[sdiy] Re: DIY Mixer - please help!

[thx1138]

On 9/2/09 2:15 PM, "cheater cheater" <cheater00 at gmail.com> wrote:

> Terry,
> you always have good ideas and good stories coming from your
> experience. I was wondering what you thought about all this, and if
> you could shed some light upon my confusion..
> 
> Thanks a lot
> Damian
> 
> 
> ---------- Forwarded message ----------
> From: cheater cheater <cheater00 at gmail.com>
> Date: Wed, Sep 2, 2009 at 9:47 PM
> Subject: DIY Mixer - please help!
> To: synth-diy <synth-diy at dropmix.xs4all.nl>
> 
> 
> Hi guys,
> It has come so far that I can't go on without a mixer, and, well,
> nothing I see on the market is satisfying to me right now. This can be
> of great use for modular synths as well since I would want it to be
> fully CV controllable. This is in part propelled by the fact that I
> have bought a TX816 which will need a proper mixer in order for me to
> be able to use it at all.
> 
> I am currently collecting ideas as well as resources. It seems as
> though it's not so easy to find the schematics for most mixers that -
> at least I consider - are interesting. The first step is to come up
> with a good summing bus design. I think solid state is good for a
> start, but since it's all DIY, it'll be possible to swap it out for a
> tube stage if there's a need for that.
> 
> I understand this list might not be the best forum to find out about
> this stuff - but I searched about for mixer/console DIY with people
> who actually *knew their stuff* when it comes to analogue music
> hardware and I simply couldn't find much interesting. If anyone has
> any recommendations, please do tell me. I trust the people here so I
> ask you guys first :)
> 
> Here's a quick writeup of what I have in my brain right now. Most of
> it is probably wrong, so please correct me.
> 
> What I am thinking of is a simple but effective modular approach which
> consists of:
> 
> 1) multiple summing busses
> 2) multiple VCAs
> 
> Each channel is one VCA that has CV inputs, a single input, and a
> single output to a single bus. Of course a stereo channel is that
> multiplied by 2. With a CV approach it's going to be very easy to
> control two channels with just the fader of the left channel, but
> that's a trivial comment.
> The bus sums and gives a single high-headroom output.
> 
> The first thing to do is to make a good summing bus. I understand that
> to do this I will need to come up with a good op-amp design. What I am
> looking for is good headroom. Can someone recommend anything good?
> Supposedly the Harrison 4032c is pretty good. If you guys have heard
> the headroom in MJ's 'Thriller' - that's that. Has anyone got leads on
> that?
> 
> As far as the mixer's format and general set of abilities, I am
> inspired by things like Manley mixers (EveAnna many positive
> affirmations to you if you can read this) and Chandler Limited (but a
> little less so because I haven't spoken to Mr Chandler or Mr Limited)
> 
> I find that a fully voltage controllable design could be useful. For
> example a feedback compressor could be built which outputs CV that
> will be fed into the VCAs. Therefore the whole signal chain from the
> sound source to the recorder could be just two VCAs - I guess that's
> better if someone's looking for this sort of thing.
> 
> Is there some interaction between the 'mixer strip' and the summing
> bus that I have left out? Or is my concept of how a mixer should be
> designed just plain wrong? :)
> 
> Thanks guys
> Damian (probably wrong)
Well Ok I will give it a try,

I think a DIY Mixer that VC programmable and extensible might be a good
project.

I might even be coaxed into providing some DEV tools to some folks that
submit some good ideas to our marketers.

Our team in Mexico built the Guitar Hero controller and have done work with
Line6 ToneCore SDK, so I try to evangelize projects al the time.

Having worked with Digidesign and M-Audio, I see a good business coming
For low-cost possibly modular ARM/DSP based mixing platforms.

The mixers I have in my  house are :

Digidesign Command 8 with 003 Rack +

Yamaha MG12/4FX

Tascam US-428

Protools 24-Track system with 888/24 I/O but no console

Apogee Rosetta 800

EchoAudio - (2)Layla's, (1)Mona, (1)AudioFire 8

TC Audio box plus all kinds of misc. pieces.

Sorry for Non-Sequitor rambling but the one things I miss is an open system
that is able to use either open-source VST type of approaches.

No Linux controlled front panel interface or stand-alone Linux based
HardDisk recording system.

I like to mix for Multi-channel audio for DTS/Dolby type of encoded
projects.

Buss limitations to stereo output, no voltage controlled panning etc. are
yet other things that frustrate my multi-channel audio experience.

A Voltage controlled mixer with downloadable effects processing into the
local DSP system with audio busses assignable to at least 8 - to 10 channels
output.

Most of my career at Freescale has been to build multi-channel audio
encoder-decoder systems and I wish I had my own mixer design.

I am not sure this forum wants to go off into this area, but I tie this gear
into my synths and microphones.

No one has asked about my Flash based Microphone projects using Coldfire
MCF5251 or i.MXxx Arm based products. Still want to build another Drum
Synth.

The last one I built was the Drumulator and Clavia module while at E-Mu
working with Dave Rossum back in 1982-83 time frame.

Ramble, ramble ramble......

Regards,

Terry