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 III
John Curl's Blowtorch preamplifier part III
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 November 2018, 04:57 PM   #10511
billshurv is online now billshurv  United Kingdom
diyAudio Member
 
billshurv's Avatar
 
Join Date: Mar 2014
John Curl's Blowtorch preamplifier part III
As Bud Purvine makes transformers he is likely to claim that they are good?
  Reply With Quote
Old 28th November 2018, 05:14 PM   #10512
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
Quote:
Originally Posted by KSTR View Post
A nice application is active speakers with a fullrange driver.
Yes, the only application that might benefit from the current drive is a full range speaker or active speakers. However, in both cases we need DSP's to equalize for flat frequency response. It makes the thing complicated and it is questionable if several 0.1% in distortion improvement are worth bothering with more work.
  Reply With Quote
Old 28th November 2018, 05:27 PM   #10513
john curl is offline john curl  United States
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Thanks Joe for putting up with your critics all by yourself apparently.
It has always bothered me that SERVOS which usually are motors that need to be controlled, use CURRENT DRIVE, because it removes the inductance of the motor wiring from the primary equations that make the servo do its thing. What is the difference between a loudspeaker and a 'motor'? Is not a loudspeaker a form of motor? Then WHY is voltage drive specified, rather than current drive?
Of course, it goes back to Rice and Kellog (sp) back in 1925 or so. THEY apparently INVENTED the direct radiator speaker, or at least were one of the first researchers to show it in a mathematical model. They showed that other loudspeaker types could also be made, effectively. This lead to the Manger loudspeaker driver, which derives from one of the early models in the Rice ... paper in 1925 (or so), the horn loaded speaker, and who knows what else. Just take the 'dot notation' equation that they show and MANIPULATE IT for best performance of what you want. Current drive, or finite resistive drive, as well as voltage drive is possible, and something outside of what we normally think as important, MIGHT actually be useful. How can we know, if we don't look and share experience?
__________________
"Condemnation without Examination is Prejudice"
  Reply With Quote
Old 28th November 2018, 05:33 PM   #10514
scott wurcer is offline scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: Belmont MA
Quote:
Originally Posted by DF96 View Post
People might like to ponder why interstage transformers were used in the past, then were replaced by coupling capacitors.
Trasnformers can have level dependent frequency response especially at low frequencies. Easily measured and heard.
__________________
"The way up and the way down are one in the same"
  Reply With Quote
Old 28th November 2018, 05:34 PM   #10515
indra1 is online now indra1  Indonesia
diyAudio Member
 
Join Date: Nov 2010
Location: Bogor
Quote:
Originally Posted by DF96 View Post
... The fact that a 'guru' has woffled in print about something does not mean that the issue is 'noted', or even that the issue exists.
Quote:
Originally Posted by billshurv View Post
As Bud Purvine makes transformers he is likely to claim that they are good?
Progress of technology has made available direct coupling on various topologies, expensive and heavy wound parts are last choice to most designer. To be honest, I can hear the effect he attributed to coupling caps on the post I quoted. However, due to unavailable access, I can not verify that the effect is not present on a system free of any coupling cap.
  Reply With Quote
Old 28th November 2018, 05:37 PM   #10516
scott wurcer is offline scott wurcer  United States
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: Belmont MA
Quote:
Originally Posted by john curl View Post
Then WHY is voltage drive specified, rather than current drive?
John look at Joe's schematics he is not talking about current drive, he even says so frequently.
__________________
"The way up and the way down are one in the same"
  Reply With Quote
Old 28th November 2018, 05:56 PM   #10517
jneutron is offline jneutron  United States
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: In fear
Does anybody recall any amplifier stability papers where this behaviour was evident?

I do.

jn
Attached Images
File Type: jpg instability.jpg (43.3 KB, 196 views)
__________________
I hate all these smart gadgets..I refuse to buy things that are smarter than me. I've made a list of those things... Cabbage just made the list.
  Reply With Quote
Old 28th November 2018, 06:45 PM   #10518
RNMarsh is offline RNMarsh  United States
Sin Bin
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Is there a way to make current drive and speakers together which reduces thd?

can such optimized designs reduce thd to a lower level than volt drive?



THx-RNMarsh
  Reply With Quote
Old 28th November 2018, 06:54 PM   #10519
jneutron is offline jneutron  United States
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: In fear
Quote:
Originally Posted by RNMarsh View Post
Is there a way to make current drive and speakers together which reduces thd?

can such optimized designs reduce thd to a lower level than volt drive?



THx-RNMarsh
What are the entities which cause speaker distortion at small signal levels?

jn
__________________
I hate all these smart gadgets..I refuse to buy things that are smarter than me. I've made a list of those things... Cabbage just made the list.
  Reply With Quote
Old 28th November 2018, 07:10 PM   #10520
gpapag is offline gpapag  Greece
diyAudio Moderator
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by jneutron View Post
Does anybody recall any amplifier stability papers where this behaviour was evident?

I do.

jn
I had made an LM3886 guitar amplifier for my younger daughter.
It showed such unstable behaviour around the zero crossing. Excellent acoustic effect.
Never understood why it behaved like that.
After some time, I reduced the gain and the instability stopped.
So John please, link to the paper.


George
__________________
["Second Law is a bitch." - SY]
["I insist on respecting the means of the average person working in their garage/basement." -Scott Wurcer]
  Reply With Quote

Reply


John Curl's Blowtorch preamplifier part IIIHide 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 12:38 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki