I’ve been harassing my horn-maker for quite a while with an idea to go for straight, no-cheating 45-50Hx horn. We discussed it countless times and sometime probably we would go for this, and particularly if I figure out how to resolve the delays problems. I’m not taking about the ultra-short phony Edgar-Altec horns with cheating curves that run at half of their resonant frequency as the direct radiators. Those horns might please the specific hoodlums form mid-west and those horns were designed specific for the  “taste” of those Morons ™. What I am talking is the real upper bass horn, loaded “as horn” all the way down to it’s mouth rate. Thanks God I do not believe in the lower bass enclosures… :-)

Anyhow, this weekend a friend of my send me pictures of a Chinese guy who did something in the similar direction.

http://www.bbs01.com/add.php?forum=3&titid=142943&replyid=150430&page=14&style=1

Something in what that guy does (his name is Samuel) looks quite attractive: the correct size, the almost sufficient thickness of the walls and few other things. However, when I saw that to this quite nicely made horn this Chinese guy attached the flimsy Klangfilm 405 drivers with no back chambers then a sadistic smile crossed my face.

I always said that the people who spent some time with upper bass open baffles develop a permanent (or long lasting) corruption of taste to reproduced music. The open baffles at upper bass, no mater how large they are and what king drivers were used, produce completely different and completely artificial bass and this bass is VERY devastating for long-term listening experience. As the result the open baffles bass people get converted in a sort of cult where to even talk with them about sound become virtually imposable.

So, why Samuel form China built his nice horns and then ruined them by refusing to use a sealed back chamber? Go to his home page:

http://spaces.msn.com/members/turboguy/

, view his album and you will not have further questions. The upper bass open baffle is a diagnosis of this disease.

Even presuming that the throat of the Samuel’s horn is full 14” then the mass of the air on this horn’s belly is quite tangible for the Klangfilm 405’s diaphragms. As the result this horn should have quite strong throat reactance that should kill at least 10-15Hz of it lower response, but with this LF horn it might be even more. Why in the name of Rationale Samuel went for those heavy tasks of steam- or vacuum-bending those large panels but then desisted to loose the best 15Hz of his horn to the open baffles lunacy? Not to mention that his horn with completely under-damped back of the cones should weep and howl like a wolf.

Rgs,
Romy the caT

cv wrote:

Romy, Can you expand a little more on what the issue with dipole bass is and what it does incorrectly? I'm still not sure I know exactly what you mean (and I've had a look at some of your other comments on the site).

being a strong opponent of the open baffles for LF an I have written a lot about it’ misery in many places, probably even within this site. There area many reasons way open baffles should not be used: absent of drivers capable to work while the cones are un-damped, the devastating affect that the large baffles have to the imaging, the infinite problems MF propagation due to the acoustic diffraction, the severe distortions in the drivers due to the barbaric exertion while the coils dive into the arias where the flux is not linearly saturated, disability it integrate opened baffle upperbass with LF modulus and many-many others. However, the most unpleasant in the open baffles is the actually upper bass SOUND that the dipole open baffles produces.

It is imposable to convince anyone in anything and practically it is imposable to demonstrate or illustrate verbally in this post what the open baffles sound might be in comparing to a damped suspension. One should try it, preferably with many different environments and topologies and then make up his/her mind based upon own sensations.

To summarize my findings in two worlds: if you would drink the open baffle sound then it tastes like SAE 10W30 motor oil, spiced with MSG. the sound has feeling of that “thin” reality and impactfullness of that Monosodium garbage. However, under the objective light of unbiased sensations the upper bass form the open baffles is essentially very much “helped” sound.

In the case of this Chinese guy the effect even more aggressive as the misery of the open baffle in his case catalyzed by the problem from the horn.

Rgs,
Romy the Cat

Greg B wrote:

http://www.modernsolutions.com/artichoke/images/hornbwfront.jpg http://www.modernsolutions.com/artichoke/images/hornside.jpg http://www.modernsolutions.com/artichoke/images/horndan.jpg OK, here is my attempt at the big white trash sound! A really big front horn is tough to equal. I didn't see the point of flaring the bottom just to meet the ground plane, so this one was essentially 'cut in half'. Trying to equal the effortlessness of a big horn at home has been an ongoing challenge.This would not fit in my living room. It was fun to go inside. Felt as if you were swimming in a sea of music. FWIW, I agree about open baffles. Perhaps many people simply have not heard the benefits of controlled dispersion before, but OB have very low sensitivity and high distortion/excursion.

wonderful job, really the labor of love!

Interesting that my design that I was contemplating for myself was in a way similar to your, although was smaller of course. A couple years ago I have discovered that when I coupled a small sub-upperbass source at seiling but my upperbass horn to floor (all in the same vertical dimension) then I was able to “turn” my room with such a standing force that it was not even funny. I made many experiments trying to detect if it was juts an accident in my specific room and it looks like it worked in two other occasions. Therefore my design was to use of 50Hz horn, the exact replica of what you bult, only  make it flipped over 180 degree and attached to seiling. Sometimes I will go for it….

Regarding the open baffles you are very much correct: very few people heard well-controlled drivers. For many people out there the definition of speaker’s success is a situation when a driver’s cone trembles like a udder of 20-years old cow.

Rgs,
Romy the Cat

rdrysdale wrote:

We are using about an 18 foot path for the sub. What we need is for some smart electronics guy to design and build a processor just strictly for time correction, and nothing else, no EQ, or crossover built in.

Hey, good luck. To make ~7mS full range delay at the level more demanding then an average professional studios do is very complex. At least I was not able to find anyhow who would be able to challenge it. The biggest problem in there to let those “smart electronics guy” to understand the demands and the level of reference points of playbacks where this delay processor would be used. Pretty much everything starts from the ability of that “smart electronics guy” to make an absolutely transparent buffer when you plug the system with and without the buffer the sound should not be changing. The problem is that 99.99999% of those “smart electronics guy” have no idea if Sound would be changed; the distortion pastern in there is not really indicative. The ironic part is that when I spoke with 0.00001% of the “smart electronics guys” who know what I meant then they informed me that to do what I was asking is imposable.

If I use only digital then it would be easy to use 2 DACs with a delay in one of them. But if I use analog then I see not good solution. Analog delay will not work out at HF, to place a DA/AD chain into the signal path sound too barbaric, although the DA/AD processing do not do DSP. Perhaps a super expansive delay tape machine from 50s would do? :-) To be serious only because I was not able to resolve this problem I abandoned this direction… though I keep in my storage a few AK151 and crave that I will go for it sometimes…

rdrysdale wrote:

I will soon have an excuse to come to Boston, my niece has been accepted to the Boston Conservatory, I'm sure I will need to come out to see her perform.

Great, I live 5 min walk from Boston Conservatory.

The caT

Greg B wrote:

Perhaps forget about delay and align physically? This would require an interesting and large living room, but with a 50hz full sized horn, it is not impossible.

Rgs,
The cat

slowmotion wrote:

Your ears ( or some other hearing/sensing mechanism in your body ) "feels" large objects around you, and I think they will definitely "hear" relatively large upperbass horns mounted in the ceiling, even if no music is playing... It will definitely change the way your ears/body defines the "space" of your listening room, since they will be felt as being "over" you as compared to "in front" of you...

Also, and this is more imperative, in our playbacks we never, or very rarely, reproduce “the space above our heads”. In any Concert Hall we have 50-100 feet (or infinite amount) of space above us and this “space” acts as acoustic buffer-randomizer-resonator. This large amount of “space” is also act like a lowpass filter, subduing the HF but being totally transparent for the LF’s pressure waves. This waste mass of enclosed air has own LF harmonics that we do not really hear but still those harmonics modulate “something” when music transmitted to us through this “space”.  I would say that out experience of music are always “spiced” with the space above us. So, the presents of a “large object above you” is not necessary is bad thing, quite a contrary – the “alien” LF source “above us” works very well. If I could (space limitations + many other issues) I would mount a pair of a high power sub-low frequency modulator to my sealant…. Hey, do you want be my neighbor?

Well, certainly I would not propose this solution as a panacea but I feel that it is a fruitful direction; at least it worked very well in my room.

Rgs,
The caT

Jeffrey Jackson wrote:

so, my straight horns... I like them very much.. I built mine similar in style to what Greg B linked, but obviously much smaller.. mine are just under eight feet long (length of a sheet of plywood) and have a mouth roughly three feet by four feet each.. throat is nine inches by nine inches.. I used the ubiquitous EVM-12l as it's specs were just perfect for such a horn.. I have quite a few other drivers that I wish I would ever get to trying.. some nice field coil units. :^) I LOVE the sound.. it does fall a bit short of what I wanted in the 200 to 300 Hz range, but I suspect that is the woofer.. I did have to add quite a bit of 1/4" all thread rod as bracing across the panels.. it worked very well... I also had to resize the back chamber (sealed) quite a few times to get the resonance down to the proper frequency.. it made a huge differerence...

Anything like this? :-)

Jeffrey Jackson wrote:

The reason I think the driver is the weak point is because as a proof of concept I built a seven foot extension to them to try a JBL 2" exit compression driver - the alnico monster 2482... it sounded wonderful in the lower mids, but my initial throat expansion wasn't stiff enough and that came through in the blunting of bass transients in the 80 Hz area.. long horns have to be very stiff... it played quite flat down to 50, however...

I also experimented with the “LF capable” compression drivers: they are dead in midbass.  The best of them remind me the “sound” of a person who after withholding his breathe for 2 minutes is trying to count loudly from 1 to 50 without gasping any air… Try it and pay attention to your “tone”.  :-)

There are no compression drivers in existence that can handle midbass and when we do use the currently existing park of the compressions drivers trying to squeeze midbass out of them then result is always repulsive. If people do clamed that they like the compression drivers result in midbass then I think that the only wishful thinking drives them instated of objectivism…

In any rate: I have written that a driver should be able to handle painlessly at least one two octaves below the mouth rate, although the frequency below the ½ of mouth rate should not be supplied to the driver… Looking at this I’m kind of a proponent of using the regular cone drives, using them with smaller throat and damp the drivers with the back chamber, somewhere at the point when the mouth rate will be nearby to the resonant frequency….

There is a driver from GOTO/ALE, witch is LF compression driver, 110 pounds or so and many-many thousands dollars. Probably 80% of them does to the block sucking distributes and resellers… I do not know how they sound but I would not take them too seriously. The GOTO/ALE use very crappy horns at LF, not to mention that they try to write the lower octaves with their horn installations and I do not believe into the sub 40-50Hz bass horns.

Also, Rich with his friend Steve are trying to build some kind of LF compression driver. Their idea sounds noble but I do not know if they end up with interesting result. I have seen that they booked a demo room in CES that makes me quite suspicion in their entire venture: if the driver as they propose will be built then in order to perform properly it would demand a large horn that…. if this horn be built properly then it will not have any commercial value.  To bring a pair of 10 feet long, 20-25 sq feet moth horns in Vegas, install them in a reasonable room properly and to setup an fine installation around then is a superbly complicated task, not to mention that this venture would cost ~$30K. Rich and Steve would not be so heavily vested into the project, not to mention that the venture itself will be financially unreasonable if they think to make money on it. The best that they might do publicly would be to demonstrate some kind of half-ass, severally-compromised solution, the same as Bruce dose and pretty much anyone else…. Sad but true: the rules of engagement into this idiotic industry completely eliminates any possibility of introduction anything really interesting via the industry….

Rgs,
Romy the caT

It seems that I do agree with you about the sound of compression driver midbass.. at least from what I have heard in my own room.. I have heard the big ALE drivers you mention on a bent steel horn similar to what ALE builds, but of the owner's design.. it sounded great with acoustic bass that was from a recording I was unfamiliar with, but when I listened to a recording I was familiar with, the entire bass range was shelved down and it gave the impression of speed that we have all heard from lightweight bass... I left with more questions than answers..

anyway, here's what I built:



These were a quick and easy build.. but they have been in the system for a few years now.. I guess that is a testament... but I also know that I can do better in the lower midrange... I think that there are two approaches to basshorns: one, that you use a cone driver that has an Fs lower than resonance and use a horn that is just to the quarter wavelength minimum length (this is more in line with what you seem to prefer, Romy,) and two, use a light, stiff coned/diapragmed driver with a very powerful motor and don't worry about what Fs is as you will load it into a horn that is closer to half wavength.. the horn loading will swamp the driver Fs... I think that if the latter is done in a horn that is airtight and very stiff, it will result in incredible bass.. I like big dynamics, I will admit my bias.. I love the whisper passages whipping into full fury storms... and I don't like compression.. I hear it everytime now on petite speakers.. back to the horns: with the former, you have a chance at time coherence, but with the latter, no chance at all..

another shot (not up to date, but...)



I've tried them on their sides, together, aimed differently, etc, but with the very strange and small room, this is the only position that gets the bass right.. imaging suffers compared to when they were on their sides with the midhorns above, but the imaging is outstanding until tones drift below the mids - which is not until 210 Hz... so I am quite happy these days.. round horns are what I am working on now.. already spun a few, but I'm working on some larger ones.. :^)

I do need to add one last note.. I hope that there are enough true music listeners out there that have deep pockets and rooms for Steve and Rich's horns.. I actually am working on something outlandishly large and likely expensive.. I'd rather not compromise as much as what is on the market and see of people "get it" when they hear it... I suspect (and hope) that some will... if not, then I will have a nice set of horns for myself... I try to be an optomist even when I encounter morons at an alarming rate..

Peace (yeah, right)
Me

Jeffrey Jackson wrote:

It seems that I do agree with you about the sound of compression driver midbass.. at least from what I have heard in my own room.. I have heard the big ALE drivers you mention on a bent steel horn similar to what ALE builds, but of the owner's design.. it sounded great with acoustic bass that was from a recording I was unfamiliar with, but when I listened to a recording I was familiar with, the entire bass range was shelved down and it gave the impression of speed that we have all heard from lightweight bass... I left with more questions than answers…

Frankly sparking, a contrary to my expectations, I feel that it was positive reaction to the ALE bass. We generally are not familiar with proper bass reproduction and when we do hear it done “more or less properly” then we have that “mixed” feeling and do not understand what we heard. I think this situation when “we have more questions than answers: is a health state. Certainly it might be thousand reasons why it might not be the case but still what you told me about the ALE made me queries…

Jeffrey Jackson wrote:

anyway, here's what I built:

Wonderful, it was exactly what I have in mine only slightly more horizontal then vertical, with complimentary vertical braces and with back chamber. If you were somewhere in East Cost then I would love to hear them sometimes….

Jeffrey Jackson wrote:

These were a quick and easy build.. but they have been in the system for a few years now.. I guess that is a testament... but I also know that I can do better in the lower midrange... I think that there are two approaches to basshorns: one, that you use a cone driver that has an Fs lower than resonance and use a horn that is just to the quarter wavelength minimum length (this is more in line with what you seem to prefer, Romy,) and two, use a light, stiff coned/diapragmed driver with a very powerful motor and don't worry about what Fs is as you will load it into a horn that is closer to half wavength.. the horn loading will swamp the driver Fs... I think that if the latter is done in a horn that is airtight and very stiff, it will result in incredible bass.. I like big dynamics, I will admit my bias.. I love the whisper passages whipping into full fury storms... and I don't like compression.. I hear it everytime now on petite speakers.. back to the horns: with the former, you have a chance at time coherence, but with the latter, no chance at all..

Wonderful observation! I would like to add, that all large midbass hors couple diversely with rooms and it is virtually imposable to predict how it will behave until you bring the sucker in the specific room… Also, I feel the that the latter example of your would be more aplicable for a horn that peruse the lover octave and has a relatively low lowpath…

Jeffrey Jackson wrote:

another shot (not up to date, but...)

I wonder why you lift then on legs. The way how I thought is to make the seiling as a continuation of the flat side and by menace of this to gain a few hertz….

BTW, have you seen the Vincent’s 30Hz horn form my links? He told me that he is using Altec 416 drivers. It looks like it is more films created project but still I think his efforts very much deserve respect.

http://vincent.brient.free.fr/bass_horn.htm

rdrysdale wrote:

….as of now I'm convinced that a compression driver is the best way to go for fast, detailed and dynamic bass. The compression ratio needs to be just right, and the horn needs to be right, when these two are working together properly, and the room set up is right, it's the way to go.

Rich,

I would like to argue those points. Not because I agree or disagree with what you are saying but because I think “strategically” those remarks shoot slightly in a not the most fruitful direction.

First, as usually, a little attitude: I habitually afraid the so-called “fast and dynamic bass”. The “fast and dynamic bass” is a property of reproduction but NEVER a properly of “live” bass, or I would say more correctly: out reaction to the “live
 bass. The “fast and dynamic” perception usually is born within an audiophile awareness when people listen and asses the quality of bass in the rooms that have too short reverberation time for a giver LF and as the result - the bass has truncated harmonics and presented too sharp (in musical trims). The audio people are accustomed only to this bass or something that I call “fabricated bass”; furthermore this “fast and dynamic” fabricated bass is being violently cultivated by the audio propaganda and by audio industry (dealers, show rooms, reviews… go to talk with any typical idiot-reviewer about bass quality and you would feel that you talk with 5 years old about the quantum physics). Still, I have to note that the large rooms where I would say 40Hz decay at 60dB over 1sec the virtue of the size are not panacea and are not necessary resolve the problems, in fact the larger room even more complicated as the have own “hard to resolve” dilemmas. Ironically, when I visit the “good bass performing audio rooms” I always feel that the “fast” and the “dynamic” are the ejectives that bother me. I always would like to make audio bass slower and softer, though without loosing the “details”…. The “live” bass never “dynamic” and I sincerely feel that the “bass’s dynamic” is the situation when we, audio people, experience the room pressure instead of the sound pressure.

Anyhow, I can go on and on about it but let me to switch to the main subject or my reply.

I do not think that in the subject of midbass reproduction might be any “best way to go”. There are so many variables involved that so difficult could be assessed and predicted that I would be afraid to make any generalizations, or would be skeptical if someone would do them. Midbass in Reproduced sound is a property of environment, or I would say that it is a property of in many ways random Results instead of the property of the specific activities.  How do you know that the “compression ratio needs to be just right”? Are you sure that you do not deal with the horn throat reactance, or with mass of the cone projected to the flux strength, or with propagation the energy through the cone projected to the elasticity of suspension, or with reactance to the horn’s mouth coupled with the boundaries of the room, or with hundreds and hundreds of other things that is virtually imposable to predict or even to classify?

The reason I object the idea of “it's the way to go” in midbass because we Americans are damn and our consciousness is completely screwed by the evil of the multiple choice education when the educational hatchet-machine convert the infinite, continued and ever-connected analog Reality into the binary surrogate of pre-existing answers.  Unfortunately the 99.9999% of all audio people (I called them the Audio-Morons ™) when they would like to learn something about audio do recognize that the knowledge was shared ONLY if they recognize a precompiled set of concepts, conclusions or rules.  Suggesting that  “a compression driver is the “way to go” in midbass you in fact made up this “rule” and effectively sold your own subscription to the rule? Even if you get a “positive result” with your compression driver then would it be “as good as it might be” and would the “positiveness” of your result derive from the “compressness” of your driver?

What I am trying to advocate is a disassociation ourselves form the “slavery of subscriptions to the convenient sold truth”. I think we should not worship the processes and methods but the results. We should learn to distinguish the results and learn to use the results. With admiration, respect and certain intelligent skepticism to the Result we always will find out pathes to accomplish the Result. From the other bide by the agricultureing of the specific, and in many instances accidental method “to get there”, we are juts pay the tribunes to our egos….

rdrysdale wrote:

I mean that with a horn loaded compression driver, a strong motor, and a very light diaphragm, the attack and transients are more life like. Because the diaphragm can more precisely follow the recorded signal, the reproduction is more accurate than you would get from a weaker motor and a larger, heavier diaphragm, which describes most direct radiators.

Well, yes and no. At least it is how I feel, or at least to continue to play the devil advocate.

The idea of “a stronger motor and a lighter diaphragm” is intellectually and logically sound rational but it is not necessarily correlates with what I call “Applied Sound”. The motor should not be “stronger” it should be strong enough to create a saturated flux within the entire run of voice coil. Should it be stronger? I think, saturation is a binary state and since it reached it the further enlarging of the magnetic force become pointless. Someone might say that the excessive magnetic force is necessary to combat the flax modulations… one again… yes and no. You see, with bass everything is kind of twisted. I detected that slightly discharged drivers, although they do not hit the nominal sensitively, but they produce better quality sound if to pay attention only at the low frequencies. Furthermore, while I made many experiments field-coil drivers I learned that lowering the DC voltage that supplied to the magnetizing coil made bass way more interesting and natural. So, the idea of “stronger motor” is not necessary an absolute truth as far as I can see/hear it.

Now about the “light diaphragm”. Yes, there is nothing wrong to pursue the lighter mass of diaphragms but, once again, I do not know if this rule is absolute truth for midbass drivers. The bass transducer by nature has larger excursion and therefore larger inertia. We can minimize the inertia by lowering mass but it not necessary successful because the inertia itself is not a problem but the suspension that cares the inertia. We could cancel out the suspension’s influence (by implementing an infinite damping via negative output impedance for instance) by we pay for it by introducing other aggravations (burning a lot of power and forcing the amp to switch into “AB” for instance).  So, why people think that the lower mass diaphragms would necessary is more responsive if the permeability of diaphragm is mostly the property of the diaphragm’s suspension? I kind of approach the vision about drivers “as a whole” and I feel that as much as diaphragm should be aware about magnet as much as magnet and entire driver should be aware about the diaphragms and it’s suspension.

Pretend that you play tennis. If you have your rocket too heavy with too strong strings then you could shot the ball faster, however you loss control over the ball and loose your ability to spin the ball. The minute satellites of your hand is feeling and reacting to the ball will be lost and you send to the opposite side of the court juts very fast, very heavy BUT very identical blasts. Dose this keyword “identical” or “generic” make you to wonder?  I feel that very same happens with a driver when it has too light diaphragm, too strong motor and too irrational suspension. Now is the key:  there is no such a thing as too light diaphragm, too strong motor and too irrational suspension – they are all connected. Not only they but many-many other things: elasticity of the diaphragm, it’s ability to propagate different frequency with different speed, the late reported by Bud boundary effect, the cone’s ability to bend at different frequency with different rate, the type shape, material, winding techniques of the voice coil, the numerous aspects of suspension and many-many other things, to many to name. The problem is that there is not universal formula where all those ingredients could be described  - all of them work in conjunction. We, everyone (!), still make drivers completely blindly and receive better sound mostly by chance. Certainly there are some ideas: which direction might bring better luck, but still it is hardly manageable process. We could make out driver to hit some specific characteristics but we can’t not predictably to make them to do sound in a way we would like to. Furthermore, when we stick a driver into a horn and then place the midbass horn into a room then we introduce so many others conditions that…. to simplify everything juts by suggesting the “strong motor and lighter diaphragm” would be similar to believe that a healthier life-stile would prevent a person from being killed in a car crash. :-)

I’m having now a number of people who build horns for themselves and they keep asking me to give them fixed recommendations how to get the specific sound. I always hesitant to reply unless I know the exact driver, the exact horn, the exact amps and if I personally was in their specific room. Still, my confidence in the case of me perfectly family with all those conditions will be not my real ability to predict the things but only my self-mockering arrogants. I always suggest to my guys to do the specific experiments and to see how their specific installations will comply with specific sonic characteristics - It never possible to predict what will happen, and practically if a listener has the real honesty with him/herself and objectivism with the results. BTW, your pal Bruce Edgar, if to strip out of him his explainable tendency to shove 1/16 of truth into the asses of the semi-Moronic customers of his and if to dig him slightly deeper then the pop-intelligence of the AA’s idiocy then he indicates the very truthful behavior toward the midbass horns. He does not believes that any rules exist and the practice of a given inhalations is always unique and exclusive exprence.

I think what we do with midbass horns is we build the best we can, using the best of our knowledge and exercising the best out ability to react to the results… and then we (including me) begin to build the speculations and justifications why our way was the “way to go”. I think this behavior has nothing to do with real altruism to the subject but rather it portrays our egos and our desire to see our semi- pathetic accomplishments as a part of immortal efforts…

Sorry, but the “stronger motor and lighter diaphragm” does not sound to me as an inclusive explanation….

rdrysdale wrote:

So Jeffery, do you want one or two? Finally, just today I picked up a chuck that will allow me to easily finish some drivers. They are 9 inches in dia. and I've really been struggling with undersized tooling. You have to pay shipping.

rdrysdale wrote:

Our bass driver has a 12v field coil motor, it developes just over 20 kilogauss flux density using a low carbon steel pole piece. The exit diameter is 4 inches at the moment. The diaphragm is 6 inches in diameter and made of a single layer of carbon fiber with a 2 inch diameter voice coil using copper clad aluminum wire. The design of the driver is very different from most, the diaphragm is cone shaped and clamped rigidly to the center of the phasing plug, and the perimeter of the diaphragm is made of felt, and clamped with a mounting ring to hold it in place. The combination of rigid center mount and felt surround give a very well damped and precisely located diaphragm. Because the diaphragm is fastened to the phasing plug, it wouldn't be possible not to have the plug, however it would be possible to machine it in such a way that it would act as an exit throat and blend right into the horn. We haven't taken many measurements yet, and the final design is still being optimised. We are trying to find the best compression ratio by machining different exit configurations, and found some errors in calculations in our first design, which was very constricted. We redesigned the voice coil and the phasing plug and have made great improvements over the first drivers. We plan on the operating range to be from 40-50 hz up to 250-300hz. This driver is rather large, the phasing plug is 9 inches diameter, and the driver weighs about 40 lbs.

lately there was here and there some unhappy voices of the pissed audio-subscribers about the fact that some idiots-reviewers lately got tendency to writhe their reviews based upon the release notes of manufactures and without actually auditioning the components. I mean: a manufacture announces a new model, the reviewer read the specifications and 20 words description of this new product and then….  the “reviewer” go over the pages and pages of audio publications spreading his fantasies how wonderful his Patricia Barber’s double bass sounded in his listening room and how much he felt the Patricia’s attendance on his laps, I am not kidding: it is what they do lately.

Well, I would like to do the very much the same and to share some my own concerns that I got after I read your description.  Feel free to disregard them and an imagination of my madness.

1) With the targeting upper frequency of 250-300hz you have no need to make any phase plug at all. The phase plug is useful to optimize the delays at the throat arriving in the situations when the wavelength is comparable to the geometry of the pathways. In case of 300hz the phase plug is juts a waste of time/money that you spent to make it available. If you need some kind of surface to  “bounce pressure off” with intention to damp the cone then there are many other, less painful ways to do so, not to mention that your cone should not be damped but rather viagranized…. (it will be more about it below)

2) The highpass of 250-300hz make me to question it. There is not good compression drivers that would confidently and with reasonable quality  to do down to 250-300hz. So, are you planning to use your driver only in context of 6-chanle installations?

3) The bandwidth narrowness of your driver concerns me and makes me wonder if the midbass that your driver does is the correct one. Let me to explain. As far as I can see it, one of the greatest problems with any bass driver is the bass-driver’s ability to introduce the HF harmonic overtones within their bass. For instance many bass driver has different type of  “bad” rubber suspension. Their paper cones do OK but the rubber 9mostly very wrong rubber used) suck the HF is and then kills all high frequency’s overtones. As the result, the driver sound completely artificial. The introduction of a complimentary HF channel matching with this rubber-death bass driver do not assist the situation but juts mask it out.. The very similar is taking place in those curved horns. Let forget that in the bent horns each section acts as a individually-tuned resonant chamber and let to look only at the overtones killing. When sound travels across a curve of horn then higher frequencies attenuated more in the curve then LF (reflections). So, the LF harmonics and the fundamentals go through but the HF get killed in the horn’s curves. That is one of the reasons why all curved horns, with conditional exception of the “J-horns”, sound like a dehydrated camel who juts cross Sahara and who is covered with a think layer of shampoo (but without water) on his skin. Looking at all of this I usually feel that a properly sounding midbass driver must be able to handle at least one octave above it’s lowpass cut off.

4) Something suggests me that the carbon fiber cone is NOT something that you will use in this driver eventually and that that the carbon fiber is primary responsible party for the paragraph #3 and #2. I am sure that the VC is trembling in the gap like crazy trying to do wider range but the carbon fiber cone holds it up saying: “Oh, shut up, you shaky little bitch. I’m the carbon fiber - the material that used to suck vibrations out of tonearms, airplanes, and sports motors. I was designed with the specific objectives to increase the harmonic dampening characteristics and you, the miserable voice-coil, should not anticipate me to have any compile with your hysterical movements, even if you’re driven by the reference signal.”  Rich, I feel that by using the carbon fiber cone you severally compromise your driver and I think you eventually will look at the different direction. Perhaps it should be a different type of fiber/cellulose, perhaps it will be metal or some kind of plastic, or perhaps you should explore the opportunity to pre-marinade the cellulose cone (some people I know report promising results with chitin). However, when everything will be working properly I would anticipate that your driver would able to care in a straight horn up to 3K without plug or 4K with phase plug.

Now, I’m as well, feel the Patricia Barber right behind me….