Keyboard output circuit - stereo/mono

f69tele · 15th September 2011, 02:44 AM

Tried to search for a topic/thread on this and didn't really find one...

when a keyboard or sound module has stereo outputs labeled as follows:

Left/mono - Right

what is the typical internal circuitry that makes the signal mono when a cable is plugged only in the LEFT/MONO output?

Michael Bean · 15th September 2011, 03:15 AM

The right channel jack has a switching contact that connects the channels together unless a plug is inserted, then it becomes stereo.

Mike

f69tele · 15th September 2011, 02:31 PM

Hmmm, ok. Thanks. So, there is no additional resistors, diodes, caps or any other components to alter the audio signal to make it MONO on the left?

sreten · 15th September 2011, 03:00 PM

Hi,

Yuo can't simply connect two separate outputs together to derive a mono mixed version.

There has to be some additional complication, e.g. the switching on the right socket
is some form of control signal that goes back to some digitally controlled mixer.

Or the mono signal is simply the left channel only ......

rgds, sreten.

f69tele · 15th September 2011, 03:02 PM

So would the mono signal be the left with a little bit of the right mixed in?

sreten · 03:18 PM

Hi, it will be L only or properly mixed L+R depending on how its done. Rgds, sreten.

(A lot of stuff is essentially mono, with the only stereo being effects e.g. reverb.
In these cases often mono out is simply the mono signal with only left effects,
the (missing) right channel being the mono signal with right effects. This was
typical of many reverbs. L and R in being mixed to mono first, any stereo
in the output was due to the reverb processing applied.)

f69tele · 16th September 2011, 12:54 AM

okay thanks makes sense. How about a signal on a digital piano where the sampled piano was either sampled in stereo, or the sampled sound has been applied across the stereo spectrum? Is there a proper way to combine the R&L stereo signal to mono so that it doesn't sound out of phase? Thanks.

sreten · 16th September 2011, 11:36 AM

Hi,

A proper stereo piano with a mono output should arrange that to be correct.

rgds, sreten.

f69tele · 16th September 2011, 03:04 PM

ok, so back to the original question. Does anyone know what the internal circuitry of said "proper stereo piano with mono output".. is?

sreten · 16th September 2011, 03:13 PM

Hi,

Any number of ways of doing it properly, What keyboard ? service manual ?

rgds, sreten.

15th September 2011, 02:44 AM	#1
f69tele diyAudio Member Join Date: Sep 2011	Keyboard output circuit - stereo/mono Tried to search for a topic/thread on this and didn't really find one... when a keyboard or sound module has stereo outputs labeled as follows: Left/mono - Right what is the typical internal circuitry that makes the signal mono when a cable is plugged only in the LEFT/MONO output?

15th September 2011, 03:00 PM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Yuo can't simply connect two separate outputs together to derive a mono mixed version. There has to be some additional complication, e.g. the switching on the right socket is some form of control signal that goes back to some digitally controlled mixer. Or the mono signal is simply the left channel only ...... rgds, sreten. __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

15th September 2011, 03:09 PM	#6
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, it will be L only or properly mixed L+R depending on how its done. Rgds, sreten. (A lot of stuff is essentially mono, with the only stereo being effects e.g. reverb. In these cases often mono out is simply the mono signal with only left effects, the (missing) right channel being the mono signal with right effects. This was typical of many reverbs. L and R in being mixed to mono first, any stereo in the output was due to the reverb processing applied.) __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow Last edited by sreten; 15th September 2011 at 03:18 PM.

16th September 2011, 11:36 AM	#8
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, A proper stereo piano with a mono output should arrange that to be correct. rgds, sreten. __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

16th September 2011, 03:13 PM	#10
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Any number of ways of doing it properly, What keyboard ? service manual ? rgds, sreten. __________________ There is nothing so practical as a really good theory - Ludwig Boltzmann When your only tool is a hammer, every problem looks like a nail - Abraham Maslow


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15th September 2011, 03:15 AM	#2
Michael Bean diyAudio Member Join Date: Sep 2004 Location: Minneapolis, Minnesota, USA	The right channel jack has a switching contact that connects the channels together unless a plug is inserted, then it becomes stereo. Mike

15th September 2011, 02:31 PM	#3
f69tele diyAudio Member Join Date: Sep 2011	Hmmm, ok. Thanks. So, there is no additional resistors, diodes, caps or any other components to alter the audio signal to make it MONO on the left?

15th September 2011, 03:02 PM	#5
f69tele diyAudio Member Join Date: Sep 2011	So would the mono signal be the left with a little bit of the right mixed in?

16th September 2011, 12:54 AM	#7
f69tele diyAudio Member Join Date: Sep 2011	okay thanks makes sense. How about a signal on a digital piano where the sampled piano was either sampled in stereo, or the sampled sound has been applied across the stereo spectrum? Is there a proper way to combine the R&L stereo signal to mono so that it doesn't sound out of phase? Thanks.

16th September 2011, 03:04 PM	#9
f69tele diyAudio Member Join Date: Sep 2011	ok, so back to the original question. Does anyone know what the internal circuitry of said "proper stereo piano with mono output".. is?

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