DCAudioDIY.com

DC Area Audio DIYer's Community
It is currently March 28th, 2024, 7:01 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 35 posts ]  Go to page Previous  1, 2, 3, 4  Next
Author Message
PostPosted: June 23rd, 2021, 11:19 am 
Offline

Joined: July 17th, 2016, 6:24 am
Posts: 1099
Roscoe Primrose wrote:
Waveform distortion can cause the average value to no longer be 0V.....

Roscoe


That only effects the DC offset of AC, but that does not mean there is actually DC current in the wires.
Walt's question is valid IMO.


Top
 Profile  
 
PostPosted: June 23rd, 2021, 11:24 am 
Offline
Site Admin
User avatar

Joined: February 28th, 2013, 10:38 am
Posts: 1682
Cogito wrote:
Roscoe Primrose wrote:
Waveform distortion can cause the average value to no longer be 0V.....

Roscoe


That only effects the DC offset of AC, but that does not mean there is actually DC current in the wires.
Walt's question is valid IMO.


Yes, it does. That's where toroidal transformers have problems, they're not at all happy with even small DC currents since most of them have no gap.

Roscoe

_________________
I can explain it to you, but I can’t understand it for you.


Top
 Profile  
 
PostPosted: June 23rd, 2021, 11:46 am 
Offline
User avatar

Joined: July 24th, 2015, 4:17 pm
Posts: 1701
Location: Parkville, Maryland
Roscoe Primrose wrote:
Waveform distortion can cause the average value to no longer be 0V.....

Roscoe

The zero crossing point is the same whether or not the sine wave is distorted or not. So -- where does the DC come from if at all?

_________________
Walt


Top
 Profile  
 
PostPosted: June 23rd, 2021, 12:04 pm 
Offline
User avatar

Joined: February 19th, 2017, 9:43 am
Posts: 530
Why wouldn't the average value settle to 0 VDC?

_________________
I have too much stuff - https://www.pleasebuymystuff.com


Top
 Profile  
 
PostPosted: June 23rd, 2021, 12:13 pm 
Offline
Site Admin
User avatar

Joined: February 28th, 2013, 10:38 am
Posts: 1682
https://eprints.usq.edu.au/75/1/AshleyK ... -_2004.pdf

_________________
I can explain it to you, but I can’t understand it for you.


Top
 Profile  
 
PostPosted: June 23rd, 2021, 12:53 pm 
Offline

Joined: April 22nd, 2013, 12:58 pm
Posts: 285
If you integrate the positive and negative waveforms independently you will get results that are not equal. The difference between them will create a DC offset.
Here's a wildly exaggerated example:
Image

SoundMods wrote:
Roscoe Primrose wrote:
Waveform distortion can cause the average value to no longer be 0V.....

Roscoe

The zero crossing point is the same whether or not the sine wave is distorted or not. So -- where does the DC come from if at all?


Top
 Profile  
 
PostPosted: June 23rd, 2021, 1:26 pm 
Offline
User avatar

Joined: July 24th, 2015, 4:17 pm
Posts: 1701
Location: Parkville, Maryland
Roscoe Primrose wrote:
https://eprints.usq.edu.au/75/1/AshleyKarlZEIMER_-_2004.pdf

OK. I read that kid's white paper and I get it. But when the electronics "see" DC from the smoothed full-wave bridge with storage caps smoothing out the ripple, and maybe, if you're lucky, a choke coil that takes it further, then you have shunt or series regulation that does its thing -- how on earth can that DC component even possibly have any impact on sound quality? :confusion-confused:

I mean -- WOW!-- This whole "DC thing" is right up there with UFO sightings.

_________________
Walt


Top
 Profile  
 
PostPosted: June 23rd, 2021, 2:30 pm 
Offline
User avatar

Joined: January 15th, 2015, 7:19 am
Posts: 1697
Location: Baltimore MD
Rod Elliott "ESP"
Said the same thing DC blocker will have nothing to do with the sound quality on buzzing transformers
I have mentioned this in other threads that once in a while I would come into my sound room and hear a tranny buzzing. I determined that it was the Toroid tranny in my isolation transformer for my line-level equipment.
I would unplug the iso and a whole later plug it back in and the buzzing was gone, until the next time.
Since I have been fooling around with DC blockers I have not had that problem.
I have heard no changes to the music due to this.


Top
 Profile  
 
PostPosted: June 23rd, 2021, 3:47 pm 
Offline
User avatar

Joined: January 13th, 2016, 9:14 pm
Posts: 787
In the case of toroidal power transformers, getting rid of the AC line DC eliminated the mechanical hum in my case by dropping the line distortion.

Just about any amount of DC to the toroidal core saturates it as Roscoe said earlier and makes them mechanically hum.

That gets rid of acoustical noise in the room. Important in a quiet room.


Top
 Profile  
 
PostPosted: June 24th, 2021, 1:07 pm 
Offline

Joined: March 2nd, 2013, 2:43 pm
Posts: 216
Location: Potomac, MD
A half-wave rectifier will put dc on the power line. Equipment that uses half-wave rectification has low power draw, so it would be small. Inductive loads, transformers, including the mains transformer will shunt most of this. Distortion is probably the bigger issue making transformers buzz. Of course a half-wave load will make distortion. Anything with a power factor less than 1 makes distortion too. I put power factor correction in my power amps for this reason. For preamps I don't bother because the power draw is low.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 35 posts ]  Go to page Previous  1, 2, 3, 4  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 36 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group