electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » Circuit Bending
grounding confusion!
Post new topic   Reply to topic Moderators: dnny, v-un-v
Page 1 of 1 [5 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
cburn



Joined: Feb 22, 2015
Posts: 4
Location: Earth

PostPosted: Sun Feb 22, 2015 5:05 am    Post subject: grounding confusion!
Subject description: quasi bend of car eq Sparkomatic GE50
Reply with quote  Mark this post and the followings unread

Hi,

Is it bad to use several grounding points for a device? Especially when it comes to input and outputs? I just can not get this device to work as I want.

...

Longer description:

I am really just trying to get the ins and outs of a Sparkomatic car audio EQ to rca female or some other audio connector (the speakers included).

It has 4 channels out (speakers) with a ground connection each and 2 channels out with a shared ground.

When I disconnect the ground at for example the input channels something good happens at some place (like hum goes away), something else is gone (like panning).

[/img]


DSC_0049.JPG
 Description:
 Filesize:  1.86 MB
 Viewed:  20 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

DSC_0049.JPG


Back to top
View user's profile Send private message
PHOBoS



Joined: Jan 14, 2010
Posts: 2233
Location: Moon Base
Audio files: 415

PostPosted: Sun Feb 22, 2015 5:46 am    Post subject: Reply with quote  Mark this post and the followings unread

I can't say a whole lot about it but car amplifiers are usually the bridged type, which means that there are
2 amplifiers for each speaker with one being inverted. So the - is not the same as GND!

If you want to use this signal it should work if you only take the + speaker out and use the common GND,
or you could use a suitable transformer. You'll probably have to bring the signal level down though if you
want to convert it to RCA. With a transformer that can be done in one go otherwise 2 resistors as a voltage
divider could do it.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

_________________
"My perf, it's full of holes!"
http://phobos.000space.com/ http://www.acidtrash.com/ Stickney Synthyards
Back to top
View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger MSN Messenger
cburn



Joined: Feb 22, 2015
Posts: 4
Location: Earth

PostPosted: Sun Feb 22, 2015 9:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Ahh, ok thanks. I need to do some wiki reading on ground, earth, common etc.

But in the meanwhile, common GND would be the one from line in, right?

Also, say that I just want to attach a bunch of headphones (which would be equivalent to speakers), would your suggested solution still apply?

Thanks a lot!
Back to top
View user's profile Send private message
PHOBoS



Joined: Jan 14, 2010
Posts: 2233
Location: Moon Base
Audio files: 415

PostPosted: Sun Feb 22, 2015 10:53 am    Post subject: Reply with quote  Mark this post and the followings unread

yes the common GND is the shared GND which should be the one on your line in and the - of your power.
At least for car stereo where the - is GND. Earth doesn't apply here it's what you have on a mains connection and is literaly
a connection to the earth. Usually this will also be connected to GND but in some cases this can cause problems.

For headphones you wouldn't need anything special since it's just some speakers so you connect them in the same way.
Be careful though the output might be more than your headphones can handle. If you use a connector for your headphones
than you have to make sure it's isolated from the chassis/GND. (because of the bridged amplifier)

edit: just realized that on a headphones both - connection of the speakers are connected together so that
wouldn't actually work. However I think connecting it between + speaker output and GND should.

_________________
"My perf, it's full of holes!"
http://phobos.000space.com/ http://www.acidtrash.com/ Stickney Synthyards
Back to top
View user's profile Send private message Visit poster's website AIM Address Yahoo Messenger MSN Messenger
cburn



Joined: Feb 22, 2015
Posts: 4
Location: Earth

PostPosted: Tue Feb 24, 2015 3:02 am    Post subject: Reply with quote  Mark this post and the followings unread

I got it working now, thanks a lot.

I too assumed that the shared - on the headphones would be a problem, but I "solved" that by using a pair of headphones on each channel.

Maybe I will try a more flexible solution later, but this is the setup originally intended so it will do fine.

awesome!

Btw, one pair of the headphones makes a "sucking " sound, as if the speaker violently moves (maybe the wrong way), when I connect it to one of the (rca) jacks. Could this be the symptom of common GND touching the + or -? Of course I will just go over the connections, still it is nice to if possible know the reason.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: dnny, v-un-v
Page 1 of 1 [5 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Circuit Bending
Jump to:  

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 vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use