accurate beyond 1kHz if done properly.

IME, 600Hz is usually of the upper limit, depending on the size, aiming and distance of mic from DUT (which makes aiming less of a concern as you are >> away from the DUT).

 

[amirm]

On another note, im suprised that amir did not bother to do a measure with the port sealed since this could be the main cause of the poor measurements we see.

This is a speaker designed to be used with its ports open so that is how I tested it. It is not like it comes with any kind of plugs (which would be hard to do with rectangular ports). Bass response will also suffer. The near-field measurements have already shown the problem anyway. We don't need to spend an entire day re-measuring a speaker like this that in grand scheme of things, is not common.

Let's remember that external services charge $1000 to $1,500 for a measurement like I do. That is the opportunity cost when you ask me to keep measuring the same speaker rather than moving to another one.

 

[GimeDsp]

Psychoacoustics. Perhaps there was expectation bias or placebo helping you to enjoy it before you knew it measured terribly. Ascend is an ID company that sells many speakers based on the fact that they publish superb looking measurements. I could definitely see where expectation bias(based on the published measurements) could trick one's brain into enjoying a sound that they don't actually enjoy based on pressure waves alone. Once that placebo is removed(by ASR), the sub-optimal pressure waves take over the brain's impression.

I went out to lunch with a friend yesterday, I got a burrito. I loved the first bite and hated the last bite. Our senses react differently all the time.
Just like Amir says speakers with hyped up treble can sound good and sell in the stores/demos but at home, after a while you get tired of them, fatigued.

 

[CDMC]

The problem I see here is that Ascend's measurements do not correspond to the product delivered. As several speakers designers have pointed out the issues that both Lunas have don't require specialized equipment to discover, they are readily apparent with normal measurements. This leaves two possibilities on the part of Ascend either 1) they are so incompetent they don't have any clue how to measure basic speaker performance, or 2) they fudged their results to make their product look good. Given Dave's year of updates and claims of multiple design revisions and prototype custom drivers, either he was just weaving a tale and not actually designing and measuring the speakers, or 2) knew of the issues and played with the measurements Ascend posted to make them look better. Both possibilities are misleading.

It seems to me that if you are a small manufacture and you are selling your speakers based on objective measurements the path forward in the future is going to be to pay the $1,000 to 1,500 to have your final product tested by an independent third party. While not cheap, even for a small manufacture it provides verifiable results for comparison.