simple mixer circuit for wet/dry on effects unit...

[Dj Task Manager]

Im building a little effects thingy and want to add a knob to mix the dry signal with effected signal.  How do i do this with out it feeding back?

Something that lets the audio signal just travel one way or something i guess, the sort of thing that must be in a mixer...

Any thoughts on this would be greatly appreciated!

Dj Task Manager

[Matt the Modulator]

A crude but very  simple way is to get a pot lets say 100k wire the dry to the left pin and the wet to the right pin center pin is the out put through a 10uf elect cap (center pin to +ternanal) with a 1meg resistor to ground. try differant pots for which gives you the best mix. you may however find that you need to buffer the signals (especially the dry) if your using a low level signal like guitar this probably  wont work. try this mixer

http://www.muzique.com/schem/mixer.gif

you can always use a velleman amp with two inputs  hope this helps and good luck

[Gordonjcp]

You need to buffer the input signal with something.  Stick "unity gain buffer" into Google and a million sites will show you how to wire up an opamp to, erm, not amplify.

If you really want to, you can buffer the effect output too.  You can even make a unity gain inverter, and mix the input out of phase with the effected output - you might actually *need* to do this if your effect flips phase.

[Dj Task Manager]

thanks yall,
looks like a unity gain buffer is the way forward!

[Dj Task Manager]

Hmmm ive had a good search and i cant seem to find any schematics for a unity gain buffer...

Let me exp[lain the project a little better...

The unit im making is a tape delay with a dictaphone for recording the input signal then a walkman playing back the recording.

I could of course get a signal out of the headphone out of the dicaphone and simply mix this with a pot with the out from the walkman and i guess this would not feedback as the amp bit of the dicatphone would stop that,

but i though that if the input signal was sufficient (like a line out from a keyboard or whatever) then it would be better to split it send it through one of these unity buffer fellows then mix it with the output signal, thus having the wet part of the mix cleaner due to not having gone through the dicaphone circuits. 

Does this make any sense?


Cheers 

[Matt the Modulator]

i think i get what your tying to doo sounds a nice project! iam not sure if the links below are exactly what your looking for but hey aving a look cant doo any harm ! enjoy

a set of simple buffers can be found here http://www.muzique.com/lab/buffers.htm the article also gives some explanation.

you may find it usefull to have a active splitter aswell (creates two copies of one input signal) http://www.muzique.com/lab/splitter.htm

main link to AMZ schematics http://www.muzique.com/lab/main.htm

[Gordonjcp]

http://www.facstaff.bucknell.edu/mastascu/eLessonsHtml/OpAmps/OpAmp3Note1Buffer.html

First hit on Google.

[Dj Task Manager]

Thanks for the tips, I feel vaguely flummoxed as I cant keep up with the technical language.  I think I will prototype it using the output from the dicaphone as this will be easy to do. 
If I rename it as a delay and distortion unit it then its fine!

Cheers yall