Stepped Pan Controls

[abbey road d enfer]

OOOOOOOOPS!!!!
I should put the brains in gear before typing...
Since it is passive summing, putting both bus in parallels already introduces 6 dB attenuation.
Making the attenuation in mono mode adjustable would imply loading the bus when they are separate and loading them less when in mono.
Seems like it would take a 4PDT switch to select alternate resistors/pots.
I'm actually travelling, away fom home for a couple of weeks, typing on a notebook, I can't draw schematics.

 

[earthsled]

Since it is passive summing, putting both bus in parallels already introduces 6 dB attenuation.

Interesting. So, for 6 dB attenuation, I can simply parallel the left and right outputs with a switch?
Schematic attached...

 

[abbey road d enfer]

Yes, as simle as that!

 

[earthsled]

Okay, here's some pics just for fun...

50 resistors per switch times 24 switches...

the 1-inch square PCBs carry the input resistors and the bus resistors...

front pannel before connecting up the XLRs...

balanced left and right are "daisy-chained" from one switch to the next...

with knobs!...

D-subs before wiring parallel to XLR inputs...

all inputs connected - mono switch still unhooked...

whew!!! finally!!!...

now where did I put those chassis screws???...

one more pic with the lid off...

(front)

(rear)

Many thanks to Abbey!
I couldn't have pulled this off without your technical guidance!

 

[abbey road d enfer]

Wow! Nice build. I must see it in the flesh next time I go to Nashville.

 

[tmuikku]

Hi earthsled! Cool project! Do you have the photos still online somewhere? The ones linked here don't work anymore and I would like to take a peek Thanks!

 

[earthsled]

Hi tmuikku.

Try this link: http://twin-x.com/groupdiy/thumbnails.php?album=483

Let me know if you need other pics or info. I'm happy to share!

 

[tmuikku]

Thanks! Whoa, serious amount of resistors

Did you use these switches?
http://uraltone.com/kauppa/product_info.php?info=p1077_Rotary-switch--2x24.html

How is the quality, have you had any problems with the switches?

The bread board piggybacking the switch is actually pretty cool idea, there could be even some active buffer if needed... hmm. Thanks again for the pics

 

[earthsled]

Those look like the same type of switches.

I got mine from eBay - direct from Hong Kong. The quality is okay - some switches seemed to require more torque to turn than others. Otherwise, they work well but aren't as nice as Grayhill or Electroswitch. If I had to do it again, I might go for fewer steps and better quality switches. These were good for a prototype.

Active buffers are a good idea. I think most would favor having line-level outputs from a summing box.

Cheers!