2. speakers
  3. 1080384372

Current Trends in multi thousand dollar speakers

Have any of you been paying attention to the current trends in larger multi-woofer speakers that cost multiple thousands of dollars? So that many of you can follow along, i'll use the Legacy Focus 20/20's at $6K, the Piega C8's at $15K and the Aerial 20T's at $23K as points of reference. All of these have been reviewed in Stereophile over the last few months. If you're not familiar with these, all of them are vertical dynamic designs using multiple woofers in vented cabinets.

If you look at the response of of these speakers, they all have very pronounced bass peaks with elevated low frequency plateau's taking place. Of these three, the Legacy's are by far the worst of the bunch. Not only do they diverge from neutrality the most ( +7 dB peak @ 100 Hz ), their elevated bass output or "low frequency plateau" levels out at 40 Hz and at 400 Hz. That is over 3+ octaves of "extra" output that wasn't on the recording. Above 400 Hz, the output levels off with very noticeable rippling slightly above that point in the midrange and multiple large peaks with a dip up in the treble response. Below 40 Hz, the output drops like a rock. The reason that the plateau levels out at 40 Hz is because of the associated sharp roll-off associated with vents below their point of resonance.

To sum things up, this speaker, which Paul Bolin raved about in Stereophile, is anything but "smooth" or "linear" in reproduction. As can be seen in the graphs, there is a very definite "boom & sizzle" type of response taking place here. As a side note, i found that the Legacy Signature III's showed a similar large bass peak centered at appr 100 - 110 Hz, so this would seem to be a consistent design attribute / "house sound" / "family voice" to Legacy speakers.

Moving onto the Piega's, their overall response looks to be measurably smoother than the Legacy's from the midrange on up. As far as bass goes, the Piega's peak occurs at an amplitude of +5 dB's and is centered at appr 85 Hz. Their "bass plateau" is quite wide, actually just as wide as that of the Legacy. Both show the same appr "elevated output" aka "bloat" from about 40 Hz to 400 Hz. Much like the Legacy's, the Piega shows the typical sharp roll-off below 40 Hz due to the output of the vent being out of phase with that of the undamped woofer. Even though both speakers show very similar plateau's and a similar F3 ( -3 dB point ), the Legacy's bass plateau has both a higher peak and a higher average.

Moving up to the $23K price range, we've got the Aerial 20T's. Similar to the Piega's, the Aerial's are reasonably smooth in response from the mids on up with a few low amplitude peaks and dips. Side by side comparisons though, it would appear that the Piega's are a little "flatter".

When it comes to low frequency performance, the Aerial's produced a +5 db peak centered at appr 60 Hz. Of the three speakers mentioned here, the amplitude of the peak is the same of the Piega's ( +5 dB's ), which is much lower ( 66% reduction ) than that of the +7 dB peak of the Legacy's. Even with this 66% reduction of the peak amplitude at resonance compared to the Legacy's, we are still talking about a divurgence of +5 dB's here!!!

As far as the "bass plateau" goes with the 20T's, this speaker is much more linear than either of the above. While the Aerial's also level out at appr 40 Hz and drop like a rock below that point, the upper end of the bass region is MUCH smoother. Whereas the others were contributing added output up to appr 400 Hz, the Aerial's are leveling out at appr 120 Hz or so. In effect, the Aerial's appear to offer the most controlled bass with the least amount of bass colouration. Then again, they are by far the most expensive also.


As far as low frequency extension is concerned, the Aerial's resonance peak is centered the lowest of the three i.e. 60 Hz for the Aerial's vs 85 Hz for the Piega's and 100 Hz for the Legacy. Even though the Aerial's have a resonance that is 25 Hz below that of the Piega's and 40% lower in frequency than the Legacy's, all of their -3 dB points are within a very few Hz of each other. While the graph's aren't completely legible, it appears that the F3 ( -3 dB point ) for all of these speakers are right about 34 - 38 Hz or so. How do such different designs achieve similar F3's? It has to do with the tuning of the vents and the amplitude of the peaks at resonance.

By creating a huge peak at resonance, it takes longer for the amplitude of the signal to fall off. As such, the Legacy's much larger peak at resonance allows it to achieve appr the same F3 on paper that the other designs worked harder to achieve. As such, were the Legacy's designed this way because they like the sound of massive bloat? Were they designed this way so that they could claim a lower F3? Could it be a combo of the two? We'll probably never know.

What does all of this add up to? Judged in comparison to each other and strictly talking about bass linearity, the Aerial looks the best on paper by far. Why just on paper? Because we have to factor in the added gain associated with in-room response. Our ears hear the entire presentation i.e. the speaker and how the speaker loads up / pressurizes & excites the room. As such, what looks the best on paper may not be what you like the most in your room. If you're room is properly set-up, the results on paper and the results in the room should pretty well jive. That is, at least as far as frequency response & linearity go. There are a LOT of other factors going on here though, not to mention personal preference.

What happens if the room isn't properly set up? Compared to anechoic responses, all speakers will have greater output / added extension when placed in an average listening room. While specific speaker placement comes into play in terms of the extension and amount of boost, most rooms will produce maximum ouput somewhere in the 50 - 80 Hz range. Obviously, this varies with the size and shape of the room.

The net effect is that these speakers are going to produce even MORE bass than what they already show in these graphs. Not only are we picking up low frequency output from what is called "room gain" ( "cabin gain" in a vehicle ) by pressurizing the room, we are also going to be exciting the resonances of the room too. All of this adds up to GOBS more "apparent bass". Add in the fact that this bass lacks speed and control* and you've got "bloated, ill-defined thump" running rampant.

Other than that, one has to wonder just how extended the bass response of these designs would be if they didn't have such HUGE peaks? After all, the higher the peak at resonance, the lower the -3 dB point of the speaker appears to be. Do we have to add "bloat" to get extension? How do you get around all of this and still keep good sound? That's easy but it is a completely different subject : )

What i want to know is, what do you folks think about this type of performance at these price levels? Is there anything that we can learn from this? Do we see a specific trend taking place here and in other parts of the audio market? Inquiring minds want to know : ) Sean
>

* vented designs all suffer from a lack of transient response, increased ringing, over-shoot and phase problems. In this respect, a well designed port is typically "more linear" than a passive radiator.
sean

Showing 4 responses by trelja

trelja
3,223 posts
 
Ah Sean, you have hit on one of my true sensibilities, tuning speakers to sound like they have more bass!

I guess I should really understand why they do it, but like you, I don't like it much at all. A manufacturer often tunes the bass so that we mere mortals think, "Wow, that speaker has really great bass" or "It sounds a lot bigger than it really is". Of course, one could argue that this speaker will also sound richer at lower listening levels. However, once you start to goose the volume up, bad things begin to happen.

In my experience, the issue will manifest itself in either port noise(which I somehow have become quite sensitive to of late) or congestion (where things just seem to back up and more power results in mostly more distortion - which many people actually seem to enjoy or mistake for volume). I can go into examples of speakers which suffer from each malady to illustrate my point, but that often seems to inflame.

Of course, I can also list loudspeakers which eschew this practice. Over time, they have earned my appreciation and respect.

The point of speaker manufacturers reacting to public pressure to produce the kind of sound that customers demand is an excellent one which TWL among other makes. However, we in the high end community are supposed to be different. We take pride in thinking we know what music should sound like. However, one point which Sean's post makes quite well is that just like the stereo shops of the 70s, boom and sizzle is the way to sell a speaker. That seems to hold true regardless of price. If we weren't buying them, they wouldn't be making them.
trelja
3,223 posts
 
Time has shown the difficulty in designing a good Transmission Line. Also, as the name has a certain magic to it, some have claimed their designs to be TL, when in fact, they are not. I think the problem is that it requires a unique personality to achieve the goal. One with intelligence, creativity, self confidence, and the right balance of objectivism and subjectivism.

The key to building a TL is experimentation, and the ability to do so. A "test mule" must be constructed, which allows access to the inside of the cabinet, in order to try different materials and varying amounts of said material. Two important things to first get right are the line itself and the driver to be used in the line. The driver's Q must be capable of matching the line, as line damping can accommodate some variation, yet only to a point.

In terms of line damping, this can be likened to the style of cooking or sauce one implements. We know we are eating beef - the TL, and that it will fried, then finished in the oven - the driver. However, the implementation of which can vary a lot - that is the damping.

I have found often that lines are overdamped, which phenomenally lessens the amount of bass the speaker will produce and makes me wonder why a TL was the choice in the first place. A TL that makes no bass is not worth the trouble in the first place. Hopefully, the cabinet has the abilty for the designer to get in there and alter the stuffing.

A TL isn't something that one will get right on their first, or even third attempt, and that is probably a reason they haven't achieved more market share. While it can be said that complexity and cost are big factors, and I do agree, we audiophiles have proven we are willing to pay the freight when it comes to expensive gear.
trelja
3,223 posts
 
I will have the good fortune of having a true transmission line loudspeaker in my main system for the weekend. It will allow me the opportunity to compare and contrast these two alignments in my room, using my system.

Heretofore, my experience with TL bass is that it has been able to achieve more realistic deep bass than ported speakers. Unfortunately, in only one circumstance have I heard them in what is a "good" room in the past. The pair I am considering did not impress me last year, which I in part attributed to the room, but it turns out the line was incorrectly damped and the crossover values were wrong. With the corrections, the bass was improved to a point, but I still feel they were up against the limitations of them being in a difficult room.

My room, being smaller, and possessing boundaries which should definitely show the speaker in a more favorable light, and also being familiar to me, will allow me to get a better handle on things.

One concern I do have is that the achilles heel of the AtmaSphere amps is there lack of low frequency sock. If I begin to feel this is taking away from the experience, I will be switching in the Jadis and/or NAD 2600A to get a broader picture of things.

Personally, despite all the discussion back and forth, I think Sean has laid out some very cogent arguments in this thread. The inherent benefits in the sealed alignment's ease of design and transient response make me wonder why the high end has gone so far in the direction of ported speakers in the past 15 years.

From memory, things were more balanced between sealed and ported in the past. I am unsure of how accurate the conventional wisdom of ported speakers gaining 3 db of loudness over sealed speakers is, but that is normally one of the first arguments thrown out there. I have been under the impression that the resurgence of tube amplification and musical tastes of late account for the scales being tipped in the way they have been, or at least a fair amount of it.
trelja
3,223 posts
 
Sean, thank you for the kind words, but I think you are more than capable of taking care of things here. You prove yourself here on Audiogon on a day in - day out basis. You demonstrate knowledge, experience, curiosity, truth, and passion when it comes to audio. And, you probably know that that statement right there is the highest praise I can ever bestow on anyone here on Audiogon.

Incidentally, my initial impressions of the TL speakers I have right now are incredibly favorable. While "only" sporting an 8" woofer, the size of the cabinet is pretty large, and I am quite impressed with the bass response. In my room, it is probably as good as things can get. I think we sometimes lose sight of the fact that a room will support a certain level of low frequency response, and again, I believe these speakers are putting out as much as the room will allow.

The AtmaSpheres are having no trouble at all with these speakers. Despite the "conventional wisdom" that TL drops efficiency by about 3 db, these relatively unmuscular amps are driving them to very high sound pressure levels, with explosive dynamics, without any strain whatsoever. I now subscribe to the other theory, that a TL actully presents a kind load to an amplifier. OTL amps do not normally take a hold of a woofer's voice coil, but in this circumstance, I have no complaints. In fact, the sensitivity is quite close to my Coincidents, which are incredibly easy to drive. My Line Tunnel Fried A/6 are not as efficient as these.

I will nevertheless try other amplifiers just to see what more they coax out of these speakers.

Overall, I am now more convinced that TL bass is the best one can get. There is a unique rightness to it, in addition to the weight and thunder. However, I will say that the Coincident Troubass subs(with a larger woofer, in a good sized cabinet) that I have do not take a backseat to these speaker's low frequencies, and I wonder if the added complexity of a TL is required. Perhaps in a different room the superiority of this design would be allowed to come forward, if it is there.

So, in the end, I think that while the TL reigns supreme, one should see if the design merits a purchase for them.
More to discover