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[tom eaton]

Hey folks-

The talkback button on my Otari Elite sends a rather loud click down the headphone feeds when I push it.  Is there something I can put in the audio line to soften the switching in of the talkback mic?  The physical switch is easily accessible, and then feeds all 8 sends.  I don't know if there's amp post switch.  I'll have to check the schematics, which I have.  

Any thoughts appreciated.

-tom

[Geoff_T]

TER wrote on Sun, 19 September 2004 06:18

Hey folks- The talkback button on my Otari Elite sends a rather loud click down the headphone feeds when I push it.  Is there something I can put in the audio line to soften the switching in of the talkback mic?  The physical switch is easily accessible, and then feeds all 8 sends.  I don't know if there's amp post switch.  I'll have to check the schematics, which I have.   Any thoughts appreciated. -tom

Hi

The usual reason for clicks is a voltage difference between the off and on contacts. Usually there's an amplifier feeding the switch that has to be tied to the same 0v as the bus bar it's feeding. The output coupling cap shouldn't be leaky (check that) and should have a pull down resistor to that same 0v potential.

You can also tie high value resistors around the contacts of the switch but my instincts tell me that's a bodge and you need to fix the real fault.... perhaps that cap?

Did it always click?

[bobkatz]

Make you sure it's not an acoustic pickup of your heavy fingers by the talkback mike itself  

BK

[Mark Donahue]

Dear Tom,
One other thing to check is if the switch is actually actuating a relay to route the talkback or if the switch is actually passing the audio directly.
If it is a relay system there are a couple of things to check. Does the coil of the relay have a diode across the coil? If it doesn't, this is often a source of a large click.
All the best,
Mark
*******************
Mark Donahue
Soundmirror, Inc.
Boston, MA
www.soundmirror.com
*******************

[tom eaton]

Thanks for feedback so far...

I don't know if it always clicked, I've only owned the board for a month.  I'll check to see if the switch is triggering a relay, not sure.  

What makes you think my fingers are heavy, Bob?

I'll check on the output cap, too.  Sounds like you all are thinking there's some DC on the line going through the switch...I wonder if the ambient noise in the control room (or noisy talkback mic preamp) is keeping some constant signal there and that's the source of the click voltage.

My original thought was to put a cap just after the switch to absorb the burst of noise...not sure if that would do it, though, or what value to use.

It's way louder than it should be, though...enough that folks with the phones on are mentioning it.  I'd love to have a 30 or even 50ms ramp up...that would be so much nicer in the cans than the sudden control room ambience.  

I'll check the schematics and post my findings tomorrow.

Thanks so much for the help-

Tom

[bobkatz]

TER wrote on Sun, 19 September 2004 23:40

What makes you think my fingers are heavy, Bob?

No offense intended! It was followed by a sign!  Just wanted to eliminate the possibility of acoustic pickup by the microphone. I've seen it happen, mike is mounted on the console surface and picks up drumming fingers....

You could also try a compressor/limiter on the preamp. Keeps the musicians from suing you for lost eardrums.


BK

[ssltech]

On Neve V-series for example, it was an acoustic pickup of the mechanical activastion of the switch itself. -All V-series did it! -We looked into adding a slowly-ramped off FET mute circuit, but I never got round to it.

Keith

[Rich Breen]

ssltech wrote on Tue, 21 September 2004 15:47

On Neve V-series for example, it was an acoustic pickup of the mechanical activastion of the switch itself. -All V-series did it!... Keith

Yup, lots of consoles do this - one of the reasons I'll frequently use a remote talkback switch even though the main switch is right in front of me...

best,
rich