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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 30th March 2013, 08:58 PM   #37591
simon7000 is offline simon7000  United States
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Originally Posted by gpapag View Post
That’s why I wrote MEMS construction. Orders of magnitude shorter time constants possible.

George

S/N !!

The technical issue with sound intensity is the price of the sets of phase matched microphone capsules. The DSP costs are now trivial compared to that. Electret mics just aren't stable enough!

Last edited by simon7000; 30th March 2013 at 09:01 PM.
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Old 30th March 2013, 09:20 PM   #37592
bcarso is offline bcarso  United States
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S/N !!
Electret mics just aren't stable enough!
Particularly temperature-sensitive too, unless carefully compensated.

I may have related the story of a disastrous dog-and-pony show by the Harman Applied Technology group for the executive due to take charge of the group. Electret mics were part of a noise-cancellation demonstration in a car. Everything had worked fine during setup and calibration, but the car sat in the sun for a while afterwards.

Said executive was in conversation with one of the group later, and referred to the division as "The Toy Factory". That employee decided at that moment to reconsider an offer from the automotive group to transfer. HAT was shut down not long thereafter.
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Old 30th March 2013, 09:27 PM   #37593
jan.didden is offline jan.didden  Europe
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The code date says early 1989.

Jan,

Who is it that keeps saying 741s aren't used anymore? You seem to be getting use out of one, for an image at least.
There's equipment around that uses them and that equipment works as well (or not) as it did 30 years ago, so what's the problem?

jan
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Old 30th March 2013, 10:09 PM   #37594
simon7000 is offline simon7000  United States
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Jan,

For some they are fine. Some still don't use indoor plumbing. But most technical gizmos have improved. The exception to prove the rule is around here digital TV we have higher resolution with lack of audio sync and off air transmission problems that analog TV fixed in the 50's.
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Old 30th March 2013, 10:13 PM   #37595
gpapag is online now gpapag  Greece
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John Curl's Blowtorch preamplifier part II
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S/N !!
You mean that hot wire anemometers, no matter of what size, will have an inherent low S/N ratio due to principle of operation?

George
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Old 30th March 2013, 10:15 PM   #37596
jan.didden is offline jan.didden  Europe
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Jan,

For some they are fine. Some still don't use indoor plumbing. But most technical gizmos have improved. The exception to prove the rule is around here digital TV we have higher resolution with lack of audio sync and off air transmission problems that analog TV fixed in the 50's.
... or a super-duper car that just decides to stop because of a software bug that went undetected
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Last edited by jan.didden; 30th March 2013 at 10:19 PM.
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Old 30th March 2013, 11:30 PM   #37597
simon7000 is offline simon7000  United States
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You mean that hot wire anemometers, no matter of what size, will have an inherent low S/N ratio due to principle of operation?

George
Yes
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Old 30th March 2013, 11:30 PM   #37598
john curl is offline john curl  United States
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Well, another set of CTC Blowtorch boards have been constructed, and I have a new amp. My associate, Carl T, the board designer for both the new amp and the Blowtorch boards has told me his history of circuit board layout, and it is rather impressive. I will leave it at that, so I won't seem to be 'name dropping' or some such. '-)
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Last edited by john curl; 30th March 2013 at 11:34 PM.
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Old 30th March 2013, 11:41 PM   #37599
simon7000 is offline simon7000  United States
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QUOTE=jan.didden;3434588]... or a super-duper car that just decides to stop because of a software bug that went undetected[/QUOTE]

Parts of the US west are known as big sky country because the land is flat there are few trees or other obstructions. So when you are standing and looking around you are the tallest thing and most of what you see is the sky

Unfortunately my car has a Micosoft logo on the dash for the Bluetooth hands free cellphone. So when I drive in big sky country as soon as my car gets on any rise and all you can see through the windshield is clear blue sky, it stops running. When you try to restart it unlike normal cold starts it takes two to three minutes.

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Old 31st March 2013, 12:16 AM   #37600
gpapag is online now gpapag  Greece
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John Curl's Blowtorch preamplifier part II
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Yes
Damn! So this could only be compensated for with "hot" sounds (end of dream)

George
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