Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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
Closed Thread
 
Thread Tools Search this Thread
Old 29th October 2011, 01:21 AM   #17071
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Well, this one is actually not PCM but it claims an analog SNR of -116dB.
Grimm AD1
 
Old 29th October 2011, 01:22 AM   #17072
Joachim Gerhard is offline Joachim Gerhard  Germany
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
http://www.grimmaudio.com/product_info/Manual%20AD1.pdf
 
Old 29th October 2011, 01:28 AM   #17073
abraxalito is offline abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Send a message via Yahoo to abraxalito
-116dB is still a substantial distance above 24bit quantization noise. It's equivalent to around 20bits.
__________________
'The total potential here must be nothing less than astronomical.'
'Nothing less. The number 10 raised almost literally to the power of infinity.'
 
Old 29th October 2011, 01:30 AM   #17074
scott wurcer is offline scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by simon7000 View Post
Now if you allow the premise that some humans (I know a presumption on my part) can perceive distortions of -140 db to -160 db re the peak sound pressure level, then many of these issues would actually have a basis!
I don't. There is no evidence in any context for this exaggerated claim. At some point you have to stop sending random resistors to folks and asking for their uncontrolled anecdotal comments and presenting it as evidence.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
 
Old 29th October 2011, 03:17 AM   #17075
hitsware is offline hitsware
diyAudio Member
 
Join Date: Mar 2002
> At some point you have to stop sending random resistors to folks
> and asking for their uncontrolled anecdotal comments and presenting
> it as evidence.

And how do you define that 'point' ..........
I'll take some of your samples .....
__________________
 
Old 29th October 2011, 03:28 AM   #17076
scott wurcer is offline scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: dorchester ma
Quote:
Originally Posted by hitsware View Post
> At some point you have to stop sending random resistors to folks
> and asking for their uncontrolled anecdotal comments and presenting
> it as evidence.

And how do you define that 'point' ..........
I'll take some of your samples .....
__________________
You make up some test where some resistors measure -140dB vs -150dB distortion and then you send those resitors to a third party and ask them to use them in some circuit and they line them up in your empirical model of what matters. And then you claim this means that stuff at the -150dB level matters.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
 
Old 29th October 2011, 04:02 AM   #17077
john curl is offline john curl  United States
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Over the decades, we hi end designers have discussed differences in resistors. Audio designers used to use carbon resistors, sometimes 'lousy' carbon resistors as standard. Allen Bradley in the USA seemed to make a pretty good carbon resistor, and Ampex used them for everything except precision attenuators. Back in those days, a 1% precision resistor might cost the equivalent of a cafeteria lunch.
Still, exceptions were found in resistors that added excess noise or distortion. As our measurements got better, we noticed this more. Richard Heyser pointed this out to me, over 40 years ago. In the 1980's 'HFN' came up with an article that measured distortion in both caps and resistors, AND they even tried to evaluate them by listening. They did a very good article.
In any case, all my best designs include specifying certain resistor brands and size. It is part of the design process for me, and I will stick with it. By some coincidence, one of my favorite resistor brands, the German made 'Resista' the standard component in my Vendetta Research phono stage and the Blowtorch, MEASURES really well, compared to some other Resistors, and they only cost me $.05 in limited quantity of 100 or so. Today I rely on Ed Simon to guide me on what is still available and how well it works.
__________________
"Condemnation without Examination is Prejudice"
 
Old 29th October 2011, 08:05 AM   #17078
chrissugar is offline chrissugar  Romania
diyAudio Member
 
Join Date: Jul 2004
Quote:
Originally Posted by abraxalito View Post
-116dB is still a substantial distance above 24bit quantization noise. It's equivalent to around 20bits.
The best high-end mastering converters have 127dB SNR that is equivalent to 21 real bits of audio. The remaining 3 bits are noise. This is the maximum that is possible to obtain considering the difference between the Johnson noise and the maximum levels used in balanced proaudio (0Vu = +4dBU vith 24-26db headroom) which is way more than the -10dBV used in unbalanced hifi. So there is no real chance to improve this 127dB, except if the whole level standard would be changed to a much higher one (no chance) or to imerse the whole converter into liquid nitrogen to reduce Johnson noise.

Anyway even if it would be possible it wouldn't matter because the SNR situation is already compromised long before any AD or DA conversion at the microphone and mic preamp.

chrissugar
 
Old 29th October 2011, 09:20 AM   #17079
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
John Curl's Blowtorch preamplifier part II
Permanent mismatch here between narrow band FFT resolution and SNR calculated over whole 20kHz width of frequency band - as in any amateur discussion.
 
Old 29th October 2011, 10:48 AM   #17080
SY is offline SY  United States
On Hiatus
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by PMA View Post
Permanent mismatch here between narrow band FFT resolution and SNR calculated over whole 20kHz width of frequency band - as in any amateur discussion.
Well, that and the failure to distinguish resolution from signal-to-noise.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
 

Closed Thread


John Curl's Blowtorch preamplifier part IIHide 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

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 02:13 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki