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
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* 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
Sean, your comments remind me the owner's manual of Avalon Radian HC, where I read a lot about sealed vs vented, Q factor and transient's response, muddy bass of vented speakers, superior accuracy of sealed etc etc... Try a search. How Firebat said, Avalon also changed from sealed to vented and I'm curious if this change is a gain or a mistake for the bass accuracy and speed. Thanks, Luca.
As this astute individual points out selecting the optimum speaker at the high end is difficult. And only a few points were made and as Sean has said there are many others. The problem is that there is no direct correlation between price and performance. I have not trusted ANY reviews ANYWHERE for the last 20 years. My suggestion is spend some money on a decent condenser mike [B&K] and stand, connect it to a laptop based spectrum analyzer and with some test CDs measure the response of the desired speaker yourself in the showroom. Mostly you will be shocked and very occasionally pleasantly surprised. When the objective measurement and subjective listening are both positive[a rare thing in the real world] it might be worth auditioning in your listening environment. The biggest ally of purveyors of big buck scam boxes is the ignorance of consumers. I found the best education was building loudspeakers and a sound engineering course. I have found fault with EVERY speaker I have ever listened to, Tannoy HPD & Monitor Gold 15in great imaging and good bass & mids in the right cabinet but early roll off and peaky ragged response in the treble and lacked the type of microdynamic detail a good planar can give. ESL III Aussie customs about the size of a large door had like the Quad 57 a distinct mylar coloration and beamy imaging in the treble Quad ESL 63 were like being punched with a feather. Great detail but no visceral impact.Finally with all electrostats ,snap crackle and pop are things I enjoy in my rice bubbles not my speakers. Apogee mini grands were one of the best but a pig for any amplifier to drive and the Bass modules were poorly integrated,I found them bloated and boomy. Klipshorns surprisingly good but rolled off at the extremes and a distinct horn coloration but was at least to my ears not honky or unpleasant. Home made Beyema based horns that were good enough to find fault with my test CDs but had early overload and intermodulation distortion issues and the treble although excellent drew attention to itself through poor positioning. Manger Zero boxes were detailed like electrostats but had a dip in the upper midrange and lacked impact but very good overall. Multi- driver loudspeakers have several issues 1. They need a complex crossover that is hard to correctly design and match as stereo pairs given the variability of manufacturing tolerance for dynamic drivers and crossover components 2. As previously mentioned unless they are located in a large dedicated correctly proportioned listening room with the correct acoustic treatment they can overload a room in the bass. 3. Distinct colorations between the different drivers handling different parts of the frequency spectrum and unless cleverly designed will always lack the imaging coherence of a point source like the Tannoys. The exeption being wide range line arrays. I am currently considering some Ambiance Reference 1600s that despite a slight comb filtering effect of the long ribbon and the slight artificial sparkle of the aluminum material used and an early roll off in the upper tip of the treble I find it very pleasant to listen to. I could go on but this would turn into a book. The bottom line is EVERY loudspeaker has some kind of issue and it is simply a question of finding one that annoys you the least or what it does best outweighs what it does least for YOU and that all comes down to individual taste regardless of price.
I think Sean is done w/ Audiogon. I've gotta say it's weird to know that my speakers on paper should sound a bit bass heavy or have some bass slop. I can't stand bass slop or low-end muddiness. It's actually one requirement for me in a speaker that the bass is articulate and well defined, not overbearing. If you want to hear heavy bass, try some of the new Martin Logans (Vantages or Summits)... now THAT is some serious bass slop!
Sean's assertion that an increase in impedance results in 'less power, less control' is incorrect. In fact 'control' (which is a poorly defined term and can only be related to damping factor) increases with impedance. Furthermore, many tube amplifiers will have lower distortion and greater power into higher impedances.