Controlled directivity speakers

[Bjorn]

Has anyone heard these yet? The only thing that turns me off is having to go through an A/D and D/A conversion in order to use the digital crossover.

I have obviously. I have a pair. But I assume you're asking someong else.
I don't know what you believe but if you're asking about feedback from someone who listened to them at a show, I would say that's pretty much a waste. Demos at shows will almost always be poor no matter how good the speakers are. Naked room with flutter-echo, loads of specular reflections and standing waves doesn't exactly create the hifi nirvana. Not to mention very little time to set up the speakers and the challenge with several listening positions.
The question one might ask though is; Does one have to audition speakers at all or is it enough or even better to buy speakers based on measurements? I would say the latter is sufficient and also better. One only need to take into the account the room they will be playing in. Will the room be ok with 72 tweeters firing loads of energy and speakers that disperse almost 90 degrees to the sides?

Double conversion? Not sure I understand.
Use a Hypex DLCP or a miniDSP 4x8 HD. They can work as crossover, converter and preamp. The Behringer DCX2496 is something I would avoid.
An active crossover has clear advantages. You can tailor the response to your room and it's much easier to integrate subwoofers.

 

[mep]

Bjorn-I didn't understand that you own these speakers so I would love to hear your impressions of them. I thought these speakers need four channels of amplification and that the signal from the preamp had to go to an outboard digital electronic crossover which meant the analog signal from the preamp is converted to digital prior to the electronic crossover and then back to analog after the electronic crossover and then the signal is fed to the amplifiers.

 

[iansr]

Bjorn
have you heard the Geddes Abbeys?

 

[Bjorn]

Bjorn
have you heard the Geddes Abbeys?

I would have to say yes to that considering I have them. I have a full surround system with Geddes speakers.
They are great speakers.

 

[egidius]

geithain?

@Mark:

Controlled directivity has become the latest buzzword used equal or more often by those who don't understand the realities as those who do.

well indeed, I really don't understand. But recently heard in my technicians studio some Geithain speakers, I just picked up, that they call their fave technique a "Bassniere" (bass kidney), which makes most bass go forward as opposed to non directed..

http://me-geithain.de/highend/index.php?option=com_content&view=article&id=81&Itemid=177&lang=en

What's your take on that? Considering Geithain being one of the more successful studio outfitters, there must be something in it.

 

[Bjorn]

@Mark:



well indeed, I really don't understand. But recently heard in my technicians studio some Geithain speakers, I just picked up, that they call their fave technique a "Bassniere" (bass kidney), which makes most bass go forward as opposed to non directed..

http://me-geithain.de/highend/index.php?option=com_content&view=article&id=81&Itemid=177&lang=en

What's your take on that? Considering Geithain being one of the more successful studio outfitters, there must be something in it.

Cardioid bass works great as being directional outside or in large concert halls. In a smaller room the directivity below the schroeder freqeuncy is mostly lost and swamped by room modes.

 

[iansr]

I would have to say yes to that considering I have them. I have a full surround system with Geddes speakers.
They are great speakers.

But you think the CBTs are much better?

 

[Bjorn]

But you think the CBTs are much better?

I'm a little hesitant to say much at this point. I can give a more in depth comparison later.
We're talking about two very different speakers. The Abbey has controlled and limited horizontal dispersion above 900 Hz, resulting in less sidewall reflections in that particular area. The CBT has very wide and uniform dispersion (almost 90 degrees) and vertical controlled directivity where one avoids vertical reflections too a large degree. What's best would depend some on the goal and environment.
But I do I beleive the CBTs are objectively better in some areas:
- The powerrespons is more uniform and even over a wider frequency range. Resulting in an overall flatter response
- They sound more open and transparent
- They sound more "powerful". Not sure if that's related to a more even bass and midrange response, more SPL or better dynamics or a combination

 

[iansr]

Thanks Bjorn. I am interested in this because I'm close to finishing a pair of Abbeys, but I'd be tempted by the CBTs if I thought they would be a significant improvement. However one thing that puts me off is that I'm on the waiting list for what should be an absolute SOTA DAC (it's not going to be commercially available so don't bother asking what it is) which will be in a different league to the DAC in say the miniDSP and given the number of channels you need for the CBT I can't see how I could avoid the miniDSP doing analog/digital conversion, which would defeat the object of having the DAC.

 

[Bjorn]

Yeah. The minDSP 4x10 Hd is an encredible product for the price. It's close to being transparent sounding, but does lack some. I may buy the Hypex DLCP soon, which may be more or less completely transparent.
Anyway, I believe you will enjoy the Abbeys. I don't know of many commercial speakers, no matter what the cost is, I would swab them with.

 

[iansr]

Thanks Bjorn, keep us posted as your impressions of the CBTs develop.

 

[KlausR.]

The goal is to greatly reduce or eliminate the first reflections from the side walls and floor and ceiling. The reflections that do hit your ear are later in time and blur the sound less

To the best of my knowledge there is no evidence that first reflections are a problem as a matter of principle, i.e. in each and ever case, regardless of circumstances. When Richard Heyser invented his method of Time Delay Spectrometry in the late 1960’s it was possible for the first time to “visualize” boundary reflections in room response curves. Without ever having done psychoacoustic research to see what human perception “thought” of these reflections, the reflections were declared undesired, disturbing, hence the “need” to eliminate them. What people tend to forget is that the fact that reflections are audible not necessarily means that they are disturbing. I had a good look at the relevant literature and there is simply no research where a 2-channel stereo system reproducing music in a typical domestic setting has been used.

As far as speaker directivity is concerned, the direct sound is the first to arrive at the listener’s ears, and is the reference with which all sounds coming later are compared. The precedence effect works well within its time window provided the spectra of direct sound and first reflections are no too different. Floyd Toole has further found that listeners prefer speakers with response that is flat on-axis and smooth off-axis.

Hence there is a need for controlled directivity, which does not mean that its purpose should be to reduce or eliminate first reflections. When looking at speaker measurements many speakers perform rather poorly in this respect, but they also perform rather poorly when looking at on-axis response.

I’m with Bjorn when he says

The question one might ask though is: Does one have to audition speakers at all or is it enough or even better to buy speakers based on measurements? I would say the latter is sufficient and also better.

Like Earl Geddes said in a recent interview: “Personal preferences have such a low stability as to be an almost completely pointless thing to stake a claim to. “Hi-Fi” does not mean “pleasant” — it means “accurate”; accuracy, as opposed to preference, is absolutely quantifiable and extremely stable – as stable as I care to control in my lab from day to day or test to test (but in any case its uncertainty is easy to quantify and understand). Decisions based on accuracy are therefore much more likely to be valid than decisions based on “how it sounds.” I do not see how one could ever support a position that “preference” trumps “accuracy.” That’s simply taking a giant step backwards in the evolution of Hi-Fi.”


I for one did buy my speakers based on measurements alone, taking Toole’s results as guide and also looking for the most accurate ones.

Klaus

 

[iansr]

Klaus
And those speakers were Klein & HummeL 0500C according to your profile yes?

 

[KlausR.]

Klaus
And those speakers were Klein & HummeL 0500C according to your profile yes?

Yes, indeed. While shopping I took a subscription to Stereophile. I also contacted manufacturers asking for measurements and all I got was audiophile gobbledygook.

Klaus

 

[iansr]

Looks like they cost $20k new? They look rather like a 3 way version of the Geddes Abbey (albeit active, DSP etc). Out of interest have you heard the Abbeys?

 

[KlausR.]

Looks like they cost $20k new? They look rather like a 3 way version of the Geddes Abbey (albeit active, DSP etc). Out of interest have you heard the Abbeys?

The K+Hs were designed around the year 2000, when did Geddes launch his Abbeys? Now they are discontinued, $20k was roughly the price when they were still available. I bought them back in 2001, and no, I did not hear the Abbeys.

Klaus

 

[iansr]

The fact that you have had them for more than a decade clearly says something about how happy you are with them. Care to comment? Shame about the looks though. Do you have grills on yours? ( looks like it was an option).

 

[KlausR.]

The fact that you have had them for more than a decade clearly says something about how happy you are with them. Care to comment? Shame about the looks though. Do you have grills on yours? ( looks like it was an option).

With small kids and a cleaning lady the optional grills were an absolute must, and I’ve got the first pair they’ve manufactured.

The overall sound is neutral, very clear and very clean even at highest levels, no sign of strain, effortless performance. Bass is very deep, powerful and clean, even at low levels. One can listen at highest levels without feeling the desire to lower the volume, on the contrary, adding some more dB is no problem at all.

The FIR-filters : The speakers come with 3 factory settings: all ways linear phase, all ways minimum phase, mixed. The differences are audible but subtle, the LLL provides somewhat tighter and better controlled bass. Since LLL (zero group delay, zero phase shift) is the correct way, I’m using that setting.

Hifi is about accuracy, accuracy can be judged upon by measurements, these are the most accurate speakers I could find back in 2001 and I think they still are. For me the journey has come to an end. As for the looks, waveguides by definition are form-follows-function. I also asked my wife for approval before buying.

Klaus

 

[Duke LeJeune]

To the best of my knowledge there is no evidence that first reflections are a problem as a matter of principle, i.e. in each and ever case, regardless of circumstances.

You're probably familiar with all of this Klaus, but I wanted to go off on a tangent here:

Some of the circumstances that can influence whether an early reflection is beneficial or detrimental (or some combination thereof) include its direction, time delay, intensity, spectral content, and whether it is diffuse or specular.

Let's look at direction. If the reflection comes from the exact same direction as the original sound, it is primarily interpreted by the ear/brain system as coloration. Move that same reflection around to the side, and it is primarily interpreted as enriching the timbre and adding a sense of ambience. Move it over to the opposite side, so that it arrives at the opposite ear from the first-arrival sound, and now it enhances ambience even more to the point of introducing a sense of envelopment.

As far as speaker directivity is concerned, the direct sound is the first to arrive at the listener’s ears, and is the reference with which all sounds coming later are compared. The precedence effect works well within its time window provided the spectra of direct sound and first reflections are no too different. Floyd Toole has further found that listeners prefer speakers with response that is flat on-axis and smooth off-axis.

Very well said.

To the best of my knowledge Toole didn't really investigate speakers with well-executed polydirectional radiation patterns, which preserve the spectral balance of the first reflections while increasing their time delay and/or intensity and often modifying their arrival direction.

Hence there is a need for controlled directivity, which does not mean that its purpose should be to reduce or eliminate first reflections.

I think there are many types of controlled directivity, though they may have widely divergent goals as to what should be done regarding reflections - from filling the room with them a la MBL, to reducing them to insignificance a la Sanders Sound. Different designers have different goals, and often the road to that goal lies through their vision of a correct reverberant field. If I recall correctly, the Klein & Hummels you have do an exceptional job of generating smooth off-axis response, and imo that sets them apart from monitors which fail to do so. If the price of entry hadn't been so darn high, I'd have become a Klein & Hummel dealer about ten years ago.