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Author Topic: Consoles and Mods - External Mix Bus...  (Read 2355 times)

fezzle

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Consoles and Mods - External Mix Bus...
« on: June 25, 2014, 11:50:52 am »

Hi Folks,

I was hoping to get some peoples knowledge on an idea I had for a small console I have. I am not a tech at all but if anyone could advise me on whether this sort of thing is possible to do or not, I would love to hear from you.. 
I have a small 16 channel console, and I wondered if it is possible to do a mod/upgrade in the 2 master channels so that I can use outboard mic preamps for the mix bus instead/as an option..  Basically I have some high end Jensen coupled clean mic pre's here that sound awesome, deep and wide with nice euphonics and massive headroom... I would really like in an ideal world to mix on my console then have two XLR outs retrofit that put out the consoles 'summed mix' instead of the master channels on the board. Is this sort of thing do-able?? If so are there issues with the length of cable/wire from the point of summing to gain make up amplifiers??

Thanks for your time!   
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Jim Williams

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Re: Consoles and Mods - External Mix Bus...
« Reply #1 on: June 26, 2014, 12:01:23 pm »

Possibly doable, but perhaps with degraded crosstalk and THD+noise. Buss lines are very sensitive and easily pick up external noise.

You would be replacing a virual ground inverting opamp sum stage running at unity gain (but elevated noise gain) with a preamp requiring 30~40 db of gain. Add that to the mix and you will get increased noise over a quality low noise opamp. You would also need to add a low value source resistor to lower the interaction (crosstalk)across the mic preamp inputs. 150 ohms is a commonly used value.

Mic pre gain recovery designs are better suited for passive sum designs, like you see from other manufacturers or home built.
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fezzle

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Re: Consoles and Mods - External Mix Bus...
« Reply #2 on: June 26, 2014, 06:19:59 pm »

Cheers Jim!  Probably better off sticking inside the thing then, perhaps with well executed changes it could sing better anyway
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Jim Williams

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Re: Consoles and Mods - External Mix Bus...
« Reply #3 on: June 27, 2014, 11:18:31 am »

Any decent modern opamp will improve your stereo sum stage. Consider these:

LME49720, OPA1612, AD8599, ADA4898-2
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blackbee045

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Re: Consoles and Mods - External Mix Bus...
« Reply #4 on: October 25, 2014, 04:17:16 am »

I would really like in an ideal world to mix on my console then have two XLR outs retrofit that put out the consoles 'summed mix' instead of the master channels on the board. Is this sort of thing do-able?? If so are there issues with the length of cable/wire from the point of summing to gain make up amplifiers??
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