John Curl's Blowtorch preamplifier part II - Page 3190 - 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 29th December 2012, 06:36 AM   #31891
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Wavebourn, resistors have capacitance too. Earling Fredrikson told me himself that this was the reason when I visited B&K in 1974.
  Reply With Quote
Old 29th December 2012, 07:28 AM   #31892
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
They have physical dimensions, so they must have some capacitance.
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html
  Reply With Quote
Old 29th December 2012, 09:14 AM   #31893
fas42 is offline fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by RNMarsh View Post
OK Keep going... we're listening and watching.
Thanks, Richard. OK, results are in and it worked as well as I expected it to. This resampling exercise is particularly stressful because the natural fit for downsampling 352.8 is to use 88.2kHz as the go between, rather than 96 as here.

So, did the resampling, down and up, of only the right channel, which appeared to be slightly more dynamic, making it mono on the way. Then, did a diff of the original, 2L waveform and the resultant, 2 pass 352.8 file. This was what came out:

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-04.jpg

Looks pretty terrible, but then have a look at the spectrum:

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-04b.jpg

This is very suspicious, a typical noise shaping curve after 40kHz, suggests there is no real information beyond that frequency, it's purely processing "rubbish". So, apply equalisation to brickwall attenuate everything after 40kHz, and get this:

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-05.jpg

This looks much, much better, but there is still some apparent noise there. Can't zoom any more, so use the amplify function to boost it, by 50dB:

2L50SACD_tr1_DXD_stereo_2012-12-29_14-09-58-06.jpg

Lo and behold, we have our original waveform back, inverted, as demonstrated by the copy of the result of the 2 pass resampling which follows the amplified difference "noise". In other words, a slight attenuation crept in at some point, which is why the difference process didn't perfectly null -- easy to compensate for ...

Frank

Last edited by fas42; 29th December 2012 at 09:16 AM.
  Reply With Quote
Old 29th December 2012, 10:20 AM   #31894
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Quote:
Originally Posted by RNMarsh View Post
OK Keep going... we're listening and watching.
I'm not at home so i cant check any of those files.
But sure you can write to 2L and ask Information on the process used and eventual editing.

Thanks for the good work, Frank also from me.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 29th December 2012, 10:25 AM   #31895
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Frank, so from what I understand they have recorded armonics up to 40khz.
If I'm correct, this is still VERY good. I personally believe that we should aim for 50khz, and that should sound MUCH better than brick walled at 20-21k. With most modern tweeters reaching 40k this should be clearly audible.

I used their piano sonata and while that shouldn't have any harmonic above 20k, the DXD version was do much closer to the real thing...
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 29th December 2012, 10:56 AM   #31896
fas42 is offline fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by Telstar View Post
Frank, so from what I understand they have recorded armonics up to 40khz.
If I'm correct, this is still VERY good. I personally believe that we should aim for 50khz, and that should sound MUCH better than brick walled at 20-21k. With most modern tweeters reaching 40k this should be clearly audible.

I used their piano sonata and while that shouldn't have any harmonic above 20k, the DXD version was do much closer to the real thing...
The point of the exercise I did is that sampling at 96kHz, or even 88.2 was sufficient to encode all the musical, or event information of the DXD recordings that I tested from 2L. The DXD recording process theoretically can capture real audio information up to 176kHz but I haven't seen any evidence so far that the 2L crowd have done that for frequencies over 40kHz.

Which means, why do you need 352, 176, 192, etc? More space, download time, etc.

Yes, playback can sound better at the higher sampling rates, but my experiments indicate that this is a by-product of the way the playback systems work -- not because you're hearing "more information" ...

Frank
  Reply With Quote
Old 29th December 2012, 11:16 AM   #31897
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by john curl View Post
Here is some additional stuff on 30ips analog recorders. Please note date.
Thanks, John! I will study it with great interest.
  Reply With Quote
Old 29th December 2012, 11:23 AM   #31898
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by Esperado View Post
.....
At the very beginning of the digital recording, while so much sound engineers were talking of the DACs quality, i pretended that most of the audible differences were due to the analog stages after the DACs, not the DACs themselves.
Used a cheap Philips cd player with a Delta sigma 14 bits DAC followed by a modified analog stage to demonstrate-it in my studio.
.......
1. First Philips CD players weren't cheap.
2. They were 14 Bit Multi-Bit, not Delta-Sigma.
  Reply With Quote
Old 29th December 2012, 11:40 AM   #31899
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Quote:
Originally Posted by fas42 View Post
The point of the exercise I did is that sampling at 96kHz, or even 88.2 was sufficient to encode all the musical, or event information of the DXD recordings that I tested from 2L. The DXD recording process theoretically can capture real audio information up to 176kHz but I haven't seen any evidence so far that the 2L crowd have done that for frequencies over 40kHz.

Which means, why do you need 352, 176, 192, etc? More space, download time, etc.

Yes, playback can sound better at the higher sampling rates, but my experiments indicate that this is a by-product of the way the playback systems work -- not because you're hearing "more information" ...

Frank
Yes, I agree on your conclusions.
Now, why higher (than 88.2 which is min to preserve what current mics can acquire, at least those from 2L) sampling rate sounds better if the HF content is the same?
Somebody said earlier in this thread "noise", and I agree - pushing the hf noise further makes it less audible (by whichever mechanism the ear/brain use).
DAD (digital audio Denmark) affirms that 352k are required to get away with filtering. Considering the damage that analog filtering does to the music signal I agree with them. (Sorry no DBT done).
Chord believes that 1,5mhz are needed instead. I can't verify that because no multibit dac exist that can support such sampling rates.

The most sound way to reproduce digital would be using 88,2k material of good quality (ie non manipulated more than redbook) and upsample it on the fly to at least 352k, and get rid of analog filtering, or at least push it very high (>300k) where it won't destroy phase coherence up to 40khz.

If someone wants to organize blind tests, I'm all in favour of them.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 29th December 2012, 11:55 AM   #31900
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by fas42 View Post
Which means, why do you need 352, 176, 192, etc? More space, download time, etc.
Recommended reading:
http://www.lavryengineering.com/pdfs...lity_audio.pdf
  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 02:13 PM.


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