SumThing Passive Summing PCB - Schematic and Layout

[jtoole]

phatmateo -

As you may have noticed this thread and project are a bit old...  The last post was mid 2007.  Two children later my DIY time is unfortunately much more limited than it was circa 2006/2007, but thankfully I do get email notifications from the forum still, so I will do everything I can to help you out.

I will have to check more details when I get home.  I pulled up the part number (401-1192-ND) on digi-key and it looks like they may have changed the part associated with this number.  I would HOPE that they don't normally do this, but I'm suspicious because the part number now pulls up similar switches made by C&K that do seem smaller than the ones used in the project.  Are you finding that they are too short/not enough pins?

I have some of the correct switches at home, along with order receipts, etc from Digikey.  I will go through these and see if I can figure out what has happened.

Worst case I will see what I can do to get you going - maybe send you a set of switches, etc.  Mainly just because I think its really cool that someone is still building one 4 years layer ;D

If by some chance you haven't heard back in a day or two, ping me via PM on the forum or drop another note here...

Regards,
j.toole

 

[phatmateo]

thanks so much for following up.  I understand how life goes   I think its the F Series now (Digikey #401-1223-ND).  Correct me if I'm wrong.  Thanks!!!

 

[phatmateo]

jtoole, your pmbox is full!  Do you have any extra 4pdt switches for the outputs on the Sumthing?  Digikey is out of stock until june.  I'll be happy to send you the money for them.  Thanks!!!

 

[SIXTYNINER]

hey jtoole
me too interested about the docs you posted in page 1
unfortunately links are expired
please new working links about?
cheers 6t9r

 

[phatmateo]

I found the switches at mouser.  The correct part numbers for the switches are: 
F2UEE
F4UEE

Thanks for the project!  I am also looking to see if those docs are available.  I think I have everything figured out from looking at the schematic and pcb, but some things still aren't clear to me.  The schematic and pcb images you have posted aren't up to date with the pcb I have.  Thanks for your help  

 

[jtoole]

phatmateo -

Glad you found the switches - I didn't realize my inbox was full and for some reason I was not getting notifications on this thread ???, so I didn't see your response.  I have cleared my inbox and made sure I am set for notification on this thread, so I should be good now! 

I am putting together a new package of files so I can fix the links related to this project.  I will post more information as soon as possible.  In the meantime if anyone has any specific questions or issues, please let me know and I'll help in any way I can...

Cheers,
Josh

 

[Citrus Hill]

Hi JToole,
I'm also looking to build a summing box and i'd love to look at your schematic if you get a chance to repost the files.  I'm still learning at this point and just doing a lot of reading and learning.  There's a ton to figure out before i order parts.
Thanks in advance,
Citrus Hill

 

[jtoole]

Sorry for the delay.  Here is a link to all the latest SumThing files:

http://louisvilleaudioworks.com/files/SumThing.zip

This contains schematic and PCB PNG files, as well board output files if someone wants to get more board made...  ;D

Enjoy!

 

[funkmuffin]

Sorry for the delay.  Here is a link to all the latest SumThing files:

http://louisvilleaudioworks.com/files/SumThing.zip

This contains schematic and PCB PNG files, as well board output files if someone wants to get more board made...  ;D

Enjoy!

Thanks!  Funny that I just went looking for exactly this today, and here's your post with a fresh copy of the files, posted yesterday!  That's gotta be fate telling to make one!

To anyone else who's looking to start a build, let's see if we can get our selves coordinated and save some $$$ at the board house.

 

[Tweekhead]

Hello,

I'm truly exposing the nub that I am when it comes to electronics as I'm very, very green at this still ;D, but I was wondering if I could bombard you all with a few questions.
A little background, I bought the unit with the pcb stuffed already.

Ok!

1. The unit has several output options, but I plan on just using it as a passive mixer with 2 external 500 series pres for makeup gain, so would I use just output 1 " J17 ", and output 2 " J19 "?

2. On the outputs 1 and 2's 6 pin Molex connectors do I just wire 3 pins to an xlr, viewing from the top of the pcb, and left to right, pin 1,2,3 all tied together ground?, pin 4 cold "xlr pin 3", pin 5 ground "xlr pin 1", and pin 6 hot "xlr pin 2"?

I was checking continuity with my multimeter and could get audio to pass on channels 1 and 2 with selecting either a left or right channel on the push button, but not unless the main L/R bypass buttons were pushed in.

3. I wired up 3 channels of a mini DB25 snake for testing purposes, because when I tried to check for continuity with my multimeter on any channels other than 1 and 2 I get no signal out of the main outs. I hooked it up and I can get audio to pass through channel 1 and 2 with no problems as long as the L/R bypass buttons are pressed in, but nothing on channel 3, but when I checked for signal at the input 3 Molex pins " J3 " I have audio. I'm ordering some DB25 snakes on Tuesday, but as long as the Tascam DB25 wiring works I'm sure the 3 channels are wired correctly.

4. To the right of R1 are 2 holes with solder pads, do these need to connected with a jumper, or are they there just for a mod of some type?

Hopefully you can help me out with these questions, and I apologize in advance for the inconvenience!


Thanks again!


Arthur

 

[Tweekhead]

oops... Just found the thread on wiring the in/out of the sends together, and how to wire the xlrs=)

 

[jtoole]

Yes, it sounds like the no signal issues are related to the pre in/out hookup.  Sounds like you've found this, but just to clarify for any future readers, there are three options on using the pre in/out connections:

1. Wire the pre in directly to pre out.  This will make put the sum (pre gain recovery) on the main output.  The downside is that bypass will cause channel 1/2 to appear unattentuated at the main output if bypass is enabled.  This will often be too loud unless you adjust the recovery gain before enabling bypass (for true bypass you want to bypass gain recovery - see option 2).

2. Wire the pre in and pre out connectors to external jacks.  This allows the bypass switch to remove the gain recovery and send 1/2 unaltered to the main ouput.  Useful if you use it connected to a device and use 1/2 in cases where summing is not required without rewiring.  Using connectors means you can vary the gain recovery device for different applications/color, etc.

3. Wire gain recovery in the enclosure directly via pre in/out.  Essentially the same as #2 except gain recovery is a fixed device.  Saves on external connections, etc.  Bypass functions the same as #2 (bypasses gain recovery device).

Regarding your question #4, I don't have a board or docs with me presently - let me take a look this evening and get back with you...

Also let me know if you run into any other questions/issues...

 

[funkmuffin]

JT -- Thanks for the info.  I'm planning to have a board made up, but am having trouble locating a board house that's not going to charge an arm and a leg for a 16X4 pcb.  Where have others had theirs made up?

Also -- I have no need for the bypass functionality at all -- I've always got 16 summable channels connected.  Is there a way to just wire channels 1 and 2 like all of the others, skipping the extra switches altogether?  I've been poring over the schem and the layout for quite some time now (I'm a noob), and could probably tweak the whole thing to get it smaller.

Here's an idea I had (please tell me if there's any reason not to try it):

If I cut the circuit down to a simple version with 4 channels per pcb, and use terminals to connect the "bus" lines from board to board, I can get the thing down to less than 100mm X 100mm, which would allow me to have 10 boards made for $40.  I figure then at the end of the "chain", the bus connections get wired to my output connectors for gain recovery. 

Does that make sense?  The $40 price from a particular vendor is WAY better than the lowest price I've found so far for the full board, which was something like $165 after setup fees, and no volume discount -- since I only need one.

any help is much appreciated, even moreso since this project is so old from your perspective.

Thanks!

Ryan

 

[jtoole]

4. To the right of R1 are 2 holes with solder pads, do these need to connected with a jumper, or are they there just for a mod of some type?

If you are looking at two holes to the right of R1/R2 that are not perfectly parallel, these are just through holes that bring the input 1's signal out to the bypass switches (they are going from PCB front to back).  You should not jumper these, just leave them as-is.  They are there just due to some layout/space constraints (you can see input 2 is routed slightly different, this is why they only appear on input 1).

I'm planning to have a board made up, but am having trouble locating a board house that's not going to charge an arm and a leg for a 16X4 pcb.  Where have others had theirs made up?

I think the majority (if not all) the people who have built this project did it from the original run of boards.  We made 50 rev2 PCBs and they were all sold at that time (2006/2007, with some resold to others later).  I would recommend at least finding a few others to split a prototype run to save cost - a single board is rarely economical.  Our original prototype was about $150 for 3 boards, which 3 of us split at $50 a board.  The argument has also been made several times that at that price you would be better off just wiring point-to-point, so this is something to consider.  Of course if more people are interested you could get the price lower with a larger run...

If I cut the circuit down to a simple version with 4 channels per pcb, and use terminals to connect the "bus" lines from board to board, I can get the thing down to less than 100mm X 100mm, which would allow me to have 10 boards made for $40.  I figure then at the end of the "chain", the bus connections get wired to my output connectors for gain recovery.  

Is that 10 boards for $40 ($4 each) or 10 boards at $40 each? The first option would be more attractive, but I suspect it may be the later...  At $40 a board, you could probably get the whole original PCB near that price in larger quantities.  However if you're comfortable w/ the work required to make it happen then give it a go!  I can't promise that I can be very personally involved, but this forum is a great resource in general, so I'm sure the knowledge is here to help you as needed, and I will help when/if I can!

At first glance the concept seems reasonable - there are many ways to work this basic architecture.  Going to a modular design might help costs for builders that want a smaller unit or a different form factor, and other modules could be used to add bypass or other features such as multiple output routing or relay switching.

The space of the original board was primarily dictated by the push-button switches and aligning them across a single 19" rack space.  Consider that if you want pushbutton switches you'll need to account for additional space consumed by mounting multiple boards across the front of the rack - gaps between the groups of switches, etc.  Without bypass switches this may be workable, but there isn't much unused space looking at the original unit's front panel.  Keep in mind you will not have 19" of usable horizontal front panel space, only around 16" in a par-metal style 1U rack.  Take a look at the dimensions in the FPE files for the front panel if they are still floating around (I will see if I still have them).  

Of course if pushbuttons are not required this changes everything, but it also means that there wouldn't be much on the board except summing resistors and signal routing, which continues to suggest point-to-point or a prototype PCB might also do the trick faster and cheaper.

 

[funkmuffin]

At first glance this seems reasonable - there are many ways to work this basic architecture.  Is that 10 boards for $40 ($4 each) or 10 boards at $40 each.  The first option would be much more attractive, but I suspect it may be the later...   At $40 a board, you could probably get the whole original PCB near that price in larger quantities.  However if you're comfortable w/ the work required to make it happen (and you find others sufficiently interested to make your quantities) then give it a go!  I can't promise that I can be very personally involved, but this forum is a great resource in general, so I'm sure the knowledge is here to help you as needed, and I will help when/if I can!

Yeah that's $40 for 10, so $4 each from SeeedStudio's proto service.  I found them through some DIYersfrom my other hobby (Reef Aquariums) and it works out to a great price, considering the price I'm finding elsewhere.  Here's a link:http://www.seeedstudio.com/depot/fusion-pcb-2-layer-10cm10cm-max-10pcs-p-396.html?cPath=64_12.  Looks like a fit for the project's specs, as far as I can tell.

I really like the idea of having this on a PCB, as I've been thinking about building one for years, but the mess of point to point seems daunting.  That's why I was so happy to find that you'd already done the work .

Maybe I'll see what I can do about cutting the circuit down -- I tried doing the changes today in Eagle, but it's my first go-round and the learning curve is steep.

Thanks for the info -- if I do make the changes, I'll be sure to share for others.  My thinking was that there might be some others who'd like a 24 channel version, and going modular allows for many other "packaging" options.

Ryan

 

[Tweekhead]

jtoole,

Thanks so much for all the help!

 

[nyoung]

Hey funkmuffin,
I'm interested in this project and am curious if you ever took the pcb's to production.  Let me know what you decided was the best way to go.  Thanks!

Neil

 

[analag]

Dead links= fail. You don't even need a pcb to make a passive summing thing, it's basicially resistors, grounding scheme and buss wires.

 

[neodyms]

UP

the links for the schematics and the pcb are no more available

does anyone get it ?

 

[piano]

Does any one have a Sumthing PCB board they wish to sell?

I would like to buy one.