jtoole

Passive Summing Box - To PCB or not to PCB
« on: April 05, 2006, 05:58:22 PM »
Hello all...

I'm working on a passive summing box to connect to a 16-out 002R setup.  I've been debating between creating a PCB for the circuit, and using a buss bar type topology thats been described on this forum...  I'm planning on a fully passive balanced design, using external pre for gain recovery, etc.

Question:

Is there any interest from others on the forum in getting some 16->2 passive summing PCBs.  Barebones version would just allow the builder to select appropriate R values for source/dest.  Also add footprints for i/o headers, jumpers for trace configuaration, maybe other optional items...

If others are interested in this PCB I can have boards made - I a friend that will help the layout, and I think we can keep the price pretty low (<$10 or cheaper depending on volume).

Any interest?  What other options might users be interested in for a PCB like this?  If there IS interest, we'll happily post shematics and layout for feedback and tweak the design to suite everyone's needs...

Thanks for the input...  

jt


Ian MacGregor

    Echo Park, Los Angeles, CA, USA
  • Posts: 280
Passive Summing Box - To PCB or not to PCB
« Reply #1 on: April 05, 2006, 06:08:37 PM »
I did a layout a few months ago for an 8 stereo channel passive summing bus, using DB25 connectors for the inputs. I'll try and take a pic of it and post it. I don't know if I have Gerbers for the boards still (I've changed computers since) but I would be willing to reverse engineer my own work and offer the Gerbers to the LAB members.

Ian
www.blackwatchsound.com
www.standard-audio.com
 ------------------------------

jtoole

Passive Summing Box - To PCB or not to PCB
« Reply #2 on: April 05, 2006, 11:52:36 PM »
I'd love to take a look at it...  Is the db25 wired for a commercially available db25->xlr type snake or a custom cable?

Ian MacGregor

    Echo Park, Los Angeles, CA, USA
  • Posts: 280
Passive Summing Box - To PCB or not to PCB
« Reply #3 on: April 06, 2006, 12:25:31 AM »
The DB25 was wired to be connected directly to a Pro Tools 192 interface, I think they use the Tascam standard.

I need to look around and find my boards. We used it a ton at the studio I work at, but we just installed an SSL, so we have little use for it now.

Ian
www.blackwatchsound.com
www.standard-audio.com
 ------------------------------

fallout

Passive Summing Box - To PCB or not to PCB
« Reply #4 on: April 06, 2006, 04:11:40 PM »
I'd grab a PCB...

jtoole

Passive Summing Box - To PCB or not to PCB
« Reply #5 on: April 11, 2006, 12:44:23 AM »
Quote from: "fallout"
I'd grab a PCB...


Thanks fallout.  Still waiting on other responses till we decide the best course of action.  I've been out of town for a few days as well...

What are your preferences?  Would a 16->2 fully passive (no pan, gain, etc) suite your needs?

...

Josh

craigmorris74

Passive Summing Box - To PCB or not to PCB
« Reply #6 on: April 17, 2006, 12:51:52 PM »
I'd go for a fully passive PCB.

jtoole

Passive Summing Box - To PCB or not to PCB
« Reply #7 on: April 17, 2006, 11:41:45 PM »
Thanks for the response - I'm still planning to make boards, but I'm finishing up an GSSL comp inspired by the folks here and thats taken my focus for a few  :grin: i'll post pics soon!  lots of fun...

So far thats two people interested in a passive board, plus I need a few, so we'll probably do a small run of 10 boards.  I'm going to get w/ the designer and see if we can't get a schematic and layout posted here in the next week or so, then if everything looks good we'll get pricing and get it going...

Anyone else?

kruz

Passive Summing Box - To PCB or not to PCB
« Reply #8 on: April 22, 2006, 06:38:07 AM »
me interested.. maybe..

LaLaFaV

Passive Summing Box - To PCB or not to PCB
« Reply #9 on: April 23, 2006, 07:47:35 PM »
I'd also be interested
Lance


Passive Summing Box - To PCB or not to PCB
« Reply #10 on: April 24, 2006, 06:23:21 AM »
i'm in - if we have trafo options, pan and gain etc.. and maybe some aux sends

kruz

Passive Summing Box - To PCB or not to PCB
« Reply #11 on: April 24, 2006, 06:31:34 AM »
Quote from: "uk03878"
i'm in - if we have trafo options, pan and gain etc.. and maybe some aux sends

and you still call that "passive" ??
 :green:

Passive Summing Box - To PCB or not to PCB
« Reply #12 on: April 24, 2006, 06:35:32 AM »
Quote from: "kruz"
Quote from: "uk03878"
i'm in - if we have trafo options, pan and gain etc.. and maybe some aux sends

and you still call that "passive" ??
 :green:

i can dream

fallout

Passive Summing Box - To PCB or not to PCB
« Reply #13 on: April 24, 2006, 09:04:39 AM »
A mute, pan pot or LCR switch would be nice! :)

-Jay

jtoole

Passive Summing Box - To PCB or not to PCB
« Reply #14 on: April 24, 2006, 05:46:53 PM »
Quote from: "uk03878"
i'm in - if we have trafo options, pan and gain etc.. and maybe some aux sends


Pan, Gain, and Aux are beyond the originally intended scope for a passive summer.  I had considered some options like trafo, but I'm unsure the best way to handle the layout - would there be standard footprints that would be useful or would they have to be wired off-board?

My friend is supposed to be doing the PCB layout right now, so hopefully we'll have a starting point for discussion soon.  

If the interest for a more complex design is here, I'd be happy to help out, but I probably would want/need someone else to take the lead on it...

jt

jtoole

Passive Summing Box - To PCB or not to PCB
« Reply #15 on: April 24, 2006, 05:55:58 PM »
Quote from: "fallout"
A mute, pan pot or LCR switch would be nice!


To what extent do you think these options could be setup on the PCB as "optional" - I had envisioned that any extra features would be a "populate if you want" type setup.  I'm hesitant that a pan pot might be too much additional complexity (and personally I'm looking for 100% PT recall), but perhaps a simple way to add a mute/L/C/R switch might be an option.

What would be the prefered configuration for mute/L/C/R switches - would pads/headers be sufficient to wire off-board switches?  perhaps each channel could either be hardwired for M/L/C/R w/ jumpers, or attached to a switch.  This would let users setup a board for permanent 12->2 instead of 16->2 for example, if 16 ins aren't required, or choose some combination of mono vs stereo channel architecture.  Just need to think through the physical layout required to accomodate those options...

Just some thoughts... please keep the feedback coming - if anyone else wants to take a more active role getting this project going, drop me a note....

:thumb: Glad to see there has been some additional interest - It still seems that a 'swiss-army-summing-PCB' that can be configured for each users needs would be a useful item :grin: I know I need one!

Josh

Passive Summing Box - To PCB or not to PCB
« Reply #16 on: April 25, 2006, 08:53:32 AM »
Hi
A simple passive design hardly needs a PCB but anyway...
I would be interested in contributing to this excercise at some point.
I made some balanced buffer boards (Bal in and bal out) to DB25 pinout for a project like this but have not got round to using it yet (I don't have protools or a studio).
Headers for attaching switches is probably the way to go as everyone will want different types of switches.
Bung up some more questions and comments!
Matt Syson
Matt S

jtoole

Passive Summing Box - To PCB or not to PCB
« Reply #17 on: April 25, 2006, 03:14:46 PM »
Quote from: "Matt Syson"
Hi
A simple passive design hardly needs a PCB but anyway...


Well I considered using a buss bar topology mounted inside an enclosure but it seems like a PCB based design would be more robust.  A portion of my setup is mobile so I always appreciate gear that can take some handling.

Quote from: "Matt Syson"

I would be interested in contributing to this excercise at some point.  I made some balanced buffer boards (Bal in and bal out) to DB25 pinout for a project like this but have not got round to using it yet (I don't have protools or a studio).
Headers for attaching switches is probably the way to go as everyone will want different types of switches.


Agreed.  I'm also thinking that I/O signals will be placed on headers as well - this will allow people to wire in several ways:  using DB25 for a TDM PT rig, using jacks as desired (1/4, xlr, etc), or wire directly to the back of a balanced patchbay.

In case I didn't say it explicitly earlier, I'm also thinking this will be a _balanced_ passive summing circuit...

jt

kruz

Passive Summing Box - To PCB or not to PCB
« Reply #18 on: April 26, 2006, 08:23:29 AM »
Quote from: "jtoole"
I'm also thinking that I/O signals will be placed on headers as well - this will allow people to wire in several ways:  using DB25 for a TDM PT rig, using jacks as desired (1/4, xlr, etc), or wire directly to the back of a balanced patchbay


IMHO the joy of having a pcb here is to use a pcb mount DB25 connector.. avoiding the mess to solder those tiny tips one by one...
just a tought.

radiance

Passive Summing Box - To PCB or not to PCB
« Reply #19 on: April 26, 2006, 01:30:23 PM »
Quote from: "uk03878"
i'm in - if we have trafo options, pan and gain etc.. and maybe some aux sends


I'm in if we make this an active 6 buss design (2 subgroupds and 1 master), 2 aux send per channel and maybe a simple passive EQ on the busses (or maybe per channel..).
Summing might be done by these Neumann/Lawo cards or so....
So far I think Í'll only need a pcb to mount the relays for group switching.
"Knowing that you are dreaming, however, does not automatically guarantee full rationality.
Then again, being awake doesn't ensure good thinking, either." -  Lynne Levitan


 

Related Topics

  Subject / Started by Replies Last post
64 Replies
40242 Views
Last post May 19, 2017, 03:01:17 PM
by nekrosse
5 Replies
1695 Views
Last post September 15, 2009, 10:27:02 AM
by JohnRoberts
7 Replies
2317 Views
Last post June 19, 2010, 10:45:40 PM
by kodaz
16 Replies
4200 Views
Last post October 06, 2010, 06:28:26 PM
by spacelabstudio