John Curl's Blowtorch preamplifier part II - Page 4857 - 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 24th February 2014, 05:24 PM   #48561
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
Funny how some will at one point say that vacuum tube devices are the most linear while at the same time I have never seen any of this equipment that is not containing steel chassis, and many ferrous metal connection points? Do we really think that this is the answer to the final frontier in solid state circuits, removing any traces of ferrous metal anywhere in or around a circuit? Do we need to use nothing but capacitors with multi-strand copper leads so we couldn't possibly have a single boundary layer imperfection in a lead-out wire using a solid copper wire?
  Reply With Quote
Old 24th February 2014, 05:31 PM   #48562
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
That's audiophile discussion. Sometimes it matters, sometimes not

The problem with audiophile discussions is that it is a 99% ballast. 1% might be useful and bring something. The same applies for this thread.
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html
  Reply With Quote
Old 24th February 2014, 05:36 PM   #48563
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by Kindhornman View Post
Funny how some will at one point say that vacuum tube devices are the most linear while at the same time I have never seen any of this equipment that is not containing steel chassis, and many ferrous metal connection points?
Not to mention the tubes themselves. And transformers. But that doesn't count because... ... ... hey look, a squirrel!
__________________
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 24th February 2014, 05:50 PM   #48564
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally Posted by VladimirK View Post
Yes, the paper says, that if defects have been produced somehow (one possibility is by gamma-radiation in space) than some pulses of alternating currents help to restore the damaged structure.
Radiation induced defects in cold diodes is an extreme issue with superconducting accelerators and colliders. The dipole bending magnets are series connected to reduce the number of warm to cold transitions and to keep all the dipoles tracking perfectly. As a consequence, if one of the dipoles quenches (reverts to normal resistive state), it is important to bypass the rest of the ring energy around the quenched magnet. Each magnet can absorb it's own stored magnetic energy without melting, but when there are lots of them, the current has to be bypassed using a cold diode. CERN used 100mm diameter diodes, and put them within a foot of the beam path. As a consequence, the forward voltage increases with time due to radiation damage.

Every year or so, the diodes have to be brought back to room temperature so that the damage is annealed out. The problem is worse in that the diodes are planar to the beam, not normal to it. One side of the diode is closer to the beam and gets more damage as a result. If a quench occurs, the diode will go into thermal runaway in the section farthest from the beam.

I believe the space rad damaged thingy was telstar. After a failure, the engineers created a condition which heated the offending part up, and they annealed the damage out.

Quote:
Originally Posted by VladimirK View Post
Defects and their annealing in solids were a part of my former professional career, and Mr RNMarsh probably is well awared of what has been studied by computer simulation group at LLNL.
Neat. Simulation would have been easier and less expensive than experience.

jn
  Reply With Quote
Old 24th February 2014, 06:06 PM   #48565
diyAudio Member
 
Triodethom's Avatar
 
Join Date: Dec 2009
Location: Newnan GA
Quote:
Originally Posted by scott wurcer View Post
The post mortem report is public record, as usual more complicated than one thinks.

http://www.ssl.berkeley.edu/~mlampto...nReportHST.pdf
Read only the results at the beginning . That was a total management failure on the part of both NASA and the maker. Along time ago on a PA install I remember on the bid spec that there would be independent test and verification of system performance that was a job of small town . They knew they where not qualified to sign off on the work so the job was certified by a third party . Interesting that a job worth 100s of millions lacked the same level of do diligence .
  Reply With Quote
Old 24th February 2014, 06:08 PM   #48566
diyAudio Member
 
Triodethom's Avatar
 
Join Date: Dec 2009
Location: Newnan GA
Quote:
Originally Posted by SY View Post
Not to mention the tubes themselves. And transformers. But that doesn't count because... ... ... hey look, a squirrel!
BANG dead squirrel fix it for you .
  Reply With Quote
Old 24th February 2014, 06:48 PM   #48567
rayma is online now rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Default HST

Quote:
Originally Posted by scott wurcer View Post
The post mortem report is public record, as usual more complicated than one thinks.

http://www.ssl.berkeley.edu/~mlampto...nReportHST.pdf

There was a second, perfect, backup mirror in storage. All they had to do was replace the bad one with the good one, before launching it into space that is.

Ray
  Reply With Quote
Old 24th February 2014, 09:14 PM   #48568
fas42 is offline fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by Max Headroom View Post
The curious thing with fully reworked amplifiers that I have found repeatedly, is that at low levels, initially the sound is 'wrong', badly 'wrong' and this distortion gets worse as the volume is slowly raised, and reduces as the volume is decreased.

When a threshold is reached (first clip events ?), the amplifier/sound suddenly and dramatically changes for the better, and remains so, even after repeated volume changes, power up/down cycles, or fully cold restart.

This once only effect is perhaps not as stark as I have described, however a trained ear alerted to this behaviour will discern the sonic changes.
Very interesting results, Dan. There is certainly a conditioning process taking place, but my suspicions would gravitate strongly to the big smoothing caps - these things are pretty marginal as electrical components, , I would put them on the front of the suspect list.

The big Perreaux amp I started my journey with used to drive me nuts in the early days, SQ issues were clearly linked to the fat, impressive looking caps - I started by working around them, but finally bit the bullet, yanked them out and put in some decent, much smaller units in parallel - never looked back ...

As regards 'conditioning of the mind', the worst headaches for me over the years have been anomalies which do get worse with time - there is an intricate dance going on in a system as it works, some aspects are improving, others degrading - this is at a subtle, but definitely discernable level - there have been many days when I just got fed up, the sound was getting worse and worse the longer the system ran - so, just pulled the plug and forgot about audio for a few days ... then, refreshed, ready do another round of investigating ...
__________________
Frank the truth is, I just like a bit of ASMR ...

Last edited by fas42; 24th February 2014 at 09:16 PM.
  Reply With Quote
Old 24th February 2014, 09:32 PM   #48569
fas42 is offline fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by Kindhornman View Post
Do we really think that this is the answer to the final frontier in solid state circuits, removing any traces of ferrous metal anywhere in or around a circuit? Do we need to use nothing but capacitors with multi-strand copper leads so we couldn't possibly have a single boundary layer imperfection in a lead-out wire using a solid copper wire?
All my experience in this game has demonstrated that the key factor is accumulating enough 'good points', so to speak, in order to get satisfying sound to emerge. Something in the system can be 'wrong', terribly wrong, by most standards, but if the accumulation of positive ticks in other areas is sufficient then the single bad negative doesn't undermine the subjective nod of approval.

This is why "mediocre" equipment can do it - you squeeze just enough 'goodness' out of what's at hand to get you over the line in terms of the positive attributes needed - and the ear/brain filtering does the rest ...
__________________
Frank the truth is, I just like a bit of ASMR ...
  Reply With Quote
Old 24th February 2014, 09:56 PM   #48570
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
Quote:
Originally Posted by Kindhornman View Post
Funny how some will at one point say that vacuum tube devices are the most linear while at the same time I have never seen any of this equipment that is not containing steel chassis, and many ferrous metal connection points? Do we really think that this is the answer to the final frontier in solid state circuits, removing any traces of ferrous metal anywhere in or around a circuit? Do we need to use nothing but capacitors with multi-strand copper leads so we couldn't possibly have a single boundary layer imperfection in a lead-out wire using a solid copper wire?
Well, the transformers are ferrous to start with . . . So I'm kind of confused by this whole ferrous thing to be honest.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  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 08:33 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