Re: Re: New Dipole Drivers on their way
I'll let Lynn speak about the system goals but just answer about the driver a little. The Qms is much higher due to the kapton former instead of the alum former used on the TDM. Efficiency of just under 93dB at 1W and 96.87dB at 2.83V. With a pair of these drivers per channel it will be very easy to get decent levels with low power.
Lengthening the coil is a little difficult as then the coil OD would increase to keep the same DCR. The gap would also has to get wider and then you're losing flux in the gap. We did cut down the 1.5" tall gap plate to 1.125" tall to increase the flux density in the gap. We didn't want to go much farther though as that sacrifices Xmax.
John
CLS said:
Thanks a lot for sharing. And the Qms of 31.28 is amazing! What a low loss suspension! But why does TD15M come with 5.09? Are they using different formers?
And, it seems the efficiency is not high(or, it gets another 3dB by 2.83V but still about 2dB shy.... )
Is this for the high Qes setting? Would it be nice to lengthen the voice coil a little bit (shorten the Xmax, enlarge the BL) to bring the Qts down to 0.7?
I'll let Lynn speak about the system goals but just answer about the driver a little. The Qms is much higher due to the kapton former instead of the alum former used on the TDM. Efficiency of just under 93dB at 1W and 96.87dB at 2.83V. With a pair of these drivers per channel it will be very easy to get decent levels with low power.
Lengthening the coil is a little difficult as then the coil OD would increase to keep the same DCR. The gap would also has to get wider and then you're losing flux in the gap. We did cut down the 1.5" tall gap plate to 1.125" tall to increase the flux density in the gap. We didn't want to go much farther though as that sacrifices Xmax.
John
Shugg, I wish you the best of luck with completing the Ariels. As we all know, the drivers aren't available any more, and it'll take a bit of research to find equivalents. The original concept was to select the flattest and best-damped drivers out there, and use relatively simple crossovers (low-Q 2nd-order). Many modern drivers are quite peaky, for some bizarre reason, and are completely unsuitable for an Ariel re-design. The most important thing is to find a midbass that has a very smooth and peak-free HF rolloff region - there are not many of these out there, but I think they can be found.
Similarly, the dome tweeter needs to be peak-free and have clean decay characteristics. That's the reason the Ariel has such rapid decay characteristics - the drivers had the best CSD's of the day, the cabinet has large-radius edges, and the internal chamber shapes are minimized for standing waves. Using typical modern peaky drivers pretty much assures it will have the raspy and edgy sound of the overpriced "boutique" speakers (Magico Mini, anyone?).
When I started college in 1968, my first major was Economics, then I switched a year later to Psychology. My big problem with economics back then was the models for human behavior were grossly oversimplified; for example, there was no model for the effect of advertising on demand, and I knew that businesses used a tight feedback loop to evaluate the long and short-term effects XYZ campaign, and had done so since the Twenties. Macroeconomics seemed reasonable enough for gross effects on the overall economy, but errors seemed to grow for finer-grained effects where irrational choices on the part of buyers and sellers loomed larger in the picture.
My father had a Master's from Harvard in Economics, and he was head of the Economic Section of the US Consulate in Kobe, Japan, and in Hong Kong. As part of his job, our family was friends with the movers and shakers in the Kansai part of Japan and in Hong Kong, so I picked up a lot of politics and economics by osmosis. He started wearing decent suits when he retired from the Foreign Service and worked for Marine Midland Bank (in Hong Kong) from 1969 through 1973. (Cheap suits are OK for gov't workers, but certainly not for a banker making business loans in the 10 to 100 million dollar range. Gotta dress the part.)
Hong Kong was an interesting place during the mid-Sixties. A paradise of Ayn Rand laisser-faire capitalism, with a flat income tax, no sales or VAT tax, zero import or export duty or complicated EXIM paperwork, and the gov't providing free education only to 6th grade. I remember walking by the clanking pile drivers and jackhammers of yet another Hong Kong government construction site in the middle of the Central business district and my dad joking that "even laisser-faire governments have to grow!"
Hong Kong seemed to have a lively free press, but there were no elections of any consequence, since it was a British Crown Colony ruled directly from London. But it was a refuge from the horrors of Mao's Great Leap Forward and the Cultural Revolution - more than a million refugees flowed into Hong Kong during the Sixties.
We had a bank run on the Hang Seng bank while I was there. You usually think of bank runs on grainy old films from 1929, 1930, and 1931, but we watched on Hong Kong's Rediffusion TV as lines snaked around the ultramodern 30-story Hang Seng skyscraper. My dad explained to me why the Chinese depositors looked so terrified - HK had no depositor insurance at the time (Ayn Rand laisser-faire capitalism, remember), and if the bank failed, their hard-won life savings would be wiped out. The bank went under, and the remnants were bought by a better-capitalized HK bank for pennies on the dollar.
Sound familiar? As I write this, I have a portion of my retirement income in UBS bank in Switzerland, and today's stock price for UBS is US$9.36 (down from a peak of $65.36 in April 27, 2007). You bet I watch the markets; growing up in the turmoil of the Fifties in Japan and the Sixties in HK and the USA, I've seen the collisions and instabilities of capitalism, socialism, and communism at very close range.
Dr. Geddes, thanks for the info about the Detroit car biz. I've been reading the "GM Death Watch" series on The Truth About Cars, and it seems the only way out of the deadweight of thousands of non-performing dealers, and way too many badge-engineered models, is a Chapter 11 restructuring for GM. The only alternative to that is an even worse Chapter 7 liquidation for pennies on the dollar. At current stock prices, you'd think this would be a golden opportunity for Honda, heck, even Hyundai or TATA, to buy the Chevy/GMC truck factory for cheap, cheap, cheap, and throw away the rest of the company.
Similarly, the dome tweeter needs to be peak-free and have clean decay characteristics. That's the reason the Ariel has such rapid decay characteristics - the drivers had the best CSD's of the day, the cabinet has large-radius edges, and the internal chamber shapes are minimized for standing waves. Using typical modern peaky drivers pretty much assures it will have the raspy and edgy sound of the overpriced "boutique" speakers (Magico Mini, anyone?).
When I started college in 1968, my first major was Economics, then I switched a year later to Psychology. My big problem with economics back then was the models for human behavior were grossly oversimplified; for example, there was no model for the effect of advertising on demand, and I knew that businesses used a tight feedback loop to evaluate the long and short-term effects XYZ campaign, and had done so since the Twenties. Macroeconomics seemed reasonable enough for gross effects on the overall economy, but errors seemed to grow for finer-grained effects where irrational choices on the part of buyers and sellers loomed larger in the picture.
My father had a Master's from Harvard in Economics, and he was head of the Economic Section of the US Consulate in Kobe, Japan, and in Hong Kong. As part of his job, our family was friends with the movers and shakers in the Kansai part of Japan and in Hong Kong, so I picked up a lot of politics and economics by osmosis. He started wearing decent suits when he retired from the Foreign Service and worked for Marine Midland Bank (in Hong Kong) from 1969 through 1973. (Cheap suits are OK for gov't workers, but certainly not for a banker making business loans in the 10 to 100 million dollar range. Gotta dress the part.)
Hong Kong was an interesting place during the mid-Sixties. A paradise of Ayn Rand laisser-faire capitalism, with a flat income tax, no sales or VAT tax, zero import or export duty or complicated EXIM paperwork, and the gov't providing free education only to 6th grade. I remember walking by the clanking pile drivers and jackhammers of yet another Hong Kong government construction site in the middle of the Central business district and my dad joking that "even laisser-faire governments have to grow!"
Hong Kong seemed to have a lively free press, but there were no elections of any consequence, since it was a British Crown Colony ruled directly from London. But it was a refuge from the horrors of Mao's Great Leap Forward and the Cultural Revolution - more than a million refugees flowed into Hong Kong during the Sixties.
We had a bank run on the Hang Seng bank while I was there. You usually think of bank runs on grainy old films from 1929, 1930, and 1931, but we watched on Hong Kong's Rediffusion TV as lines snaked around the ultramodern 30-story Hang Seng skyscraper. My dad explained to me why the Chinese depositors looked so terrified - HK had no depositor insurance at the time (Ayn Rand laisser-faire capitalism, remember), and if the bank failed, their hard-won life savings would be wiped out. The bank went under, and the remnants were bought by a better-capitalized HK bank for pennies on the dollar.
Sound familiar? As I write this, I have a portion of my retirement income in UBS bank in Switzerland, and today's stock price for UBS is US$9.36 (down from a peak of $65.36 in April 27, 2007). You bet I watch the markets; growing up in the turmoil of the Fifties in Japan and the Sixties in HK and the USA, I've seen the collisions and instabilities of capitalism, socialism, and communism at very close range.
Dr. Geddes, thanks for the info about the Detroit car biz. I've been reading the "GM Death Watch" series on The Truth About Cars, and it seems the only way out of the deadweight of thousands of non-performing dealers, and way too many badge-engineered models, is a Chapter 11 restructuring for GM. The only alternative to that is an even worse Chapter 7 liquidation for pennies on the dollar. At current stock prices, you'd think this would be a golden opportunity for Honda, heck, even Hyundai or TATA, to buy the Chevy/GMC truck factory for cheap, cheap, cheap, and throw away the rest of the company.
Nothing really new, but the same thing happens to many large corporations. I felt this same problem before I got married, and was recommended this reading by a minister of a church while I was in the DFW area.gedlee said:
http://www.amazon.com/Barbarians-Bureaucrats-Corporate-Cycle-Strategies/dp/0449905268
Lynn,
Most of us feel your pain. I basically lost a sizeable chunk of my 401(k) value in a very short period of time (my employer is one of those being bailed out, so employee stock went to peanuts fast). However, being a long ways from retiring I have the luxury of time. My folks and in-laws are in your camp.
Most of us feel your pain. I basically lost a sizeable chunk of my 401(k) value in a very short period of time (my employer is one of those being bailed out, so employee stock went to peanuts fast). However, being a long ways from retiring I have the luxury of time. My folks and in-laws are in your camp.
Well, I'm not really in pain. I'm just having to do a lot of fast steering with a complex, very diverse portfolio. For example, I put about 20% of it into gold (at $450/oz) when Bush nominated Condi Rice for Sec of State in December of 2004. Considering how badly she had mishandled the run-up to 9/11, a promotion to State (failing upward) boded disaster.
Disaster predictably arrived over the next four years, although I think all of us were stunned by the scale, scope, and sheer inventiveness of what happened. I sold about 2/3's of the gold at $730/oz a few weeks ago, and that is now parked in Treasuries and various bond instruments, where it awaits further developments in the markets.
The balance of the portfolio (in Vanguard) remains about 50% US bonds, 35% US equity index funds, and 15% international index funds. So the 50% decline in the S&P 500 over the last 2 years has given me a haircut of about 10~15% of the entire portfolio, while I await something that looks like a market bottom (these are typically very choppy and may have a W-shape with two bottoms). Once some direction is established in world markets (I expect massive infrastructure spending in wind, solar, and low-emission transportion systems over the next ten years), I'll move the Treasuries and some of the bonds back into the markets.
Bottom-fishing is an uncertain enterprise, since no-one really knows where market bottoms are. When you visit Dshort.com, and scroll down to "Meditation on the Dow", there's a chart of the market trend going all the way back to 1900 (shown below). All of the market bottoms had different characteristics, as you can see from the chart, and several other articles on the web-page.
Disaster predictably arrived over the next four years, although I think all of us were stunned by the scale, scope, and sheer inventiveness of what happened. I sold about 2/3's of the gold at $730/oz a few weeks ago, and that is now parked in Treasuries and various bond instruments, where it awaits further developments in the markets.
The balance of the portfolio (in Vanguard) remains about 50% US bonds, 35% US equity index funds, and 15% international index funds. So the 50% decline in the S&P 500 over the last 2 years has given me a haircut of about 10~15% of the entire portfolio, while I await something that looks like a market bottom (these are typically very choppy and may have a W-shape with two bottoms). Once some direction is established in world markets (I expect massive infrastructure spending in wind, solar, and low-emission transportion systems over the next ten years), I'll move the Treasuries and some of the bonds back into the markets.
Bottom-fishing is an uncertain enterprise, since no-one really knows where market bottoms are. When you visit Dshort.com, and scroll down to "Meditation on the Dow", there's a chart of the market trend going all the way back to 1900 (shown below). All of the market bottoms had different characteristics, as you can see from the chart, and several other articles on the web-page.
Attachments
gedlee said:
You got me, Earl – I always like the interchange of ideas.
Here we go :
From Power Compression towards Thermal Distortion / developing on a point of view
http://www.diyaudio.com/forums/showthread.php?postid=1664871#post1664871
Michael
Lynn,
Then you did a lot better than most. I do this stuff for a living so I don't usually like to think about it when I am not being paid to, but your analysis looks sensible to me.
Couple of minor points. The Dow Jones index is not worth looking at IMO. Its an index that the media likes to quote but no pros use it for a few good reasons. It is price weighed instead of the far more logical market cap weighted. Which means that whatever stock has the highest price makes the largest impact. Except that price of a stock is a bit arbitrary. Imagine if Berkshire Hathaway was in the index.
The S&P500 is the better index for large companies and before ~40's we usually use NYSE index. The same graph with the S&P 500 substituted for the DJ Index looks a bit different.
Second, a linear regression isn't really appropriate. Indexes are compounded just like returns are. Therefore, the right way to look at simple trends is to take the log of the index, run a linear regression and then exponeniate the results. You get an exponential trend (small exponent) with a bit of curve to fit the compounding effect. Or you can graph the index on a log scale and draw the linear regression in the log scale...same thing.
Then you did a lot better than most. I do this stuff for a living so I don't usually like to think about it when I am not being paid to, but your analysis looks sensible to me.
Couple of minor points. The Dow Jones index is not worth looking at IMO. Its an index that the media likes to quote but no pros use it for a few good reasons. It is price weighed instead of the far more logical market cap weighted. Which means that whatever stock has the highest price makes the largest impact. Except that price of a stock is a bit arbitrary. Imagine if Berkshire Hathaway was in the index.
The S&P500 is the better index for large companies and before ~40's we usually use NYSE index. The same graph with the S&P 500 substituted for the DJ Index looks a bit different.
Second, a linear regression isn't really appropriate. Indexes are compounded just like returns are. Therefore, the right way to look at simple trends is to take the log of the index, run a linear regression and then exponeniate the results. You get an exponential trend (small exponent) with a bit of curve to fit the compounding effect. Or you can graph the index on a log scale and draw the linear regression in the log scale...same thing.
JoshK said:
Isn't that what his graph did? The vertical scale was log and the line was straight meaning an exponential fit. Do you agree that the current market is still high of the long term trend by some 25% or not?
By the way, several months ago when Oil began to skyrocket, I sold 75% of my market holdings and moved them into money markets. I'm happy about that move at least. Living in MI however, its hard to be happy about much of anything.
Yep, it did plot it on a log scale. Don't know how I missed that. I thought I remember seeing a linear scale. 
Do I agree that prices are still 25% high? No not really. I think prices are starting to look pretty attractive, but the problem is that typically prices get absurdly cheap in these type of environments. Plus picking a bottom right now is tricky business as Lynn points out.
If you are a long-term buyer then take how much you want to invest, split it up fifths, tenths or whatever and buy in in equal intervals. This averages in the price. Then hold for >5 years and you ought to be fairly well positioned.
My gut feeling is we are still months away from the real bottom. Like Lynn said, there might be a powerful rally and then sell off to retest or set new lows, creating a W like shape. In general the street is calling for an economic bottom in Q4'09 to mid'10. Just based on loose history, that puts the market bottom in spring to winter of '09 depending on when the economy bottoms. Market isn't likely to be real productive in the near term.
Lots of big pension funds are writing off '08 and not rebalancing. That takes a lot of would-be buyers out of the market. If talk is cheap and they do rebalance that would give a lift to the market in December. I am not holding my breathe.
If I could give you any advice, I'd take a chunk of that money in your money markets and buy treasury bonds (10 year). T-bonds generally out perform cash in these environments for even sometimes after the recession is over. It has to do with a steep yield curve which we have now.
Do I agree that prices are still 25% high? No not really. I think prices are starting to look pretty attractive, but the problem is that typically prices get absurdly cheap in these type of environments. Plus picking a bottom right now is tricky business as Lynn points out.
If you are a long-term buyer then take how much you want to invest, split it up fifths, tenths or whatever and buy in in equal intervals. This averages in the price. Then hold for >5 years and you ought to be fairly well positioned.
My gut feeling is we are still months away from the real bottom. Like Lynn said, there might be a powerful rally and then sell off to retest or set new lows, creating a W like shape. In general the street is calling for an economic bottom in Q4'09 to mid'10. Just based on loose history, that puts the market bottom in spring to winter of '09 depending on when the economy bottoms. Market isn't likely to be real productive in the near term.
Lots of big pension funds are writing off '08 and not rebalancing. That takes a lot of would-be buyers out of the market. If talk is cheap and they do rebalance that would give a lift to the market in December. I am not holding my breathe.
If I could give you any advice, I'd take a chunk of that money in your money markets and buy treasury bonds (10 year). T-bonds generally out perform cash in these environments for even sometimes after the recession is over. It has to do with a steep yield curve which we have now.
Try years.
I have been expecting a bounce because dollar is overbrought, and when dollar comes down, everything else will go up. But after this bear market conter-trend rally, the decline will continue. My guess just by looking at the chart is that the market will go back to the level at 1995 if not lower.
The dollar may not survive as the reserved currency, and the last 30 years of sham economy will be revealed as nothing but fraud. Stay away from T-bonds. They are not that safe.
Thanks for the "street" info - good to hear from those in the biz. I don't understand "technical" analysis - I look at things from a macroeconomic perspective combined with a broad technological overview.
This means I see wind power as a (limited-scale) mature technology, akin to hydropower, while solar has several decades to mature, and "clean coal" (carbon sequestration) as a mirage due to the very limited number of places where the recovered, compressed, and liquified CO2 can be pumped into the ground, not to mention the local hazards of blow-outs and slow leaks. (A coal-fired power station uses up a mile-long coal train in less than a day, which tells you something about the volume of liquified CO2 it will generate.)
What makes this economic disruption harder to predict is the necessity for a worldwide conversion to non-fossil fuels. In the 1930's, the USA was the world's largest producer of oil and gas. It was the shutoff of oil to Japan that triggered the 1941 attack on Pearl Harbor; Japan, then as now, has essentially no sources of oil and gas to fuel its industries, and faces calamity if international sources are not available. Thanks to putting off the conversion as long as possible, the USA is starting to look more like prewar Japan - with the added disadvantage of three decades of de-industrialization. If Detroit goes under, then the de-industrialization will accelerate and ripple throughout the whole economy.
I found out from Bud Purvine there is now only ONE source of transformation laminations in the USA. The rest are in Europe and (mostly) in Asia. Transformer lams are heavy and not really worth shipping overseas. Thus, when that one source disappears, then all transformers (which are used in nearly all electrical and electronic equipment) will be made overseas. This pattern has repeated in key industrial sectors, like machine tools, which are essential in any industrialized economy.
John Atwood, Gary Pimm, and I noticed how many minor household items (like shower curtains) were made in Europe when we visited Zurich and Munich in 2004. In the USA, this kind of minor item is almost never made in the USA. De-industrialization has been the darling of the MBA's for the last thirty years, and the so-called "service" economy is supposed to be the new wonder of the age. I don't see how you can run an economy based on building more and more houses, creating Web pages, video games and action-cartoon movies, and selling each other stocks, bonds and a bewildering variety of mumbo-jumbo financial instruments. It looks like the classic economic joke of a town that supports itself by taking in each other's washing.
I see the difference between a first and third-world nation as mechanization, efficient water supply and sewage, electrification, and a sophisticated capital, transportation, and information infrastructure. Important parts of the US economy (such as the Interstate highway system) suffer from decades of neglect; a large part of industrial capacity has been lost; and the US, along with the rest of the world, faces the enormous conversion away from fossil fuels dictated by Peak Oil and climate change. All of this on top of a worldwide credit collapse thanks to a large proportion of the world's growth potential over the last ten years diverted into a $60 TRILLION derivatives market.
This certainly fits the Chinese definition of a "crisis" - the potential for both disaster and opportunity. Here's an interesting paper from Deutsche Bank that combines financial analysis, global energy flows, and a look at different near and long-term energy systems.
Taking a look at this pie chart, is it any wonder that an Administration composed of Texas oil-company executives decided to put most of America's military power into the Mideast? It brings to mind the story about John Dillinger, the most notorious bank robber of the Depression era: asked by a newsman why he robbed banks, he replied: "That's where the money is!"
This means I see wind power as a (limited-scale) mature technology, akin to hydropower, while solar has several decades to mature, and "clean coal" (carbon sequestration) as a mirage due to the very limited number of places where the recovered, compressed, and liquified CO2 can be pumped into the ground, not to mention the local hazards of blow-outs and slow leaks. (A coal-fired power station uses up a mile-long coal train in less than a day, which tells you something about the volume of liquified CO2 it will generate.)
What makes this economic disruption harder to predict is the necessity for a worldwide conversion to non-fossil fuels. In the 1930's, the USA was the world's largest producer of oil and gas. It was the shutoff of oil to Japan that triggered the 1941 attack on Pearl Harbor; Japan, then as now, has essentially no sources of oil and gas to fuel its industries, and faces calamity if international sources are not available. Thanks to putting off the conversion as long as possible, the USA is starting to look more like prewar Japan - with the added disadvantage of three decades of de-industrialization. If Detroit goes under, then the de-industrialization will accelerate and ripple throughout the whole economy.
I found out from Bud Purvine there is now only ONE source of transformation laminations in the USA. The rest are in Europe and (mostly) in Asia. Transformer lams are heavy and not really worth shipping overseas. Thus, when that one source disappears, then all transformers (which are used in nearly all electrical and electronic equipment) will be made overseas. This pattern has repeated in key industrial sectors, like machine tools, which are essential in any industrialized economy.
John Atwood, Gary Pimm, and I noticed how many minor household items (like shower curtains) were made in Europe when we visited Zurich and Munich in 2004. In the USA, this kind of minor item is almost never made in the USA. De-industrialization has been the darling of the MBA's for the last thirty years, and the so-called "service" economy is supposed to be the new wonder of the age. I don't see how you can run an economy based on building more and more houses, creating Web pages, video games and action-cartoon movies, and selling each other stocks, bonds and a bewildering variety of mumbo-jumbo financial instruments. It looks like the classic economic joke of a town that supports itself by taking in each other's washing.
I see the difference between a first and third-world nation as mechanization, efficient water supply and sewage, electrification, and a sophisticated capital, transportation, and information infrastructure. Important parts of the US economy (such as the Interstate highway system) suffer from decades of neglect; a large part of industrial capacity has been lost; and the US, along with the rest of the world, faces the enormous conversion away from fossil fuels dictated by Peak Oil and climate change. All of this on top of a worldwide credit collapse thanks to a large proportion of the world's growth potential over the last ten years diverted into a $60 TRILLION derivatives market.
This certainly fits the Chinese definition of a "crisis" - the potential for both disaster and opportunity. Here's an interesting paper from Deutsche Bank that combines financial analysis, global energy flows, and a look at different near and long-term energy systems.
Taking a look at this pie chart, is it any wonder that an Administration composed of Texas oil-company executives decided to put most of America's military power into the Mideast? It brings to mind the story about John Dillinger, the most notorious bank robber of the Depression era: asked by a newsman why he robbed banks, he replied: "That's where the money is!"
Attachments
Here's another fun graph from the Deutsche Bank paper. A little bit of digging turned up this interesting ETF: a Global Wind Energy Portfolio. The still-too-high P/E ratio and the calamitous return over the last year indicate plenty of risk - but still, if the index is a rational collection of heavy-industry wind-energy suppliers around the world, might be interesting over the next ten years.
When you look at the companies that comprise the solar-energy industry, it's a flakier group of high-tech spinoffs from the volatile, capital-intensive silicon-wafer industry, while the folks that build those gigantic 130-foot turbine blades are heavy industries like ABB and Mitsubishi. Considering the numerous obstacles facing new construction of coal-fired plants in the developed world, wind takes some of the pressure off the coal-fired baseload system, which is at or near capacity in much of the world.
(Clean-burning natural gas is good for peaking requirements, but very expensive for baseload, and hydro long ago reached full capacity in the developed world. Solar-thermal makes a good complement to wind-energy, although a good baseload system is still required when it's dark and there's no wind. Nuclear is the only real alternative to fossil fuels for baseload generation.)
When you look at the companies that comprise the solar-energy industry, it's a flakier group of high-tech spinoffs from the volatile, capital-intensive silicon-wafer industry, while the folks that build those gigantic 130-foot turbine blades are heavy industries like ABB and Mitsubishi. Considering the numerous obstacles facing new construction of coal-fired plants in the developed world, wind takes some of the pressure off the coal-fired baseload system, which is at or near capacity in much of the world.
(Clean-burning natural gas is good for peaking requirements, but very expensive for baseload, and hydro long ago reached full capacity in the developed world. Solar-thermal makes a good complement to wind-energy, although a good baseload system is still required when it's dark and there's no wind. Nuclear is the only real alternative to fossil fuels for baseload generation.)
Attachments
Here's the foreign-policy aspect of the above:
http://www.pbs.org/moyers/journal/08152008/watch.html
http://www.pbs.org/moyers/journal/08152008/watch.html
The ??? End ??? of American Exceptionalism
- I mean, people run for the presidency in order to become imperial presidents.
- the fabric of democracy, I think, really has worn very thin
- ultimately, we the American people, refuse to look in that mirror
- Well war - wars are competitions. The adversary develops capabilities
- What we should learn from history is that preventive war doesn't work.
- We should return to the just war tradition...Which sees war as something that is justifiable for defensive purposes.
Spot on in many regards – not so for the titel
Thanks for the link, sby
And - everybody easily can transpose (too) many points to us – the rest of the world...
Michael
- I mean, people run for the presidency in order to become imperial presidents.
- the fabric of democracy, I think, really has worn very thin
- ultimately, we the American people, refuse to look in that mirror
- Well war - wars are competitions. The adversary develops capabilities
- What we should learn from history is that preventive war doesn't work.
- We should return to the just war tradition...Which sees war as something that is justifiable for defensive purposes.
Spot on in many regards – not so for the titel
Thanks for the link, sby
And - everybody easily can transpose (too) many points to us – the rest of the world...
Michael
Ahem - to return to loudspeakers, the Dipole15 (LO Version) drivers arrived yesterday via UPS from Wisconsin. Heavy things, about 28 lbs each. Pictures to follow after Turkey day. (Thanksgiving, the notorious American holiday where we visit our relatives and eat ourselves silly. American football viewing optional - I don't follow the game myself. We are having an unusual long-lasting Indian Summer here in Colorado, sunny blue skies for days on end, clear blue skies and that bright, bright high-altitude sun as I look out the window right now)
To recap how I'm thinking about things, the minimalist version of the project is nothing more than an updated Lansing Iconic, a simple two-way system with the GPA/Altec 288 Alnico-magnet compression driver, the AH-425 Azurahorn, and one of three potential 12/15" drivers: the GPA/Altec Alnico 414, 18Sound 12NDA520, or AESpeakers TD15M. Bass cabinet a mini-Onken or anything with HF Olson style 45-degree slant sides.
I'll start with the most difficult crossover, the 800~900 Hz crossover between the horn and the 12" drivers I have on hand (GPA/Altec Alnico 414 and 18Sound 12NDA520). Once that is refined (with the 12" midbass driver in open baffle) and is sonically acceptable, I'll go on to the rest of the system, which is the pairs of Dipole15-LO's for the separately powered bass OB module, and the RAAL 140-15D supertweeters with amorphous-core transformers.
To recap how I'm thinking about things, the minimalist version of the project is nothing more than an updated Lansing Iconic, a simple two-way system with the GPA/Altec 288 Alnico-magnet compression driver, the AH-425 Azurahorn, and one of three potential 12/15" drivers: the GPA/Altec Alnico 414, 18Sound 12NDA520, or AESpeakers TD15M. Bass cabinet a mini-Onken or anything with HF Olson style 45-degree slant sides.
I'll start with the most difficult crossover, the 800~900 Hz crossover between the horn and the 12" drivers I have on hand (GPA/Altec Alnico 414 and 18Sound 12NDA520). Once that is refined (with the 12" midbass driver in open baffle) and is sonically acceptable, I'll go on to the rest of the system, which is the pairs of Dipole15-LO's for the separately powered bass OB module, and the RAAL 140-15D supertweeters with amorphous-core transformers.
Thanks for the info on the 'minimalist' system Lynn. Anything clues you can throw out to us about a three-way ( with one 12" or 15" bass driver ) will be very helpful .
I think I'll be following your lead on the RAAL 140-15D and GPA 288's fairly soon ( just as soon as I can sell the old 325iS ! ).
Now on the amorph-cored RAAL, I was under the impression that was some sort of special high-impedance version for direct drive by an SE amp, but is there an 8-ohm amorphous version ?
I can easily e-mail Alexander of course .
ILPS
I think I'll be following your lead on the RAAL 140-15D and GPA 288's fairly soon ( just as soon as I can sell the old 325iS ! ).
Now on the amorph-cored RAAL, I was under the impression that was some sort of special high-impedance version for direct drive by an SE amp, but is there an 8-ohm amorphous version ?
I can easily e-mail Alexander of course .
ILPS
Yes, there is an amorphous-core version of the 8-ohm RAAL. Production is temporarily down to a supplier issue, but will be back up again in a matter of a few weeks, if not already. I would urge anyone thinking of getting a pair of AH-425 Azurahorns to move quickly, Martin may be having supplier issues in the near future as well. This stupid economic mess is hitting suppliers all over the world (banks are being difficult about credit to businesses). Do our specialist friends a favor and buy now - I don't think handmade products like the RAAL, Azurahorn, or GPA are going to be any cheaper in the future. (Think of high-end audio priced in ounces of gold and you'll have a truer picture of prices over time.)
Alexander wanted me to try his special direct-to-power-tube Hi-Z version of the RAAL tweeter, but my interest in building yet another amplifier is zero. I am very happy with the Karna amplifier, and it has plenty of bandwidth and power for what I want to do. In subjective terms, the Karna sounds like a 60-watt Citation II, or a 100-watt transistor amplifier - a huge amount for a 97~98 dB/metre system. For the talented folks who can knock out a 3-watt SET amplifier on a weekend, I am hearing very happy reports about the high-Z variant of the RAAL tweeter. In terms of the sweetest sound, yes, a dedicated supertweeter amplifier is almost certainly the nicest way to go - and it does protect your ribbon from the worst effects of clipping the "main" amplifier.
John Atwood reports excellent results listening to the Altec 288 with the Tangerine phase plug and Tractrix horn all the way out to 15 kHz. My own experience with the 288 is that it doesn't sound particularly bandwidth-limited, in comparison to a Lowther, AER, or Feastrex, where it's pretty obvious that there's not much beyond 12~15 kHz.
The Oswald's Mill Audio (OMA) system at the RMAF had outstanding integration between the RAAL and the big conical horn, and Alexander described the crossover as very simple, not much more than first-order with a moderate amount of overlap in the 2~7 kHz region. I didn't hear any sonic disjunction between the ribbon tweeter and the big horn at all - and I was listening very carefully for it. Dynamics tracked perfectly - and this is an area where most audiophile speakers really fall down badly, particularly with Chinese ribbons and Vifa/Scanspeak/Seas midbass drivers.
Alexander wanted me to try his special direct-to-power-tube Hi-Z version of the RAAL tweeter, but my interest in building yet another amplifier is zero. I am very happy with the Karna amplifier, and it has plenty of bandwidth and power for what I want to do. In subjective terms, the Karna sounds like a 60-watt Citation II, or a 100-watt transistor amplifier - a huge amount for a 97~98 dB/metre system. For the talented folks who can knock out a 3-watt SET amplifier on a weekend, I am hearing very happy reports about the high-Z variant of the RAAL tweeter. In terms of the sweetest sound, yes, a dedicated supertweeter amplifier is almost certainly the nicest way to go - and it does protect your ribbon from the worst effects of clipping the "main" amplifier.
John Atwood reports excellent results listening to the Altec 288 with the Tangerine phase plug and Tractrix horn all the way out to 15 kHz. My own experience with the 288 is that it doesn't sound particularly bandwidth-limited, in comparison to a Lowther, AER, or Feastrex, where it's pretty obvious that there's not much beyond 12~15 kHz.
The Oswald's Mill Audio (OMA) system at the RMAF had outstanding integration between the RAAL and the big conical horn, and Alexander described the crossover as very simple, not much more than first-order with a moderate amount of overlap in the 2~7 kHz region. I didn't hear any sonic disjunction between the ribbon tweeter and the big horn at all - and I was listening very carefully for it. Dynamics tracked perfectly - and this is an area where most audiophile speakers really fall down badly, particularly with Chinese ribbons and Vifa/Scanspeak/Seas midbass drivers.
Hi Lynn,
I think we're calling those drivers the LO15 here to keep them straight from the other dipoles. Make sure you give them a listen fullrange without xover. Not that you'd use them that way in the system, but you'll probably be pretty surprised at the high end that can come out of them on axis.
John
I think we're calling those drivers the LO15 here to keep them straight from the other dipoles. Make sure you give them a listen fullrange without xover. Not that you'd use them that way in the system, but you'll probably be pretty surprised at the high end that can come out of them on axis.
John