John Curl's Blowtorch preamplifier part II - Page 3376 - 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 28th January 2013, 03:05 PM   #33751
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by john curl View Post
Interestingly enough, Hi Fi books from the '50's used to suggest the same thing. It was easier then, with just two leads, and no 3'rd wire ground, at the time.
Even at the risk of an occasional "hot" chassis.
__________________
Silence is so accurate.
  Reply With Quote
Old 28th January 2013, 03:16 PM   #33752
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by john curl View Post
Finally, some common sense about ground leakage!
If you consider swapping hot and neutral at the AC mains outlet to be "common sense," you should get out of the business.

Quote:
Interestingly enough, Hi Fi books from the '50's used to suggest the same thing. It was easier then, with just two leads, and no 3'rd wire ground, at the time.
And in the 50's, it was common to wire the equipment chassis to neutral. So yeah, now let's go and flip the plug around on one piece of equipment.

*sigh*

se
__________________
The Audio Guild
  Reply With Quote
Old 28th January 2013, 03:30 PM   #33753
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by Steve Eddy View Post
I don't know how you do things over in France, but over here, you should NEVER change the sense of the AC mains hot and neutral.

They should always be wired like this:

Click the image to open in full size.

se
What he is talking about is the winding closest to the transformer core should be connected to the neutral. To conform to code this should be corrected inside the piece of gear.

Most transformers pay no attention to which primary wire is the winding start.

I do have a sample of a Chinese R core power transformer where the 120 Volt hot lead is color coded green!!!!

The other issue is the use of Belden 1023A cable. It is a shielded twisted pair with a foil shield. HOWEVER one conductor is copper the other is constantan! It is intended to attach to thermocouple and not introduce any voltage errors.
  Reply With Quote
Old 28th January 2013, 03:35 PM   #33754
diyAudio Member
 
Join Date: Nov 2010
Location: The City, SanFrancisco
I presume they are talking about swapping the primary transformer phase so that the secondary capacitively sees more of the neutral end.

Thanks
-Antonio
  Reply With Quote
Old 28th January 2013, 03:36 PM   #33755
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by magnoman View Post
I presume they are talking about swapping the primary transformer phase so that the secondary capacitively sees more of the neutral end.

Thanks
-Antonio
Actually I think it is the leakage to the core that is more of a concern.
  Reply With Quote
Old 28th January 2013, 03:37 PM   #33756
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by simon7000 View Post
What he is talking about is the winding closest to the transformer core should be connected to the neutral. To conform to code this should be corrected inside the piece of gear.
Yes, but he wasn't talking about doing it inside the piece of gear. He was talking about doing it at the AC outlet.

Quote:
I do have a sample of a Chinese R core power transformer where the 120 Volt hot lead is color coded green!!!!
Not surprising. A Chinese amp and DAC maker (Audio g-d) was shipping his gear with power cords that had the hot and neutral reversed.

se
__________________
The Audio Guild
  Reply With Quote
Old 28th January 2013, 03:38 PM   #33757
diyAudio Member
 
Join Date: Nov 2010
Location: The City, SanFrancisco
Quote:
Originally Posted by simon7000 View Post
Actually I think it is the leakage to the core that is more of a concern.
In general or does that change with primary phase?

Thanks
-Antonio
  Reply With Quote
Old 28th January 2013, 03:49 PM   #33758
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
In the '50's and '60's, almost all hi fi and other appliance AC plugs were just 2 and NOT 3. AND they were NOT polarized.
I worked at UL Labs, about 50 years ago, for about 1 year as a test tech. Which way you plugged in the plug just was not a concern at the time. So many 'far fetched' conditions had to occur before any serious injury, that extreme measures did not seem to be important enough to consider. You could even suffer a mild 'shock' from a guitar amp, for example, and it was considered OK, so long as it could not be fatal. Of course 3 prong plugs existed in restaurant appliances and such, when exposure to water and water pipes was much more common.
Later, plugs became polarized, and then 3 prong plugs became more standard, especially with metal cased audio equipment.
The most dangerous appliance I have seen in today's world is a toaster.

Last edited by john curl; 28th January 2013 at 04:00 PM.
  Reply With Quote
Old 28th January 2013, 03:54 PM   #33759
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by jneutron View Post
However, the twisted pair will share a common centroid by integration along the cable length.
That's what i was trying to explain. Same thing if the two wires are strait and the drain symmetrically situated all the way.
Belden take care of those details, as, by example, the way wires are shielded, for they don't change their geometry when the cable is creased.
One other thing, i don't know if it is the metals used, (Coper, Constantan), but the sound is very neutral and detailed comparing the whole box length with a short circuit.

About the grounding tip, i suppose we have some norm about hot and neutral, never respected. But norm is severe with earths diameter and impedance. my suggestion was not to modify wall outlet, but what you call "Power distribution units" ? Right ?


Click the image to open in full size.
Click the image to open in full size.
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein

Last edited by Esperado; 28th January 2013 at 04:09 PM.
  Reply With Quote
Old 28th January 2013, 04:01 PM   #33760
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Some more info to add to the fun, one article on shielding 2 on interference free systems (ie reducing EMC)
Tony Waldron's EMC ranting and ravings
  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 12:27 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