Ascend Sierra Luna Mini-Monitor Review

[andreasmaaan]

It doesn't show in Ascend's measurements, so something is either wrong with their measurements, or something is wrong with the sample.

Yeh, but my point was not that they did measure it, but rather that they easily could* have.

As to the possibility it's a problem with the specific sample, I find it hard to imagine how that could be. The port's behaviour is essentially a function of the dimensions of the port and the enclosure, and the damping inside the enclosure (if any).

The dimensions themselves can't change on a sample-by-sample basis, and the internal damping shouldn't, I would have thought.

*EDIT: and should!

 

[VeerK]

This is why I enjoy ASR so much, it’s a much needed data point that can be used to fact check manufacturers. Ascend has long been an internet direct darling, and the Sierra 2 and now Sierra Luna have come up a bit short in my eyes. I don’t necessarily think Ascend is being malicious, but it’s obvious they need to invest more time in their measurement and RD methodology especially if they’re being open with their FRs.

As a former Sierra 2 owner, I’ve always been annoyed with their claims of their magical special SEAS woofers, it was fine in the S2 but nothing groundbreaking. I am a fan of the RAAL 70-20, not the 64-10 in the Luna, but it really does need to be used in a 3 way to take advantage of the decreasing distortion as you go higher in the frequency range. Perhaps this is why many claim to hear more air up top.

I like the fact that Ascend has helped popularize the RAAL ribbon, but I feel at these prices the technology isn’t there, some kind of DSP is needed in the design process. On that note, I am planning on a serious comparison between my 70-20 RAAL and my new Bliesma T25-B6 Be tweeter. Let’s see if the ribbon holds up, especially above 5K

 

[GimeDsp]

It's hard to support USA made companies when they don't live up to the value or performance of other HiFi.

 

[MZKM]

On that note, I am planning on a serious comparison between my 70-20 RAAL and my new Bliesma T25-B6 Be tweeter. Let’s see if the ribbon holds up, especially above 5K

If a 2-way, the 34B models seems like a better offering, it doesn’t have as wide of dispersion up top and starts to beam a bit choice, but it can be crossed as low as 1500Hz, even 1000Hz if you pad the upper range. The 25B can be crossed as low as ~2kHz.

 

[dougi]

I'm still scratching my head around how exactly did the port design get through like that. My own experience of changing the woofer type (and convert to active) in my old Proac Tablette iiis (blew the old ones up and put in the only ones that would easily fit) was that the existing tuning should have been OK but ended up being a bit honky. Measured the port and there was a big resonance at 1kHz, equal in level to port output. Converted to sealed instead (woofer suited both) and that problem solved. If it is so easy for a layman to at least identify why not a manufacturer?

 

[richard12511]

Small, slot ports tend to have a high air velocity that causes resonances. I think the WOW1 measurements looked much better than the Luna:

https://www.audiosciencereview.com/forum/index.php?threads/salk-wow1-bookshelf-speaker-review.14842/

The WOW1 does seem to measure significantly better. Actually looks excellent outside of that one (pretty bad) flaw.

 

[BYRTT]

That's my sense of it. Given the fact that they publish measurements, should they have seen the reality, they would thought twice. This is a common theme with many smaller manufactures making rough measurements like this. With advent of NFS scanner and service cost as low as $1000 to get spin data, companies small or large should get proper measurements. There is no excuse anymore.

Its getting reality too hot in Ascend design/marketing HQ within a night or so pinky sign some NFS or service contract ..

 

[andreasmaaan]

Small, slot ports tend to have a high air velocity that causes resonances.

I might be missing something, but I don't see why slot ports should have any greater issue with resonances in particular (turbulence is another matter ofc). Or is there something you're thinking of that I might have overlooked?

 

[CDMC]

I might be missing something, but I don't see why slot ports should have any greater issue with resonances in particular (turbulence is another matter ofc). Or is there something you're thinking of that I might have overlooked?

I probably shouldn’t have limited it to slots. It is my understanding it happens to any port that is too small for the air volume the driver is moving. I could be wrong.

 

[AndreaT]

This is a review and detailed measurements of the Ascend Sierra Luna small bookshelf 2-way speaker. It was kindly sent in by a member. The Luna costs US $588 each or US $1,148 for a pair.

The Luna is one of the smallest speakers I have measured:

View attachment 90565

Despite its small size, it is a very dense and heavy speaker. As you see it is front ported.

The back panel shows nicely machined in provisions for wall mounting which should come in handy for home theater Atmos (height) speakers and such:

View attachment 90566

The label says it is designed, engineered, and assembled in US. Does it mean it is manufactured fully in US? Or do they get the boxes from overseas and put the parts in it in US?

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 800 measurement which resulted in error rate of less than 1% throughout the range.

Temperature was 61 degrees F. Measurement location is at sea level so you compute the pressure.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Reference axis was the tweeter center.

Ascend Sierra Luna Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 90567

OK, this is a very jarring response. A woofer doesn't dance up and down so sharply by itself in a few hundred hertz? Fortunately I measure each driver at point blank and this tells us the problem:

View attachment 90568

See the port response in orange? It peaks (resonates) so much that its response actually exceeds that of the woofer creating those two "horns." It continues to mess up the woofer response even past that.

Strange to see the woofer response flattening post crossover point. Maybe it was also resonating? Regardless, if that was pulled down more , the combined response with tweeter would have been better.

Back to the spinorama, note that the efficiency to a few hundred hertz is only 80 dB or so. Indeed, I had to boost the signal by 6 dB compared to average of what I use for most speakers to get to 86 dBSPL output. Better have a lot of amplifier power. Don't be fooled by the small size of this speaker.

Early window response shows the same problems we see on-axis since port response is more or less omnidirectional:

View attachment 90569

Combined we get what dominates the on-axis:

View attachment 90570

Impedance is good bit higher than what is typical for 2-way speakers:

View attachment 90571

Resonaces are visible by the way in kinks in the impedance graph (little ripples).

Distortion is naturally high at levels exceeding 86 dBSPL but I was surprised the speaker did not bottom out:

View attachment 90573

View attachment 90574

A highlight is the horizontal beamwidth:
View attachment 90575

Because the woofer is not much larger than the tweeter, their beamwidths blend together much better than in larger configurations.

View attachment 90576

Vertically is a mess as it typically is:

View attachment 90577

Makes sure your ears are more or less at the height of the tweeter.

Ascend Sierra Luna Speaker Listening Tests
I tell you, marketing guys are right that the first impressions of a bright speaker are positive. Such was the case during the first few seconds: "oh listen to the details!" This changed though after a minute or so to: "man this is bright!" The sound was lispy as well but not super annoying. Just bright. So I pulled out the EQ:

View attachment 90579

Despite the aggressive shelving filters I put in for high frequencies, the outcome was still a bit too bright but much more manageable.

Fixing the two port created resonances only made a subtle difference -- certainly less than what jumps out in the frequency response graph. A more accurate EQ may generate better outcome though than my eyeballing.

On a positive front, this speaker can handle a ton of power and get quite loud! Lack of bass response means that the little woofer does not bottom out -- not easily anyway. I was pretty impressed by this and should make the speaker more suitable for home theater applications.

Conclusions
Despite being very small, the Luna seems well built. Alas, poor port response wreaks havoc on the bass response. And elevated tweeter response makes the overall response too bright. Directivity is generally good so EQ seems to work well. Power handling is excellent due to not attempting to change the laws of physics and generate more bass than it is capable of.

As a perfectionist of course I want to see near ruler flat on-axis response at these prices. We don't have that here so score should be way down. I am not going to absolute bottom though as I hate distortion and lack of power handling in small speakers which the Luan does not suffer from.

Overall, I can't recommend the Ascend Sierra Luna but put it out there for people to optimize it with EQ to get respectable sound.

------------
As always, questions, comments, recommendations, etc. are welcome.

We are fortunate to live in a place where wild chanterelle mushrooms grow abundantly. My wife bought a basket recently:

View attachment 90582

Made a Chinese vegetarian stir-fry using our garden peppers and they were delectable! There is a farm near us where they would actually pick them but they had a ton of pine needles in them which made a pain to clean. The above were almost free of them which was great.

As always appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

I have rarely seen a bass reflex with a slotted port behave well.

 

[andreasmaaan]

I probably shouldn’t have limited it to slots. It is my understanding it happens to any port that is too small for the air volume. I could be wrong.

Ok, I think you might be conflating pipe resonances and turbulence (which are the twin evils of ports) here.

Turbulence is definitely more likely to occur in slot ports than in cylindrical ports, i.e. for a given cross-sectional area, a slot port is more likely to exhibit turbulence. This causes power compression, distortion, and (when extreme) chuffing.

Pipe resonances OTOH occur as a result of standing waves forming across the length of the port. These correspond to wavelengths twice the length of the port, the length of the port, half the length of the port, etc. These resonances will only be excited if the resonant frequencies are present inside the enclosure, hence they tend to be most problematic in small 2-way designs with minimal internal damping.

I can't think of any reason why pipe resonances might be more severe in slot ports, but that doesn't mean there isn't one!

 

[sam_adams]

An interesting paper:

Maximizing Performance from Loudspeaker Ports; Salvatti et. al.

 

[DDF]

The designer may have been valiantly trying to coax out some sensitivity, and so elevated the upper mids, trading off neutrality for outright level.

That will sell better (because its louder) but in the long term, I think satisfy less. For neutral sound in tiny boxes, some better options are:
1. a modest sub and less expensive sealed satellites coming in cheaper than an attempt at an expensive ported mini monitor. Dollars can't beat physics
2. If running without a sub, the modest low end should be balanced off with some softening of the high end, not elevating it

I wanted a very small very neutral and clean system that could play loud and integrate easily with a modest sub, so bit the the bullet and designed a 3L sealed :
https://www.diyaudio.com/forums/mul...s-compact-2-punches-weight-5.html#post5308843

Its completely free of any port colourations, has room for stuffing further cleaning the mid range, has great spins, plays loud in a small room using a large amp, has low distortion thanks to a very robust driver in a sealed box (<50 dB down at decent levels) and can cross to a sub without a high pass without excursion penalty like you'd have in a ported. This allows it to take allot of power and ultimately play louder without offensive noises than a ported design that artificially bumps up the mid range.

Ported designs are extremely hard to make resonance free and port resonances are often very audible unless the box is large and the designer took the time to place the port location where standing wave coupling is minimized. KEF puts allot of energy into this, and they show the challenge in one of their white papers:

To me, its a shame to choose electronics where spurious colourations are > 100 dB down to only ruin it all with a speaker that has spurious port colourations 10 or 20 dB down.

 

[ROOSKIE]

I might be missing something, but I don't see why slot ports should have any greater issue with resonances in particular (turbulence is another matter ofc). Or is there something you're thinking of that I might have overlooked?

I could see why the slot port may have a higher chance of resonances due to being essential a very short port. My understanding is that shorter ports are more susceptible to resonances in the midrange area. I might be wrong though as I am still just learning to really the fine tune in my own designs.

 

[ROOSKIE]

The designer may have been valiantly trying to coax out some sensitivity, and so elevated the upper mids, trading off neutrality for outright level.

That will sell better (because its louder) but in the long term, I think satisfy less. For neutral sound in tiny boxes, some better options are:
1. a modest sub and less expensive sealed satellites coming in cheaper than an attempt at an expense ported mini monitor. Dollars can't beat physics
2. If running without a sub, the modest low end should be balanced off with some softening of the high end, not elevating it

I wanted a very small very neutral and clean system that could play loud and integrate easily with a modest sub, so bit the the bullet and designed a 3L sealed :
https://www.diyaudio.com/forums/mul...s-compact-2-punches-weight-5.html#post5308843
View attachment 90809View attachment 90808
Its completely free of any port colourations, has room for stuffing further cleaning the mid range, has great spins, plays loud in a small room using a large amp, has low distortion thanks to a very robust driver in a sealed box (<50 dB down at decent levels) and can cross to a sub without a high pass without excursion penalty like you'd have in a ported. This allows it to take allot of power and ultimately play louder without offensive noises than a ported design that artificially bumps up the mid range.

Ported designs are extremely hard to make resonance free and port resonances are often very audible unless the box is large and the designer took the time to place the port location where standing wave coupling is minimized. KEF puts allot of energy into this, and they show the challenge in one of their white papers:
View attachment 90806

To me, its a shame to choose electronics where spurious colourations are > 100 dB down to only ruin it all with a speaker that has spurious port colourations 10 or 20 dB down.

Great post and thanks for mentioning KEF, I meant to do that earlier. One look at the R3 and that is a well designed ported system and the port placement strategy they use is something to learn from.

 

[CDMC]

Ok, I think you might be conflating pipe resonances and turbulence (which are the twin evils of ports) here.

Turbulence is definitely more likely to occur in slot ports than in cylindrical ports, i.e. for a given cross-sectional area, a slot port is more likely to exhibit turbulence. This causes power compression, distortion, and (when extreme) chuffing.

Pipe resonances OTOH occur as a result of standing waves forming across the length of the port. These correspond to wavelengths twice the length of the port, the length of the port, half the length of the port, etc. These resonances will only be excited if the resonant frequencies are present inside the enclosure, hence they tend to be most problematic in small 2-way designs with minimal internal damping.

I can't think of any reason why pipe resonances might be more severe in slot ports, but that doesn't mean there isn't one!

Thanks. Looks like I conflated two concepts.

 

[Maiky76]

HI,

Here is the EQ.
Score no EQ: 1.28
Correct Spinorama

Directivity:
better stay at tweeter height
Horizontal is not too bad

Better listen off axis -/+20deg with some toe in

EQ design:
Score with EQ: 4.33 still mediocre
The EQ needs to stray rather far form the flat target showing directivity issues
Even boosting LF only achieve middling performance

APO config file attached
Note that the preamp gain is set to avoid overloading the speaker at LF.
Be cautious not to destroy the speaker if/volume the gain is not changed!

Ascend Sierra Luna APO EQ Score 96000Hz
November022020-114635

Preamp: -2.8 dB

Filter 1: ON PK Fc 64 Hz Gain 3 dB Q 1.17
Filter 2: ON PK Fc 158.5 Hz Gain -1.92 dB Q 1.5
Filter 3: ON PK Fc 530 Hz Gain 1.47 dB Q 4
Filter 4: ON PK Fc 598 Hz Gain -5 dB Q 12.7
Filter 5: ON PK Fc 1693 Hz Gain -3.82 dB Q 3.14
Filter 6: ON PK Fc 3134 Hz Gain -1.77 dB Q 6.93
Filter 7: ON PK Fc 6600 Hz Gain -2.92 dB Q 2
Filter 8: ON PK Fc 12144 Hz Gain -2.93 dB Q 0.7

EQed spinirama

Zoom PIR-LW-ON

Regression - tonal: almost flat ON after EQ

Big improvements but subpar for the price many cheaper speakers measure significantly better especially after EQ.

One example just to illustrate the point for 300USD pair including the amps, it has its own issues but still:
https://www.audiosciencereview.com/...ctive-speaker-review.13436/page-3#post-477799


Rest of the data attached

 

[BYRTT]

Great post and thanks for mentioning KEF, I meant to do that earlier. One look at the R3 and that is a well designed ported system and the port placement strategy they use is something to learn from.

Note woofer is ported and mid looks not, but in woofer sits behind a 400Hz crossover we had to bypass the low pass filter and let it reach tweeter teritory to see if its interference free.

 

[VeerK]

If a 2-way, the 34B models seems like a better offering, it doesn’t have as wide of dispersion up top and starts to beam a bit choice, but it can be crossed as low as 1500Hz, even 1000Hz if you pad the upper range. The 25B can be crossed as low as ~2kHz.

I’m aware of the 25Bs limitations, it’s a game of trade-offs. That being said, in a 2 way I’d be inclined to use a WG, which would be useful in the critical 2-3k region for directivity matching a woofer. Distortion profiles seem to be a tad worse for the 34B vs the 25B according to HiFiCompass, so I’m not sure the 34B would be as good of a match with the Purifi woofers, for example. Both blow the RAAL away in terms of distortion sub 4K anyway

 

[riker1384]

If the worst problems are caused by the port, maybe trying blocking it and retesting them to see how much they improve?