Summing Mixer

[mathtracks]

Can anyone post,send me,or point me in the direction of a schematic for an active summing mixer?

Michael has a nice one here http://www.digital-synthologie.de/summingmixer/index.html
but he won't write me back.


thaught i had seen a schemo here before but i can't find it


here are my ideas so far....
simplified block diagram version.
http://www.lunarrecording.com/Summing.pdf


o.k. here is the first schematic
can someone help me figure out a few things on this.

the gain of this mixer should be 0 right?

1-What value should the resistors be in the feedback loop on the OPA134's?

2-What value should the resistors be on the output of the OPA134's(10K)?

3-Coupling caps before the input to DRV134(probably)?

4-Best place to put master attenuator?

let's spark this monster to life! or not........

http://www.lunarrecording.com/SummingMixer.pdf


links to the i.c.'s used:
INA134 http://focus.ti.com/docs/prod/folders/print/ina134.html

OPA134 http://focus.ti.com/docs/prod/folders/print/opa134.html

DRV134 http://focus.ti.com/docs/prod/folders/print/drv134.html

 

[Cainester]

http://www.groupdiy.com/index.php?topic=820&highlight=bus

 

[mathtracks]

cool thread but i want an Active Summing Mixer.like the dangerous unit.
i know they use burr brown from this article.
http://www.findarticles.com/p/articles/mi_m0HEO/is_11_27/ai_108258093

 

[mathtracks]

Active summing mixers like the dangerous unit seem to be a taboo topic around here or something. :shock:

No one wants to give up their design or schemo for some reason.Just pics of a finished product.

I'm surprised Gyraf or some other DIY'er doesn't have one out yet

 

[peter purpose]

Why don't you buy one and reverse engineer it for US.

 

[mathtracks]

I wish.

i'm so broke i cant pay attention. :wink:

 

[Ian MacGregor]

[quote author="mathtracks"]Active summing mixers like the dangerous unit seem to be a taboo topic around here or something. :shock:

No one wants to give up their design or schemo for some reason.Just pics of a finished product.

I'm surprised Gyraf or some other DIY'er doesn't have one out yet [/quote]

Check this out: http://www.forsselltech.com/schematics.htm

Fred Forssell has some cool schematics here. There is an ACN (Active combining network) schematic in there.

Good luck, let us know what you end up building and tell us how it sounds!

Ian

 

[Consul]

One of our members (I can't remember who offhand) designed a completely passive summing mixer that was designed to use any pair of mic preamps you wanted for gain make-up. It needed about 40dB, if I recall correctly. I always thought that was rather clever.

He offers them up for sale. Hopefully, he'll chime in here before too long.

 

[mathtracks]

thanks for the input guys.
i have seen forssell's schemo in the past but it is not really what i'm looking for in terms of active.
i would still like to build a passive/active unit but i wanna know how the channels sum/interact through i.c.'s only.
i believe this is how dangerous does it .

BB INA134 and 137 (instrumentation amps), OPA 134 (op amps) and DRV 134 (output drivers)
never looked in a dangerous unit and i'm curious why these boxes cost so much built with cheap readily available i.c.'s.


could someone bust out with the dangerous gear porn shots already....

 

[thedug]

[quote author="Consul"]One of our members (I can't remember who offhand) designed a completely passive summing mixer that was designed to use any pair of mic preamps you wanted for gain make-up. It needed about 40dB, if I recall correctly. I always thought that was rather clever.

He offers them up for sale. Hopefully, he'll chime in here before too long.[/quote]

That was me. But I was inspired by the Scott Hampton tape op article and Brad Avenson pointed me to the forsell schematics.

I just have 16 inputs. The are TRS and are grouped in "2s". going L-R L-R L-R etc. I just ran 4 strips of big copper as "buss bars" mounted on barrier strips. The build out resisters just when from the connector to the appropriate buss. So I had L+ buss, L- buss, R+ buss, R- buss.

The busses went over to xlr outputs.

I just send my sub groups out of my daw, they are already panned. So I have L/R pairs out...

The hardy sounds great for makeup gain. So does the api 3124!

Fun stuff.

d./

 

[SonsOfThunder]

[quote author="thedug"]I just have 16 inputs. The are TRS and are grouped in "2s". going L-R L-R L-R etc. I just ran 4 strips of big copper as "buss bars" mounted on barrier strips. The build out resisters just when from the connector to the appropriate buss. So I had L+ buss, L- buss, R+ buss, R- buss.[/quote] Could we trouble you for a photo? Sounds nice!

Peace!

 

[thedug]

 

[SonsOfThunder]

As simple as it sounds...cool!

Thanks for sharing!

 

[mathtracks]

thanks for the pic thedug!


this forum provides knowledge seeking fools like us much insight.invaluable resource. :guinness:

 

[thedug]

BTW: If you look close you'll see I got switched jacks.
So that when nothing is plugged in the buss is shorted to ground via those resisters.

This will insure that your gain requirements won't change as you plug stuff in and out.

d./

 

[Marik]

I needed a three channel tube mixer, with L and R as main channels, and a mid channel, panning between them. I added one more channel to my stereo tube pre. The summing happens in the tube itself--I paralleled anodes and cathodes of one half of the mid channel tube and tube of the L channel, and mid signal comes to a grid. The second half of the tube I connected to the R, on similar manner. When the mid signal should be in the center, the two grids of mid channel tube halves are paralleled.

 

[Gulistan]

I have a complete schematic of CrestAudio V12 console, with symetric buses.
File is VERY big (about 25Mo), so I can redesign a summing bus, if anyone want it.

 

[daArry]

Hey Gulistan,

Is that online anywhere? i'd be interested to have a look at it for some ideas n whatnot...

If you cant upload sumwhere I provide an ftp you can upload too :thumb:

Cheers!

 

[kvintus]

I would like to see that one too!

/Anders

 

[Gulistan]

Is that online anywhere? i'd be interested to have a look at it for some ideas n whatnot...

It's not online... sorry...

If you cant upload sumwhere I provide an ftp you can upload too

I only have low speed connection. But, next month, I'll have hi-speed. I'll put schem on a ftp
But before, I can provide some pages, some high interest ! EQ, Mic preamp, DirectOut, SummingBus.