Something stirs in the Undergrowth

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Lynn Olson
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#856

Post by Lynn Olson »

As a small contribution to improve the S/N ratio, all non-audio posts have been moved or deleted. Have fun with your new speaker, IslandPink!
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IslandPink
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#857

Post by IslandPink »

Oh, thanks Lynn.
I should be able to post something more meaningful in the next week or two . I have some basic test gear ( microphone/pre-amp ) loaned from Nick, so will get up some basic results of the TT on OB , unfiltered and with my existing crossover elements.
Maybe we will get some input from JamesD once he's out of his hospital bed in Dubai and back in circulation :( :roll:
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )
Lynn Olson
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#858

Post by Lynn Olson »

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IslandPink
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#859

Post by IslandPink »

Yes, it was pretty bad in North Wales this evening . At about 4-30pm the scene outside looked like typical TV hurricane coverage . I'd come back from the dentists with antibiotics for a painful tooth abcess, and it was not a good combination. It will take a couple of days to assess the damage.
I had to move a switch-mode power supply and a Fane driver in a box from the 2nd-floor landing and replace them with a bowl to catch the water coming through the ceiling.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )
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andrew Ivimey
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#860

Post by andrew Ivimey »

In the grand scheme (or lack thereof) of things what's happening to parts of the UK isn't much really. We've had much worse floods and many more have died. Other parts of the world, so far, show us how bad things can get. The US has appalling weather and other parts of the world have incredible and terrible disasters.

Now is it climate change and is it man made? I think so. It does seem to be getting worse all over.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
Lynn Olson
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#861

Post by Lynn Olson »

Colorado had its 500-year floods some time around last September. The little creek that's normally 5 feet wide and home to coyotes and cottonwood trees grew to a roaring river that was 200 feet across. The Town of Erie wisely created a generous floodplain set-aside, so our house is about 60 feet above and 500 feet away from the creek which became a river. Thanks to the set-aside, the 500-year flood was not a danger. (The "500-year" mark is somewhat arbitrary, since the first European settlers arrived in the 1850's, and there are no written records before that.)

Folks in the adjacent town of Longmont weren't so lucky and had some houses and streets swept away ... no loss of life, fortunately. By sheer good luck, no serious accidents happened on the hundreds of gas-well fracking operations that are all over this part of Colorado. This place is the Wild West in more ways than one.

It's true that severe weather is the Colorado norm; 100~120 mph microbursts happen several times a year, and tornadoes happen every few years. Most houses here have large, dry basements which can used as emergency tornado shelters, and the airports and public buildings all have reinforced-concrete tornado-shelter rooms.

I've been through typhoons when I lived in Hong Kong, and 100 mph winds-and-rain are no joke, especially if you have to do any traveling. I hope the folks that are exposed to coastal winds have a good place to shelter until things settle down a bit.

If this is what weather is like now, I'm a bit concerned what it will be like in twenty to fifty years if global CO2 levels continue to increase. Coastal towns may have real problems with hurricane-force winds and tidal surges.

Colorado will batten down the hatches against the winds, but the real long-term threat to the Front Range cities are long-term drought conditions. That's what drove out the Anasazi Indians a thousand years ago, and it could happen to us. The American West is littered with ghost towns; that could be the future of desert cities like Phoenix and Las Vegas.
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#862

Post by IslandPink »

Yes, I've seen a lot of changes in the last 10 years. That flood in Lyons canyon ( was it that one ? ) a year or two back was worse than the one in the 80's, from correspondance with my friend in Denver/Estes Park . Here in the UK the cloud levels and rainfall seem to have significantly increased since the 80's - I have a pretty good memory of how many good and bad days we got in a typical year, being a photogrpaher and cyclist, and the trend is depressing.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )
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#863

Post by IslandPink »

OK - here's a technical loose-end I wanted to check, mentioned a few pages back .
Today while evaluating the 7297 chip amp, I played it on the GPA288 compression driver for a while.
Since this was unfiltered - full range - I decided to check the diaphragm movement , with the back carefully unscrewed and opened , so I could see the aluminium diaphragm close-up. I kept one screw in, near the connections.

With the volume turned-up to a level above what I would ever need on real music with the full speaker system playing, I had a careful look . Given that I'm very short-sighted, I could focus from about 4 inches distance, with a strong light .
I could not see ANY movement of the diaphragm . If I put my finger on there, I could feel it moving, but I reckon the movement must be less than 0.1mm, as it was not even slightly blurred.

So, that sets my mind at rest regarding any potential damage , or any problems specifically with excessive excursion with 1st-order high-pass, for my application.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )
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slowmotion
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#864

Post by slowmotion »

You're pretty safe as long as you keep it at reasonable levels in a home setting. I would be more careful with beryllium diaphragms just because they are so damn expensive.
With regard to how it sounds I really think it's a question of what you like.
I used to like steep filters but have gone from generally using steep filters to using 6dB filters or even no filter at all.
- Jan -
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Ali Tait
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#865

Post by Ali Tait »

IslandPink wrote:Yes, I've seen a lot of changes in the last 10 years. That flood in Lyons canyon ( was it that one ? ) a year or two back was worse than the one in the 80's, from correspondance with my friend in Denver/Estes Park . Here in the UK the cloud levels and rainfall seem to have significantly increased since the 80's - I have a pretty good memory of how many good and bad days we got in a typical year, being a photogrpaher and cyclist, and the trend is depressing.
Interestingly, while spells of very wet weather have increased in frequency, rainfall in the summer is actually less than it used to be-

http://www.cru.uea.ac.uk/documents/4219 ... 3f6785a40e
Lynn Olson
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#866

Post by Lynn Olson »

IslandPink wrote:OK - here's a technical loose-end I wanted to check, mentioned a few pages back.

Today while evaluating the 7297 chip amp, I played it on the GPA288 compression driver for a while. Since this was unfiltered - full range - I decided to check the diaphragm movement, with the back carefully unscrewed and opened, so I could see the aluminum diaphragm close-up. I kept one screw in, near the connections.

With the volume turned-up to a level above what I would ever need on real music with the full speaker system playing, I had a careful look. Given that I'm very short-sighted, I could focus from about 4 inches distance with a strong light.

I could not see ANY movement of the diaphragm. If I put my finger on there, I could feel it moving, but I reckon the movement must be less than 0.1mm, as it was not even slightly blurred.

So, that sets my mind at rest regarding any potential damage, or any problems specifically with excessive excursion with 1st-order high-pass, for my application.
That's reassuring. Your real-world experiment is very much appreciated. The 1st-order HPF is looking better.

I'll bet the output of the chip amp was in the microwatt range most of the time, with brief excursions into the tens of milliwatts. There's something to be said for large diaphragms and ultra-high efficiency.
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g3dahl
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#867

Post by g3dahl »

Had a delightful time Saturday afternoon when audio-talk members Harry Zweben, Gary Pimm and three others from the Portland area stopped by for a visit and listening session. I guess this was the "debut" for my Beyond the Ariel speakers…first time they have been heard by serious listeners (other than me) since the installation of the new drivers.

Gary Pimm heard them a few months ago, when they still used TD15M's, ceramic/aluminum 745's and Aurum Cantus G-3 tweeters. The new version uses GPA 416's (alnico), 745NeoBe's and Raal Lazy Ribbons. The separately-amplified TD15H bass boxes remain unchanged. Gary P's assessment of the differences between the old and new version matched my own pretty closely.

We listened with and without the Raal ribbons, which some listeners deemed unnecessary. I prefer to use them, but really like having the option of turning them off for some recordings.

Gary Pimm brought his own amp to the party…it sounded tremendous.

Gary Dahl
So many tubes, so little time...
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#868

Post by simon »

It's a forum tradition to post photos Gary.

(Yes, we'd all love to see some :-D )
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g3dahl
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#869

Post by g3dahl »

Some of the guys took pictures; I didn't, sorry! Harry, did you get any pictures?
So many tubes, so little time...
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IslandPink
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#870

Post by IslandPink »

Sounds great - pics or not.
Which amp did Gary bring ?
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )
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