Passive summer, balanced, stepped panning?

[cactus]

Don't know if it's been covered yet, but I've been entertaining the idea of a balanced summing box with stepped (fixed res.) panning. Not for building a mix so much, more for summing cabinet mics to 1 track to tape, tom tops & bottoms into 1 track, etc...

Going along with the 10k load as in the F*lcrom summer, I thought I could preload the mono line with a 9k9, then maintain a 100Ohm resistance between the parallel L/R lines with the different switch positions:
ie
90%L 1k(R), 111(L)
60%L 250(R), 167(L)
80%R 125(R), 500(L)
or whatever - I'm new to this stuff.

Should give ~10k total, no?

My main question is how to construct the switch.
1 pole, 12 (or more) position, 4-deck:
Deck1- Left +
Deck2- Left -
Deck3- Right +
Deck4- Right -
does that make sense?

These ideas are for what would be the RIGHT decks. LEFT decks, the inverse...
The number inside the circle is the % RIGHT..
http://www.anicorettenightmare.com/diy/panclose.jpg
http://www.anicorettenightmare.com/diy/panfull.jpg
sorry, pics taken with sorriest phone ever.

Lorlin doesn't appear to make a 1 pole, 12-way, 4-decker, which makes me think I'm approaching this the wrong way.
Any input would be great!
Thanks

 

[cactus]

Still wondering if anyone knows if this will work. I know NYDave had a stepped pan option, but I couldn't wrap my head around it.

I'm trying to make a stepped-pan-able summer based on the F*lcrom circuit that will MAINTAIN A 10KΩ LOAD in any position.

If someone can tell if this will work, mathematically, I can start ordering stuff.

Please have a look: (sorry if it's confusing)
http://www.anicorettenightmare.com/diy/step-pan-dia.jpg

The values shown are what should be needed (1 value in L path, 1 value in R path) to force the signal to the specified % L or R...

Any input greatly appreciated. I'm VERY new at this.

 

[pucho812]

IIRC daves stepped pan was actually only 3 positions L, R, Center

 

[AudioguyII]

Hi,
Sorry to butt in and to ask such a newbie question.... but I'm looking around to build a simple F*lcrom summing bus.
Finding very mixed versions out there... you mentioned the 10k Load. could you please elaborate on this. Is F*lcrom using 10k resistors on each tip and ring of a balanced XLR to a summing node.... but then ? Do you have to connect a 250 ohm resistor across the each summing node.
Sorry for being so naive, trying to do this but not finding real specific info.
Thanks again.

 

[AudioguyII]

Hi,
Sorry to butt in and to ask such a newbie question.... but I'm looking around to build a simple F*lcrom summing bus.
Finding very mixed versions out there... you mentioned the 10k Load. could you please elaborate on this. Is F*lcrom using 10k resistors on each tip and ring of a balanced XLR to a summing node.... but then ? Do you have to connect a 250 ohm resistor across the each summing node.
Sorry for being so naive, trying to do this but not finding real specific info.
Thanks again.

 

[AudioguyII]

sorry for the double post...???!!!

 

[emrr]

I think Dave had a 5 position version too. Without sticking my head into the math before I've had coffee this morning, I'll add the classic Altec and Langevin pan pots for 600 ohm systems are pairs of either T or Ladder type attenuators with corresponding reverse relationship tapers to arrive at -3 dB in center position. They are usually 23 $tep, I recall.

You don't have to worry so much about maintaining 10K exactly on the input side. It can vary. You've not said it, but assumption is that you want a 150-250 ohm output for feeding a mic pre as make-up gain. What you have to worry about is the crosstalk factor of the variable resistance values you choose. How many channels are you building? Does it have to be stepped, or can you use one of the standard pot type passive panners? There are several discussions I've seen here about this.

Several switch variables. For max number of steps you may need more than 2 decks. If you can find 23-24 position 2-deck switches you can build it with them.

AudioguyII: if I hadn't posted after you, you could nuke your last post to kill the double (triple) post. There's an 'X' next to 'EDIT' for nuking your post.

 

[AudioguyII]

Thanks Doug, and sorry about that guys!