Loud plop on input

[Gordon Youd]

Can some kind soul out there help??

I am switching sound outputs from various sound chips into a mixer using
logic switching, when it switches there is a loud plop I don't know how to
get rid of it.

Kind regards, Gordon

 

[Sir Charles W. Shults III]

"Gordon Youd" <gordon@nospamgyoud.demon.co.uk> wrote in message
news:c3eu5g$nv7$1$8302bc10@news.demon.co.uk...

Can some kind soul out there help??

I am switching sound outputs from various sound chips into a mixer using
logic switching, when it switches there is a loud plop I don't know how to
get rid of it.

Kind regards, Gordon

This is caused by different DC levels on the various signal inputs you
are switching. You need something that will eliminate that difference or
get around it.
The typical answer is a "no-thump keyer". That is a device that
switches "slowly" by ramping a FET on to allow the input signal to be
switched. Instead of a rapid transition, you get a smooth, slowly rising
waveform that cannot thump.

Cheers!

Chip Shults

 

[JeffM]

device that switches "slowly" by ramping a FET
Chip Shults

As Win points out in AoE section 3.12 (Glitches),
the area under the curve doesn't change.

The trick is to shunt the output of the switch network
as the series connection is being changed.
Some IC makers (and one might extrapolate, some switch manufacturers)
design this in.

 

[Sir Charles W. Shults III]

"JeffM" <jeffm_@email.com> wrote in message
news:f8b945bc.0403191104.1302acdc@posting.google.com...

device that switches "slowly" by ramping a FET
Chip Shults

As Win points out in AoE section 3.12 (Glitches),
the area under the curve doesn't change.

The trick is to shunt the output of the switch network
as the series connection is being changed.
Some IC makers (and one might extrapolate, some switch manufacturers)
design this in.

I'm not sure what you are getting at- I have made three of these for
musicians and they work. Empirical observation beats theoretical work any
day.

Cheers!

Chip Shults

 

[JeffM]

I have made three of these for musicians and they work.
Chip Shults

Empirical data is good stuff.
Walter Harley has been trying something similar
and in his application it doesn't give him the results he needs.
http://groups.google.com/groups?q=%22the+longer+I+ramp,+the+more+of+the+first+note+I+lose%22&hl=en&lr=lang_en&ie=UTF-8&oe=UTF-8&safe=off&scoring=d&selm=c3je8n%24ndb%240%40216.39.172.65&rnum=1