24 channel mixer the "Stereotype"

Totally agree on all points. I have been working with the channel width limit at 1.5" for the exact reason you mentioned. I should have some cool stuff to post later this week. This will be a dense board, but I think it will be a very powerful little system.

don

Very nice to hear Don,looking forward to it!

Have a nice weekend,

Udo.

This works for me also...the modules I'm building are not standard sizes but it works. One thing though- 1.5" is standard channel width so shouldn't the boards be a mm or two narrower to allow clearances?
Jay

You're right Jay,
I bet Don has thought about this since he was talking about 1,5" as the channel width limit.Some clearance is needed of course.

Udo.

So here is a very rough mockup of the front panel of a fully stuffed board. I did not have as much time as I would have liked to work on this this week but progress is continuing. What you are looking at is two channels next to eachother (just shy of 1.5" spacing). The grid is .25 inch, the large circles are pots with the inner ring representing a 1/2" knob and the outer a 15mm, the little ovals are small toggles for pre/post switching of auxes. These toggles are set back so the bat is just above flush with the panel. The medium sized circles are mute, solo, and stereo bus A/B (yeas there is a second stereo bus). These are also recessed so that they are as far back as they can be while still being pushable.
Overall the idea is to keep the toggles and buttons back so you don't notice them while messing with pots. The fader is the second pot down and looks a little congested, but is actually fairly wide open at the altitude your fingers will be using it. I am however seeing things I want to move around a bit but overall I think it is close.
Oh and the vertical line is one side of the pcb, that's why it is of center.

just a quick update
don

Hi Guys !
Anyone tried resistor values for the switch PCB ?

This is EXACTLY what I've been looking for!

Looking forward to this!

/
Emil

Hello,

it's a really nice project.
I look at the schematic and it's a lot of inspiration for a mixer project.
http://www.hakanairecording.com/mixerpics/Stereotype%20mark%202.pdf
Can i use a 10k pot in place of the 9 pole switch for pan ?

Ok so this is what the new board is looking like:

1 footprint for a fader (pot)
1 footprint for a pan (pot)
8 pre fade aux taps
1 pre fade transformer out tap
8 post fade aux taps
1 post fade transformer out tap
1 mute
1 discreet fader buffer

Click to expand...

Do you have a schematic for this options ? I'd like to know how to add 2 aux send to your original schematic.

Cheers,
Guillaume

Hey Don,

Any updates ? are the older board still in production ?  ??? I have parts sitting here waiting for a pcb

Thanks,
_Dave

Sorry for the long silence. Between the holidays, moving, planning a wedding, and just flat out not wanting to be reminded of the hurricane, the mixer has been getting little attention. But now I have spent the last two days working on the new boards. This project is alive a kicking (kicking my @ss). The layout for the channel board is proving tricky but I think I am getting there, and should be able to actually order something soon (intentionally vague).

Yes a 10k pot can be used for the pan. Jeff (classicapi) has some 10k's with a center detent that would work.

I may have a few boards left, I have had a few people ask over the last few weeks but have lost track of them. Unfortunately I have a whole stack of boards that I can't sell. The hurricane soaked them in toxic salt water and now they have pads falling of.  I am working on a revised 4 channel input board to go along with the channel boards. i think the 4 channel format will make for easier case layout, and it will also have an additional benefit for anyone planning on using the channel boards. I'll expand on what that is as things come together.

changes to the channel board since last update:
the front panel layout has changed significantly. details as things solidify
I am thinking there is just not enough real estate to do the DIP 8 foot print and the 2520 footprint. I currently working with the 2520 footprint. I am guessing the preference is to keep it discreet or would you guys rather the IC fooprint? unfortunately it's one or the other.

I'll be updating things here regularly.

Don

Hi Don,

nice to have you back here!
Personally I'd prefer the 2520 footprint.

Cheers,

Udo.

thanks! good to be back in it.

I suspect you will be with the majority in your preference for the 2520. It is what is on the current version of the board.

don

I just noticed the question about the schematic to add aux sends to the original board. The new board uses a buffer amp to make sure everything is happy. adding aux sends without the buffer might work but it is not something I have tried or have worked out on paper.

On the channel boards a few things have been pruned and a few things have been added.

there is only a pre fade direct out. it has the necessary circuitry for either an active or transformer output stage.
there is a second SELECTABLE stereo bus. meaning this is an either/or type bus. You can't send 1 channel to both stereo buses at once.
my aforementioned ghetto solo system (glorified aux send on a pushbutton) should work nicely.
and finally I can only fit one pre/post fade switch for the aux sends. I am thinking it will simply control Aux 4, and the other 3 will be hard wired pre or post (you pick). I could also see it switching 2 aux sends. So Aux 1 & 2 are hardwired and 3 & 4 are switchable together. What do you guys think? I kind off want to make it do the latter (switch 2 aux sends together). Let me hear some opinions on this.

oh and the new front panel layout should make it very easy to use faders for anyone wanting the real console feeling.

don

Hi Don,

cool,personally I'm o.k. with the direct out being pre-fader.
Also quite interested in the solo system and how it works.
Switching auxes 3&4 together is o.k. for me.In general jumpers instead of hard wiring might be a good idea if anyone wants to change later on?
And yes,I'd go for long throw faders anyway.Do we still have the choice concerning fader resistance values then (could be I slaughter some old stuff/broken consoles soon)?
Also with the fader buffer circuit,will we have the classic say 10dB gain then?

Keep up the good work Don,

best regards from germany,

Udo.

I'm going to try and wiggle a trim pot onto the buffer so you can have as much gain in hand as you like, but even without it I think you can get 20db of gain out of the buffer no issues. As it is at the moment you decide this with one resistor value, so you will have your 6db no matter what.

The solo is flat out a pre fade aux send. It simply has a pushbutton switching to one end or the other of a 1k resistor instead of a pot. It will then hit it's own little IC summing amp, and I am going to have a panel mount toggle on the monitor out that switches between the main out and the solo bus. This basically side steps all the usual convolutions and headaches of solo. While not being as slick to use, it should serve the purpose and be relatively painless to implement.

faders can still be whatever I said previously (1k-10K? I forget right now). Also all of the pots will have a slugging resistor footprint (except pan) so linear taper pots can be used.

don

Hi Don,

Thanks for your pm.
So solo will work with latching/permanent switches and solos will sum up then,yes?
How will you switch the monitor feeds then,will it be relais or transistor-based?

What I wasn't able to translate was "slugging resistor footprint".Does that mean I can use linear faders instead of log types as a channel fader???That would be fantastic because I have a lot long throw types from an ssl console.These became useless (vca-based console) for me.They're Penny & Giles.If so it would save me a lot of money,hahaha......so how does that work?

I know,questions over questions,but i'm curious now,forgive me.
Cheers,

Udo.

Solo will not automatically take over the monitor output. You push solo and it simply sends that channel to the solo bus. To listen to it you will flip a DPDT toggle (for example) on your monitor out. Then you will hear only your solo bus. In this way there is no control circuitry to move around the mixer.

Slugging resistors are explained here:
http://www.geofex.com/article_folders/potsecrets/potscret.htm

So yes you can use linear pots and faders for this project.

don

Ahh! just realized I have been saying you need a 10k log for the pan and that is not right! you want a linear or you want to make the switch with your own DUAL taper. sorry for this blatant miscommunication on my part

don

hakanai said:

Ahh! just realized I have been saying you need a 10k log for the pan and that is not right! you want a linear or you want to make the switch with your own DUAL taper. sorry for this blatant miscommunication on my part

don

Click to expand...

No, I mean the channel fader!

Cheers,

Udo.

I was commenting on other posts with the pan.

The channel fader can be linear but it will need to be higher than 1k, probably 10k is ideal.