[Danny Richie]

Some interesting articles on "fast/slow bass" for those who have not read these yet.....

Myth or Fact:
http://www.soundstage.com/maxdb/maxdb061999.htm

Woofer Speed:
http://www.stereointegrity.com/Files/WooferSpeed.pdf


Medium Jim:  Fiscus Trees?  Wouldn't that be reflection and not diffusion?

Actually most of what was said in those articles are simply false and misleading. So I wouldn't put much stock in them. I'll come back to this as soon as I have more time to post.

[kevin360]

How do you know your subs are in phase with your main speakers?

OK, fair enough, 6FT it is.  That is still a long way off in terms of wavelength matching at the crossover point.

Frankly, I don't know and I'd like to have a proper answer. Those subs are firing in 3 directions too – more so to the sides than the front. I've removed the sock and watched one of them. The active driver  does not move as much as the radiators. Regarding the phase control, I can only state that I did find, by trial and error (can't be the best way to go about it), a setting that worked best – not saying I have perfect synchrony, just that I worked with what settings could be adjusted to get where I am now – happy (a process which took months).

You aren't beating a dead horse at all – even if this line of discussion has played out a thousand times. The crossover is a Bryston 10B Sub set with 18 dB/oct slopes around 60Hz. At the crossover point, 6' is right at a quarter wavelength.

[Davey]

Actually most of what was said in those articles are simply false and misleading. So I wouldn't put much stock in them. I'll come back to this as soon as I have more time to post.

Please, no. 
The guys are doing just fine without another servo sales pitch.

The OP has labeled the thread title with 'fast' and I believe everyone understands the connotation, and can differentiate subjective from objective.

Cheers,

Dave.

[Danny Richie]

No Davey. This isn't about servo or non-servo.

What the guy from sound stage was attempting was to state that everyone equates "fast bass" with ability to accelerate. And thus the reason to use lighter weight moving mass cones. He is right in that it is not about acceleration. But the reason the lighter moving mass cones are perceived as faster is because their settling time or time of recover is so much faster not because of how fast they move. He misses entirely how fast bass is achieved.

And while phase relationships are very important for integration it has little to do with what is perceived as bass speed. He fails to realize that even if the subs are perfectly in phase with the main speakers there can still be comb filtering effects that cause out of phase cancellation or peaks in the bass response just from room reflections alone. I have had speakers perfectly in phase with the subs and measured them to be perfectly in phase and still have room related peaks and dips. That does not change the bass responses perceived "speed". That just changes amplitude.

The reason the electrostatics are fast is they have very little stored energy. The moving mass is low. Surface area is great. X-Max levels are tiny. So they recovery very quickly.

The same principles apply to cone based drivers. Some of the fastest bass response that I have ever heard down to 20Hz was with line sources using 6.5" woofers. Moving mass was low. Exertion per woofer was very minimum. So stored energy is low, and recovery time is very fast. So the bass sounds very fast (fast bass). 

[josh358]

But dipole bass requires 6 dB/octave bass equalization, and so dipole woofers ring like crazy. Yet in my experience they sound "fast" by comparison to dynamic woofers, if a bit growly at times.

I don't think it's a matter of mass affecting air damping, since at bass frequencies, electrical damping predominates. A critically-damped sub should stop quickly (though a boomy home-theater-tuned sub wouldn't).

One possibility would be that the author of the first article is right, and that it is the extended frequency response of these drivers that makes them sound fast, not because the speed is required in the bass as of course it isn't, but because of issues above the crossover point.

Another could be that dipoles are less likely to excite room modes, which don't just create amplitude response aberrations, but ringing that can be severe. I've seen waterfalls that are horrific. And of course dipole woofers don't suffer from stored energy problems in the cabinet, although the baffle can certainly resonate and judging by the effect of bracing it (6 dB more bass output on Satie's Tympani IV's) is storing a fair amount of energy.

Then there's group delay. Passive radiator designs have more of it than vented designs, and vented designs more of it than sealed designs. Whether this is causes audible smearing or not appears to depend on the design. We're talking about delays higher than 25 ms or so, so more than you'd get from positioning your subs behind your speakers. Unfortunately, some designs do have this magnitude of group delay. To make matters worse, source material typically suffers from group delay in the bass, and the error is cumulative. So even a difference in woofer group delay that's inaudible in and of itself could become audible when fed with an already-delayed signal. It's certainly true that sealed designs have the reputation of being fastest, although group delay isn't the only difference between them.

[Danny Richie]

But dipole bass requires 6 dB/octave bass equalization, and so dipole woofers ring like crazy.

Not necessarily.

Yet in my experience they sound "fast" by comparison to dynamic woofers, if a bit growly at times.

Just like a sealed box design a dipole bass system can be boomy, sluggishly slow, or bloaty, or the complete opposite. But not exciting room nodes is a big deal. Often the room can easily contribute towards causing some of the worst attributes. 

One possibility would be that the author of the first article is right, and that it is the extended frequency response of these drivers that makes them sound fast, not because the speed is required in the bass as of course it isn't, but because of issues above the crossover point.

You can measure a drivers speed by how high it can play, but those areas are well out of the pass band of most subs and have no effect on perceived bass speed.

You are absolutely right about cabinet resonances. Cabinet wall resonances can severely color the bass response. And most boxes subs that are commonly available do suffer from these issues to some degree.   

[medium jim]

Some interesting articles on "fast/slow bass" for those who have not read these yet.....

Myth or Fact:
http://www.soundstage.com/maxdb/maxdb061999.htm

Woofer Speed:
http://www.stereointegrity.com/Files/WooferSpeed.pdf


Medium Jim:  Fiscus Trees?  Wouldn't that be reflection and not diffusion?

No, they're definitely diffusion:

http://www.audioasylum.com/cgi/vt.mpl?f=mug&m=171587

http://www.hawthorneaudio.us/forums/viewtopic.php?f=21&t=3893

I tend to use clutter to help my bass. 

Jim

[josh358]

(Dipole woofers ring like crazy)
Not necessarily.

The ones I'm most familiar with (Maggies) do ring, and yet the bass sounds extremely fast. This seeming discrepancy has long puzzled me. I've seen reports that say that dynamic woofers in sealed and ported enclosures end up having a very high Q and are actually worse than intentionally-underdamped dipoles, but I've also seen reports that say the dipoles (in this case, Maggies) are worse. Roger Sanders complains that the bass of electrostats is flabby owing to the primary diaphragm resonance, and says that Maggies ring less than dynamics. (Maggies also ring in the bass, but they have distributed resonances, as do the Sound Labs.) Peter Moncrieff complained about the ringing in dynamics:

"However, most woofer enclosures impart a very, very slow fall-time to their enclosed drivers, creating a very large, very long-lasting amount of overshoot and ringing.  As discussed and measured in IAR over the years (starting in Journal 3), this bass overshoot and ringing lasts many times longer than even the slow fall-time of the original bass note as recorded.  The ear/brain perceives this long-lasting bass overshoot and ringing as bass boom, an excessive bass heaviness that makes the bass sound slow and poorly defined, and which also obscures the rest of the music (including higher frequencies) that immediately follow the bass note, thus degrading the clarity of the whole speaker system."

Peter Aczel, by way of contrast, complained vociferously about the ringing in Maggies.

Also, I understand that dipole cancellation is minimum phase, so some of the ringing may cancel at the listening position. Has anyone measured?

[josh358]

I tend to use clutter to help my bass. 

Have to remember that line next time I get a complaint about leaving dishes in the sink.

[jaylevine]

Looking forward to the weekend, I'll bet.

Yup! Tea For The Tillerman in HiRes -- Yummy

[medium jim]

Yup! Tea For The Tillerman in HiRes -- Yummy

Sort of turns you on your side...

Jim

[jaylevine]

Sort of turns you on your side...

Jim

Yeah, never can figure that part out....

[SteveFord]

[medium jim]

Ah, that's better!

Jim

[jaylevine]

Ah, that's better!

Jim

They sound better upright too....

[SteveFord]

I don't know if it's really such a good idea to listen to Davey about suspending them from the ceiling but they're your speakers, so, whatever.

Enough silliness. 
Any initial impressions?

[jaylevine]

I don't know if it's really such a good idea to listen to Davey about suspending them from the ceiling but they're your speakers, so, whatever.


Enough silliness. 
Any initial impressions?

Everything I loved about my 1.7s--resolution in the mid-range, natural voices. Has a stronger mid-range and deeper lower-end to be sure. A bit of apples to pomegranates since I last heard my 1.7s in a totally different room (we moved from a very large condo, all concrete and glass room to a old city house with a narrow/long all wood and plaster living room). Compared to my Paradigm S2 v3 plus Rel Strata IIIs (what I've been using for a year) no comparison. The Paradigm are great small room speakers, super tweeter but small soundstange and simply no low-end to speak of. I'd call the Paradigms bright to the point of fatiguing, the Maggies are just natural sounding--listening to Here, There and Everywhere as I type--it is as if Lennon and McCarthy are in the room with me....

[medium jim]

Why is the room spinning...

Jim

[Danny Richie]

Your sound stage will be a bit larger with the tweeters to the outside. And I don't mean swap them both and put the feet in the same place. That actually moves them in. Mark where the main panels are (that is what determines the image placement and focus), and swap the two speakers putting the main panels in the same spot, but with the tweeters to the outside. That will open up the sound stage a bit.

[jaylevine]

Your sound stage will be a bit larger with the tweeters to the outside. And I don't mean swap them both and put the feet in the same place. That actually moves them in. Mark where the main panels are (that is what determines the image placement and focus), and swap the two speakers putting the main panels in the same spot, but with the tweeters to the outside. That will open up the sound stage a bit.

"...swap the speakers putting the main panels in the same spot...."

If I understand you this will move the speakers farther apart relative to their inside measurement when the tweeters where 'in"?

BTW: listening to "Truth" by Amaan and Ayaan Ali khan--stunning and simply beautiful on the 3.7s