John Curl's Blowtorch preamplifier part II - Page 1437 - 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 27th July 2011, 06:23 PM   #14361
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Chris,

I though profanity was not allowed, Computer power supl....! Wow what a nasty term!

Actually my scope throws off enough energy to show up on sensitive measurements!

I just found it real interesting that the IEC connector disconnect and reconnect had that much difference!

Have Fun.

ES
  Reply With Quote
Old 27th July 2011, 06:25 PM   #14362
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by Speedskater View Post
Last winter I measured several IEC cords using a 4 terminal Ohm meter. I was surprised on how bad a few cords were!
Mention that to SY, we were discussing what peak current demands do to real power cords!
  Reply With Quote
Old 27th July 2011, 06:40 PM   #14363
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Hang in there, Joshua. Almost every audio component is sensitive to power cord quality and cleanliness.
  Reply With Quote
Old 27th July 2011, 06:52 PM   #14364
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
OK, here is what I was doing today.

Instead of showing what happens on a scope when a very low level signal goes through a component, I decided to show how noise is generated. Shown is a switch switching two different signals both a 1k sine wave, but one 100 times the voltage of the other. The lower voltage creates much more noise because it is not being switched cleanly.

Also shown is a soldered jumper. It is quiet even at the lower voltage.

Yellow is the capacitor from yesterday at the higher voltage. Magenta mostly hidden by the almost the same red is the switch at higher voltage. Dark blue is the switch at lower voltage. Light blue is the jumper. The red is a pot wiper in the mix. It is at high voltage and is slightly noisier than the switch, but better than the cap.

You can see the difference in test voltages but only the top color shows (The light blue hides the dark blue as both are exactly the same.)

Just to be sure the AP is powered from the AC iso transformer!

0 db is around 1 V rms
Attached Images
File Type: jpg 1 nv sw 100nv sw 1nv short.JPG (459.4 KB, 213 views)

Last edited by simon7000; 27th July 2011 at 07:03 PM.
  Reply With Quote
Old 27th July 2011, 07:27 PM   #14365
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Ed,
Quote:
I though profanity was not allowed, Computer power supl....! Wow what a nasty term!

Pretty much!
Quote:
Actually my scope throws off enough energy to show up on sensitive measurements!
I have a Philips PM3070 scope that shuts down any FM calibration. It's is horrible for RF emissions! Keep in mind that I've owned this from new, so it's lived a known, easy life. I got another of the same model, same problems. That's got to be pretty bad in anyone's books. I just got a Tek 2465B CT. I sure hope it doesn't suffer the same faults!

On the current peaks ... yes. What can go on may really be an eye opener for some people out there.

Hi John,
Quote:
Almost every audio component is sensitive to power cord quality and cleanliness.
I'm really sorry John, this isn't true for all equipment. There are some designs where the power supply has been done correctly. The end result of a well designed power supply (and the rest of it) is that they are relatively immune to minor power supply problems. These certainly are immune to a problem where they can sound different depending on what power cord is used. In fact, if what you are alleging is true, nothing short of a permanently attached power supply cable would be acceptable.

Now, before we start to go on about equipment that doesn't have enough resolution (hogwash), just consider all the extremely sensitive test equipment out there that use IEC power cords. These are far more sensitive than any audio equipment made by anyone - sorry.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote
Old 27th July 2011, 08:18 PM   #14366
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally Posted by simon7000 View Post
There is no power at 0 volts.
ES
Huh? And the rocketts only perform twice on saturday..

I need more splainin dude..

Cheers, John
  Reply With Quote
Old 27th July 2011, 08:31 PM   #14367
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by jneutron View Post
Huh? And the rocketts only perform twice on saturday..

I need more splainin dude..

Cheers, John
What I am looking for is what happens when you go from no power to some small level. The common assumption is that ohms law holds. I think that when there is a contact some minimum voltage must occur before conduction starts.

The electrolytic capacitor was used because it has mechanical connections inside a reasonably well sealed case. Of course there are lots of other issues in that case. I was trying to demonstrate the issue with a scope plot. Seems that was not clear enough. So instead I am showing how "Noise" increases as level drops across a switch but not in a soldered connection.

I also expect "Noise" to increase with other factors, but a few more tests need to be done.

Now if you want to talk about voltage and phase shift current in a 1000 uf cap at 20 mv from a 100 ohm source to a 5m input it is there but it ain't much!
  Reply With Quote
Old 27th July 2011, 09:21 PM   #14368
diyAudio Member
 
vacuphile's Avatar
 
Join Date: Apr 2011
Location: Seaside
Quote:
Originally Posted by jneutron View Post
Huh? And the rocketts only perform twice on saturday..

I need more splainin dude..

Cheers, John
I still don't get it either.

Last edited by vacuphile; 27th July 2011 at 09:23 PM.
  Reply With Quote
Old 27th July 2011, 10:03 PM   #14369
diyAudio Member
 
Joshua_G's Avatar
 
Join Date: Nov 2008
Location: Small village, Israel
Quote:
Originally Posted by anatech View Post
Hi Joshua,
At the risk of freaking you out, Ed isolated what caused his troubles in that case. The trouble was caused by poor connections in his IEC power connection. A real problem that he fixed. You are extending this into directions far beyond what that evidence would support.

Iff (if and only if) you solve a problem, you may improve the performance of a system. Sometimes you have to solve many actual, real problems before a system behaves at a high level expected of it.
You aren't freaking me out in any way.

There are 2 separate issues here, yet, they are connected.
Actually, it's but one issue, observed under two conditions.
It turns out that electricity supply, in many cases has a big impact on sound systems (and on measurement systems).
Isolation transformers do make a difference.
The resistance of power cords do make a difference.
The screen of power cords do make a difference.
The resistance (or oxidation) of power connectors do make a difference.

Now, it seems that there are two parties here, concerning the views about the real impact of electricity supply on sound systems. One party tend to deny such in impact, on the ground that such impact isn't proved scientifically. As long as it isn't proved scientifically, to them, it doesn't exist, not in reality, apart from the imagination of "audiophiles".

When such an impact is shown in a measurement system, as was the case Ed Simon reported here, the "imagined" impact isn't valid anymore.

Most audiophiles don't make measurements on their sound system, especially not on the system as a whole. Yet many audiophiles report audible impact of isolation transformers, different power cords and power outlet sockets.

My point is that the impact of those things on the sound of a system may well be a very real one, not imagined one. Ed Simon's report is an indication for such a possibility, for a real and genuine impact on the mains power supply on the sound of the system.
  Reply With Quote
Old 27th July 2011, 10:08 PM   #14370
diyAudio Member
 
Joshua_G's Avatar
 
Join Date: Nov 2008
Location: Small village, Israel
Quote:
Originally Posted by anatech View Post
I'm really sorry John, this isn't true for all equipment. There are some designs where the power supply has been done correctly. The end result of a well designed power supply (and the rest of it) is that they are relatively immune to minor power supply problems. These certainly are immune to a problem where they can sound different depending on what power cord is used. In fact, if what you are alleging is true, nothing short of a permanently attached power supply cable would be acceptable.
This may well be so (that there is audio electronics gear on the market that is immune to whatever may happen on the mains power supply).

Only, so far I haven't encountered such gear.
It may be useful if you'd give actual examples.
  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 02:13 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