John Curl's Blowtorch preamplifier part II - Page 2276 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 28th April 2012, 09:39 AM   #22751
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by scott wurcer View Post
Never saw that one but it looks promising. In general some of the Primo capsules are a perfect compromise between size and performance. I wish Jan and SY had picked a cut with harmonica, I have never heard such a nice separation of the reeds.
I'll see Southpaw tonight; if I can get permission to post "The Last Remaining Beatle," that had a nice harmonica bit.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 28th April 2012, 10:38 AM   #22752
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by SY View Post
I'll see Southpaw tonight; if I can get permission to post "The Last Remaining Beatle," that had a nice harmonica bit.
If you look at the spectra, it's interesting how much it looks like a multi-tone test signal at a fairly high frequency. The guys from Lexicon told me the reed sound on sax was excellent for judging A/D 's or DAC's.

BTW this is a nice recorder comparison, the Tascam that Wavebourn mentioned is OK but I am reluctant to part with the Fostex. A comparable Tascam model is $$$. http://www.avisoft.com/recordertests.htm
__________________
Silence is so accurate.

Last edited by scott wurcer; 28th April 2012 at 10:45 AM.
  Reply With Quote
Old 28th April 2012, 11:01 AM   #22753
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
The comparison I'd like to see (and haven't found yet) is the S/N of the line inputs. I use an external mike preamp with the TASCAM just because the internal ones aren't super quiet.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 28th April 2012, 11:05 AM   #22754
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by SY View Post
I use an external mike preamp with the TASCAM just because the internal ones aren't super quiet.
That's why I did the +20dB mics.

__________________
Silence is so accurate.
  Reply With Quote
Old 28th April 2012, 11:07 AM   #22755
gpapag is online now gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Quote:
Originally Posted by john curl View Post
George, thanks for the input. Looks interesting.
Mr. Curl

To be fair, that posting of the link was a bit of a provocative move.
The equations are “heavy stuff” (not for my shoulders).

As I see it, addressing the issue of Heavyside’s “modifications” of original Maxwell equations, may be justifiable, may be not:

Heavyside - seems to me - did what an outstanding Engineer would ever be hoped to be able to achieve. He made things easier for the theory to be applied in practice.

What I think is of importance is, that Heavyside can not be accused of burning Maxwell’s papers. He did not cut them in pieces and swallowed them, furnishing his own work as the only existing treatise on the subject.
He just produced his own work.

True,every simplification leaves out something.
If there is something important left out in his work, which “something” was part of Maxwell reasoning, it is here – now and then - to be exploited.

All the original Maxwell work is online now (and it was always on the bookselves of the libraries).
The usefulness of reading these, comes from the point of understanding that, these equations were derived out of a fluid analogy. Out of first principles and with a marvelous reasoning.

Do I understand all these equations? No.
Can I handle them? No (I feel OK that I can work with the “telegrapher’s equation”)

But that’s irrelevant and totally unimportant. Me not understanding something does not equate in my mind as this ”something” being paradoxical or false.
If there is anything that can be explained to me, I am all ears and eyes.

George
__________________
["Second Law is a bitch." - SY] ["The Road To Heaven:Specify the performance & accept the design. The Road To Hell:Specify the design & accept the performance"-Bruno Putzeys]

Last edited by gpapag; 28th April 2012 at 11:09 AM.
  Reply With Quote
Old 28th April 2012, 01:26 PM   #22756
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Thanks a second time, George. This is essentially what I was looking for. I, too, am a bit rusty, but it is a challenge to see how 20 equations fit into 4, and what was 'compromised' in the process. I have heard about this for years.
I have 'The Scientific Papers of James Clerk Maxwell' (3'' thick) next to me, as well as 'Electromagnetic Theory' Vol.1 and 2 by Heaviside on my bookshelf. They have been there for years, in order to attempt to delve deeper into this stuff.
About 25 years ago, I had an earlier book, published by the IEEE on Heaviside that I found fascinating, especially his quest for better telegraph transmission and his debates with Lord Kelvin (kind of reminds me of around here), and the difficulties he had being believed, when he came up with an answer (nobody seemed to believe him for years, as I remember). Of course, NOW he 'walks on water', yet does he have 'feet of clay'? Did he, in fact, modify the original intent of Maxwell's work, losing something subtle, but important? I hope to learn more than just be 'assured' that all is well, etc. etc..
  Reply With Quote
Old 28th April 2012, 02:21 PM   #22757
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by scott wurcer View Post
Never saw that one but it looks promising. In general some of the Primo capsules are a perfect compromise between size and performance. I wish Jan and SY had picked a cut with harmonica, I have never heard such a nice separation of the reeds.
The folks who made Astatic and CAD microphones seem to have cleaned out their warehouse and sold it to this surplus house.

The prices on many of the small capsules are higher than new, but some seem to be a good deal.

The particular capsule was used in their high end microphone. I seem to recall it used a pair to be variable pattern.

The downside to their version was that it required so much current in use that it had built in rechargeable 9V batteries. So if you didn't leave the phantom power always on they could discharge. Although the mic would still fire up on phantom only it wasn't quite the same.

I did use some for stadium announcer's microphones and they worked well for the professional announcers who could actually remember to talk into the microphone!
  Reply With Quote
Old 28th April 2012, 02:28 PM   #22758
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
George,

When you get a paper like the one you posted, it is a summary of lifetimes of work. Keep in mind it took more than hours and more likely weeks or months to write. That is from someone who is an expert in the field.

So it is reasonable to expect to spend a month really reading and examining the material.

Although with a good engineering math background you might be able to do it faster, I suspect doing so will miss a lot of the subtle stuff.

ES
  Reply With Quote
Old 28th April 2012, 04:00 PM   #22759
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by simon7000 View Post
expect to spend a month really reading and examining the material.
Mr Simon,

that is somewhat amusing.

It took me less than a hour to read this paper : http://staff.polito.it/domenic.dambr...-2009-3910.pdf
(Jacobian included for Joshua His Brother Mo was also quite a character)

Takes 7,5-8 years average to get an MSc here ( Engineer's degree - Wikipedia, the free encyclopedia ), 12 math exams in the first two years.
Aero, mechanical, and naval folks also have classes on stuff like fluid mechanics, with Navier-Stokes equations, Reynolds numbers, the works.

Frankly, how someone without "a good engineering math background" does that paper in a month, with the "subtle stuff" , is beyond my feeble skull.
Indeed, and also on the geometry !
__________________
The buck stops Here
  Reply With Quote
Old 28th April 2012, 04:06 PM   #22760
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by jacco vermeulen View Post
Mr Simon,

that is somewhat amusing.

It took me less than a hour to read this paper : http://staff.polito.it/domenic.dambr...-2009-3910.pdf
(Jacobian included for Joshua His Brother Mo was also quite a character)

Takes 7,5-8 years average to get an MSc here ( Engineer's degree - Wikipedia, the free encyclopedia ), 12 math exams in the first two years.
Aero, mechanical, and naval folks also have classes on stuff like fluid mechanics, with Navier-Stokes equations, Reynolds numbers, the works.

Frankly, how someone without "a good engineering math background" does that paper in a month, with the "subtle stuff" , is beyond my feeble skull.
Indeed, and also on the geometry !
I did note two errors in the paper you cited. I meant http://www.rexresearch.com/maxwell1/20equations.pdf !


I have a bit of bother with the notations I have never used before and all the implications.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 10:45 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2