Need a DIY Stereo Blend Control

[x-pogo]

Have worked up some acoustic panels for the walls and ceiling and they have knocked out a lot of L/R crosstalk. This is GREAT for most recordings.

But some material from the late 60's forward is mixed with WAY too much separation for my taste. I remember there were blend controls on some old factory stereo gear to deal with this very problem but it seems not much info survives.

Anybody know where to find a schematic to blend from "normal" to almost mono with constant total output?

Thanks

 

[cyclotronguy]

Variable resistor between the left and right "hot" between the pre and power-amp. Perhaps a cap if you want to only blend the higher frequencies.

Cyclotronguy

 

[mlloyd1]

if you want something a bit more complex that works well, search for the APT preamp schematic.

mlloyd1

 

[djk]

Or a Crown IC150 schematic.

 

[x-pogo]

Another few Google hours turned up two sources in Popular Electronics, Feb and Oct 1978 issues. Drove over to the local university library and finally got the microfilm loaded.

Yup, a four op-amp circuit that blends all the way to reversing left to right with a two gang 10K pot. The text says it maintains constant output level across the range of adjustment.

It will be a while before I put one together but will post back later.

Thanks for the help.

 

[HankMcSpank]

I've searched high & low & surprisingly can't find such a circuit.

I need to blend two separate audio signals into one (both are being sourced from the output of a prior TL072 opamp), with the option of having either just input 1, just input 2 or a combination of both (that'll be the blend bit)

There was a circuit called B Blender which looks as if it would suit my needs, but alas the website itwas posted up to has now gone, here's the description...

http://tinyurl.com/5k5yt6

& here's a thumbnail (larger gif can't be sourced)

http://www.tinyurl.com/6qnpoq (& I can't make it out!).

therefore I'm proposing this embarrasingly simple circuit...

An externally hosted image should be here but it was not working when we last tested it.

This will feed a standard guitar amp - can anyone spot any issues with what I'm proposing or suggest a more elegant implementation? (I have two opamp stages free of a quad opamp chip on my present circuit board.

 

[djk]

I would be inclined to do something more like this, you can delete the tube stage and just use the blend if so desired:

http://www.paia.com/manuals/docs/9305-tubehead-schematic.pdf

 

[nelsonvandal]

You should search in the land of headphones, at Head-Fi.org and Headwize.com for instance.

Meiers cross feedfilter has a good reputation.
http://www.meier-audio.homepage.t-online.de/
http://headwize.com/projects/index.htm

 

[Nordic]

where they call it crossfeed...