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
Dawgbyte,

With due respect to you & to others on this forum - I do not wish to offend anyone as there is no need to. So, all that I write further is merely for purposes of discussion. I'd like to get that straight first of all.

I think that you might have missed the point in Sean's original post? I personally did not conclude him to be a Mr. Know-it-all. Rather, I found his post to express his extreme/emphatic frustration at the present trends in multi thousand dollar speakers. I found him to exclaim that designers of these multi thousand dollar speakers were NOT keeping in mind the fundamentals of speaker design. Rather they were just blindly feeding the consumer whatever he/she asked for. Now, one could say that "the customer is king" so the manuf. should make whatever the customer likes. True to a point. What if the customer goes hay-wire & makes an inordinate request? An inordiante request would one that degenerates the audio hobby. What is the manuf. to do? 2 things as I see it: (1) be true to the hobby & gently coerce the customer to see his flaw & (2) forget about the inordinate demand and simply consider revenue - to the hell w/ the audio hobby! REMEMBER, we are talking about multi thousand dollar speakers ONLY! Not the ones affordable many of us w/ our reasonable ranges of incomes.
What Sean has expressed is his frustration at seeing the manuf. choosing option (2), which in his mind (& to many others including myself) is not right for the greater well-being of the hobby.
If you look at History, look at Senior management, the President's office, leaders manufacturing, in sevices, etc. What do expect of them? We expect them to be true to their respective causes. We expect them to reformists to some extent where they will preserve the original mission statement.
We expect the same from audio manuf. esp. those of noteable reputation. We expect them to lead the speaker design & manuf. wave-front & to excel it to new heights.
I don't know why you got into this hobby (we never discussed it, I mean) but I got into it to reproduce live music into my listening room as best I could & with the limited budget I had. I know that it is only a dream but a well thought out system can be very convincing! If I am to remain true to this objective, these multi thousand dollar speakers are a totally failure!!! From their measurements, they are very likely to sound anything but real. Yes, measurements are NOT the be-all & end-all of speaker design BUT it is quite correct to say that flawed measured results do produce flawed performance. If one cannot hear it, it's because one's ear needs better training or one's electronics is flawed or one's room is untreated or one has an hidden agenda.
Many of us feel that charging multi thousand dollars for speakers that have very mediocre to bad performance w.r.t. reproducing live music in one's room as best one could is a serious blow to the long-term stability of the audio hobby. We feel let down by manuf. that should have been leaders in this art & science. They have razed the bar rather than raising it.
Would you accept sub-standard NEW products from leaders like Pfizer, Mercedes Benz, Rolls Royce, Rolex, General Electric, SAP or any other leader for which they charged you a PREMIUM price?
If the answer is "no" then WHY are you going to accept a sub-standard product from a speaker manuf that is SUPPOSED to be SOTA??? REMEMBER, we are talking about multi thousand dollar speakers ONLY!
There is a market for speakers that alters the music signal. People buy these speakers. Nothing wrong w/ that at all. If it floats your boat, please buy it.
However, if you are going to charge multi thousand $ for a speaker, call it SOTA & then have it perform mediocre to bad, what do you think you SHOULD get from the customer base??? Accolades? I think NOT! However, this is what we are giving them!
This might be a hobby for you & me but anyone in the business of making audio gear should be judged by business standards & not by hobby standards. It's not a hobby for these manuf. they are in it for real & not casually.
Maybe we don't push the manuf. harder to perform better 'cuz we, the audio hobby group, don't know what music should like in the home environment? Maybe our ears are not trained to register timbral accuracy of instruments & voices? I have made an observation over time that all those audiophiles who attend lots of live concerts of any sort mostly do NOT have any of the commercially know speaker brand names! Can you think why this is? See if you can come to the same conclusion yourself (or if you can refute my emperical conclusion). The speakers they have are either of esoteric brands or are DIY or are from real mom & pop speaker manuf. that seem to still hold the course of accurate, real music reproduction.
Anyway, I've rambled on long enough. Hope that this dissertation was useful to you & that you can see things in another light. I HOPE that you will find less reason to be contentious.
Of course, just my view-point. FWIW.
Sean, what are your thoughts on transmission lines? Transmission lines have much smoother impedance curves through the bass region than most other enclosure types. One current commercial design that I'm familiar with uses an "8-ohm" woofer and the impedance peak in the bass region doesn't go over 11 ohms. There may well be others that do even better.

Or what about pressure-relief enclosures? No time-delayed output from the damped opening, and once again a much smoother impedance curve in the bass region.

Seems to me either of these approaches are inherently even less resonant than a sealed box.
Transmission lines have potential but are phenomenally hard to build and fine tune. Given that most manufacturers can't design / build simpler products, i don't hold much faith in them getting a more complex product like a TL right.

As a side note, AudioXpress had some recent articles about a TL design. From what i walked away from that article with, my thoughts about them being very complex / hard to optimize were only reinforced. Tons of higher frequency rippling taking place, etc... along the length of the tunnel. Even more than a poorly designed port. Obviously, one would have to do a lot of experimenting with different types, densities and placement of damping materials to get things dialed in. As such, sealed and stuffed is hard to beat from either a mass production or hand built / tweaker point of view. In many cases, simpler really is better.

As far as "pressure relief" enclosures go, are you talking about Aperiodic's aka "vario-vents"? Sean
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Re: transmission line speakers, mechanical & electrical modelling is now available for quarter-wavelength speaker design. Never tried it -- but thanks to a few audiophile engineers it looks like we've taken a large step forward from the trial & error situation of yesteryear. D Dlugos' site has general info on the subject and, of course Martin J King who actually developed the computer-based mechanical modelling.
Cheers
In my opinion, and with 50 years of experience building speakers (mostly by the old fashoned trial and error method) transmission lines are the best boxes, but as sean says are hard to get right. Sealed boxes are almost idiot-proof, and so, in the real world, in most cases will outperform TLs. Furthermore, because of their gradual and well controlled roll-off, electronic equalization is effective. The key to speaker building is "don't screw it up". It's too easy to do that with a TL.