Mixer project finally completed (DONE!)

Over a year ago I got the urge to build a small mixer that would fit my needs.  There's plenty of cheap stuff out there but lacking in quality and lot of expensive options with too my bells and whistles.
So here's what I've got:
12 channels (when money becomes available it'll go to 16 with 4 mono returns)
3 auxes - the first 2 switch between pre and post fader
mutes
pans
100mm faders
6 rack spaces, 2 inches deep
It's based on the THAT 1510, Burr-Browns for fader buffer and 1646s for the auxes.
CNC'd front panel, butchered back panel.
Holy learning experience.

The PSU is external - I just used 2 9k PSU boards I had lying around.
Again - thanks Bruno2000 for the extra parts I needed.

Nice work! DIY is as good as it gets.

Joe

Yes, looks like top quality work!

Did you use a pot for the 1510 gain?

Les

fantastic! it needs a name, what shall you call it??

leswatts said:

Did you use a pot for the 1510 gain?

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For the 1510 gain I used the little trimmer you can see on the bottom picture.
All the inputs are intended as line inputs only - once they're trimmed I'll hopefully never touch them again.

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WOW!  thats impressive. this type of project crossed my mind but those simple sections get a whole lot more complicated when you start connecting sections together and even worse when your making multi-channels. i'll be "stuck" with my mackie for a long time i think.
great job.

jeez... good stuff geoff 

do you mind asking you for an estimated cost so far?

warpie said:

do you mind asking you for an estimated cost so far?

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Here's my break down (I'm sure I'll forget something):
faders - $96
1510s - $50
other ICs - $30
pots+switches - $75 (futurlec sells alphas cheap)
caps,trimmers,resistors,sockets - $50
face plate - $35
bottom chassis - $35
knobs+caps - $30
blank PC boards+ etching stuff - $20
PSU stuff - $20
I had a bunch of parts lying around too - like the box the PSU is in.

CNCing front panel was $175
so right now I'm in to it for around $650-700 (though that seems a little high to me)
I figure another $100 to finish it up - mostly ICs and faders.

I'm still excited about it - it's one of those 'why didn't I think of that?' kind of things, except I did.
And it not like there aren't cheaper options but like drpat said, I just need faders and sends with a great 2-bus output (I've got the talkback covered).

That's awesome! There a few great little purpose-built mixers showing up around here.

Very inspiring, as I'm working on something similar.

fantastic job!  I love the idea of mixing and matching make up amps for the output.

way to go!!!

awesome!

Simple and to the point.  Very nice.  ;D

So here's a question - I've been using the mixer for a couple days now and really enjoying it.
Today I finally hooked up a compressor before the input and it sounds horrible - in between no sound and a lot of distortion.  My comps have true-bypass.  Out the sound is fine, in it's bad.
Here's my current setup - Interface-> S800 8 channel EQ -> mixer.  If I insert the comp I put it between the eq and the mixer.  I haven't tried it before the eq yet.
Any ideas? Impedance mis-match with the channel input?
How can I fix it so my compressors will work?

shouldn't have issues with the comp going first. 

Can you post a schematic so that we can see what the input is like?  What compressor is driving it?  (un)Balanced?

I think we need to know more before coming to a conclusion.

Obvious question...  does the compressor work fine on its own?  Is the interconnect balanced?  

Svart said:

Can you post a schematic so that we can see what the input is like?  What compressor is driving it?  (un)Balanced?

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it's the same with both my LA4 and my LA2 - both comps work well.
balanced inputs and outs on both.
I'm also running 2 reverb units in with no problem.
the schematic is kinda from memory - it's right off the 1510 data sheet with the added 604(what's this - basically a 5534?) for fader buffer.  then pan pot.

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After more testing I've found it doesn't like being fed a transformer.  Electronically balanced outputs are good.  Remedies?

whenever I see the mixer builds, its the same reaction:

holy CRAP!!


maybe one day I'll get the courage.
Thing looks great!

So to recap - the thing sounds nice but if I try to use something with a transformer output in to the mixer it's not happy.  I've tried compressors, mic pres and DIs and the result is the same: distorted sound cutting in and out.
I ran my LA2 before my S800 EQ then in to the mixer and that works fine.

What did I miss or leave out?