Sound Quality Vs. Measurements - Page 19 - 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 26th December 2011, 06:34 PM   #181
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
Quote:
Originally Posted by john curl View Post
Pano, you only have 1/2 the story. Class A is not necessarily the most thermally stable operating condition. It can be shown that heavy Class AB-1 is as good or better, if you go back to the root equations. However, thermal stability, both transient and long term is really important, and real designers make sure that the THERMAL CAPACITANCE is very high by close mounting the output devices on good insulators (if necessary) properly torqued down and used with thermal grease on a substantial heatsink . This removes most of the short term gain changes due to temperature.
High input stage operating current, using only a part of the class A portion can also be helpful.
Interesting John , could you elaborate more on your previous comment about toroid transformer vs a super-quality EI or R core transformer.
  Reply With Quote
Old 26th December 2011, 06:42 PM   #182
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Bandwidth.
  Reply With Quote
Old 26th December 2011, 06:47 PM   #183
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
In truth, the JC-1 should outperform the Ayre on difficult loads, but apparently it does not always, even with very large electrostatic speakers. This was one of my first 'upsets'.
  Reply With Quote
Old 26th December 2011, 07:18 PM   #184
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by Pano View Post
Sure, SY. But there might be in typical tube amps.
Sure, like a cat does not need to run before jumping on a fence, tube amp does not need to have such low THD and DF to sound nice. However, my Pyramids have lots of feedbacks, stabilized voltages, and they show comparable with transistor amps DF and THD. I designed them to drive high-end line arrays, but as far as I know all prototypes I made drive Maggies and speakers with crossovers meant to be driven by SS amps.

I.e. you can design and build tube amps with low THD and high DF, but nobody actually needs it. Especially those who drive full-range high efficiency speakers. That's why you don't see so many tube amps with extremely good parameters that are not actually needed. Especially, when they lead to horrible transients on overload, in all amps, no matter made they on diamonds, or on steam engines.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 26th December 2011, 07:24 PM   #185
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by john curl View Post
Pano, you only have 1/2 the story. Class A is not necessarily the most thermally stable operating condition. It can be shown that heavy Class AB-1 is as good or better, if you go back to the root equations.
John; it is true only for biased in class A complementary followers. My amps that have bootstrapped source follower loaded on counter-modulated current source mean totally different story: power dissipation varies with variation of load impedance only, not with the signal.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 26th December 2011, 07:31 PM   #186
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
The problem for of the toroid power transformer is that it has too much bandwidth due to the high cap coupling between input and output windings.
  Reply With Quote
Old 26th December 2011, 07:34 PM   #187
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Well, Wavebourn, that does not completely take you 'off the hook', then?
  Reply With Quote
Old 26th December 2011, 07:42 PM   #188
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by john curl View Post
Well, Wavebourn, that does not completely take you 'off the hook', then?
It is not about hooks, John; it is about class A amps and heat - aided distortions.

Edit: I am going to spend some money on silicone carbide devices, to try if some difference will be heard or not...
__________________
The Devil is not so terrible as his math model is!

Last edited by Wavebourn; 26th December 2011 at 07:53 PM.
  Reply With Quote
Old 26th December 2011, 08:01 PM   #189
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
'off the hook' means: Out of potential trouble. Sorry, there are many other meanings as well.
  Reply With Quote
Old 26th December 2011, 08:18 PM   #190
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by john curl View Post
'off the hook' means: Out of potential trouble. Sorry, there are many other meanings as well.
Potential troubles are always here, when we register mechanical waves by electricity, and reproduce them by electricity. Microphone preamps and power amps are always bottlenecks.
__________________
The Devil is not so terrible as his math model is!
  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 01:02 AM
Sound Card for Measurements Marik Solid State 2 2nd January 2012 09:59 PM
Sound Card Recommendations (For Audio Measurements) dchisholm Equipment & Tools 5 16th July 2011 10:40 AM
How to protect sound card during amp measurements? okapi Everything Else 13 2nd September 2008 04:06 PM
Sound cards - test and measurements jackinnj Everything Else 2 5th July 2003 04:02 PM


New To Site? Need Help?

All times are GMT. The time now is 09:45 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