[Duke]

I enjoyed PaulHeligman's in-depth reply.  The only thing I'd take issue with is this:  I don't think the ear is sensitive to the floor and ceiling reflections being non-coherent.  My understanding is that the ear derives directional primarily from the first .68 milliseconds of a sound impulse, and then largely ignores repetitions of the original signal (reflections) for sound source localization purposes.  The ear still factors in reflections from the standpoint of loudness and timbre, but I don't think it's concerned with the coherence of the reverberant energy - only the spectral balance. 

While it's possible that lack of coherence in the energy reflected off the floor and ceiling is detectable, I doubt that it's audibly significant.  But I may be wrong - if so, let me know.

Duke

[NewBuyer]

Just following up a previous post (curiousity forces me to do this):

I believe I understand the basic idea discussed here, i.e. that a speaker's design and construction will itself induce time and phase distortion of the signal and frequencies received from an amp.

Is this the same notion of 'phase distortion' that also comes up in audio electronics design? For example, the idea of audio frequency band 'phase distortion' also arises with reference to audio transformers, op-amps, coupling capacitors, etc.  In fact, phase distortion has been suggested as a possible reason why different conductor materials, such as silver in speaker/ic cables, results in perceived differences in sonics.

Obviously 'phase distortion' is being referred to here in totally different system areas (loudspeakers vs electronics), but I'm wondering if the basic definition of audio frequency 'phase distortion' is the same in both cases? If so, can an audio signal possibly be already "out of phase" in this sense, before even reaching the speakers? (and obviously I don't mean signal "phase-inversion" here, which is a totally different concept...)

[PaulHilgeman]

Just following up a previous post (curiousity forces me to do this):

I believe I understand the basic idea discussed here, i.e. that a speaker's design and construction will itself induce time and phase distortion of the signal and frequencies received from an amp.

Is this the same notion of 'phase distortion' that also comes up in audio electronics design? For example, the idea of audio frequency band 'phase distortion' also arises with reference to audio transformers, op-amps, coupling capacitors, etc.  In fact, phase distortion has been suggested as a possible reason why different conductor materials, such as silver in speaker/ic cables, results in perceived differences in sonics.

Obviously 'phase distortion' is being referred to here in totally different system areas (loudspeakers vs electronics), but I'm wondering if the basic definition of audio frequency 'phase distortion' is the same in both cases? If so, can an audio signal possibly be already "out of phase" in this sense, before even reaching the speakers? (and obviously I don't mean signal "phase-inversion" here, which is a totally different concept...)

Sorry I meant to respond to this earlier, but I forgot.  Good question.

As far as electronics go, as long as it is not advertised as a product that will change time and phase, most can be considered minimum phase devices, in that any phase shift that they impart is directly related to any shift in frequency response.  The two are tied together.  So, for the most part, with audio electroncs, if they have suitable bandwidth and do not have sharp drop-offs outside of this usable bandwidth, the phase response within this bandwidth will be very flat.

As above, same thing applies to cables.  Unless they are altering frequency response to some large degree, they arent going to alter phase response.

Hope this helps,
Paul

[PaulHilgeman]

I enjoyed PaulHeligman's in-depth reply.  The only thing I'd take issue with is this:  I don't think the ear is sensitive to the floor and ceiling reflections being non-coherent.  My understanding is that the ear derives directional primarily from the first .68 milliseconds of a sound impulse, and then largely ignores repetitions of the original signal (reflections) for sound source localization purposes.  The ear still factors in reflections from the standpoint of loudness and timbre, but I don't think it's concerned with the coherence of the reverberant energy - only the spectral balance. 

While it's possible that lack of coherence in the energy reflected off the floor and ceiling is detectable, I doubt that it's audibly significant.  But I may be wrong - if so, let me know.

Duke

I think scientificaly there have been AES studies and articles that prove this, however, would you place a reflective object in a position where a total path length difference is 9 inches?  This would be like placing it 5 or 6 inches from a side wall.  I think the consensus would be that this would not be a good thing for home music reproduction.

I cant remember the numbers exactly, but also if the ear only determinted directionality from the first .68 ms, that means that directionality only comes from frequencies of 1600Hz and higher, this sounds a bit off to me. 

Really complex subject though, there are many more factors at play.  Maybe someone with more experteise in localization of sounds, reflections and reverberance can chime in here.

Good post!
Have a great day,
Paul Hilgeman

[steve_osugi]

Hi,

I'm surprised that no one here has mentioned Dunlavy or Vandersteen.  Both loudspeakers are time and phase accurate, as well as being very solidly built.  Not to mention that Vandersteen is supposed to use tightly matched components per pair of loudspeakers.  There are several great interviews with Richard Vandersteen and John Dunlavy where they cover their design goals/philosophy.

- Steve O.

[gooberdude]

Hey Paul,

Do you have a shop in Chicago?   I just checked out your site and your speakers
look really, really cool.   I'm a huge fan of bamboo too.

So far the only salon set-up i've dug is Jon Van L's speakerworks, in the City at 5100 N. Western.

I haven't ventured into the 'burbs yet though...

GD

[PaulHilgeman]

No, no shop.  But you are more than welcome to come over for a demo of either the passive or digital version.  Both are set-up at the moment.

Sometime later in the month of November, I will be hosting an event of sorts for the Chicago area expressly to hear the Ronins and the new Ronin 1.0d.  I will be sure to let you know all of the details, and post them here when they are all set in stone.

Thanks for the compliments on the Bamboo, many people really like it, some don't.  I'll be doing a veneered pair shortly, but it will still be constructed of bamboo for the environmental, and rigitity reasons.

Have a good one,
Paul

[Duke]

Hi Paul,

Thanks for replying.

The .68 milliseconds I cite comes from the work of Helmut Haas, and has been confirmed by subsequent research.  After .68 milliseconds the "precedence effect" (or "Haas effect") kicks in, so that we don't pick up false directional cues from reflections (though a strong, distinct reflection can still skew the image).  The precedence effect allows us to accurately localize sound sources in a highly reverberant environment. 

Now the ear/brain system uses two mechanisms for sound source localization:  Intensity and arrival time.  Intensity is the primary mechanism above roughly 1 kHz, and arrival time is the primary mechanism below  roughly 1 kHz - but both play a role in both regions. 

My understanding is that the transition occurs because the nerves in the ear cannot fire more rapidly than about 1,000 times per second, so at higher frequencies the mechanism shifts from primarily phase & time related to primarily intensity related. 

As mentioned in my previous post, that .68 millisecond window before the precendence effect kicks in is related to the path length delay around the head from one ear to the other. 

If you can point me to an AES study that confirms the audibility of coherence/incoherence in reflections arriving after .68 milliseconds, I'd like to read it.

An AES paper published in the 80's by James M. Kates, entitled "A perceptual criteria for loudspeaker evaluation", studies the coloration introduced by a reflection arriving at the same ballpark time delay as the first floor bounce.  He found that reflection to be a significant source of coloration even though the precedence effect suppresses it as far as directional cues go.  So the ear is processing timbral and localization cues independently!  This of course leaves open the possibility that a non-coherent reflection will be perceived differently from a coherent one, but that issue would probably have to be studied independently.

Thank you, and best of luck with your innovative loudspeaker design, and your equally innovative marketing strategy!

Duke

[PaulHilgeman]

If you can point me to an AES study that confirms the audibility of coherence/incoherence in reflections arriving after .68 milliseconds, I'd like to read it.

An AES paper published in the 80's by James M. Kates, entitled "A perceptual criteria for loudspeaker evaluation", studies the coloration introduced by a reflection arriving at the same ballpark time delay as the first floor bounce.  He found that reflection to be a significant source of coloration even though the precedence effect suppresses it as far as directional cues go.  So the ear is processing timbral and localization cues independently!  This of course leaves open the possibility that a non-coherent reflection will be perceived differently from a coherent one, but that issue would probably have to be studied independently.

What I was saying is that I think that you have it right in general, I didn't remember .68ms being the number, I thought it was about 2-3x longer, but if that's the number, that's the number .

But I totally agree with that second paragraph, I would agree at least to my perception that the difference I hear are mostly timbre/tonal based, but also other more abstract things that are too hard to study like soundstaging, size of sounds etc, the little things.

I agree with the first stuff and have heard it before as well.

Now, get this....  If you take a look at the 50 degree off-axis plot of that two-way speaker the peak of the midrange pulse is about .75ms after the tweeter pulse.  So, the sound reflecting off a surface above, the tweeter signal will arrive that much before, what does the earbrain do then???   Same sound, different sound, first a HF sound, then a LF sound?  It must get fatiguing listening to non-coincident speakers with poor power response.  (That was totally a joke, I hope people can take it as lightly as I do, I listened to them for years!!!)

As to my innovating marketing strategy, the strategy is the product.  I am letting a pair roam the country with minimal guidance, no 'salesmanship', magic-tricks, fiddling with things...  Just trust and respect in/for the fact that ACers as a whole are a pretty good group that knows what they are doing.

Have a great afternoon,
Paul Hilgeman

[topround]

Well I can't comment on the science involved here but I can say that the Ronins are sounding very, very nice in my house!
God knows I'm not time aligned

I also have a pair of GMA europas which are time aligned, and when set up correctly they really can knock your socks off with detail, soundstage and impact. And they sound good too.

mike

[PaulHilgeman]

Good to hear you got them all set-up and ready for Saturday.

Keep playing with placement, toe in, listening distance, speaker-speaker distance, speaker-wall distances etc.

They will get better, worse, better, better, much worse, way better, better, better, worse, better and then perfect... maybe in that order but you get the idea.

What did you think of the impedance compensation networks?  I suspect the difference was small but audible with you amps.  I suspect that you have enough power to play them to sufficent volumes.

Have a great time on Saturday.  I wish I could be there, but shipping plus plane tickets adds up real fast.

-Paul Hilgeman

[NewBuyer]

BBE Sound Inc. makes a processor product called the Sonic Maximizer, which is supposed to correct issues with time/phase/amplitude distortions in a loudspeaker. About two-thirds of the way down this page link, under the big red font heading "A New Era In Sound Fidelity Begins With BBE Technology", a good explanation of the problem, and their approach to correcting it, is given.

What do those around here think of this technology, and its approach to the problem discussed here?

[Daygloworange]

I know a number of years ago, these types of devices started showing up in the recording industry, primarily for voiceover/ post production stuff. They were used to liven up dull or poor recordings. They were called "aural exciters" and the like......they added harmonics to the original signal. They were pretty awful. They were intended mainly to add sparkle to voiceovers, to aid in intelligilitby, without a gain in volume.

I don't know about this BBE device personally, but I'm sure if it had any audiophile merit, a lot of people here would be talking about it, and or have it in their systems.

Cheers

[Russell Dawkins]

The original aural exciter by Aphex which at first you couldn't buy at all but rented and paid for by the finished minute of master resulting from its use, or something like that, apparently added an adjustable amount of even order harmonics to the signal, much as some tube amps do. The BBE claimed to have a similar effect but achieved it, if I remember correctly, by bringing the "presence range" (2-4 kHz, roughly) forward by default, by delaying all the other frequencies somewhat. I read this in their advertising copy back in 1990 or so, hope I have it right.

The CBC, Canada's national broadcasting corporation, bought a lot of BBEs, I understand, but replaced them around 1991 with "spl Vitalizers" - up-market German devices which did a similar thing, but using different techniques (totally proprietary, of course!). These devices, of which I still own one - I had a BBE before it, were much more adjustable and were capable of affecting stereo width as well as bass quality. In fact they said it was aimed at addressing the two most common problems encountered in mastering - lack of clarity (muddy or veiled presence range) and flabby bass.

All of these devices were client pleasers in that the client almost always liked the effect but the danger, as you might imagine, was over-use. They could improve a pop mix if used in moderation, but were often over-used and often were not necessary at all. If over-used, the result was fatiguing.

[NewBuyer]

I know a number of years ago, these types of devices started showing up in the recording industry, primarily for voiceover/ post production stuff. They were used to liven up dull or poor recordings. They were called "aural exciters" and the like......they added harmonics to the original signal. They were pretty awful. They were intended mainly to add sparkle to voiceovers, to aid in intelligilitby, without a gain in volume.

I don't know about this BBE device personally, but I'm sure if it had any audiophile merit, a lot of people here would be talking about it, and or have it in their systems.

Cheers

I found this on the BBE website FAQ page:

Do BBE Sonic Maximizer processors create any harmonics like exciter and enhancer effects units?

No. BBE technology does not work like exciter and enhancer effects. Typcially, exciter effects are associated with creating artificial harmonics through small amounts of overdrive in the high frequency band. This can prove useful in some recording studio situations, particularly in remastering older analog tapes. However, in today's recording and playback audio environments, there is no need to artifically simulate high freqencies lost through degradation of the original source tapes.

Enhancers are generally associated with equalization, however there are some products which attempt to combine exciter and enhancer effects with the result being harsh and fatiguing to the ear with no actual improvement in clarity and definition. Generally, enhancer products are marketed to appear as though they are more sohpisticated than multiband or parametric equalizer units, however, this is seldom true.

BBE is totally different than exciter and enhancer effects units. BBE High Definition Sound technology is not an effect, but restructures the signal in such a way which allows speakers to more correctly and faithfully reproduce the signal. The best analogy for BBE technology is like eyeglasses for your audio system.


Actually many people are talking about these Sonic Maximizers, and also have them in their systems.

I am personally trying a BBE 882i in my own system right now, and to my ears (and everyone else in my family too) it sounds fantastic. There is a 'Process In/Out' button on the unit that lets you compare the sound with, and without, the BBE enhancement. The difference is amazing! If this is what time/phase coherent speakers do all by themselves, then I'm totally hooked, time to start saving some money. 

[Daygloworange]

I re- read the original link you posted, I think this unit is trying to correct anticipated shortfalls of drivers and electronics. How in the world they think they can do that given the multitudes of different parameters that abound in the audio world, and the multitudes of ways different components reproduce signals, I don't know. Unless it had artificial intelligence ( as in a diagnostic function akin to automobile onboard diagnostics) I don't see this as something I would want to put in my signal path.

They even discuss how they start playing with transients, and how they try to restore the wave the way it shouldbe.....

I dunno

Cheers

[Russell Dawkins]

as I said, the BBE impresses initially, when you push the process in/out button. But if I remember process "in" is just a little louder. When you are making comparisons always watch for this. It is a well-known phenomenon, and used by the unscrupulous, that identical signals compared, where one is louder, always favor the louder.

Beware.

Also, leave it playing for a long while and get used to the sound then bypass it (adjusting the loudness to compensate). Does the sound suddenly become "easier"?

To my ears although more exciting, the sound is also coarser and tiring, like the difference between a nasty early 70s solid state amps and the best modern ss amps.

Be careful - I don't think you are on the right track at this point. There is a fork in the road; don't go the wrong way. You could waste a lot of money to get back to where you are now. Simpler is usually better.

Pursue better speakers first, then better amps. Or, if you can find an indulgent high end dealer or friend who will allow you the time, listen to a well set up high end system (not necessarily expensive - a pair of Omegas and a Signature 30 would probably be enough), then insert the BBE and judge for yourself whether it is an improvement.

You know you are on the right track when:
1. You are constantly wanting to play your system.
2. You listen for longer before turning it off.
3. You frequently forget that you are listening to a reproduction and get lost in the music.

[Daygloworange]

I agree with all the above statements. Nicely put Russell.

Cheers

[NewBuyer]

Thanks Russell Dawkins, I will try the things you've said. I too am aware of the "just a little louder" method for tricking the ear, but I assure you this isn't what I'm hearing from this component. Neither did I want to put something new in the signal path, this made me a bit nervous deviating from the "simpler is better" principle.

But so far at least our impressions are unmistakable. As BBE claims, the music is given a much nicer clarity and definition. It sounds more "live". You know, like how a drum sounds crisp and impactful when you hear it live? Or how in a live performance, a plucked guitar string sounds crisp and super-defined? That extremely pleasant, gripping, nice and vibrant quality that musical instruments and vocals have when you are standing in the same room with the performers. That is what the BBE brings to the table. It also enhances and corrects soundstage, so speakers disappear more, and all the musical elements "get out of each others way" so you can hear details in the music that previously were hidden or obscured. The entire sonic portrait is more natural and "musical".

I'm wondering, has anyone else here had a chance to audition the current BBE Sonic Maximizer products? The current 482i (unbalanced) and 882i (balanced) units were released at end of 2002. They are used by many well known musicians in both recording and live applications. I hope you will have a chance to try one of these current products. I do wish they had an all-black version or all-silver version though. That would look nicer in a music system - the current ones are red and silver, so they kind of stand out against the other components.

[bkwiram]

For those interested in linear phase crossovers (as well as driver linearization, time alignment, phase shift/group delay correction in the bass, room correction, etc.) I suggest a look at the software found at:

http://www.acourate.com/

In particular for the topic of this thread, I recommend:
http://www.acourate.com/XOWhitePaper.doc

The graphs are quite persuasive (pictures worth 1000 words, etc.). Or look at published step responses from reviews, if you can find some. They'll show the same thing. The bottom line is that you won't get real 'coherent' behavior with any conventional crossover. Only crossovers implemented in the digital domain and designed to be linear phase from the beginning will provide time/phase coherence.

(Disclosure: I have purchased Acourate but have not yet implemented it, as I am waiting on most of the necessary hardware to arrive. I *have* received a step response graph from Acourate's designer Uli Brueggemann. It is from his triamped personal system, running Acourate of course and with cone/dome main speakers and the Lyngdorf W210 corner woofers. It is the only step response I have ever seen that looks like a real step response. And that includes some electrostat step responses I have looked at. This is not to say that I know Acourate to sound good or bad - it is only to say that if you really want time/phase coherent behavior at the single point of the listening position, over the entire frequency spectrum, you want no passive devices between your amps and your drivers, and you want serious digital processing power upstream.)

I would also like to plug magnetically-actuated dipole line source speakers (above 100hz at least), but I suppose that's not really on-topic.

best,

Brandt