Romy the Cat wrote:

Make an experiment, and I will simplify the case quite assertively. Take a typical compression driver, cross it at 800Hz, second order and load it into a proper contemporary horn (Tratrix or JMLC) of 300Hz. Listen that horn, you will get some sort of sound that let accept as OK Sound. Now begin to very slow lower the crossover point and keep listening the channel. While you lowering the crossover point, somewhere around 550Hz (I took this number purely arbitrarily as it would depends from VERY MANY circumstances) the horn will begin to demonstrate what I call “choked sound”. The “choked sound” is HOW HORNS SOUND IN 99% OF ALL HORN INSTALLATIONS OUT THERE – people just too damn to deal with it. The “choked sound” is the satiation when Sound produced by a driver can’t be “processed” by horn. In this “choked mode” a horn produces the “sonic boom” that was made by the horn’s bell and that “sonic boom” screw up the enter band-pass of the channel - the game is over.  Increasing of the crossover point for ¼ octave (for instance) will fix the situation - so we have approximately one octave between horn’s rate and mix crossover point…

Romy the Cat wrote:

The Upper Bass 115Hz Tractrix. That is another candidate to employ the Exponential “thump” but let look deeper. In the Jessie’s case the Upper Bass will be the only properly implemented Upper Bass that I ever seen. No one, including me, can afford to have 115Hz Tractrix and to cross it at 240Hz. All our horns are fundamentally compromised because we are trying to push more bass out of our horn running them the last “octave down”. Jessie has no need to push the “last drop” from his Upper Bass horn as he has his Mid Bass horns.

Well, I was dreaming to play with it for years and now it is the reality. With the new 6-channel Super Milq the  Macondo’s UpperBass is driven with own amp with over 14 attenuation, that means that I might use in the UpperBass channel any driver I wish – I have power and gain to drive it.

My UpperBass horn is John Hasqiun made, glued SDF, heavy, 4” into 35”, fully Tratrix, tunes for 115Hz, floor-sitting, “Macroimbedded” in the room, pushing at listening spot ~95Hz-100Hz at 109dB sensitivity. It crossed from 70Hz to 500Hz – first order of course. It uses 103dB sensitive Fane Studio 8M (paper- clothe, long external spider), used as a compression driver. Years ago when I researched the subject of the drivers for my UpperBass horns and when I was trying many alternatives I was restricted by sensitivity (6db was coming from horn and I was targeting for 109dB). Now I do not restricted by sensitivity. The channel does very-very nice, without exercising the unnecessary humbleness I would testify that it does better then any other front-loaded upperbass I have heard. Still, it is not the perfect upperbass as I feel that I cross it too low. I do not want to rise the crossover point at my woofers towers – which is 65Hz and I have no midbass horn.

So, I slowly begin to think what kind drivers, loading methods, of anything else I might use it order to tune off the crossover proximity effect in the direction I envision. My primary route of exploration, as I see it now, will be going away from the compression driver topology as I feel it is not right direction for bas. I feel that the bass cones should not be dumped too much as it takes place in a compression drivers. Perhaps a different dumping model, or perhaps some help from amp’s output impedance, of perhaps to drive a driver with an idle plate might do the trick - will see… I very much open to try other drivers as well – anything from 4” to 10”… as long they will handle my TTH demands.

In future when I finish the Second Super Melquiades and will set my playback up as it should be I will be slowly experimenting with my Upper Bass drivers… If you have any interesting ideas on your radars then feel free to dump them in this thread. I will slowly update the thread with my progress…

CO wrote:

If you havent already, why not explore the Infinite baffle concept? Or a long terminated back chamber for that matter. Current drive should also be very good on the lower registers.

Romy the Cat wrote:

CO wrote: If you havent already, why not explore the Infinite baffle concept? Or a long terminated back chamber for that matter. Current drive should also be very good on the lower registers. I did it. Any situation where sealing of back chamber does not increase resonance frequency is effectively an infinite baffle configuration. Still, my primary objective at this point is not the different back loading but trying to lose the compression driver configuration. I would like to find as 4” -5” cone driver with resonance frequency of 70-90Hz, with HARD suspension and to load if directly into the throat of my horn. It is very difficult to found such a driver as no one would use it in typical applications. I would be l flexible even with cone material and with any other characteristics. That type of driver in my current back chamber (80% smaller then it is) will be in fact infinite baffle for any 4-incher. I can always then narrow down the chamber to tune is as I wish… I look though the various drivers and so far I do not see anything that I would found interesting... The caT

Bud,

Thanks for pitching the A45a and FR4.5, I never dealt with both of them and will consider them, though it is slightly disconcerting that all those drivers meant to be wide bandwidth and therefore have too much HF in them. Still, my initial candidate most likely be smaller 4” drivers, something thing like Pioneer A11EC80-02F or Radio Shack 40-1022.

Regardless the EnABL process I do not think that it is my concern at this point. As you suggest the EnABL process might help to hemp or to Lowther in open air but only God know what a driver might need what it loaded into a horn. Be advised that all front-loaded horns the you have seen among those the Lowther people use are not horns but pure and simple crap – they all are to wide and with too large throat for a proper loading.

Also, there is another moment. You suggest that EnABLing makes the driver smother but it is exactly opposite of what I would looking in my upperbass driver. I would very much welcome some narrow-bandwidth nastiness – if I able to use it. I have very clear picture how I need this channel to sound. It is not an accident that I liked the article about the “Resonating Oops” to this thread.

op.9 wrote:

I agree, there is probably very little to learn luthiers that is directly applicable. However, I've always been interested in the similarities between good speaker cones and thin lacquerd spruce. Sort of a crispy pingy sound even with just a gentle tap. Anyhow, its not a BaD way to make an enclosure.. stiff as you like - with very little stored energy. Also, the resonaces of a violin front are many and chaotic, having the affect of spreading out the resonances. I thing it will be fun to play with the back-chamber back - adding little very light stiffening bars accross - in the manner of a bass bar on a violin. I plan to get lucky!

op.9 wrote:

When I said PR107 i meant PD107 of course

op.9 wrote:

I'm interested in the amp damping discovery. I will be able to experiment with this too.  Would electrically over damping affect the optimum size of the back chamber do you think? I still am not sure what size to start with anyhow...

Romy wrote :

"...Years ago when I researched the subject of the drivers for my UpperBass horns and when I was trying many alternatives..."

And in the Warfdale thread :

"... I had in past a few Goodman drivers but I was looking very different things from them then they were made for..."

I have been doing the same, and have recently been listening to a pair of 10" French-made Ferrivox drivers (Ferrivox used to make drivers for use in cinemas etc) which I like very much. This driver has a paper cone and surprisingly soft paper suspension.




Above is an image of one I found on the internet ; this particular example looks a bit rough.

I have stopped worrying about the sort of duty for which a driver may have originally been conceived... There are no T/S parameters for the drivers I've been trying; I just buy them, plug them into the horn, listen, and figure that if they are not suitable for this application (upper bass horn) then it will be audible in the form of poor performance. This driver for example does not have a particularly stiff suspension, so in theory it is not ideal for horn loading... Nevertheless, I like what I hear.

Did you ever try the Goodmans Axiette 8" in your upper bass horn? I have not... Not yet anyway.

jd*

Years back, when I was doing B/W photography very serious (I was 12-14 then), I always had in my mind an idea of “different” film processing methods. I had a notion that film shell be developed in a certain way, very different they it was done by default D76 developer. I do not want to load people with technical detail – no one will understand it anyhow but my purely abstract vision at that time was after a few year of my experiment materialized in an absolute stunning recipe of developer that use 4 developing agents: Metol, Hydroquinone, Glycin, Phenidone in unique combination; a very mild PH environed with alkaline made from sodium sulfate’s own “PH feedback”; with extremely low, virtually non-present restrainers that cooked film by my envisioned “starvation-saturation” atmosphere. It did the necessary .65 gamma nut by very different means and while it gained file density it did some other inimitable things (like the border-effect of the silver halides’ grains, the quality of tone and many other… ) that made my developer very different from another else. If what I arrived in US the world still have interest and commercial state in high-end B/W then I thought to license my developer to Kodak and many a lot of money on it. Well, that boat had already sailed even in the beginning of 90s….

Doing audio I am ironically have the very same adolescent attitude toward to drivers – I always feel that might discover some secretive driver that would do everything different. Some people and perhaps myself have the same syndrome with tubes as well. With all intellectuals understanding of the naivety of this thinking I have to admit that it always happen to me. I have “discovered” the Fane 8M driver and then I discovered the S2 driver. I did not invent them but I adopted their results is a way I have seen before….

So the thing do happens like this and it is very possible that there is a “next” better driver for my application and it is possible that French-made Ferrivox might be one of those finds. The treasuries revile themselves to the people who dig holes in ground…

Hello Paul,

If I were to come across such a thing, I would not say no to a little experiment with a driver that used a neodymium magnet.

All drivers I've been trying lately use AlNiCo magnets... Compared to some of the other drivers in what has become "my little collection", the Ferrivox drivers have modestly dimensioned magnets, especially when considering their output.

I will post an image of their frequency response as compared to others (as soon as I get the horns installed in their frames... Currently painting the frames).

jd*