Sound Quality Vs. Measurements - Page 499 - 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 2nd May 2012, 08:02 PM   #4981
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by DF96 View Post
We are clearly talking about different things. I am interested in truth. You, by your own admission, are interested in utility. No point in arguing, although it would help communication if you did not express your utility in the form of truth statements. From now on, perhaps I should assume that when someone says "X is right" he may mean "I find X to be useful, so please don't tell me that X is wrong".
What use a therory not proved in practice?

But yes, you are right, I am concerned with how something works in hard everyday practice. Or doesn't, as the case may be. I am not into theorizing.

In my case, you would be right to understand that it's MY truth - I am too old and experinced to search for the absolute truth. MY truth simply means that if it works for me as theory has it down to a +/- 5% tolerance, to me, that is the truth.

If my phrasing has caused you to misunderstand, I do apologize for that, it was surely not my intent to make it sound so.
  Reply With Quote
Old 2nd May 2012, 08:19 PM   #4982
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Truth? What is 'truth' when it comes to feedback design? That Cordell has made a prototype or two that he likes? I don't remember hearing his amp, or any INDEPENDENT reviewer having access to one. That is what we mean by 'utility'. Make something, give it out for everybody to try, as wide a selection as possible, and get their listening feedback about what you have done. I can almost NEVER follow Otala's philosophy exactly. I just don't have enough gain-bandwidth, except for my one-and-only open loop design, the CTC Blowtorch. However, Charles Hansen of Ayre has made a number of designs, both preamp and power amp and gives me a real run in listening contests, you know, serious ones, like major reviews, etc. HE is MY competition, not Bob Cordell, and he believes in open loop design even MORE than Matti Otala.
If you think we are kidding ourselves, just look at the number of A rated components that Ayre and I make in 'Stereophile' or 'TAS'.
  Reply With Quote
Old 2nd May 2012, 08:33 PM   #4983
a.wayne is offline a.wayne  United States
diyAudio Member
 
a.wayne's Avatar
 
Join Date: May 2008
Location: Front Row Center
Was there ever a Cordell designed Amplifier made available to the public .......? The Ayre product ( as others ) has the same issue that we were discussing earlier, about high distortion in the mili-watt area, distortion starts high and then decreases before increasing again ...

EDIT: This is not to say it is a bad product, just a pointer to what was being discussed previously ..

Ayre MX-R monoblock power amplifier Measurements | Stereophile.com
Attached Images
File Type: jpg Ayre-1.jpg (33.2 KB, 77 views)

Last edited by a.wayne; 2nd May 2012 at 08:43 PM.
  Reply With Quote
Old 2nd May 2012, 08:44 PM   #4984
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Quote:
Originally Posted by john curl
Truth? What is 'truth' when it comes to feedback design?
The same sort of truth as Kirchoff's laws and Maxwell's equations. Maybe some people regard those as a matter of belief too?
  Reply With Quote
Old 2nd May 2012, 08:45 PM   #4985
a.wayne is offline a.wayne  United States
diyAudio Member
 
a.wayne's Avatar
 
Join Date: May 2008
Location: Front Row Center
For the record , Bob is an amplifier Guru ....

The Amplifier Guru speaks
http://jipihorn.free.fr/Documents/Di...linterview.pdf
  Reply With Quote
Old 2nd May 2012, 08:48 PM   #4986
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
I doubt that the distortion increases at low levels, as that is the Class A region, and the laws of engineering show that the distortion decreases with decreasing level in a Class A region of an amp. What you see is measurement noise residual.
  Reply With Quote
Old 2nd May 2012, 08:50 PM   #4987
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by john curl View Post
What you see is measurement noise residual.
More likely amplifier noise.
__________________
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 2nd May 2012, 09:02 PM   #4988
a.wayne is offline a.wayne  United States
diyAudio Member
 
a.wayne's Avatar
 
Join Date: May 2008
Location: Front Row Center
Quote:
Originally Posted by john curl View Post
I doubt that the distortion increases at low levels, as that is the Class A region, and the laws of engineering show that the distortion decreases with decreasing level in a Class A region of an amp. What you see is measurement noise residual.
Yes, we had originally thought such and there was a discussion on this earlier John and it was shown that the distortion on a lot of amps in the mill-watt area was very high, even full class-a amplfiers.

I will try and link this ...!!!


As to the graph posted on the Ayre, Distortion starts out higher then lower before rising again, are you saying below one Watt, what is being measured is Measurement noise residual ..?

This is that all important 1st watt ...
  Reply With Quote
Old 2nd May 2012, 09:08 PM   #4989
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Amplifier noise, then.
  Reply With Quote
Old 2nd May 2012, 09:17 PM   #4990
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Quote:
Originally Posted by a.wayne View Post
Yes, we had originally thought such and there was a discussion on this earlier John and it was shown that the distortion on a lot of amps in the mill-watt area was very high, even full class-a amplfiers.

I will try and link this ...!!!
Although if an amplifier has a stable and smooth set of nonlinearities in the vicinity of zero signal, the net distortion should fall off predictably with decreasing level, it's not inconceivable that the concatenation of stages of some sort might have an overall signature, a curve-of-growth, that actually produces net distortion that is non-monotonic with level.

Also, another gotcha is to suppose that the measurement equipment itself has no problems at lower levels. If you've ever tried to make a really good true-rms converter, or even just a good low-level rectifier, you quickly come to appreciate the difficulties.

If given an amplifier with a claimed rise in low-level distortion, independent of the residual noise, it might be a good idea to use the traditional analyzers in conjunction with a careful nulling approach, and see if the results are in agreement.
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quality Control differences = variations in sound quality? KT Class D 3 4th June 2014 12:02 AM
Sound Card for Measurements Marik Solid State 2 2nd January 2012 08:59 PM
Sound Card Recommendations (For Audio Measurements) dchisholm Equipment & Tools 5 16th July 2011 09:40 AM
How to protect sound card during amp measurements? okapi Everything Else 13 2nd September 2008 03:06 PM
Sound cards - test and measurements jackinnj Everything Else 2 5th July 2003 03:02 PM


New To Site? Need Help?

All times are GMT. The time now is 09:39 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