rotary selector switch

[salomonander]

hey
i have a simple question.
when fitting a rotary switch in a consoles channelstrip for group selection duties... do i want a shorting or non-shorting switch?
also, can i switch the audio only and simply have all ground connected (everything is unbalanced)?
again, thanks alot

 

[ruffrecords]

That depends on whether active or passive mixing is used and if active, whether you want to leave unused  bus feed resistors floating or grounded.

Cheers

Ian

 

[salomonander]

That depends on whether active or passive mixing is used and if active, whether you want to leave unused  bus feed resistors floating or grounded.

Cheers

Ian

hey Ian
i just read this paper: http://www.forsselltech.com/media/attachments/summing_buss.pdf
im afraid i have no clue if my mixer uses active or passive summing. is there an easy way to find out? i do have schematics but im too much of an idiot to tell....
all channels have a 3,6k resistor that connects them to their summing bus which then has a step up transformer and gain makeup...  if that helps.

In the article it says that the number of channels going into a bus shall not be changed. sounds like i can forget about group selection in that case? if yes, i pray that its active. all wiring is fixed at this point (channel 1-7 go to group 3/4 all other channels go to group 3/4).

 

[ruffrecords]

Perhaps the best thing to do would be say say which make/model of mixer you have.

Cheers

Ian

 

[salomonander]

Perhaps the best thing to do would be say say which make/model of mixer you have.

Cheers

Ian

you wont know it im afraid. its a german broadcast desk made by eab/tbg. all discrete and amazing sounding and build (haufe transformers, all switches are stepped etc) but no one knows it.... as i have said i do have schematics. would you need to see the group channels and their gain makeup or general wiring in order to tell? i can upload the schematics if maybe you have the time to take a look.

thanks

 

[salomonander]

ps: when looking at the wiring it seems like all bus wiring is unbalanced and all grounds are connected - if that helps.
also, all channels use the same 3,6k resistors before going to the busses. regardless of how many channels are now hard wired to the bus (its 8 channels going to group 1/2 and 12 channels going to 3/4)

 

[ruffrecords]

OK. Understood. A schematic of a channel and a group gain make up would be a good start.

Cheers

Ian

P.S. Very nice looking mixer!

 

[salomonander]

OK. Understood. A schematic of a channel and a group gain make up would be a good start.

Cheers

Ian

P.S. Very nice looking mixer!

cool
here you go:

these are the channels gain makeup:

 

[salomonander]

this is the wiring into one of the group modules (the auxes called 550A. but the other groups have the same layout)

 

[salomonander]

this is the 550A module (not showing the input transformer)

 

[salomonander]

and here is the actual group gain makeup

 

[ruffrecords]

OK, these makes sense as individual circuits but not overall. Is there an overall block diagram you can post to help me understand it better?

Cheers

Ian

 

[salomonander]

OK, these makes sense as individual circuits but not overall. Is there an overall block diagram you can post to help me understand it better?

Cheers

Ian

maybe this one?
it shows how the mic preamps (e610) are connected  to the channel modules (e510) and how these are connected to the busses (my desk has group 1/2 and 3/4 in addition to the L/R summing bus).

 

[salomonander]

and this is the channels wiring. let me know if i should translate or if you need anything else. i do have plans for all modules in this drawing

 

[salomonander]

and then i have these:

 

[salomonander]

but i think they are mostly showing the monitoring facilities....

 

[ruffrecords]

I have downloaded those pics. I'll have a look at them and get back to you.

Where are the 3.6K resistors you referred to??

Cheers

Ian

 

[salomonander]

I have downloaded those pics. I'll have a look at them and get back to you.

Where are the 3.6K resistors you referred to??

Cheers

Ian

hey Ian

thank you so much! i really appreciate it.
the 3.6k resistors can be seen on the last image (TRE400 Main 2 small.jpg).
they are the bus feed resistors placed between the channel outputs and busses.

i spend all day reading into the subject and things are getting a bit clearer.
am i right in that:

- when using an active summing structure one can leave the unassigned bus feed resistors floating (meaning unconnected). in this case i could use a rotary switch - say a 2pole 3 way (for group 1/2, 3/4 and L/R) - and simply connect the channels outputs to both rotary's input poles and connect the rotary's outputs to the according bus (via resistor).

- when using passive summing one has to connect the  unassigned bus feed resistors to ground.
  in this case i'd have to use pushbuttons for group assignment (due to lack of poles).

is this correct?

again, thanks

 

[ruffrecords]

Yes, that is correct. From what I have seen so far it looks like yours uses passive mixing.

Cheers

Ian

 

[salomonander]

Yes, that is correct. From what I have seen so far it looks like yours uses passive mixing.

Cheers

Ian

so every unused bus feed resistor to ground?
darn... that kills my 2x3 rotary approach.... but thank you so much fot telling me!
i would have screwed up big time without this info.
i dont really have the space for 3 pushbuttons im afraid. i guess a rotary like this could do:
http://de.onlinecomponents.com/grayhill_71a30-03-4-03n.html?p=11455400
it would give me 8 poles 3 positions. i would wire it "backwards" (each pole feeding a bus) so that i can wire each open connection to a resistor that connects to ground. do you think this will work?
would i want shorting or non-shorting for this application?

thanks a lot