mixer and crosstalk..help!!! - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 23rd May 2012, 05:48 PM   #1
diyAudio Member
 
Join Date: May 2012
Exclamation mixer and crosstalk..help!!!

please help me ...

I'm making a circuits audio but there is a problem with the circuit ..

so this story:
I'm making some of the mixer group. each of these mixers have no connection at all with the audio mixer other, only the power supply connections to connect all the mixer (+12 v, 0 v, -12 v) ..

each mixer is connected with some "pre amp + mic​​" and "power amplifier headset +" ..
I use the input-output Unbalanced and cable length between the pre amp with a mixer and mixer with power amplifier is more than 1 meter ....

My question is why there is a kind of crosstalk interference in the audio system?!?! audio on each mixer can be heard in another mixer ..
what is the solution to solve the problem?!?!

This attachment is a schematic of the audio system that I created
Attached Images
File Type: png mixer grup.png (25.7 KB, 84 views)
  Reply With Quote
Old 23rd May 2012, 10:49 PM   #2
diyAudio Member
 
Speedskater's Avatar
 
Join Date: Sep 2002
Location: Lakewood, Ohio
Are these balanced or un-balanced inputs and outputs?
Each and every signal, power supply and ground wire has to be considered. There is a correct way to connect each of these wires and many incorrect ways.
A common power supply can also cause crosstalk problems.
Do you have more detailed drawings of the sub-sections?
__________________
Kevin
  Reply With Quote
Old 23rd May 2012, 10:56 PM   #3
diyAudio Member
 
Speedskater's Avatar
 
Join Date: Sep 2002
Location: Lakewood, Ohio
This paper is a good start on wiring.

Audio Component Grounding and Interconnection
__________________
Kevin
  Reply With Quote
Old 25th May 2012, 07:43 AM   #4
diyAudio Member
 
Join Date: Feb 2006
Location: On a hill, in a wooden shack, next to the woods, in Somerset.
Look to your grounds. I would guess that you have common paths back to the main ground. If it is from one mixer console to another, which is what it sounds like then the grounds from those two should meet only at the ground chosen from your power supply.
  Reply With Quote
Old 25th May 2012, 03:36 PM   #5
diyAudio Member
 
Join Date: May 2012
I've tried doing a ground connection type star, but still there is crosstalk ..

This is a sub section of my circuit .. pre amplifiers and power amplifiers are located on one PCB and connected to the mixer with a cable length of more than 1 meter ... type of headset and mic that I use is a computer headset and mic ..

is there something wrong with the circuit?!?!
Attached Files
File Type: pdf mixer section.pdf (33.4 KB, 27 views)
File Type: pdf amplifier section.pdf (33.9 KB, 20 views)
  Reply With Quote
Old 27th May 2012, 08:48 AM   #6
diyAudio Member
 
Join Date: Mar 2012
You can troubleshoot the channel with crosstalk by grounding signal path in safe for components points .
So far thereís unclear how your power amp and pre-amp switches are working.Switch can be closed by applied small positive current and opened by negative ,relatively to emitter, voltage . Filtering capacitor wouldnít hurt here at switch output too.
It was possible to transmit in two times higher level signal through cable if pre-ampís R12 and R16 resistors were placed at mixer board. At least you can use SMD to replace R16.
  Reply With Quote
Old 27th May 2012, 04:10 PM   #7
diyAudio Member
 
Join Date: May 2012
sw_preamp and sw_pwramp connected to I / O microcontroller so that the headset and / or mic can be enabled or disabled by the microcontroller ..

I agree with Speedskater and ChristianThomas,, may be the cause of my problem is ground path from the common power supply ..

if i use a power supply for each set of audio, switching circuit can not work because the ground is connected to the other power supply ... should I separate the ground for circuit switching with audio ground?!?!

is there an additional circuit to eliminate crosstalk?
my Should alter or Unbalanced input and output into a balanced input and output?!?!

is there any advice?!?!
  Reply With Quote
Old 27th May 2012, 08:05 PM   #8
diyAudio Member
 
Join Date: Mar 2012
Preamp works in very small current modes, only two milli-amper ripples are here.
I canít help here with grounding. These things you have to check yourself. Ideally, mixer and phone amp boards should have decoupling capacitors.
Schematically, the weakest place is cable between mixer and preamp. For example, when trim resistor R12 is set in middle position your output resistance is 47kOm, in min and max position 22-24kOhm. Such connection will be very sensitive to any capacitive or inductive influences from other cables. In context of stable output resistance the decoupling capacitor at switch output becomes a must.
  Reply With Quote
Old 30th May 2012, 03:28 AM   #9
diyAudio Member
 
Join Date: May 2012
What is your opinion if I add the 78xx and 79xx regulators on each mixer for grounding problem?!?! will be affected?!?!

Is the addition of regulator look like using the power supply to each mixer?
  Reply With Quote
Old 30th May 2012, 07:11 AM   #10
diyAudio Member
 
Join Date: Mar 2012
As far you don’t have a problem with power noise rejection, there would be enough of using the decoupling, film or ceramic, capacitors 0.25-1mkf,mounted right on the board.
I hope your power supply has enough of juice to hold the null potential.
If you have o-scope, you can connect power rails by two series capacitors, bypassed by resistors. Their central point will give you virtual “ideal” ground to check if there are noises in real ground.
The crosstalk from ground can came from grounded differential inputs in mixer and power amp section . Just short the signal path to the ground, at mixer input, and it will be clear is it preamp with its cable or ground problem.
By the way, boards, especially without strong decoupling capacitors, must be powered from star type connection too.
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
mixer and crosstalk herryawan Solid State 0 23rd May 2012 05:44 PM
Interaural crosstalk eStatic Everything Else 3 28th February 2008 04:53 PM
2 channels to 1 crosstalk dreamtear Parts 1 19th January 2008 01:42 AM
Crosstalk cancellation Prune Digital Source 10 19th January 2006 02:19 PM
A question on crosstalk sardonx Solid State 6 21st June 2004 11:45 PM


New To Site? Need Help?

All times are GMT. The time now is 03:45 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