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 6 responses by subaruguru

subaruguru
1,374 posts
 
Phew! Lots of reading....
Glad to see that "Q" was discussed. Balancing enclosure size, driver characteristics, vent frequency and sensitivity is certainly an art. Not having heard the 20T, I would nonetheless find it a bit difficult to believe that Mike Kelly would purposely let a bloated high Q speaker out the door at 23k. Likewise I've learned that JA's cut 'n patch fr curves can be a bit misleading...as are most such attempts at describing response in a real environment. My assumption is that the 20T is for LARGE roms, where the big bass plateau can be appropriate. These ARE big speakers in my book....
I think it may be a bit too easy to criticize vented designs. Certainly if the vent frequency is low, and the driver well-controlled with a very low Fs, in an appropriate nonresonant enclosure, excellent results can be had. I understand the nherent problems, yet had moderate success loading a 3-way (8+5+0.75, vent 32-35Hz) a while ago. The problem wasn't so much the bass response, but other issues higher in frequency (matching driver sensitivities with loose OE specs!). Yet the speaker did have characteristic "vent" sound. Maybe we're all too much used to it, and Sean is partly right....
So it was quite a shock to hear how clean and tight the response is from my now-3yr old Verity Ausio Parsifal Encores, for example (8+5+1). Stunningly fast bass response that matches its incomparably-quick midrange. I asked Pelchat et al at VA how they did it, and mentioned that the Encore was predominantly about getting an extremely "fast" woofer custom spec'ed from Dynaudio, for which they pay a fortune. Sounds it...really hard to believe there's a lagging vent huffing and puffing in this design.... I suspect a low Q keeps things quick and flat, too, as I measure fla response to 30Hz in-room, falling precipitously below that, of course, as is typical of a tuned vent. You should listen to this speaker, Sean, before castigating all vented designs further....
Comments about boom-cha favored response (the old West Coast saddle-curve...aka Bose?) I find intriguing, and can't comment upon whether current designers are influenced by unnatural bass level pop music tastes....
Some posters correlate that flat bass frequency response is somewhat correlated with price. certainly this is only slightly true, vis a vis enclosure size cost. It's really not harder to design a $1k speaker with a reasonably flat and "chosen-Q and vent freq" than a $20k one. Thiele/Small, Q, vent geo, etc., are givens, so Aeriel's $23k speaker doesn't have smoother bass than the $6k Legacy for THAT reason. Hell, my Spendor 3/1p ($1400) have a nice smooth bottom. It's just good design....
There's too much to comment on here later....
Cheers. Ern
subaruguru
1,374 posts
 
Hi Sean. Sealed is smaller? I think you meant compared to TL, of course, since manufacturers use vents specifically because of that free bass from a cheaper, smaller enclosure. And you know, given that the lower 2/3 of a speaker's height is relatively free aesthetic real estate, it's just too easy to fill a tower with woofers compared to selling monitors with stands at the mid-price points.
Your response to me above exhibits so much cynicism, Sean. It's been raining here in Beantown for 4 days. Let's all lighten up, eh? When my audio-naive friends visit and sit in the sweet spot I don't have to train them how to listen.
The music-lovers, especially, relax into deep rapture all by themselves. I think the market malaise is more about that most of the public simply doesn't want to be entertained by simple audio. I have several friends in the pro audio and musical instrument manufacturing biz who simply don't sit and listen to recorded music anymore. Busman's holiday? Hmmm...maybe somewhat, but lots of folks want a visual element. I cleave the two with separate high rez 2ch and HT systems, but most won't, as we all know.
subaruguru
1,374 posts
 
Sean, not with the same total bass output. Vents = free extra bass SPLs, good or bad.
subaruguru
1,374 posts
 
The "thickening" in response when one tries to get more bass warmth by taking advantage of walls' reinforcement is more due to the automatic "revoicing" of the upper-bass/low-mids region due to the change from in frequency of the 2pi/4pi transition. MOST speakers sound muddy and congested when wall/floor mounted if they're designed to work in free space. It's interesting to note that the JM Labs and PSB surrounds seem to be their normal 2 way monitors stuffed into a different cabinet, without modification of the crossover, and hence these speakers sounded quite wrong when wall-mounted, yet very nice on stands. OTOH the Boston VR-MX surrounds, for example, sound very well balanced when wall-mounted, being voiced that way. Indeed some speakers do require some front wall support for proper bass response, but there's a pont where the boundary support frequency "lift" band goes up as the distance goes down, until when wall-mounted, the speaker usually sounds congested in the lower mids.
Sean, great post, but again, if a properly designed vented cabinet uses a nice low Fs, and the driver's happily within its excursion limits, what's wrong with a 24/dB drop below, let's say 30-40Hz? Of course "sealed" is easier to get right, but the total bass power response always requires a bigger cabinet.
subaruguru
1,374 posts
 
Sean, I DID read Dickason a decade ago, and contributed to the design of a couple of vented 2 ways with two pro designers. We ended up with a VERY fast and tight 2 way with a 35Hz vent. Was supposed to be an OE for Roland Digital Pianos, but never got past the first 40 pair or so.
The bottom end alignment was done by an old student of Peter Walker, using a dandy Peerless $40 woofer. I don't remember the electrical particulars, but it was a very quick, non-bloated design that was VERY dynamic, and impressed the handful of dealers I demo'd it to on the East Coast. It was a bit lean in free-space, so had to revoice it (damp the tweeter), but with a bit of normal boundary support (atop a piano or nearer a front wall) it sounded great for a modest 2-way with $300/pr total manufacturing cost....
Duke, you're absolutely correct...building a fast, damped, efficient vented design isn't that hard, although you're correct, Sean, it isn't done often due to market motivations. And what's wrong with poor performance below 30-32 Hz? These, and other well-designed modest vented two and three-ways are for MUSIC, not helicopters and earthquakes! Your posts are voluminous and helpful in reciting the liturgy, but in so doing sometimes mask objectivity. We know what we hear...and how it measured.
Cheers.
subaruguru
1,374 posts
 
Sean, you're right, but there's that hint of condescension in your post that just doesn't feel right to me, as I've always been an advocate of FFR, for example, and AM a musician, for example. But I won't belabor this....

Pbb, I agree too, but must remind us that the holy grail here is often a PERSONAL spectral tilt! Since many types of listeners have different preferences here, it's reasonable to expect that assembling components (especially transducers) into a room is not necessarily simply a matter of buying a bunch of flat-response nice products. A study done a while back (was it noted in Dickason? I forget) noted that the general public preferred a 2db/octave downward spectral tilt (THAT'S warm!), musicians preferred a 1db/octave roll, whereas audiophiles preferred a 0 to 0.5dB/octave roll. How these populations were matched for sex and age would be interesting to note, as the aging male audiophile loses sensitivity up top...so is there a compensaory preference here, or is it just that cleaner, high res equipment is more easily "acceptible" if the top octaves aren't rolled.
It's pretty clear that once speaker/room setup is completed, and electronic components are set up, we chase minor spectral flavorings in cables to attain our personal "tilt". Hence the common tendency to chase rolled-top cables that are not-so-mysteriously labelled as "smooth" or "fat-bottomed", or more musical (warmer tilt?).
That speaker manufacturers all have their "house" reference tilts that they prefer is no mystery. As long as the resultant sound of these boxes IN YOUR ROOM agrees with the manufacturer's voicers then success can be had without much secondary tweaking.
Being a Bostonian, I've followed Aeriel's history, and having briefly used the same cabinet maker as Kelly, and can attest to the difficulties he had with QA of the 10T bass cabinets. I remember seeing 10T cabs lined up, seeing the minor variations in each. Must've driven a technical design engineer like Michael nuts. I jokingly offered to consult with him on QA, but had enough of a hard time getting just 20 pair of my cabinets made consistently from Pine & Baker. That Aeriel was able to get a scandinavian high precision cabinet maker with state of the science CCM to manufacture nice complex cabinet clones for him is only a credit to their manufacturing excellence. I can't comment on Aeriel's price points...nor Michael Kelly's preferred spectral tilt, but I would expect that his design work is top notch, and perhaps Aeriel's speaker components are pretty tightly controlled, yielding reasonably matched pairs that are close to design reference. Such manufacturing precision is not just the realm of the high end, bien sure, as Boston, Snell, Revel et al have sucessfully controlled manufacturing processes tightly. Although I don't generally like the voicing of most Boston speakers (except the VR-MX surround), they DO take care to make quite nice, cloned tweeters that are much better than expected. Too bad they don't know how to implement them to my liking....
Sorry for this messy post...got interrupted by Ellen's matzoh pancakes!
More to discover