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Posted by Romy the Cat on
10-28-2007
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 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… |
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| 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. |
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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… Rgs, Romy the Cat
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Posted by Bud on
10-29-2007
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Romy,
We have discussed apottted Compression Driver's before, and I would not commit to promising performance you would like. Howere, here is a place where spotted speakers might well answer your needs, without altering anything you are currently doing.
All cone drivers have ringing on their surfaces when used. This is a particular type of enrgy emission malfunction. It is the original signal, reflected and therefore reemitted, during the first few micro seconds of the original signals emission. A hall of mirrors effect would be a useful description.
I am pretty sure that if we eliminate this bogus, extra energy, your current horn will actually work properly for most of this extra octave you must currently use it for. I will actually even commit to promising you will like the results.
No treqtment to the horn should be needed.
Bud
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Posted by Romy the Cat on
10-29-2007
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Bud,
you might be correct and “spotting” a cone might have a positive effect and I most likely will send you are driver for your torture after I found a reasonable contender. Still, what you propose and what I would like to experiment with live in different realms. To spot a cone with an intention to cures the compression driver’s crossover proximity issues is like to worry about cholesterol while a body is being destroyed by cancer. I would like to found a more successful macro-operation mode and then to wary about the particulars of the boundary emission. It is possible that what I have now a driver/horn in an optimum configuration. Still I would like prior making myself believing in it to try some other options (non-compression driver, plastic driver etc…)
Rgs, Romy the Cat
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Posted by CO on
10-29-2007
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Romy,
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.
Rgds, Collin
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Posted by Romy the Cat on
10-29-2007
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| 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. |
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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
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Posted by CO on
10-29-2007
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| 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. |
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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 |
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The IB approach is also the lack of the rear wave hitting the driver again repeatedly. An oversised sealed box is not the same.
Collin
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Posted by Bud on
10-29-2007
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Romy,
In the diyaudio thread on EnABL I cover the Hemp acoustics FR 4.5 C and the Lowther A45. Both drivers in your size range.
Since EnABL does not measurably alter any compression wave characterisitcs of the piaton mode tests, except for phase shift to nominal from lagging above 4 kHz or so, you should be able to choose almost any driver and expect to have it's sonic character remain unchanged, according to Lynn Olson and apparently Alexsander from RAAL, from the Lowther PM6A A/B test, treated against untreated at the RMAF show.
Actually, EnABL makes no tonal differences at all, as far as I could
tell - a Lowther still sounds very much like a Lowther. Time
performance for EnABL may have been a little better, the image was
definitely more spacious, mostly in the left-to-right direction. The
most evident difference was a (10 dB)* subjective drop in what sounded like 2nd
and 3rd harmonic distortion - this was mostly good, but did have the
drawback of revealing things about the system I didn't care for -
gritty-sounding Kimber Kable and possibly the Nelson Pass amplifiers.
I'm not much of a fan of hyper-expensive garden-hose-sized cables or
transistor amps on efficient speakers, so I can't honestly say how much
that biassed my impression of the overall sound.
Overall impression of EnABL: Considerably more open and revealing, but
may reveal things about your system you don't like - the tide goes
down, you see all kinds of critters you never saw before.
*inserted from a private conversation with Lynn, immeadiately after show
demonstration
In my own tests I have found no change in THD componenets, so all that is left is a removal of the "hall of mirrors reflections" obscuring the true tones, in their natural environment. In the two drivers I mentioned, at the beginning, the Hemp 4.5 would be just barely acceptable untreated, but quite nice after treatment, maybe a little uinspired, but very musical. The A45, untreated, is very good but with some diffraction and time related errors from the whizzer cone/phase plug. Treated, the A45 may be the most musically beautiful and uncolored speaker I have ever heard.
You might consider them in your research.
Bud
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Posted by Romy the Cat on
10-30-2007
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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.
Rgs, Romy the Cat
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Posted by Bud on
10-30-2007
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Romy,
All measured tests for unsmoothed frequency response actually show that the violent peaks and valleys in frequency response, that driver mfg's usually will not show you, are just accentuated by EnABL.
A friend of mine, one Gary Pimm, pointed out that this might be the pistonic essence of the process, that it allows much greater changes of direction in energy flow than an untreated driver and so, does not have the reflections that the constrained energy emission driver does.
The things are definitly not smoother to listen to, but the coincidental energy that would, in real life, be contained within a particular transient peak of an instrument, does remain contained, instead of spraying about in some shriek of terror. For this reason thery are less irritating to listen to and quite addictive too.
Bud
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Posted by Romy the Cat on
10-30-2007
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I’m not convinced at this point that it is good – I need to see it more in context of everything else - but the initial results are very promising. What I do now, I keep the compression Fane 8M in horn but I very dramatically increase dumping of it by power amp. I very aggressively idle the output stage of upperbass channel of Super Milq, experimenting with loading the half of 6C33C upto 17.200 Ohm – it is very-very high impedance and the amp develops tremendous damping against the band-passed 16R Fane in it’s overtight compression setting. I need to play and to hear the results it more... Here is where DSET kicks ass!!!
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Posted by op.9 on
11-02-2007
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"It is not an accident that I liked the article about the “Resonating Oops” to this thread."
Interesting. I'm just completing my 125hz midbass horns. And I'm deciding how to construct the back chamber. I think I will experiment with a removable and tunable back panel of the back chamber. I will tune the chamber first with a stiff panel then I'll ask my Luthier freind to help make a nice pingy, springy, lively back panel (probably with a 'bass bar' - the important structural bar under the table of a violin) out of some nice laqured spruce (2mm-4mm thick). We could start with a flat panel but it would be interesting to try an arched panel too. My hunch is that I need quite some surface area - maybe more like a large viola size than a violin. Possibly even bigger. I think I will make the back chamber elipitcal rather than circular. More worl.. but more room for experiment then.
I'd be interested if anyone has any ideas about all this... Its all a bit of a leap of faith! Anyhow if its a disater I can always replace the panel with something conventional.
BTW, against my better judgement I made the horns exponential... I couldn't decide whether to do exp or lecleach, so in the end I flipped a coin. I could always make them again ... noooo!
I'm planning to use Precision Devices PR107 drivers (they sound delightfully lively outside a horn) but I'm fascinated about the idea of the A45 lowther - has anyone actually tried them in a 125hz roundhorn?
cheers to all
op.9
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Posted by Romy the Cat on
11-02-2007
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Very cool, James, it would be very interesting if you put your ears into an investigation of “Ooopsy back chamber.” I was wondering about the A45 Lowther as well. The 125Hz midbass horns that you made, how big the input hole in there? The attempt to make the “Ooopsy back chamber” is very noble idea and I do not know a lot of people who did anything in this direction. After spending my unsuccessful efforts on the subject and come to a feeling that we should not necessarily should apply the algorithms and rules of musical instruments building (which I do not know personally) to the audio building. The Ooopy sound of string interments and the Ooopy sound of loudspeakers might derive from different means. I personally tend to feel at this point that Ooopsiness in loudspeakers is more upon the resonates of cones then upon it’s environment. The environment juts dumps the cones, still a cone should be able to crate the Ooopys… that the environment might embrace… Go figure…
Generally, as I discover recently the combination of back chamber attaching on a drive and increasing the damping factor from amps doe very-very well. Still, it is how my particular driver reacts to the things and other drivers might do different. I do not know what your Precision Devices PR107 is all about, can you post the data file? Also, one more thing. If you dive into the hunt for “Ooopsy back chamber” then try to listening your British Tannoy Red from 1960s. They do have some extremely interesting Ooopsiness that you might find worth to mimic with your upperbass horn.
The caT
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Posted by op.9 on
11-02-2007
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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!
When I said PR107 i meant PD107 of course
http://www.precisiondevices.co.uk/showdetails.asp?id=13
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...
I've been looking for some Tannoy Reds for a while, not much at the right price and condition..
op.9
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Posted by Romy the Cat on
11-02-2007
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| 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! |
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What I did detect that absence of moisture in cone is very critical. There are many ways to removed moisture from cone, some of them work very nice, still an cone with moisture has no good upper bass. Make an experiment – get a good sounding upperbass driver and just sweep it once with wet price of cloth. You will instantaneously loose the upperbass transients and for a good couple of weeks…
| op.9 wrote: | | When I said PR107 i meant PD107 of course |
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Very-very interesting driver – I never have head them. Pay attention that they are 10” but the outer spider is very wide, so it has more like 7-8” cone.
| 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... |
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More loaded plate = more harmonics, more power. Less loaded plat = less power, less harmonics. When you ridiculously unload the tube you strip all harmonics and sound become zippy, unnaturally contrasty and very hasty - it is hardly listenable – or something that Jonathan Valin calls “the best sound he ever heard”. However, if you driver do not produces HF, over-damped with back chamber and have tendencies to run sit on crossover point too close to the horn rate then the “holding” the driver from amps does produces an interesting result. It is very important here do not go very far and the channel if you go too far in the plate idling will loose the natural upperbass “bloom”. I also presume that each driver would react differently. In my case 4 time higher impedance works fine. Probably 3.5 times higher would be better but I have no such an option on my transformer.The Cat
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Posted by Paul S on
11-09-2007
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Romy, I am not clear from re-reading how low you plan to go with a 4" to 5 " dynamic driver, like you mentioned a few posts back. I thought I read that you planned to go as low as 70 Hz with this channel, which confused me when the 4 - 5" dynamic driver was discussed.
I think the nice paper 10" drivers are the best I have heard for tonal variation and "color" in the ~100 to 500 Hz range, and some are more than acceptable a good deal higher, too, depending on how hard you push them. I have no experience with horn "loading" dynamic drivers this large, but I can say that I was not successful with smaller drivers I did try because I could not figure out how to get rid of interactive effects/colorations that also screwed up and "divided" the tone into uneven "sections". Of course I am hardly an authority, since I also had "interactive" problems with "compression drivers", but they were definitely more pronounced with dynamic drivers; I don't know why.
Best regards,
Paul S
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Posted by jessie.dazzle on
06-02-2008
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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*
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Posted by Romy the Cat on
06-02-2008
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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… The caT
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Posted by Paul S on
06-02-2008
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Neodymium, eh, Jessie?
Perhaps you could use them for injection channels?
Best regards,
Paul S
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Posted by jessie.dazzle on
06-03-2008
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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*
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