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In the Forum: Horn-Loaded Speakers
In the Thread: Satisfying result: the RMAF Show + Cogent
Post Subject: Cogent 2007, True-to-Life Horn Loudspeaker - the criticismPosted by Romy the Cat on: 10/22/2007

The AudioFederation guy posted pictures from RMAF show with Cogent room. (The images are courtesy to http://www.audiofederation.com)

Cogent2007_1.jpg

Cogent2007_1.jpg

I was wrong in my previous post, as Cogent did demonstrate their loudspeakers with Ionovac ion tweeter. Yesterday I read some comments from “usual suspects” who heard the new Cogent setup. Some of them love it and sing their typical odes to Cogent. Some of them like it less. I equally discard both of them. The near-Cogent crowd, in my view, are just a pile of fucking worthless, ass kissing, religious idiots, which have no brain, no ears, no audio intellect and no more or less civilized listening demands. They blindly embrace and adore any sonic meritocracy they are exposed to – read the “The most appalling audio types” at:

http://www.goodsoundclub.com/GetPost.aspx?PostID=4611

I typically automatically discard their observations about Cogent Sound as I did last day reading their comments about Cogent’s RMAF results.

Unfortunately, the moronic surrounding in which Cogent dipped itself into does not create the environment of critical acclaim of Cogent’s Sound, and it is bad. I do not agree with what Cogent try to do in their new reiteration and I would share some of my thoughts. Be advised that I did not hear Cogent for 2 years but I do not need to as I am convinced that I have a clear knowledge how those speakers sound, much better knowledge then many of those who have them in their rooms. Ah!!!

First thing first: we have to clearly distinct between the Cogent as two guys who manufacture electro-magnetic drivers, sort of modern reincarnation of RCA driver from 30s, and the Cogent as acoustic system depicted at the images above. I have no business or intentions to criticize the Cogents’s drivers themselves – I never dealt with them – and my criticism would be applied to the current Cogent system in it’s entirety.

One of the major flows in my view in the entire Cogent concept is the Cogent subordination of their design objective to the consciousness with which the industry built their movies theater in 30s.  There were a number of good things in 30s, but there were a number of the very wrong thighs during that time. I can mention many problems of movies theater sound from that time buy anyone who is familiar with today’s sound of Western Electric, RCA, Bell and Klangfilm installations would know what I am taking about. They were always two ways, low-bandwidth systems were designed to flood large listening space with monophonic sound, creating “virtual size” with lower “midrange overload”. Interesting that none of the “overloads” of 30s had the tonal sophistication of 50s. So, we arrived to Cogent’s … two ways, low-bandwidth systems that flood a listening space with monophonic sound… of own horns.

It is very noble to go for a small throat midbass driver but it is VERY difficult to do and it is absolutely impossible in context of 2 way system. A driver loaded into a horn is not a wide bandwidth devise – it is severely compromised transducer when it approaches the limitation of one horn size. If you have two way systems and one of the horns is 50Hz then you can get have ~2.5 octaves out of this horn? That leaves too much bandwidth for the left-over horn – impossible task for horn loading. Then Cogent want to build a sexy systems that the contemporary people would put in their listening rooms – a noble task indeed. However, if you look at the Western Electric, Bell and Klangfilm (I know less RCA) movies theater’s 50Hz intentions then you see huge horns (in many instances mounted into the walls). You do not need to be smart to calculate the necessary opening for 50Hz – did I say the gradual opening? The Cogent mid bass horn is too small and has too saddened opening step. That converts the Cogent mid bass horn into two effective differently tuned resonating chambers – verticals and horizontal.  That severely compromised the sound coming from that driver. Sure, Cogent might do smoother transition and larger moth but then they will be forced to locate the MF channel higher – not good for home listening! But who even mention the home listening? In 1930s, where the 50Hz horns were made for public sound reinforcement, there was no such a concept as “home listening”…. I would not even mention the time mssalignment and a few other things – the problem with the Cogent midbass do not make of it less relevant…

Ok, let me tell you a very sad truth. I have a pair of very good “special” drivers in my storage that I dedicated for my 40-50Hz horn. Over the year I came up with many, many, many, many designs and experiments and I concluded that it is imposable to have 40-50Hz located below MF driver – imposable! No mater how you slice the channels and what you do the presents of a large opening below MF create a lot of problems not the last of the problems is MF reentry reflection off from the large mouth of the midbass horn. I have one design where the midbass horn was sitting in an “orchestra pit” below the MF channel but it would be certainly not for anybody… Otherwise the only one lucid proper way to implement 40-50Hz horn is the way how Jessie does it: hang it above the MF inhalation. I would personally couple it to ceiling as I LOVE any ceiling-loading….

The idiots reading my comment will recognize that I badmouthing Cogent but there is a reason why I’m calling and treating the specific people as idiots. My critiques has absolutely nothing to do with Cogent and it is not my fault that Cogent decided to make expensive drivers and compromise them with inadequate horn.  I do not argue with Cogent but Cogent   argue with the laws of physics. If they so warship the “old” design then should read the books written by old people. The RCA’s Radiotron clearly state  - a horn is not a wide bandwidth transducer. If you do not believe to Radiotron then believe to own mind. The definition of compression driver is that the driver meant to be used is conjunction with horn-loading. If so, then Cogent certainly should look at better midbass horn implementation if they are willing to state a claim for a better midbass sound reproduced by a horn. So, far any conversations about advantages or disadvantaged of electromagnets for midbass are truly worthless unit a proper midbass horn will be employed. Unfortunately the marketing idiots around Cogent do not invest into efforts to educate themselves what is wrong with Cogent’s upperbass but they rather to spread the ridicules anecdotes about the “compression drivers’ bass”, not to mention the rest of absurdity…

The Cogent MF channel - Bill Woods’ conical horns (that still has even number of sides). I am not a big fun of conical horns. To me a conical horn work more or less only at HF as the lower horn goes the more conical horn has problems, the reentry reflection is not the last of them. Still the conical shape is not my major problem with Cogent. I rather disagree with the size of that horn and the crossover point. Once again - Cogent starches one ass over multiple chairs – it does not work. The lower crossover point = deeper horn.  The deeper horn = more narrow radiation pattern, more HF attenuation, mode dull transients. With Cogent’s soft sounding electromagnet they need as much help in transient department as they can get. Also, any filed-coil driver are by nature not the wide bandwidth drivers and they have a very specific (much more specific then perm magnets!!!) optimum amount of flux for a given frequency.  More flux = more over-damped lover range. In their MF driver Cogent combined two major foes of wide- bandwidth operation – electromagnets and horn loading.  As I said before, Cogent desperately needs 2-octave channel to cover a gap between thier midbass and MF but if they do so then they might review the design of the MF driver that would not need anymore to go so low… Otherwise, the Cogent system will always sound as it sound now - 2 ways horn installation desperately trying to play full contemporary range. It does play “full range” but the full-range for 30s. An average movies theater goer in 30s, sitting even at it’s best spot was receiving a frequency range between 100 and 4500 cycles – and it is where Cogent more or less competitive…

The tweeter.  I regard Cogent’s use of Ionovac ion tweeter as their mental subordination to eBay syndrome. That tweeter is garbage. Cogent would need to go into a journey to discover a tweeter for themselves and position it properly (not like now!!!) However they need to do it ONLY after they resolve the “size” of this MF channel and will have a clear vision how their MF drive sound at its top knee… Anyhow, there is no visible to me proper positioning of the tweeter in context of current Cogent configuration.

In the end I think Cogent should for a while to come back to manufacture juts the drivers. I understand that it is difficult to sell juts raw drivers but then they will not be responsible for the results and should not be bothered by criticism. The Cogent’s RCA drivers are a good entry point for marketing drumbeat - now somebody need to spend efforts to convert the Cogent’s driver into palatable Sound… Then…. perhaps to expose Cogent to the slightly altered driver’s requirements…. I would certainly not say that current Cogent’s drivers might not do better but I did not see so far any attempts by anyone to employ Cogent drivers in a truly objectionable installation. Perhaps Cogent midbass driver in a proper horn combined with two Cogent MF drivers (one for lower MF and another for higher MF) would do? Then still it need a dedicated LF and HF channels… Yes, folks it will take for you a LOT of time to experiment and to listen…. in order to come up with… Macondo/Cessaro-GAMMA configuration…

Rgs, Romy the caT

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