Compact desktop line mixer?

[MidnightArrakis]

Yes, they are directly on opposite sides of the board. I didn’t go so far as to check if the footprints overlap (yet). They might need to be offset. The layout was all preliminary - like I said before, just a POC. I have done this with other project before, and while it is a pain, it can be done…as long as you solder the correct side first!

These are the rotary switches I spec’d. I used them once before and they seemed fine: https://www.mouser.com/ProductDetail/Alpha-Taiwan/SR10010F-0204-20F0B-C7-N-0027?qs=8%2Br4Hz5Xir/fy%2Bqxa0GVpg==

[ALPHA -- SR10010F-0204-20F0B-C7-N-0027] -- See below:



>> Have you determined what your PCB-outline dimensions are yet? If so, can you let me know what they are??? THANKS!!!.....

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[MidnightArrakis]

These are the rotary switches I spec’d. I used them once before and they seemed fine:

[These are the rotary switches I spec’d] -- Here's a really spiffy idea!!! How about providing a list of all of the LED's, potentiometers, switches and other electro-mechanical components' Part Numbers that go through your FPD-panel? I've got an idea!!!.....

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[MidnightArrakis]

One interesting aspect of Schaeffer's front panel service is that they can use customer provided material so, rather than buy a complete enclosure like the Takachi and have to replace some of its panels with custom ones you can send the blank panels to Schaeffer for them to use on your design.

[One interesting aspect of Schaeffer's front panel service is that they can use customer provided material] -- So.....you're saying that if you send SCHAEFFER your own panels, they will then punch them out to your own specifications??? I've never heard of or have known of any sheet-metal shop ever willing to do something like that. That's a really interesting piece of information to know.

However, I suppose "the catch" is.....is that with you supplying the material, you also end up paying for the shipping cost twice!!!

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[ruffrecords]

Yes, they are directly on opposite sides of the board. I didn’t go so far as to check if the footprints overlap (yet). They might need to be offset. The layout was all preliminary - like I said before, just a POC. I have done this with other project before, and while it is a pain, it can be done…as long as you solder the correct side first!

Absolutely!

These are the rotary switches I spec’d. I used them once before and they seemed fine: https://www.mouser.com/ProductDetail/Alpha-Taiwan/SR10010F-0204-20F0B-C7-N-0027?qs=8%2Br4Hz5Xir/fy%2Bqxa0GVpg==

I thought I had found every small rotary switch known to mankind but that is a new one for me. Very interesting.

Cheers

Ian

 

[Bebert81]

Hi OP
No, you're definitely not alone! I've been tearing my hair out for such a mixer.

I also think it's a nice project. I can confirm that designing a good, simple and useful mixer can be very exciting.

2 suggestions :
- As far as the ability to become a summing tool 16 is concerned, it might be possible to add 2 switches to allow the 2-track return and the ext input to be assigned to the main bus ? 8 input + 2 stereo FX return + 2track + ext input = 16

- In my personal workflow, a second main bus with insert is also very useful, for example to send a premix or stem to a hardware effect (glue compression or saturator or other treatment).

But maybe not usefull in your case.

Ten years ago, I was lucky enough to buy a very nice, ultra-compact mixer designed in the 80s by Jacques Sax (Sonosax) at a reasonable price.
50cm x 50cm with 10 mono inputs, 2 stereo inputs, 4 aux, very complete monitoring, pfl/solo and monitoring section, pream, eq and comp on the mono input, etc. If I wasn't the happy owner of this jewel, I would like o build something like your project and I will get an eye on it until the end.

 

[OneRoomStudio]

[These are the rotary switches I spec’d] -- Here's a really spiffy idea!!! How about providing a list of all of the LED's, potentiometers, switches and other electro-mechanical components' Part Numbers that go through your FPD-panel? I've got an idea!!!.....

/

Here are the parts I was thinking of, but none of this is finalized yet. I haven't even finished the actual circuits yet, so we're still very much in proof-of-concept mode.

Pan Pots
Level Pots
DPDT Switches
4PDT Switches (for the stereo I/O channels)
Switch Caps (available in other colors and from other vendors)
Rotary Switches (as mentioned above)
Channel Faders
Mix Bus Fader
LED Bar Graph (just one option I found that looked promising)

 

[OneRoomStudio]

2 suggestions :
- As far as the ability to become a summing tool 16 is concerned, it might be possible to add 2 switches to allow the 2-track return and the ext input to be assigned to the main bus ? 8 input + 2 stereo FX return + 2track + ext input = 16

- In my personal workflow, a second main bus with insert is also very useful, for example to send a premix or stem to a hardware effect (glue compression or saturator or other treatment).

Good suggestions. The first one is already (mostly) part of the design. The 2track return has a "to mix" button that sends it to the mix buss. The "external input" was intended to be an ⅛" jack on the front for plugging in a phone or other source, so it didn't seem to make sense to send that to mix bus (it can be selected as a source to monitor separately though). As-is, there are 15 channels for mix down - 8 regular channels, 5 FX returns (1 mono, 2 stereo), and the 2track returns.

I don't know that there would be enough room in the box for a second mix bus though...at least, not a discrete one. It's going to be tight to fit 4 discrete opamps and a pair of transformers back there as it is.

 

[inkster]

[One interesting aspect of Schaeffer's front panel service is that they can use customer provided material] -- So.....you're saying that if you send SCHAEFFER your own panels, they will then punch them out to your own specifications??? I've never heard of or have known of any sheet-metal shop ever willing to do something like that. That's a really interesting piece of information to know.

However, I suppose "the catch" is.....is that with you supplying the material, you also end up paying for the shipping cost twice!!!

/

I send them material often with excellent results, especially useful when you need a color match...which they don't do.

 

[MidnightArrakis]

Here are the parts I was thinking of, but none of this is finalized yet. I haven't even finished the actual circuits yet, so we're still very much in proof-of-concept mode.

Pan Pots
Level Pots
DPDT Switches
4PDT Switches (for the stereo I/O channels)
Switch Caps (available in other colors and from other vendors)
Rotary Switches (as mentioned above)
Channel Faders
Mix Bus Fader
LED Bar Graph (just one option I found that looked promising)

[Here are the parts I was thinking of] -- THANKS!!! I'll check them all out. Meanwhile.....here's your PCB-outline based upon the TAKACHI CF45-28 Sloped-Enclosure. While I have worked up this basic PCB-outline, I'm still tweaking the final dimensions.

FYI: The "tab" that you see over on the right-hand side fits in-between the two rear-extrusion mounting-holes and up to within 0.050" (typical distance) of the extrusion rear-panel. By the mere fact that this is a "Sloped Enclosure", makes for the weird angles.


>> For your "REFERENCE" -- The front of the PCB is 1.62" high and the rear-tab is 2.50" high. The sloped-top of the PCB is 9.54" long, while the bottom of the PCB is 9.66" long. But, as I have said.....I'm still tweaking these dimensions.

>> Now.....your next assignment is to also relate -- WHAT & WHICH -- connectors/jacks/plugs/etc. are you going to be using on the rear-panel and in what order? Also.....

• Will there be any XLR's and/or DB-25's?
• Is the power-supply internal or external? If internal, will it be a "standard" 120VAC input? And, will it be "chassis-mounted? Or, PCB-mounted?
• Are you planning on using some type of a "Bottom-Plate Mounted PCB-motherboard"? If so, Will the above "Channel-Strip" PCB's be plugged into it? If plugged into, will that be done via an "Edge-Card" connector? Or, a "Mated Connector Pair"? Or, by means of a "Ribbon-Cable" jumper assembly?

>> YOU'RE WELCOME!!!

/

 

[ruffrecords]

@MidnightArrakis a couple of points about your PCB profile.

To the left will be a panel mounted fader. These are not designed to mount art right angles to a PCB. I think the OP's plan is to have the faders mounted to separate PCB(s) so your profile needs truncating at the left to accommodate the fader.

There needs to be room for connectors and their associated ribbon cables on the bottom of the PCB. It is not clear from your PCB profile if your PCB reaches the bottom surface of the enclosure but if it does it needs to be raised to accommodate interconnects.

Cheers

Ian

 

[OneRoomStudio]

[Here are the parts I was thinking of] -- THANKS!!! I'll check them all out. Meanwhile.....here's your PCB-outline based upon the TAKACHI CF45-28 Sloped-Enclosure. While I have worked up this basic PCB-outline, I'm still tweaking the final dimensions.

FYI: The "tab" that you see over on the right-hand side fits in-between the two rear-extrusion mounting-holes and up to within 0.050" (typical distance) of the extrusion rear-panel. By the mere fact that this is a "Sloped Enclosure", makes for the weird angles.

View attachment 145192
>> For your "REFERENCE" -- The front of the PCB is 1.62" high and the rear-tab is 2.50" high. The sloped-top of the PCB is 9.54" long, while the bottom of the PCB is 9.66" long. But, as I have said.....I'm still tweaking these dimensions.

>> Now.....your next assignment is to also relate -- WHAT & WHICH -- connectors/jacks/plugs/etc. are you going to be using on the rear-panel and in what order? Also.....

• Will there be any XLR's and/or DB-25's?
• Is the power-supply internal or external? If internal, will it be a "standard" 120VAC input? And, will it be "chassis-mounted? Or, PCB-mounted?
• Are you planning on using some type of a "Bottom-Plate Mounted PCB-motherboard"? If so, Will the above "Channel-Strip" PCB's be plugged into it? If plugged into, will that be done via an "Edge-Card" connector? Or, a "Mated Connector Pair"? Or, by means of a "Ribbon-Cable" jumper assembly?

>> YOU'RE WELCOME!!!

/

Yes, as Ian said, the channel PCBs wouldn't extend the entire depth of the enclosure. Really, there would be the following PCBs (diagram attached, with the first two channels and master section illustrated):

-8 Channel PCBs
-8 Channel Fader PCBs
-1 Backplane & I/O PCB that extends the width of the mixer. This board should fit into the flat portion of the rear extrusion.
-1 FX Send/Return PCB. This one DOES extend the full depth of the mixer.
-1 Monitor/Meter control PCB. Longer than the channel PCBs, shorter than the FX PCB.
-1 Master fader, mix insert, and VU meter PCB. I still need to figure this one out, but I drew a rough idea.

Hopefully that makes sense.

 

[MidnightArrakis]

@MidnightArrakis a couple of points about your PCB profile.

To the left will be a panel mounted fader. These are not designed to mount art right angles to a PCB. I think the OP's plan is to have the faders mounted to separate PCB(s) so your profile needs truncating at the left to accommodate the fader.

There needs to be room for connectors and their associated ribbon cables on the bottom of the PCB. It is not clear from your PCB profile if your PCB reaches the bottom surface of the enclosure but if it does it needs to be raised to accommodate interconnects.

Cheers

Ian

[Your entire response] -- As I was going through the process of creating this PCB-profile part, within my mind since I am an "Electronics Packaging Designer", I had at any given moment at least 25 different thoughts on "how things could be" within the OP's chosen sloped enclosure!!! And, my thoughts ranged from "what I know" to "how things could be" to "what does the OP have in mind about this?" to "I wonder if the OP is aware that -- THIS -- could be done this way instead" and on and on and on!!!

So.....the PCB-profile that I am currently sharing/showing is merely a -- starting point -- which can then be "hacked & whacked" as is needed or required. But.....ya gotta start somewhere, right??? Well.....at least what I have, even if it's "wrong" is more than what the OP has come up with, right???

Now.....should the OP wish to share with me either an attached PDF file or a PM going into "great detail" with what it is that they have in mind about how the components, PCB's, circuitry, rear-panel, etc., etc., etc. are all desired to be placed, mounted, fastened, wired and whatever.....then, I could try to come up with some 3D CAD-models of everything all put together, so the OP can visualize for themselves how everything "might" turn-out. But.....only if they wish to do so. Should they personally desire to tackle this project entirely on their own.....that's their call. I just design things the way that I design things. I'm not going to force anyone to follow my way of doing things.








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[JohnRoberts]

Looking at some of those images I am reminded of the inexpensive line mixer (LM-8) I did for Peavey (AMR brand) last century. It was basically a single large PCB that broke apart into three sections and folded up inside into an inverted U shape. IIRC the front panel controls were PC mounted pots and switches that worked in an 0.850 height spacing. The rear panel I/O jacks were something like 0.950 height TRS 1/4" jacks. All the signal lines going from front to middle to back PCBs were connected using machine inserted wire jumpers. The final assembly labor for this was so cheap that a top company executive sent the pricing estimate back to cost engineering to recheck because they didn't believe it could be done that inexpensively.

JR

PS: Sorry if I already mentioned this

 

[ruffrecords]

[Your entire response] -- As I was going through the process of creating this PCB-profile part, within my mind since I am an "Electronics Packaging Designer", I had at any given moment at least 25 different thoughts on "how things could be" within the OP's chosen sloped enclosure!!! And, my thoughts ranged from "what I know" to "how things could be" to "what does the OP have in mind about this?" to "I wonder if the OP is aware that -- THIS -- could be done this way instead" and on and on and on!!!

So.....the PCB-profile that I am currently sharing/showing is merely a -- starting point -- which can then be "hacked & whacked" as is needed or required. But.....ya gotta start somewhere, right??? Well.....at least what I have, even if it's "wrong" is more than what the OP has come up with, right???

Now.....should the OP wish to share with me either an attached PDF file or a PM going into "great detail" with what it is that they have in mind about how the components, PCB's, circuitry, rear-panel, etc., etc., etc. are all desired to be placed, mounted, fastened, wired and whatever.....then, I could try to come up with some 3D CAD-models of everything all put together, so the OP can visualize for themselves how everything "might" turn-out. But.....only if they wish to do so. Should they personally desire to tackle this project entirely on their own.....that's their call. I just design things the way that I design things. I'm not going to force anyone to follow my way of doing things.

View attachment 145251
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[Your entire response] -- As I was going through the process of creating this PCB-profile part, within my mind since I am an "Electronics Packaging Designer", I had at any given moment at least 25 different thoughts on "how things could be" within the OP's chosen sloped enclosure!!! And, my thoughts ranged from "what I know" to "how things could be" to "what does the OP have in mind about this?" to "I wonder if the OP is aware that -- THIS -- could be done this way instead" and on and on and on!!!

So.....the PCB-profile that I am currently sharing/showing is merely a -- starting point -- which can then be "hacked & whacked" as is needed or required. But.....ya gotta start somewhere, right??? Well.....at least what I have, even if it's "wrong" is more than what the OP has come up with, right???

Exactly the conversation that regularly takes place between the electronics designer, the mechanical designer and the PCB designer in any normal project. Pretty much what this thread IS.

Now.....should the OP wish to share with me either an attached PDF file or a PM going into "great detail" with what it is that they have in mind about how the components, PCB's, circuitry, rear-panel, etc., etc., etc. are all desired to be placed, mounted, fastened, wired and whatever.....then, I could try to come up with some 3D CAD-models of everything all put together, so the OP can visualize for themselves how everything "might" turn-out. But.....only if they wish to do so. Should they personally desire to tackle this project entirely on their own.....that's their call. I just design things the way that I design things. I'm not going to force anyone to follow my way of doing things.

Now,as an experienced professional, you know as well as I do that things never happen this way and they should NEVER happen this way. We used to call it throwing the design over the wall and it is very bad practice. Design is a team effort. I am sure we will reach the level of detail you are talking about but it has to be a joint effort.

Cheers

Ian

 

[OneRoomStudio]

We're not at the final mockup stage yet. Still just a proof-of-concept. I don't know yet if the pot/switch placement would actually work, and I don't have the circuit finished to do a full board layout yet. I'm in no immediate rush on this project, and I have a busy full time job besides (I often pop in here between meetings), so I'm not going to be at the point of having final designs anytime soon.

Now that the block diagram and mechanicals are roughly figured out, it's probably time to dive back into the actual circuits.