JPHogg
Joined: 05/07/11
Posts: 25
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Pre amps rack/ summing box
#1030116 - 24/01/13 12:51 PM
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I have an 8ch soundcraft series 200b mixer. My idea was to chop it up and make a rack with
just the pre-amps and eq with insert points and output post eq. I was wondering if I
could combine this with a summing mixer by adding a pot on each channel and a button to
route to the L/R instead of the Direct Output.
I don't know much about
electronics but have someone who can do the work no problem. Just after thoughts on
whether this will work and any tips on proceeding.
Cheers
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ef37a
Joined: 29/05/06
Posts: 5622
Loc: northampton uk
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Re: Pre amps rack/ summing box
[Re: JPHogg]
#1030132 - 24/01/13 01:39 PM
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Quote JPHogg:
I have an 8ch
soundcraft series 200b mixer. My idea was to chop it up and make a rack with just the
pre-amps and eq with insert points and output post eq.
I was wondering if I could
combine this with a summing mixer by adding a pot on each channel and a button to route to
the L/R instead of the Direct Output.
I don't know much about electronics
but have someone who can do the work no problem.
Just after thoughts on whether
this will work and any tips on proceeding.
Cheers
I would strongly advise against it. Heck of a lot of
work and expense.A decent rack enclosure will set you back 50quid + for starters. Then,
building a "mixer" is not a trivial excercise, ground loops, instabilities, clicks, plops
and tweets will all need to be ironed out.
Unless this guy is going to work
long and hard for nothing, sell the Soundcraft and buy a rack mixer, even the delicious
Neve reviewed here some time ago is in the ball park of what I would charge you to build
what you want!
This looks ok...http://www.rolls.com/product.php?pid=RM82 You
can research a price!
Dave.
Edited by ef37a (24/01/13 01:54 PM)
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18348
Loc: Worcestershire
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Re: Pre amps rack/ summing box
[Re: JPHogg]
#1030172 - 24/01/13 03:57 PM
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Quote JPHogg:
I have an 8ch
soundcraft series 200b mixer. My idea was to chop it up and make a rack with just the
pre-amps and eq with insert points and output post eq. I was wondering if I could
combine this with a summing mixer by adding a pot on each channel and a button to route to
the L/R instead of the Direct Output.
So let me se if I've got this right: Basically, you want to take
a perfectly good rack-mounting mixer, hack it to bits, and then rebuild it in a rack to
make... a mixer! Er.. I think that requires one of these: 
Quote:
Just after thoughts on
whether this will work and any tips on proceeding.
Not easily. So you want to keep the pre-amp, insert point, EQ,
direct output, and fader (pot) for each of the eight channels? So you actually only want
to lose the Aux sends and surplus channael routing, and the monitoring output section...
or perhaps you want to keep taht too, so you can hear what your mix is doing. And maybe
some PFL to check channel levels, and perhasp an odd Aux in case you needed a separate mix
for something...
As I recall each channel is built on a separate channel PCB,
and it really wouldn't be practical or even possible to separate out the bits you want
from the rest of the signal path that you don't. So you'd be committed to using the
original PCBs unless you rebuild from scratch (in which case, flog the Soundcraft and
build a new mixer from scratch -- it will be easier and cheaper). And if you're going to
use the original PCBs, you might as well use the original channel strip metal work to
support it adn the controls. You could saw off the fader section at the bottom if you
wanted, but why?
And as Dave says, the cost of the metalwork to rehouse it
makes this a pointless exercise.
What's wrong with the mixer as it stands? What
can you gain by rehousing it? it's perfectly rackable as it is...
H
-------------------- Technical Editor, Sound On Sound
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JPHogg
Joined: 05/07/11
Posts: 25
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Re: Pre amps rack/ summing box
[Re: JPHogg]
#1030306 - 25/01/13 01:01 AM
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Thanks for the replies.
The desk hasn't got direct outs at the moment but it
would be a simpler solution to look at adding these rather than hacking and rebuilding it.
I couldn't afford to pay anyone to do any of this but we're quiet at work atm
so have got a bit of time to play. I will however take the advice gratefully and just look
at a way off modding the mixer.
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ef37a
Joined: 29/05/06
Posts: 5622
Loc: northampton uk
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Re: Pre amps rack/ summing box
[Re: JPHogg]
#1030331 - 25/01/13 06:50 AM
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If you go to the Soundcraft site you will find a manual with signal diagrams and a
schematic.
Personally I would simply build a box of jacks and use the inserts
as direct outs (linking tip and ring) It is a shame that these are post EQ but 1) it might
be fairly easy to move the pickoff point and 2) most folks track "flat and dry" these days
anyway.
If Soundcraft peeps are anything like A&H bods I am sure they will
advise.
Dave.
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Matt Houghton
SOS Reviews Editor
Joined: 08/08/07
Posts: 512
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Re: Pre amps rack/ summing box
[Re: ef37a]
#1030398 - 25/01/13 01:50 PM
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+1. It's a perfectly decent little mixer, and it would be way cheaper to buy something new
that does what you want and comes with a warranty. You'd be getting into chopping up the
PCBs which is an accident waiting to happen. And as has been suggested, with the right
cables (which are relatively cheap to buy/make/have made) you can use the insert points as
direct outs.
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Hugh Robjohns
SOS Technical Editor
Joined: 25/07/03
Posts: 18348
Loc: Worcestershire
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Re: Pre amps rack/ summing box
[Re: JPHogg]
#1030431 - 25/01/13 04:27 PM
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Quote JPHogg:
Thanks for the
replies.
The desk hasn't got direct outs at the moment but it would be a
simpler solution to look at adding these rather than hacking and rebuilding it.
If you don't want to use the inserts
to provide direct outs, which is the easiest option, if not the safest, then perhaps you
can get you tech to build a pcb with a bunch of TLO74 op-amps wired as buffers, taking
their inputs from the preamp out, and provide direct outputs that way. You'll just need to
find somewhere to fit a 25 pin D-sub connector, and wire to the Tascam standard. As Dave
says, you can access the schematics from the Soundcraft site.
H
-------------------- Technical Editor, Sound On Sound
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