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Horn-Loaded Speakers
Topic: The Cogent architectural problem or the Cogent++

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Posted by Romy the Cat on 09-04-2007

It looks like the Cogent boys came up with a new design. It is good that they are keep looking, even thogh they unfortunately are restricted with their desire to stretch the use of their drivers over too wide bandwidth….

The new Cogent setup look like a large sloppy genitalia, witch is not necessary a bad thing. Still, when I see those horns I would like to crawl inside, to lie down and to purr…

New_Cogent.jpg

The Cogent went for a larger opening at their upper bass horn – that is very-very good. Their older upper bass hors sounded like sewer pipe (despite all reports for different Morons ™ that you might heard), primary due to the pressure from their midbass was choked at the small mouth. This new upperbass or perhaps midbass horn is WAY more interesting solution.

But here is where we hit the fundamental limitation of any 2-3 ways installation that has “no-cheating” midbass horn – there is no way to organize other channels in nearfiled.  Let see how the Cogent boys were forced to screw up own installation because of it.

The MF channel looks like 150-200Hz horn. That would make the MF crossover point around 350Hz.  The horn sits 7 feet tall and angled down.  The horn angling is very bad thing. I also not a big fan of conical horns. It looks like Bill Woods from:

http://www.acoustichorn.com/

have sold to the Cogent boys the “BS literature” about the imaginary advantages of the conical horns. I do not buy into it, particularly for HF. So, we have the two way Cogent setup, ala Klangfilm-type of setups with MF driver shooting from the roof. Then Cogent boys added a tweeter - a long needed action.

Cogent vent for German Acapella’s ionized gas tweeter. There was in past many attempts to make the ion tweeters to work (DuKane, Electro-Voice, Fane etc) and nowadays Acapella makes them. The subject of the ion tweeters itself might a separate subject. I have problems with it when I hear it, although it should be theoretical the best solution for a tweeter. The most important is the incorporation of the plasma tweeter into the rest of acoustic system as plasma tweeter always sounds different then the rest of the channels. Even the Acapella’s own speakers do have this behavior…. However, I think Cogent might have a good shot with plasma tweeter as some idiosyncrasies that I recognize (and do not like) in ionized tweeters are presented in the sound of the Cogent’s drivers as well. I am talking about that “slippery sound” when sonic granularity goes all that way down (positive thing) but along with loosing granularity the transport for the ‘events delivering” is also diminishes (negative thing). So, perhaps the Cogent-Acapella integration might work out in their own right, though I would personally would like to see more sensitively in Cogent’s tweeter 10dB more then Acapella can handle.

Then we heat the painful part – the location of the Cogent’s tweeter – there is no right for it. The Cogent placed it at the only reasonable spot, - severely fucking up time alignment in their system – how people can listen the time-misaligned horns – do they have any idea or understating what they listen? The Cogent, however, took it further into absurdity – they aligned the tweeter’s axis with midbass horn but not with the MF horn. This setting will have the ONLY ONE proper distance where MF and HF channel will sound aligned; any other locations, even one away will reply with tweeter time offset.

What I think the Cogent boys should do (besides going for another channel) is to find the way to lover the MF channel down. Then I would like them to work with Acapella (if they like the driver) to make for them a tweeter with much smaller facade footprint, taking all Acapella’s guts, alosn with converter, off the tweeter’s board. That would allow Cogent to bring the tweeter all the way deeper and time-aligned it with the MF driver…

Until then the Cogent boys should keep experimenting. The given installation dos not look as a prototype of experiment installation but it is rather looks like completed product.  I am not impressed.

The good sign that the Cogent went for better electronics.  I heard some horrible stories how the Cogent systems were driven… I do not know how interning the Electronluv and what they know about sound but I think it should be more interesting then the typically-suffocating 300B when I was listening Cogent what I listening them a couple years ago at CES

Rgs, Romy the Cat

Posted by Paul S on 09-04-2007
Romy said:
"I am talking about that “slippery sound” when sonic granularity goes all that way down (positive thing) but along with loosing granularity the transport for the ‘events delivering” is also diminishes (negative thing)."

Romy, I have for some time called this phenomenon the "necessary roughness", and one of the things I liked (loved, actually) about Cogent's main field coil was that it did this very well indeed over about 2 octaves; in fact, it was exemplary in this respect.  However, this was the only part of the spectrum/presentation worth a fig on the day I visited.

At that time they were using 300B amps, Wavelength, I think, and not bad at all within its topological limits, quite nice over the two good octaves with the simple music they chose to play.

It looks like they either remodeled or moved since I visited, or the installation shown is not at their house.

It also at least appears that they are still approaching things in the same way, conceptually.  This could well be a stab at a marketable iteration of what I heard a while back, minus the giant plywood resonator and plus a complex tweeter with questionable value in this application.

It seemed to me while I was there that they could probably sell as much of this stuff as they could crank out, although I certainly do not know the "vintage" market, where they are well connected, as far as I can tell.

Best,
Paul S

Posted by Paul S on 09-04-2007
Thinking back, I could not remember which 2 octaves because it was less than 2 octaves, from ~300 to maybe 8oo Hz.

Not much, but very good, like Italian espresso.

Paul S

Posted by Wojtek on 09-04-2007

It only uses Cogent f.c drivers .Josh Stipich from Electronluv is the designer/maker of horns and amplifiers and Cogent role is secondary (my guess) . Electronoluv aproach is afected by Sakuma designs and using lots of transformers ,chokes ,big tubes and  MV rectifiers. AFAIK Josh likes country and bluegrass music and  in this context all your comments are meaningless.Regards


Posted by Romy the Cat on 09-04-2007

 Paul S wrote:
Romy, I have for some time called this phenomenon the "necessary roughness", and one of the things I liked (loved, actually) about Cogent's main field coil was that it did this very well indeed over about 2 octaves; in fact, it was exemplary in this respect.  However, this was the only part of the spectrum/presentation worth a fig on the day I visited.

I do not know. I do not have Cogent's drivers and if I had them I would most likely use them differently. Cogent took their idea from old RCA systems when RCA, WE, Klangfilm, Tesla, Telefunken and few others build sound reinforcement systems for mono movies theaters. It was not particularly good sound in there, quite low level of demands and completely different design architecture…

 Wojtek wrote:
AFAIK Josh likes country and bluegrass music and in this context all your comments are meaningless.

Actually if it is the case then the Josh’s comments, actions or amplifiers at that mater are meaningless in context of Audio.

Posted by Romy the Cat on 09-05-2007

I do not know the characteristics of the Cogent bass driver. I do not like the entire idea of a bass driver be electromagnetic as bass defeat itself first with field coils, still if electromagnets is something that Cogent intend to do then they are within their “constitutional rights” to do whatever they wish. What however is very obvious is that Cogent’s desperate need for one extra channel. Let me to explain.

Let presume that the Cogent bass driver can handles 40Hz. Why not? The horn loading of 40Hz requires a near 6-feet (2M) mouth. You can not go away from it. The “other” (MF+HF) channels might be positioned above, below or on the side of that large 6-feet mouth. If Cogent put it above, in time aligned position, then “bye-bye imaging” (Picture “A”). Putting them on the side is controversial as it requires a VERY sharp low-pass filter on the big horn. It is posable to put the MF at the bottom of the big horn (bringing the horn up) but the MF must be at near ears level and it will leave a large empty space under the MF driver, not to mention that now the weigh of the sound is radiated from “above”. Now look: we have a “large empty space on floor” and we have the “top prevalent” imaging… How it might be resolved? The only logical solution is introducing contra-balance channel that would be located under the MF channel. (Picture “B”).

Cogent++.JPG

However, here we hit another subject: if the “floor channels” has own bandwidth then this bandwidth not needed in other drivers… So, the selection of the drivers, horns and the way in which they might be use very different. It is possible that Cogent might use 2 of their MF driver in their newCogent++ configuration: one on 200Hz horns and one on 900Hz horn. How good would be those driver for the more narrow bandwidth – only god knows… What I know defiantly that in 2-way installation (aka RCA movie configuration) the Cogent will always be condemned to sound like…. a movie from 30s… Rgs, Romy the Cat

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