It was great fun, and I would love to do something similar again
Thanks for posting it! It does look like a lot of fun. I enjoyed the video link.
It does look as big as you can legally make it. =)
BTW, how directional is it? It looks very directional, is it?
The horn system was build to make an audible and visual protest against a titanium mine in a small place called Vevring. A special "noise composition" was written for it by Maja Ratkje. It echoed out over the fjord in a magnificent way
We even came on the news (in Norwegian): Vevring jubilerer med dommedagshorn - NRK Sogn og Fjordane - NRK Nyhende
http://www.firdaposten.no/kultur/article4594801.ece
One week later it was used here: http://www.fartoyvern.no/side.asp?Id=4981&kat=864&sp=1
It was great fun, and I would love to do something similar again
Regards,
Bjørn
Thanks for joining in, Bjorn! Well, that explains the embargo you asked for in the e-mail you sent a few months back. Hope it's OK with you that I dragged this project out into the light of day here at DIYAudio - but seeing that it appeared on Norwegian television, it sounds like the massive Fjordhorn has already had its public debut.
I admire the goals of the Vevring group - the area in the video is stunningly beautiful, and speaking as a Coloradan, we have plenty of experience with destructive mining practices. In fact, I live within sight of not one, but three gas well drilling projects, one no more than 100m from the nearest houses in my development, and the town is built directly on top of 19th-Century coal mines that serviced the railway to Denver.
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You're welcome! I use to have a bunch more using different drivers, but they were lost in a house fire and somewhere on my computer is a high res TAD 1601? loaded 825, but have yet to find it.
Anyway, a latter day Klipschorn plot:
GM
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Hmm, I think I'll find the chance to listen to a pair. It seems they have it here.
Crikey! And I thought my 416 and 604 had a rising response - midrange hump.
Some real crossover work needs to be done on the last 2 plots you posted. I hope they are raw , no filter.
Raw. All these 'shouty' alignments were designed/voiced for ~matching impedance (high output) impedance amps and/or with somewhat lower output impedance ones with adjustable DF (bass tone control), so when dialed in to the app, they are much smoother/flatter over a wider BW. The Altecs performed so well overall that they didn't start falling out of favor until SS became the norm and started blowing drivers with high power and excessive EQ.
CD horn EQ helps them a lot, but doesn't quite have the same 'syrupy' sound as when driven as they were meant to be, so wonder if NP's 'F' series amps might be the best of both 'worlds' WRT to getting an acceptable trade-off between a tube amp's euphonic distortion and a SS amp's dynamics in a relatively affordable unit.
GM
I took the liberty of post-processing the Klipschorn graph that GM posted, and it appears to be the basshorn by itself (the highest frequency, if I'm reading it correctly, is 2 kHz).
There's a sharp dip at 75 Hz, a peak at 140 Hz, a cancellation dip at 150 Hz, a peak at 165 Hz, another cancellation dip at 200 Hz, the highest peak of all at 230 Hz, and increasingly ragged response above 300 Hz. All of these consistent with a horn with multiple folds in the acoustic path.
By contrast, the gradually curved Bill Fitzmaurice DR280 appears much smoother (although we don't know how much smoothing BFM used in his chart). Still, it is nothing like the wild roller-coaster of the Klipschorn or the Altec A7.
The folded-horn nulls at 75, 150, and 200 Hz are not really equalizable, since they are due to acoustical multipath cancellations within the folded horn. Trying to increase the level of these sharp dips would merely raise distortion at those frequencies, and not do much for the null itself. If you used parametric or digital EQ to remove the peaks at 140, 165, 230, and 300 Hz, it would help, but the overall response would still be pretty rough, and the time-domain response would still be very poor, thanks to all the reflections within the horn.
The biggest problem for the Klipschorn is going to be the basshorn/midhorn crossover. The basshorn is a mess above 300 Hz, while trying to "stretch" the Klipsch midhorn all the way down to 300 Hz is going to cause gross "honking" colorations. Entirely aside from the questionable performance of the folded basshorn, finding an appropriate midhorn to meet it is not going to be trivial. Even a massive Altec 1505 multicell with a 288 driver is going to be working well outside Altec recommendations, much less the dinky midhorn PWK chose for the K-horn system.
There's a sharp dip at 75 Hz, a peak at 140 Hz, a cancellation dip at 150 Hz, a peak at 165 Hz, another cancellation dip at 200 Hz, the highest peak of all at 230 Hz, and increasingly ragged response above 300 Hz. All of these consistent with a horn with multiple folds in the acoustic path.
By contrast, the gradually curved Bill Fitzmaurice DR280 appears much smoother (although we don't know how much smoothing BFM used in his chart). Still, it is nothing like the wild roller-coaster of the Klipschorn or the Altec A7.
The folded-horn nulls at 75, 150, and 200 Hz are not really equalizable, since they are due to acoustical multipath cancellations within the folded horn. Trying to increase the level of these sharp dips would merely raise distortion at those frequencies, and not do much for the null itself. If you used parametric or digital EQ to remove the peaks at 140, 165, 230, and 300 Hz, it would help, but the overall response would still be pretty rough, and the time-domain response would still be very poor, thanks to all the reflections within the horn.
The biggest problem for the Klipschorn is going to be the basshorn/midhorn crossover. The basshorn is a mess above 300 Hz, while trying to "stretch" the Klipsch midhorn all the way down to 300 Hz is going to cause gross "honking" colorations. Entirely aside from the questionable performance of the folded basshorn, finding an appropriate midhorn to meet it is not going to be trivial. Even a massive Altec 1505 multicell with a 288 driver is going to be working well outside Altec recommendations, much less the dinky midhorn PWK chose for the K-horn system.
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It seems very odd to me that you've gone to the bill fitzmaurice designs. Nothing against them, but they're fairly rough, designed to provide sensitivity and high output as the #top priorities, as well as the ability to be constructed almost entirely with a tablesaw, where we will absolutely see some significant artifacts that can be avoided with a more focused (pun intended) design. We don't need max output, we need max linearity and S.Q. They're also diffraction-heavy compared to the Geddes and LeCleach options.
It's odd that you're focused on his graphs, too, which are single-position and heavily smoothed, vs. the SOTA horns/waveguides previously under discussion.
I certainly appreciate the value of high sensitivity and they seem well-engineered, but their raison d'etre is very different from a home hifi.
It begs the question- why not just buy a big, good pro speaker setup (maybe from bill) and call it a day?
It's odd that you're focused on his graphs, too, which are single-position and heavily smoothed, vs. the SOTA horns/waveguides previously under discussion.
I certainly appreciate the value of high sensitivity and they seem well-engineered, but their raison d'etre is very different from a home hifi.
It begs the question- why not just buy a big, good pro speaker setup (maybe from bill) and call it a day?
True enough, it would be quite a stretch! Right now I'm running Altec 15" woofers low passed L/R 2nd order at 300Hz and Altec 291 on 300Hz horns high passed at 400Hz (L/R 2nd). It works well, but it IS a stretch. No lesser horn need apply! And massive is the correct word.....
Covering the same range with a 10" or 8" driver should be much easier.
If I recall right, the Geddes Summa uses a direct-radiator 15" woofer with a specified 94 dB/metre sensitivity. This is 2 dB higher than the Ariels (which are 92 dB/metre), but I would like substantially higher efficiency (firmly in the triode camp here, not going to switch to transistors).
There are pure JMMLC horns that go down to 100 Hz, but they are extremely large and not trivial to build. Same story for equivalent-size Tractrix horns - very very large, building is a major project, and shipping is not trivial either.
So what choices are there - even granted a highish 80~100 Hz cutoff - in the 103~106 dB/metre range?
1) A huge vented box with pairs or even quads of 15" high-efficiency woofers - basically, a full-sized studio monitor.
2) A very large straight horn, too big to fit in my living room. I need two of them, after all, and building them into the house is NOT going to happen. I don't want to mess with digital delays, so the midhorn would sit a ridiculous distance behind the mouth of the straighthorn.
3) A folded horn, with all of the problems we see in the Klipschorn. (Same issue with differential path delay.)
4) A curved horn, along the line of a DR280 or even the antique Western Electrics. This is going-off-the-deep-end stuff, beyond where I want to go. I'd rather have others design this kind of thing - this would take many many tries, and much measurement of assorted different prototypes. I'm not sure even Bjorn's BEM simulations can do this sort of thing - maybe they can, I dunno. (Same issue with differential path delay.)
5) A shorthorn with a vented rear chamber. The trick is to balance the horn cutoff with the magnitude, frequency, and Q of the vented-box resonance, while keeping the response well-behaved in the transition region. The path delay is conveniently nearly the same as the midhorn, following the practice of theater Altecs.
Are the BFM's the final answer? I doubt it. More like a usable starting point to explore the high-efficiency realm. Options 2 through 4 are just too big and too complex. Option 1 is a fallback if option 5 just doesn't work out.
If there are other options in the 103~106 dB/metre range, I'd like to know.
There are pure JMMLC horns that go down to 100 Hz, but they are extremely large and not trivial to build. Same story for equivalent-size Tractrix horns - very very large, building is a major project, and shipping is not trivial either.
So what choices are there - even granted a highish 80~100 Hz cutoff - in the 103~106 dB/metre range?
1) A huge vented box with pairs or even quads of 15" high-efficiency woofers - basically, a full-sized studio monitor.
2) A very large straight horn, too big to fit in my living room. I need two of them, after all, and building them into the house is NOT going to happen. I don't want to mess with digital delays, so the midhorn would sit a ridiculous distance behind the mouth of the straighthorn.
3) A folded horn, with all of the problems we see in the Klipschorn. (Same issue with differential path delay.)
4) A curved horn, along the line of a DR280 or even the antique Western Electrics. This is going-off-the-deep-end stuff, beyond where I want to go. I'd rather have others design this kind of thing - this would take many many tries, and much measurement of assorted different prototypes. I'm not sure even Bjorn's BEM simulations can do this sort of thing - maybe they can, I dunno. (Same issue with differential path delay.)
5) A shorthorn with a vented rear chamber. The trick is to balance the horn cutoff with the magnitude, frequency, and Q of the vented-box resonance, while keeping the response well-behaved in the transition region. The path delay is conveniently nearly the same as the midhorn, following the practice of theater Altecs.
Are the BFM's the final answer? I doubt it. More like a usable starting point to explore the high-efficiency realm. Options 2 through 4 are just too big and too complex. Option 1 is a fallback if option 5 just doesn't work out.
If there are other options in the 103~106 dB/metre range, I'd like to know.
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A variant of Option 1 would be a closed-box vertical array of high-efficiency woofers - maybe 4 or even 6 12-inchers? Let's call this Option 1B, and the most likely fallback if Option 5 doesn't work out. I'm not a big fan of line arrays, but they are a simple way of getting the efficiency up.
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These are funny comparisons regarding the Klipschorn. That graph was neasured in (quasi) 1/8 space loading and I don't know about the other. But the real issue is the The Klipsch graph has little or no averaging. The other certainly does not appear to be "raw". It is not a real comparison.
Two points I wanted to make. First, the roughness in the repsonse (which is how raw data usually look) may be due to to multiple reflections in the horn or it could be due to a inadequate mouth size. In this case the "impedance transformation" is incompletely accomplished by the horn and a portion of the waveform is reflected back into the horn rather than being transmitted. But you already know this, but others may not.
The second point is that graph is taken from the JAES (2000) article by Delgado & Klipsch. In it a newer bass horn is presented (with performance measures) that show a much better HF extension (about 40 Hz to almost 1000Hz). This is remarkably better than the original Klipschorn. Additionally it has better efficiency and lower distortion. All this done with a comparable footprint.
I guess some progress has been made in the decades since the Klipschorn was first designed. Gviven some of the other comments made above, I would encourage folks to realize the graphs in that article are "honest" ones, with a minimum of smoothing. Unfortuntely folks are freqeuntly not used to seeing the various bumps that do occur in real speakers with real measurements.
I do encourage you (collectively) to read the JAES article. It is a remarkable achievment from someone who made a significant contribution to audio. One that has stood the test of time (in spite of the various bumps in the graphs and using some economical descisions in the choice of drivers etc).
Two points I wanted to make. First, the roughness in the repsonse (which is how raw data usually look) may be due to to multiple reflections in the horn or it could be due to a inadequate mouth size. In this case the "impedance transformation" is incompletely accomplished by the horn and a portion of the waveform is reflected back into the horn rather than being transmitted. But you already know this, but others may not.
The second point is that graph is taken from the JAES (2000) article by Delgado & Klipsch. In it a newer bass horn is presented (with performance measures) that show a much better HF extension (about 40 Hz to almost 1000Hz). This is remarkably better than the original Klipschorn. Additionally it has better efficiency and lower distortion. All this done with a comparable footprint.
I guess some progress has been made in the decades since the Klipschorn was first designed. Gviven some of the other comments made above, I would encourage folks to realize the graphs in that article are "honest" ones, with a minimum of smoothing. Unfortuntely folks are freqeuntly not used to seeing the various bumps that do occur in real speakers with real measurements.
I do encourage you (collectively) to read the JAES article. It is a remarkable achievment from someone who made a significant contribution to audio. One that has stood the test of time (in spite of the various bumps in the graphs and using some economical descisions in the choice of drivers etc).
Not if the wiring contractor used Altec's wire sizing chart which results in a very low voltage drop over distance. Ditto RCA's.
GM
I agree, just so happens this came up this morning on the HE forum: High Efficiency Speaker Asylum - RE: Could I upgrade my Midrange Horns ?............................ - GM - October 20, 2009 at 10:09:55
GM
So you're letting extreme high efficiency dictate the rest of the design. If you're using the BFM stuff, then this thread can end right here. 'cause it's not your design anymore.
Exactly the point. Back when the K-horn was designed, the choices on the hifi market were very limited. Even the AR-1 was a few years later, and that had a totally different set of tradeoffs (that later went on to dominate the market). PWK stressed the importance of low IM distortion and wide-range dynamics at a time when the rest of the speakers on the market were gradually dropping in efficiency and size, and the commonplace assumption was that enough watts could substitute for anything. The panacea of "cheap watts" curing all problems gained much more force with the advent of the Crown DC300 and the Phase Linear 700, and this way of thought (more is better) dominates the market to this day.
As good as the Orion is - and it is a superbly-designed speaker - it is designed around the assumption of powerful amplifiers overcoming the massive equalization requirements of the design. 20 dB of boost in the bass - that's a power ratio of 100 to 1! Even the midrange uses 6~8 dB of equalization over the working range, which translates to a power ratio of 4~5 to 1, not exactly a small ratio. And this is starting with drivers that are well under 1% efficient - so at least 99% of those cheap watts ends up heating the voice coils, instead of doing useful work.
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The folks who use Class AB, Class AG/H, and Class D transistor amps can choose from many different types of loudspeakers - there really is no upper limit for this type of amplifier. The kilowatt milestone was passed several years ago.
The folks who like Class A tube amplifiers are in a different situation; we can jump into the deep end with transmitting triodes and transmitter B+ voltages, but these require quite exotic output transformers - preferably with oil filling in order to get around the problems with corona arc-overs, which are no fun with 1000+ volt power supplies. This is the domain of fan-cooled, rack-mounted amplifiers with dedicated AC service lines.
Or we can stick with our old friends, the 45, 2A3, 300B, EL84, EL34, and KT88/6550, a B+ voltage between 300 and 500 volts, and conventional output transformers. This results in power levels between 2 to 60 watts, or less if we want to stay in Class A operation. Loudspeaker efficiency now starts to matter.
The more efficient end of audiophile speakers are in the range of 92~95 dB/metre - the easy pickings, as it were. The speakers that are derivatives of large-format studio monitors fall in the 95~102 dB/metre range. Anything above that is traditionally considered horn territory.
During a recent conversation with John Atwood, we were discussing how casually loudspeaker designers treat a 1 dB difference in system efficiency. It's barely audible, after all, so why worry about it? But amplifier designers do. A 1 dB decrease in speaker efficiency means 26% more watts must come from the power amplifier. That means more quiescent current flowing through the output tubes, running closer to the dissipation limit, and pushing the B+ voltage a bit closer to the maximum the power supply capacitors will accept. It means using up safety margins built into the amplifier.
Those watts are also expensive. The Karna costs $3000 in parts alone, and puts out 20 Class A watts per channel. Putting out more would require a radical change in topology, or completely different output tubes. The best-value tube watts I know of are the Bob Latino VTA120 amplifiers, at 60 watts/channel and an assembled price of $1245 (including all tubes).
Tube amps are pretty much against the wall in terms of power. Transistor amps are not - more heatsinking, various switching schemes, getting the efficiency even higher, all will do the trick. But those tricks don't work for tube amps. So the only place left to look are the loudspeakers.
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Maybe it's because I haven't tried every amp in the world.... But IMHO, for bass, when individually optimized, tube has no advantage over sand. (mid-high is another story and I love tubes on that, too)
For bass, limited size and ultra high sensitivity just don't come together, period.
Typical 96~98dB/w pro style woofer with any amps under 100W in ordinary living space can deliver the acoustic power to rattle the house already (and good SQ, too, of course). The last extra several dB for catching up the mid-high will inevitably cost vastly in every respect.
For bass, limited size and ultra high sensitivity just don't come together, period.
Typical 96~98dB/w pro style woofer with any amps under 100W in ordinary living space can deliver the acoustic power to rattle the house already (and good SQ, too, of course). The last extra several dB for catching up the mid-high will inevitably cost vastly in every respect.