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 8th November 2011, 06:54 PM   #17751
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
biological variations don't necessarily (or even often) result in smooth, symmetric, "infinite tail" distributions

assuming Gaussian distribution may be the "default" for some "canned" statistics packages but that doesn't make it predictive of real world data distributions

My objection is the that some want to "assume their conclusions" as a method of argument, "proof"

to me the data in peer reviewed papers is not yet conclusive, 44.1 kHz is not "obviously" inadequate for Music reproduction
many accepted measurements, detailed models for human auditory perception, even typical recording, playback equipement limits make it plausible that content above 20 kHz isn't of 1st order importance


small "time difference" resolution numbers, IATD, keep getting misinterpreted as implying channel bandwidth of ~ 1/dt - this has been pointed out as logically wrong many times now
see Kunchur's slide: (my Paint underlines, arrows)
Attached Images
File Type: png Kunchur.png (77.6 KB, 223 views)

Last edited by jcx; 8th November 2011 at 06:57 PM.
  Reply With Quote
Old 8th November 2011, 08:14 PM   #17752
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by scott wurcer View Post
Yes, RF carriers are meant to be demodulated. Scaling these effects directly to audio is a stretch, but you are welcome to.
Did you get to the part about micro diodes?

I have a problem with calling all non-ohmic response evidence of diode action. The coherers mentioned before seems to rely on slightly polar to polar molecular alignment changing conductivity. I see that as different than a semiconductor junction, where there is no molecular movement required.
  Reply With Quote
Old 8th November 2011, 08:35 PM   #17753
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by simon7000 View Post
Did you get to the part about micro diodes?

I have a problem with calling all non-ohmic response evidence of diode action. The coherers mentioned before seems to rely on slightly polar to polar molecular alignment changing conductivity. I see that as different than a semiconductor junction, where there is no molecular movement required.
Missed that, the rate of change of the fields here are rather high and think about RF burns. Hard to do that with a preamp output.
__________________
“The earth's rotation will slow within days and stop for several days just prior to the pole shift. This is when you and your loved ones should be situated at your safe location.”
  Reply With Quote
Old 8th November 2011, 08:57 PM   #17754
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by scott wurcer View Post
Missed that, the rate of change of the fields here are rather high and think about RF burns. Hard to do that with a preamp output.
Actually cell site transmitters as things go are quite small so they don't go over range. The receive levels can be just above the noise level. A receive level can be 1exp-9 watts and a transmit level 25 watts or 104 db dynamic range. A 17 bit converter would work!

So there might actually be some applicability!
  Reply With Quote
Old 9th November 2011, 02:02 AM   #17755
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
I would again like to comment about the 'essence' of quality audio. We appear to be making progress in digital 'compromises' thanks to T and PMA, which might be the making of a technical paper in future by somebody. It is important to be able to tell the difference between specs. and performance. Sometimes, specs. can be misleading.
Let me give a parallel example:
Almost 60 years ago, I got a Tasco (Japanese) 60mm refractor telescope for Christmas. I was overjoyed, because at the time, I had hoped to be an astronomer (I still sometimes wish I had gone in that direction). Of course, this small telescope had limitations, BUT not as many as you would think. I saw the normal stuff, but sometimes, with a little effort, I could resolve what I was told that a scope this size could not resolve. It is no secret, in retrospect, why. This little scope was well made, perhaps by people who made military optics during WW2. In any case, it really worked to the extent of its specifications and it gave me years of enjoyment. Had it not been stolen, perhaps 5 years later, I would have continued to use it, until something bigger and better became affordable.
Well, years later, I decided to buy another Tasco telescope, much like the one I lost. I found one, seemed to work, BUT it just was not the same quality, YET it had the same optical specifications. I tried several Tasco telescopes, over the years, and settled with a slightly bigger one, 90mm, and it's a 'dog' too! Why? I should have had an optical advantage with the somewhat larger scope. Well, specs. are specs. and user quality is above and beyond the specs. It is the same with audio. A well maintained Dyna Stereo 70, coupled to the right speakers can operate beyond its 'specifications' in sound quality, I have heard it, myself, with another audio professional's systems. Of course, you have to work within its limitations, but with a pair of LS3-5A's it was awesome! Yet, I make amps with up to 20 times more power, almost effortlessly, but I would not have chosen a JC-1 pair of amps in this set-up. Of course, the guy's wife worked full time for Reference Recordings, etc., etc. so they had confidence in their trade-offs, and pulled it off! Enough for now.
  Reply With Quote
Old 9th November 2011, 02:41 AM   #17756
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by john curl View Post
Almost 60 years ago, I got a Tasco (Japanese) 60mm refractor telescope for Christmas. .
Wow, me too! The objective was not that good actually.
__________________
“The earth's rotation will slow within days and stop for several days just prior to the pole shift. This is when you and your loved ones should be situated at your safe location.”
  Reply With Quote
Old 9th November 2011, 02:43 AM   #17757
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
You must have gotten a later one.
  Reply With Quote
Old 9th November 2011, 03:36 AM   #17758
rsdio is offline rsdio  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Seattle
Quote:
Originally Posted by jlsem View Post
The best DAC I've ever heard uses a first order 22kHz filter.
Gee, John, was that a 1st-order filter with a corner frequency of 22 kHz? That would mean it is only down 3 dB at 22 kHz, and vastly insufficient for the requirements. A great deal of frequencies above the corner frequency are allowed through the transition band and stop band of a 1st-order low-pass.

I'm not saying that a 1st-order filter wouldn't work, I'm merely stating that it's corner frequency would have to be sufficiently below 22 kHz in order to suppress a reasonable amount of the aliasing. I'd say that a low-pass at about 1 Hz, or maybe at low as 0.33 Hz, should be sufficient to bring 22 kHz down more than 90 dB (assuming 16-bit DAC). That really wouldn't leave much in the audio band, but it should remove the aliasing.
  Reply With Quote
Old 9th November 2011, 03:38 AM   #17759
rsdio is offline rsdio  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Seattle
Quote:
Originally Posted by scott wurcer View Post
I have a folk LP from 1965 where one cut sounded far better than all the rest, when the CD came out in 1999 that cut was missing. Upon inquiry it turns out that cut was an audience tape made on a Nagra and was lost.
Sorry for the sarcasm, but if vinyl is such a great recording medium, then why didn't they just convert the track from the LP after they couldn't find the Nagra tape? I've certainly purchased many modern CDs where the track shows obvious rumble and surface noise because they didn't go back to pre-vinyl masters.
  Reply With Quote
Old 9th November 2011, 03:42 AM   #17760
rsdio is offline rsdio  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Seattle
Quote:
Originally Posted by SY View Post
Where do these signals come from in actual recordings? Are you aware of any studios that don't use antialiasing filters?
SY, I believe that Jakob is referring to digital processing during mixing and/or mastering, not merely the A/D process. Even assuming proper A/D resulting in kosher original recordings, there are many digital effects, including modeling of analog effects, that can create frequency modulation components that are not 'legal' in the data stream. This can be partially reduced by digital oversampling followed by digital anti-alias filtering, but sometimes the processing power is not there, the programming chops are not sufficient, or it simply becomes difficult to mathematically predict the highest sample rate to completely avoid frequency artifacts above Nyquist. One example is fast changes to the gain, such as during dynamics processing, which create modulation components.
  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 07:06 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