Hello everybody, noob here.
I want to mix the left and right channel of an mp3 player into one. I've seen some schematics which ony use a potentiometer and a resistor per channel and then combining the outputs into one. Can I just ditch the pots and just use a resistor? What value would be ideal?
I'm sorry if this question has been asked many times but I've done some research but I could not find the answers to my questions.
I want to mix the left and right channel of an mp3 player into one. I've seen some schematics which ony use a potentiometer and a resistor per channel and then combining the outputs into one. Can I just ditch the pots and just use a resistor? What value would be ideal?
I'm sorry if this question has been asked many times but I've done some research but I could not find the answers to my questions.
A single resistor from each channel to a common output works fine. From headphone outputs, resistors of about 1000 Ohms each, give or take a lot, should do ya.
This simple mix has the unintended effect of exaggerating signal that was already common to both channels, worst case by 6dB. This is minimized by adding a third resistor from the output junction to ground, the smaller the less common-mode effect. Of course this costs you some signal level, so you'll need to experiment. Maybe try another 1000 Ohm resistor and see if you like it.
All good fortune,
Chris
This simple mix has the unintended effect of exaggerating signal that was already common to both channels, worst case by 6dB. This is minimized by adding a third resistor from the output junction to ground, the smaller the less common-mode effect. Of course this costs you some signal level, so you'll need to experiment. Maybe try another 1000 Ohm resistor and see if you like it.
All good fortune,
Chris
Are you sure? With two resistors you get the average of the two channels, delivered at an impedance of half the resistor value plus half the source output impedane. Adding a third resistor merely attenuates that signal and reduces the source impedance. You still get the average of the two channels, but a bit smaller. Mr. Thevenin has something to say about this.Chris Hornbeck said:
This may be what you are looking for...schematic on page.
http://www.rolls.com/pdf/M_MX41.pdf
btw, these are only $45.
http://www.rolls.com/pdf/M_MX41.pdf
btw, these are only $45.
some DAP may do this in sw - look for a way to select "mono" or set stereo separation to 0
certainly can be done in ROCKbox Rockbox - Free Music Player Firmware
still shouldn't short R,L outputs together - make a cable adapter if you need 1/8" mono ouput
certainly can be done in ROCKbox Rockbox - Free Music Player Firmware
still shouldn't short R,L outputs together - make a cable adapter if you need 1/8" mono ouput
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Let's imagine a worst case, signal in one channel only, no loading on output of the mix. Each channel sees the other (zero source Z) through two series resistors, so signal to the output is reduced 6dB. Now same signal on both channels, no loss to outputs. Active mixers use (active) virtual grounds to eliminate this effect.
Actually, it's complicated by the 3dB summing of two speakers into a room, but...
Thanks,
Chris
You are confusing two quite different issues. Active mixers use virtual grounds to eliminate something else: the interaction between slider positions which a simple mixer would give.Chris Hornbeck said:
As I said, two resistors give the average of the two channels. Your example confirms this: the average of 1 and 0 is 0.5; the average of 1 and 1 is 1. Adding another resistor to ground does not change this, as the output gets reduced by the same ratio. For example, if the resistor to ground is equal to half the other two, then you get 0.25 and 0.5 respectively as the output signal is halved. This is a simple application of Ohm's Law and knowledge of potential dividers.
If you want something other than the average of the two channels, scaled by some constant, then you need to do something far more sophisticated.
Doh! You're right - there's no simple resistive Y that doesn't give a 3dB boost to signals common to both channels (over the 3dB summing of speakers in rooms). Thanks much for the lesson - I've been drifting along with an old saw from the Klipsch derived center channel days that's never been true.
It must have come from analogy to stereo panpotting practice, where a source panned center is reduced 3dB to each channel compared to its level panned fully left or right. From speakers this adds as not correlated, and all's well. But simple resistive mixers (apparently, now that you've made it clear) add to 6dB, 3dB hot. Simple panpots can mix correctly, but simple resistive Y's can't undo it. Very interesting.
Thanks, as always,
Chris
You put a link to a MSN password protected page. Is that what you wanted to do?An externally hosted image should be here but it was not working when we last tested it.
Try attaching your picture directly like this,
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
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