Compact desktop line mixer?

[Brian Roth]

That's making me think (along with the comments from @ruffrecords and @Brian Roth) that we might be able to "kill two birds with one stone" by making the rear panel PCB also the bus PCB.

@Brian Roth - I know you said you prefer to wire connectors, but man, I hate unnecessary wiring. I've used pcb-mount jacks in lots of projects, and as long as they are both board-mounted AND panel-mounted, I've had zero issues. If the rear panel PCB was both bus and i/o, the channel cards (each) would only need one 3-wire connection to the fader PCB, and one 15-conductor ribbon to the rear pcb (specific pinout TBD):

1) Mix L
2) Mix R
3) Aux 1
4) Aux 2
5) Aux 3L
6) Aux 3R
7) AFL Bus
8) AFL Relay
9) Line Input +
10) Line Input -
11) Audio Ground
12) +16V
13) Power Ground
14) -16V
15) Meter Signal (?)

The master PCB (including Aux masters, FX Returns, Mix bus inserts, summing amps, and Mix outs) could connect to the same board with the same ribbon.

There have been multiple requests for DB-25 rear panel connections. Perhaps that option should be accommodated.

Bri

 

[ruffrecords]

1) Mix L
2) Mix R
3) Aux 1
4) Aux 2
5) Aux 3L
6) Aux 3R


The master PCB (including Aux masters, FX Returns, Mix bus inserts, summing amps, and Mix outs) could connect to the same board with the same ribbon.

I don't think crosstalk in the ribbon cable is going to be a real issue with line level signals but I would certainly separate each audio bus with an Audio Ground. And you also need a chassis connection unless you are happy to rely on the mechanical connection of modules to the enclosure.

Cheers

Ian

 

[MidnightArrakis]

More Metal Musings <g>......

Side cheeks for this mixer project could be 1/4" aluminum cut into an irregular trapezoid or pentagon (hexagon.....yada) to define the profile. The extrusions act to hold the chassis together in the 3D world while also providing mounting points for the front panels.

[Side cheeks for this mixer project could be 1/4" aluminum cut into an irregular trapezoid or pentagon (hexagon.....yada) to define the profile] -- HEY!!! -- I've got a "cheeky" question for you!!!.....Do you think you could provide me with some generalized dimensions for the "Compact-Mixer Side-Cheek Profile" that I have created and shown below? Just place your suggested dimensions into the chart I have included down below, at least down to the nearest 0.25". THANKS!!!



A =

B =

C =

D =

E =

F = XX-degrees

I just wanna see what this beast could possibly end-up looking like.

>> Any preference between 5052-H32 or 6061-T6 0.25" THK Aluminum?

5052 Aluminum Sheets and Bars
Known for being one of the easiest types of aluminum to weld, 5052 is also recognized for its ability to resist salt water. It's widely used for the bodies of boats, buses, trucks and trailers, as well as for chemical drums.

6061 Aluminum Sheets and Bars
The most widely used aluminum, 6061 is fabricated into everything from pipe fittings and containers to automotive and aerospace parts. It is strong and corrosion resistant, plus it's easy to machine and weld.

/

 

[OneRoomStudio]

[Side cheeks for this mixer project could be 1/4" aluminum cut into an irregular trapezoid or pentagon (hexagon.....yada) to define the profile] -- HEY!!! -- I've got a "cheeky" question for you!!!.....Do you think you could provide me with some generalized dimensions for the "Compact-Mixer Side-Cheek Profile" that I have created and shown below? Just place your suggested dimensions into the chart I have included down below, at least down to the nearest 0.25". THANKS!!!

View attachment 144178

A =

B =

C =

D =

E =

F = XX-degrees

I just wanna see what this beast could possibly end-up looking like.

>> Any preference between 5052-H32 or 6061-T6 0.25" THK Aluminum?
View attachment 144179
5052 Aluminum Sheets and Bars
Known for being one of the easiest types of aluminum to weld, 5052 is also recognized for its ability to resist salt water. It's widely used for the bodies of boats, buses, trucks and trailers, as well as for chemical drums.

6061 Aluminum Sheets and Bars
The most widely used aluminum, 6061 is fabricated into everything from pipe fittings and containers to automotive and aerospace parts. It is strong and corrosion resistant, plus it's easy to machine and weld.

/

Well, if we do away with the “meter bridge,” it may be more of a wedge shape, like the X-desk (the face would be multiple panels though):

 

[OneRoomStudio]

I don't think crosstalk in the ribbon cable is going to be a real issue with line level signals but I would certainly separate each audio bus with an Audio Ground. And you also need a chassis connection unless you are happy to rely on the mechanical connection of modules to the enclosure.

Cheers

Ian

Are you saying there should be an audio ground conductor in between each audio conductor (i.e., Mix L, GND, Mix R, GND, Aux 1, GND….etc.)? I’ve never seen a console ribbon cable setup that way before.

You’re right to call out chassis ground, as long as we prevent ground loops through the metal panels/chassis.

 

[OneRoomStudio]

There have been multiple requests for DB-25 rear panel connections. Perhaps that option should be accommodated.

Bri

As this is a DIY site, folks are free to accommodate whatever they would like

I’ll be building this with TRS, since that’s how my rig is setup.

 

[ruffrecords]

A = 15.75"
B= 0
C = 5.25"
D = 20"
E = 2.0
F = 0

Cheers

Ian

 

[JohnRoberts]

Seeing all this bloviation about designing mixers is giving me DejaPU (sorry- no offense).

JR

 

[MidnightArrakis]

Well, if we do away with the “meter bridge,” it may be more of a wedge shape, like the X-desk (the face would be multiple panels though):

[if we do away with the “meter bridge,” it may be more of a wedge shape] -- I was basing my "Side-Profile" shape based upon this manner of front-panel design approach, since I was at least under the impression that end-users were going to be plugging-in their "500-Series" modules into the upper-frame area:


/

 

[MidnightArrakis]

A = 15.75"
B= 0
C = 5.25"
D = 20"
E = 2.0
F = 0

Cheers

Ian

Based upon your provided dimensions, the following "Side-Profile" looks like this:



And....."104HP" equals -- 20.80" (528.32mm) -- which is the inside dimension width???

/

 

[ruffrecords]

Are you saying there should be an audio ground conductor in between each audio conductor (i.e., Mix L, GND, Mix R, GND, Aux 1, GND….etc.)? I’ve never seen a console ribbon cable setup that way before.

That is exactly what I am saying. It almost eliminates capacitive coupling between buses which can be an issue at high frequencies. I don't do it on the backplane PCBs in my tube mixers because the pins of those connectors are 0.2 inches apart but a 0.1 pitch ribbon has wires just 0.05 inches apart

You’re right to call out chassis ground, as long as we prevent ground loops through the metal panels/chassis.

The chassis/panels should not be carrying any signal current so they should not cause ground loops. The chassis and analogue 0V should be connected at just one place.

Cheers

Ian

 

[ruffrecords]

[if we do away with the “meter bridge,” it may be more of a wedge shape] -- I was basing my "Side-Profile" shape based upon this manner of front-panel design approach, since I was at least under the impression that end-users were going to be plugging-in their "500-Series" modules into the upper-frame area:

I was under the impression this was a compact desktop line mixer. Provision for 500 series modules to plug in has not been discussed AFAIR.

Cheers

Ian

 

[MidnightArrakis]

I was under the impression this was a compact desktop line mixer. Provision for 500 series modules to plug in has not been discussed AFAIR.

Cheers

Ian

[Provision for 500 series modules to plug in has not been discussed AFAIR] -- I'm bouncing around and between too many threads, I guess.

[And....."104HP" equals -- 20.80" (528.32mm) -- which is the inside dimension width???] -- Am I right???.....

>> 1.50" channel-width X 12-Channels = 18.00".....leaving 2.00" for the output section. Or.....???

/

 

[ruffrecords]

Based upon your provided dimensions, the following "Side-Profile" looks like this:
View attachment 144193
View attachment 144194

And....."104HP" equals -- 20.80" (528.32mm) -- which is the inside dimension width???

/

That looks about right. It is more or less an X-desk shape with some extra space at the back which I know from experience will be needed to accommodate all the cabling

By the way, it is probably not necessary to have 0,25" thick cheeks. 1/8th is what most of the major mixer manufactures use.

Also regarding the material, anodised aluminium is more often used for mixer cheeks, especially black anodised.

Cheers

Ian

 

[MidnightArrakis]

That looks about right. It is more or less an X-desk shape with some extra space at the back which I know from experience will be needed to accommodate all the cabling

By the way, it is probably not necessary to have 0,25" thick cheeks. 1/8th is what most of the major mixer manufactures use.

Also regarding the material, anodised aluminium is more often used for mixer cheeks, especially black anodised.

Cheers

Ian

[it is probably not necessary to have 0,25" thick cheeks] -- The 0.25" thick cheek was suggested by Brian Roth. That's what I used.

[1/8th is what most of the major mixer manufactures use] -- Works for me!!!

[anodised aluminium is more often used for mixer cheeks, especially black anodised] -- I am quite surprised that anodized aluminum would be used, especially as the anodization is prone to discoloring and being stained. I, personally, would prefer a type of black powder-coating that can be easily cleaned just by wiping it off with a cloth. And, you can get the powder-coating in a wide variety of colors, finishes and textures. I have a large "Powder-Coating Sample Ring" right here next to me as I write this message. There's white, light-grey, dark-grey, brown, a rainbow of red's, yellows, blue's, magenta's and all kinds and types of black's!!! Matte, smooth, glossy, low-glossy, fine/medium/coarse textures, Sandtex, semi-gloss, high-gloss, polyester, etc., etc., etc.

In addition, getting sheet-metal powder-coated is a whole lot easier these days than it is to get something anodized.

/

 

[Brian Roth]

As this is a DIY site, folks are free to accommodate whatever they would like

I’ll be building this with TRS, since that’s how my rig is setup.

Hey, I'm with ya! I'm trying to wrap my head around a "standard" form factor that allows some degree of customization using standard metal parts as much as possible to avoid the case costing a bunch more than the guts <g>. Otherwise, it will be smarter to buy a used x-desk.

Bri

 

[Brian Roth]

Seeing all this bloviation about designing mixers is giving me DejaPU (sorry- no offense).

JR

I fully understand! I've been kicking ideas in this thread since I have literally been snowed-in at my house since Jan 4. Finally was able to get out of the driveway Wednesday.



Bri

 

[ruffrecords]

[it is probably not necessary to have 0,25" thick cheeks] -- The 0.25" thick cheek was suggested by Brian Roth. That's what I used.

[1/8th is what most of the major mixer manufactures use] -- Works for me!!!

[anodised aluminium is more often used for mixer cheeks, especially black anodised] -- I am quite surprised that anodized aluminum would be used, especially as the anodization is prone to discoloring and being stained.

I have never had either problem with anodised aluminium

I, personally, would prefer a type of black powder-coating that can be easily cleaned just by wiping it off with a cloth. And, you can get the powder-coating in a wide variety of colors, finishes and textures. I have a large "Powder-Coating Sample Ring" right here next to me as I write this message. There's white, light-grey, dark-grey, brown, a rainbow of red's, yellows, blue's, magenta's and all kinds and types of black's!!! Matte, smooth, glossy, low-glossy, fine/medium/coarse textures, Sandtex, semi-gloss, high-gloss, polyester, etc., etc., etc.

I have never tried powder coating because it is simply too expensive for small quantities

In addition, getting sheet-metal powder-coated is a whole lot easier these days than it is to get something anodized.

/

My experience is the exact opposite. The companies that make Eurorack extrusions also make anodised aluminium cheeks, Schaeffer offers anodised aluminium in a variety of colours and it also does powder coated which is a lot more expensive then anodising.

Cheers

Ian

 

[JohnRoberts]

I fully understand! I've been kicking ideas in this thread since I have literally been snowed-in at my house since Jan 4.

I've been kicking around mixer-console ideas for several decades.... I don't consider this fun. But that's my problem... ya'all have fun.

JR

Finally was able to get out of the driveway Wednesday.



Bri

 

[Brian Roth]

OK....my latest goofy packaging ideas.....

Side cheeks are a pair of aluminum plates with a wedge/trapezoid profile. I mentioned 1/4" thickness, 1/8" is probably OK (thicker might "look better" at a casual glance?) 6061 seems standard.

I'm fascinated by the synth boys' Eurorack components like the module mounting rails, which offer many length alternatives compared to the standard DIN rail lengths.

OK, four rails going left to right, to hold the modules in place and partially tie the side cheeks together.

Everybody sit down on your fainting couch and have your smelling salts ready. Length of the rails?

95 HP. WHAT???? Well that is 19". Where do we get those? Many places sell cut-to-length rails, such as:

https://modularsynthlab.com/product/custom-size-eurorack-rails-silver-cut-to-length/?v=0b3b97fa6688

But, but...that is not an even number!! Who cares? The module panels have to be custom made anyway. So you can have 8 channel modules with an identical width (8HP/1.6"? 9HP/1.9"? etc.) and whatever is left over is used for the master control module.

In fact, the height of the module panels doesn't have to be 2/3/4/5..... RU tall. This is a custom frame.

Rear panel with the connectors is a standard rack panel...2? 3? RU tall.

Bottom plate is another rack panel....however many RU tall, as required. Rubber feet to raise this contraption above the table.

The vertical front edge plate ("below" the faders) is a 1 RU panel.

How to attach those three rack panels to the side cheeks? While I've used standard rack rails (L-shaped steel with a bazillion holes drilled and tapped at proper rack spacing) inside custom wooden "furniture" racks, the short lengths required here probably don't exist. So, standard L-brackets from McMaster-Carr, Home Depot, Lowe's, etc.

If needed for additional cheek to cheek bracing (to avoid a chassis shape turning into a 3-D parallelogram! lol) something like this attached to the cheeks with L-brackets:

https://www.legrandav.com/products/...le_management/lbp_horizontal_lacer_bar/lbp-1a

Cosmetics.... The 1 RU panel along the front is quite visible. I've seen blanks with only a single mount hole on each side, but whatever. 6061 blank rack panels are available unpainted. The side cheeks and that 1 RU panel can be left naked, painted, anodized, powder coated, covered with contact paper (LOL).

The "joints " at the edge of top of the upper modules and the bottom edge of the fader module plate(s) where they intersect with the chassis is yet to be determined.

So, custom metal parts:

1. Side cheeks. From a machine shop.

2. Custom length 95 HP rails. From a synth Eurorack vendor.

3. Module face plates. Maybe PC board panels as discussed at various points on this page?

https://groupdiy.com/threads/metal-work-for-500-series.89714/post-1185733

4. Rear plate for connectors. Standard 19" blank with holes. Drill it yourself, Front Panel Express, whatever.



Bri