John Curl's Blowtorch preamplifier part II - Page 1513 - 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 18th August 2011, 07:57 PM   #15121
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by gpapag View Post
Seems like a mono recording, 2 tones ~ 1kHz and ~8kHz. I guess there are some more peaks above 20kHz (I bet that there is one more main tone).

What worries me is that I can’t hear the amplitude modulation (useless ears)

Regards
George
A brave soul with accurate but incomplete results!

It is 1 K and 9 K at 10/1 but there is a change 1/2 way through!
  Reply With Quote
Old 18th August 2011, 09:08 PM   #15122
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Quote:
Originally Posted by simon7000 View Post
A brave soul with accurate but incomplete results!

It is 1 K and 9 K at 10/1 but there is a change 1/2 way through!
He He
I was quite curious myself
Going to full zoom (down to 23us step), I checked the repetition pattern.
I checked 4 complete periods of the main frequency (~1kHz).
The pattern on each period is almost the same , but not exactly the same.
Working with time period and converting to frequency, I noticed the following:
The main frequency components are : 1002Hz, 8849Hz and 8772Hz.
The (much) weaker frequency components are 11111Hz, 10989Hz, 2339Hz, 2140Hz and 77.6Hz. These may be intermodulation products or/and folding back components from the digitization process.

May be it is this "change 1/2 way" (the meaning of which escapes me) that produces the difference btn my findings and your two frequency components.

Regards
George
__________________
["Second Law is a bitch." - SY] ["The Road To Heaven:Specify the performance & accept the design. The Road To Hell:Specify the design & accept the performance"-Bruno Putzeys]
  Reply With Quote
Old 18th August 2011, 09:18 PM   #15123
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
It should be 1K and 9K at 10/1 with the 9K 15 degrees before the 1K until 1/2 way when it changes to 15 degrees after!

How did you capture it? And is there an error in the compression expansion process? I could not just post a .wav file.
  Reply With Quote
Old 18th August 2011, 09:22 PM   #15124
Account disabled at member's request
 
Join Date: Oct 2008
Listening to the file I would say its a distorted 1k and a distorted 9k, about half way down a close to 9.5k click.
  Reply With Quote
Old 18th August 2011, 09:24 PM   #15125
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by stinius View Post
Listening to the file I would say its a distorted 1k and a distorted 9k, about half way down a close to 9.5k click.
The click is the switch from phase shift before to phase shift after. The sin waves should be undistorted.
  Reply With Quote
Old 18th August 2011, 10:06 PM   #15126
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Quote:
Originally Posted by simon7000 View Post
It should be 1K and 9K at 10/1 with the 9K 15 degrees before the 1K until 1/2 way when it changes to 15 degrees after!

How did you capture it? And is there an error in the compression expansion process? I could not just post a .wav file.


Quote:
How did you capture it?
I unzipped what you posted and then I opened the unzipped wave file with Steinberg Wavelab 4.

Quote:
And is there an error in the compression expansion process? I could not just post a .wav file.
The unzipped wave file has a duration of 3s998.050ms exact. Please check the exact duration of your initial wave file.

Quote:
It should be 1K and 9K at 10/1 with the 9K 15 degrees before the 1K until 1/2 way when it changes to 15 degrees after!
OK!
This 30 degrees delta phase may do some of the harm.

Watching the “glitches”, I can tell that the amplitude ratio is around 10/1. (Visibly, it varies from 7:1 to 11:1).

The attachments below show -with progressive zooming-the exact middle of the unzipped file (the vertical multicolour line is at 1s999.025ms)

Regards
George
Attached Images
File Type: jpg 2-1.JPG (87.4 KB, 168 views)
File Type: jpg 2-2.JPG (63.9 KB, 150 views)
File Type: jpg 2-3.JPG (54.6 KB, 149 views)
__________________
["Second Law is a bitch." - SY] ["The Road To Heaven:Specify the performance & accept the design. The Road To Hell:Specify the design & accept the performance"-Bruno Putzeys]

Last edited by gpapag; 18th August 2011 at 10:14 PM.
  Reply With Quote
Old 18th August 2011, 10:24 PM   #15127
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Quote:
Originally Posted by john curl View Post
It would have been a good idea though, but impractical.
Excellent one imo, and very practical for a DIY person.
(in particular for those with extensive experience with kevlar prepreg plus vacuum injection)

The servo's impact greatly depends on the secondary selection level of the JFETs, no ?
__________________
The buck stops Here
  Reply With Quote
Old 18th August 2011, 10:24 PM   #15128
rsdio is offline rsdio  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Seattle
Quote:
Originally Posted by john curl View Post
Of course, the servo operates below 1 Hz, AND the circuit operates perfectly fine WITHOUT the servo, except that there will be a little inherent offset due to the slight factory generated errors in the selected high current 2SK389-2SJ109 combination. The servo is deliberately 'detuned' to have the minimum effect possible on the audio path and have to 'work' even to obtain 0 offset, usually having about 2V or so at its output, for perhaps, correcting 10mV offset, total, or less.
Nothing wrong with minimal feedback. Seems like it would be more accurate to describe the Blowtorch as having minimal audio feedback, rather than "no feedback." Considering all of the misguided discussions of feedback and whether it is good or bad (in general or in specific cases), I would personally prefer accurate descriptions.

P.S. I've been a fan of Parasound products for a dozen years or so, long enough to see products outlast their amazing ten-year warranties!
  Reply With Quote
Old 18th August 2011, 10:27 PM   #15129
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
My FFT was clean over a 110dB range. I used a Houdy7 window.
See the inverse FFT of 1 sec of the first part and 1 sec of the second part.
I listened two both but they sounded similar to me.
Attached Files
File Type: pdf Simon tones FFT.pdf (13.8 KB, 29 views)
File Type: pdf Simon tones first part red, second part black.pdf (9.7 KB, 20 views)
  Reply With Quote
Old 18th August 2011, 10:50 PM   #15130
Account disabled at member's request
 
Join Date: Oct 2008
Quote:
Originally Posted by simon7000 View Post
The click is the switch from phase shift before to phase shift after. The sin waves should be undistorted.
Ok, but I only listened to the file and it sounded distorted (using some crappy desktop loudspeakers) BTW the file "sounded" different before and after the "click"
  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 12:04 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