John Curl's Blowtorch preamplifier part II - Page 1707 - 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 October 2011, 08:21 PM   #17061
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
7th or 9th harmonic distortion is detectable at very low levels. Simon is on track.
  Reply With Quote
Old 28th October 2011, 08:27 PM   #17062
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by simon7000 View Post
Well when I posted ninth harmonic distortion at -60 db only a few couldn't hear that. We could try 9th at -80 db, that shows up on our in house listening test for some folks. So the issue most likely is what are you listening for?
Why not add the -60 or -80dB 9th harmonic to music and see if anyone can hear that?
__________________
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 October 2011, 08:29 PM   #17063
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by john curl View Post
7th or 9th harmonic distortion is detectable at very low levels. Simon is on track.
How low?

se
__________________
The Audio Guild
  Reply With Quote
Old 28th October 2011, 08:30 PM   #17064
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by SY View Post
Why not add the -60 or -80dB 9th harmonic to music and see if anyone can hear that?
Oh, the tests were done using pure tones?

se
__________________
The Audio Guild
  Reply With Quote
Old 28th October 2011, 08:44 PM   #17065
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
you could just try 2 passes through analog tape - "0" dB recording level is specd @ % of 3rd harmonic distortion from tape saturation

suppose many loud musical pasages recorded/produced before the 1980's ever had less than -80 dB 9th harmonic?
  Reply With Quote
Old 28th October 2011, 08:46 PM   #17066
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Easier to do it digitally.

Quote:
Originally Posted by Steve Eddy View Post
Oh, the tests were done using pure tones?

se
Yes.
__________________
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 October 2011, 08:52 PM   #17067
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by SY View Post
Yes.
Oh. Pfffft!

se
__________________
The Audio Guild
  Reply With Quote
Old 28th October 2011, 08:57 PM   #17068
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by SY View Post
Cute, Ed, but I didn't argue that. You do, of course, understand the difference between a signal that's 65dB down from full scale and a signal that's 65dB down in the presence of a full-scale signal.
If a secondary signal is 65 db down from the peak level of music and the music has dynamic range of 60 db, I expect the secondary to show up. I am not clear as to how the demo was done. If the secondary is always 65 db below the music and is not seriously distorted I would expect that to be masked. I suspect for most folks the masking margin can actually be as low as 15 db!

Now if we have a mechanism that causes a ninth harmonic to appear late when there is less masking from the fundamental that should be more objectionable than one tightly linked.

In live music a forte in performance is 10 db louder than a forte in practice. But all of the musicians will tell you a forte is always a forte. Now how you play a violin 10 db louder is a mystery to me. That just shows perceptions shift due to environment, nothing new.

So when I hear something wrong, I take measurements to see what it might be. That way I can adjust the parameter under consideration to "fix" the problem. It is a related, but independent experiment to create test tones with fixed harmonic distortion, phase shift, etc. to see what levels I or others around here can detect.

Yes I have tried switching cables from the worst I have measured to the best. Some folks can tell them apart, most can't. Fully scientific... no, because I can't find a way to change cables with out a person swapping them on the spot without having far greater distortion in the switch.

Almost everyone here can tell that my rotary switch has a different sounding position #1. It is a Lorlin silver plated plastic cased switch.

On my list of testing I would like to try is wideband noise levels. Exactly how to measure it is an open question.
  Reply With Quote
Old 28th October 2011, 10:12 PM   #17069
rsdio is offline rsdio  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Seattle
Quote:
Originally Posted by simon7000 View Post
Some of us aren't using recordings! But even with a 24 bit recording (As far as I know there aren't any really there yet) that would allow you more than 140 db of resolution.
I'm not sure what you're trying to say about 24-bit recording equipment. There are A/D options available that are truly 24-bit in terms of digital bit depth and quantization noise. The catch is that the analog stage in front of any A/D is generally going to be 111 dB at best. Sure, there are a rare few better analog stages, but my point is that it is the analog stage that is not really there yet, not the digital converter. Granted, there are 24-bit A/D chips with much worse than 24-bit quantization noise - those cases are truly a failure to live up to the "24-bit" claim, but not all 24-bit converters fall into this.
  Reply With Quote
Old 29th October 2011, 12:01 AM   #17070
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 99
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by rsdio View Post
There are A/D options available that are truly 24-bit in terms of digital bit depth and quantization noise.
Which?
__________________
It doesn't have to take the form of a conspiracy, rather a consensus... James H Kunstler
  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 08:21 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