24 channel mixer the "Stereotype"

[Dr Gris]

You've been busy, looks great!!!!

Best
//Magnus

 

[kante1603]

As you can see the panel is not 19" because it will be attached on to the existing steel backpanel of the rack housing,I made a cutout for it.
That´s it for now,hope to be able to show more pics soon when some more work is done.
Still a long way to go,but I´m having a lot of fun with it.

Cheers,

Udo.

 

[lkipod]

Wow Udo!

That's some nice DIY!

 

[Dr Gris]

I've been watching this project on and off for some time because I'm interested in getting a rack mountable line mixer in the future. The ultimate goal would be something I could use as a FOH mixer in small venues as well as a home studio mixer/summing mixer.

The PCB available at this moment is only for summing, right?
I'm sorry but I feel a bit confused about where this project is right now.

Best regards
//Magnus

 

[kante1603]

I've been watching this project on and off for some time because I'm interested in getting a rack mountable line mixer in the future. The ultimate goal would be something I could use as a FOH mixer in small venues as well as a home studio mixer/summing mixer.

The PCB available at this moment is only for summing, right?
I'm sorry but I feel a bit confused about where this project is right now.

Best regards
//Magnus

Hi Magnus,

from what I understood it is a 4-ch. Input stage atm,see here:

http://groupdiy.com/index.php?topic=41430.msg718634#msg718634

Nearly the same as the  previous 8-ch. boards (that I use in my build).
The new ones can carry a level pot and an LCR switch per channel on board,but it is not a must.Easy to wire them off board,there are provisions to tap these points off close to them (easy to see in the pics hakanai provided).So you might want to go for channel faders or a pan pot etc.

Basically a debalancing circuit formed around a 2520 footprint DOA per channel with the option to have a level pot/fader and a pan switch/pot after it,four times per board.
The output signal on each channel then goes to a (stereo)-bus via 47k resistors.
From there the signal must be summed up which is done by a summing amplifier.
Here's the one we all use from Jeff at CAPI:

http://classicapi.com/catalog/product_info.php?cPath=22_46&products_id=403

It consists of two parts:The first called "ACA" (Active Combinig Amplifiers) is the before mentioned summing amplifier,there are two on the board for stereo operation.So from here we have a summed up stereo signal (balanced,summed up with 2520 style DOAs driving the output transformers to get it balanced).

Then you might want to have a fader or pot for master level after it.
This signal will drop down then which is then amplified by the second stage on board called "BO" (Booster).Again a 2520 style DOA doing the job driving another transformer to form your final master output.Again two channels on board.Has options for master mute,solo and talkback done by a transistor as switch.

So as an example you might want a 16 input in two (or stereo) bus you will need 4 of the Hakanai boards (4 x 4 channels) and one ACA-BO.

This will form a fully discrete API-style mixer or better:Audio-porn!

Hope to have helped,

best,

Udo.

 

[Dr Gris]

Thanks Udo for your very informative answer. It's what I thought.
But what happened to the board with direct out, aux sends, solo and mute? If there ever was one for sale?

Cheers
//

 

[kante1603]

Thanks Udo for your very informative answer. It's what I thought.
But what happened to the board with direct out, aux sends, solo and mute? If there ever was one for sale?

Cheers
//

From what I know this was handeled as an add-on project by Don (hakanai),but I think it's not finished (yet).Recently he gave me a note that he'll be back on the mixer project in september,so let's wait and see

Best,

Udo.

 

[Dr Gris]

I'll wait and see. The things I've read and the pics I've seen so far looks fantastic!!!

Thanks again Udo, looking forward to see your mixer when it's done!

Best
//M

 

[hakanai]

Udo, everything looks great! Your front panel layout is reminding me of the Manley mixer I have always wanted to take for a test drive.

Yes, Udo has gotten everything right in answering the last few questions. I am hoping to get back to the mixer in September and have it be a very elegant and scalable system.

But for now I need to keep an eye on this little one week old my wife just popped out. Cute little bugger.

Don

 

[kante1603]

Congrats Don!

All the best to you and your little family from germany,

Udo.

 

[kante1603]

Hi Don,

excuse me disturbing you and your family.Have sent an email 3 or 4 days ago.Did you receive it?

Best,

Udo.

 

[hakanai]

I did get your email, sorry for the slow response. Email sent.

Don

 

[kante1603]

Here´s how I derive some points for the scale of my masterfader.I printed out a template in FPD (thanks Frank),put it on cardboard,attached the pot through the center hole and marked the points while monitoring levels in circuit.

Forgot to say:Masterfader pot is an ALPS RK Series ("Blue"),the beautiful knob is from Jeff (CAPI).

 

[kante1603]

Last but not least I managed to set up a 2-channel little line receiver on veroboard to get me a balanced pre-fader insert return point.Fully discrete of course .
30 DOAs in the box now......

 

[kante1603]

My little insert board...

 

[kante1603]

...and a closeup from the audio connectors.You might notice the bazillions of yellow jumpers....I have all posible options for grounding in the build....nice to have and easy to do....

 

[AUDIO-ON]

Looks amazing!!!!!!!! What approach have you used for the line receivers after the insert point?

Rafael

 

[kante1603]

Looks amazing!!!!!!!! What approach have you used for the line receivers after the insert point?

Rafael

Hello Rafael,

sorry,but I don't get what you mean,do you want to know how I made it or what it is for?

Cheers,

Udo.

 

[AUDIO-ON]

Hi, thanks for the reply. I wanted to know how you made them. I was looking in the forum for schematics of balanced to unbalanced line receivers with the 2520, but didn't find anything. I also wondered if I can just take the schem from the input channel from Hakanai's board without the 47k resistor and feed the pot before the Bo directly...
Thanks, Rafael

 

[kante1603]

Hi Rafael,

that's exactly what I did.Just build it up to the fader point from the original board,omit the pan and bus resistors,done.The circuit drives my 10k fader easily.

Have fun,

Udo.