Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Foo Off-Topic chit chat with no general subject.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-17-07, 09:20 AM   #1
Nicodemus
Feral Member
Thread Starter
 
Nicodemus's Avatar
 
Join Date: Apr 2004
Location: Roma, Italia
Bikes: yes, I have one.
Posts: 2,666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
electronics problem - arcing in audio system

Hey all, I thought I'd throw this out to Foo in the hope that some bright spark is lurking here...

We've got an audio system chaining from source through to preamp, then audio actuators on to voltage controlled amps, then to power amps.

The problem is in the steps from audio actuators to the power amps. When you switch channels on (via controls in the listening rooms), the relay contacts in the actuators close and since the power amp is always on it's pulling down the current.

Thus arcing occurs in the actuator and this results in an almighty 'pop' at the speaker end. It's really quite unacceptable.

(did that make much sense?)

What are some possible ways of dealing with this? There doesn't seem to be any way of controlling any "ramping up" of voltage in any of the amps, and the power amp is not controllable (i.e. must always be on).
__________________
Quote:
Originally Posted by KrisPistofferson View Post
Did you just say "minarchist?" I'm going to start a 10-page vaginathon because only Libertarians can define Libertarianism. Also, you're mean.
Nicodemus is offline   Reply With Quote
Old 09-17-07, 01:39 PM   #2
Tom Stormcrowe
Out fishing with Annie on his lap, a cigar in one hand and a ginger ale in the other, watching the sunset.
 
Tom Stormcrowe's Avatar
 
Join Date: Mar 2006
Location: South Florida
Bikes: Techna Wheelchair and a Sun EZ 3 Recumbent Trike
Posts: 16,118
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Change out the channels switch to a fader? Fade from A--->B--->C instead of a hard switchover?
Quote:
Originally Posted by Nicodemus View Post
Hey all, I thought I'd throw this out to Foo in the hope that some bright spark is lurking here...

We've got an audio system chaining from source through to preamp, then audio actuators on to voltage controlled amps, then to power amps.

The problem is in the steps from audio actuators to the power amps. When you switch channels on (via controls in the listening rooms), the relay contacts in the actuators close and since the power amp is always on it's pulling down the current.

Thus arcing occurs in the actuator and this results in an almighty 'pop' at the speaker end. It's really quite unacceptable.

(did that make much sense?)

What are some possible ways of dealing with this? There doesn't seem to be any way of controlling any "ramping up" of voltage in any of the amps, and the power amp is not controllable (i.e. must always be on).
__________________
. “He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you.”- Fredrick Nietzsche

"We can judge the heart of a man by his treatment of animals." - Immanuel Kant
Tom Stormcrowe is offline   Reply With Quote
Old 09-17-07, 02:19 PM   #3
Nicodemus
Feral Member
Thread Starter
 
Nicodemus's Avatar
 
Join Date: Apr 2004
Location: Roma, Italia
Bikes: yes, I have one.
Posts: 2,666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
The point of the actuator is to control channel switching from control panels in the rooms. Unfortunately there is no inherent fade or ramping ability in the devices.

The arcing occurs because the power amp is always on. So as soon as the contact closes it yanks the power from the actuator which causes the arcing.

We even tried a time delay by giving power to the intervening voltage-control amp after the actuator switches, but no dice.
__________________
Quote:
Originally Posted by KrisPistofferson View Post
Did you just say "minarchist?" I'm going to start a 10-page vaginathon because only Libertarians can define Libertarianism. Also, you're mean.
Nicodemus is offline   Reply With Quote
Old 09-17-07, 02:32 PM   #4
DannoXYZ 
Senior Member
 
DannoXYZ's Avatar
 
Join Date: Jul 2005
Location: Saratoga, CA
Bikes:
Posts: 11,606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
A capacitor will dampen the arc. Calculate what value you need to as to not filter any of the audio signal. This would be based upon the impedance of the circuit along with the inductance of the wires.
DannoXYZ is offline   Reply With Quote
Old 09-17-07, 03:00 PM   #5
Nicodemus
Feral Member
Thread Starter
 
Nicodemus's Avatar
 
Join Date: Apr 2004
Location: Roma, Italia
Bikes: yes, I have one.
Posts: 2,666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
^ yeah, a capacitor is the best thing we've thought of so far. If no other ideas come to mind I think we'll have a stab at sticking a capacitor in each circuit. It just may be the brilliantly simple solution we need.
__________________
Quote:
Originally Posted by KrisPistofferson View Post
Did you just say "minarchist?" I'm going to start a 10-page vaginathon because only Libertarians can define Libertarianism. Also, you're mean.
Nicodemus is offline   Reply With Quote
Old 09-17-07, 03:07 PM   #6
randya
Senior Member
 
randya's Avatar
 
Join Date: Jul 2003
Location: in bed with your mom
Bikes: who cares?
Posts: 13,689
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
the relays are normally supposed to provide a delay that prevents power surges from being heard as a pop through the speakers. Capacitors are normally used to filter 60 cycle hum out of the power supply. are you sure you're using correctly sized relays and the correct relay circuit?
randya is offline   Reply With Quote
Old 09-17-07, 03:07 PM   #7
jsharr
You Know!? For Kids!
 
jsharr's Avatar
 
Join Date: Apr 2005
Location: Just NW of Richardson Bike Mart
Bikes: '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
Posts: 6,157
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
MacGuyver it with three tic tacs, (one orange, two wintergreen, duh) the tang off your belt buckle, a gum wrapper and a strip of duct tape. The duct tape is not entirely necessary, but lends authenticity.
__________________
Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
Quote:
Originally Posted by colorider View Post
Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.
jsharr is offline   Reply With Quote
Old 09-17-07, 05:31 PM   #8
Nicodemus
Feral Member
Thread Starter
 
Nicodemus's Avatar
 
Join Date: Apr 2004
Location: Roma, Italia
Bikes: yes, I have one.
Posts: 2,666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Quote:
Originally Posted by randya View Post
the relays are normally supposed to provide a delay that prevents power surges from being heard as a pop through the speakers. Capacitors are normally used to filter 60 cycle hum out of the power supply. are you sure you're using correctly sized relays and the correct relay circuit?
We have no control over the relays - they're just the bits inside the actuators that we're using. They're supposed to be used with the same brand power amp (presumably that would eliminate the problem), but their power amp is a POS.

There's no hum. We had good fun sorting out the myriad grounding issues, but that's clean now.

We'll try some capacitors I reckon.

That or the MacGyver solution
__________________
Quote:
Originally Posted by KrisPistofferson View Post
Did you just say "minarchist?" I'm going to start a 10-page vaginathon because only Libertarians can define Libertarianism. Also, you're mean.
Nicodemus is offline   Reply With Quote
Reply


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



All times are GMT -6. The time now is 08:48 PM.