pask

Semrau mixer modification
« on: September 20, 2017, 03:20:02 AM »
Hi there,

First of all, thanks for making this website happen!

A few years ago, I drove to Germany to get what seems to be a fairly rare model of German broadcast console of the Semrau brand. Sold it for Studer mixers and got it back a few weeks ago.
I like its punchy forward sound and its super compact size!

Now, the preamps are super solid sounding (Haufe trafos on the inputs) and the EQ is pretty radical but maybe a tad extreme for my taste.
I'd ideally like to have the EQ sound a bit smoother and enlarge the Q of the mid band.
I can see it has quite a few ICs and I guess it would be possible to change some of these to stretch it a bit in the smoother/broader brushstrokes direction?

Let me attach pictures of a standard mic/line channel and pictures of the schematics.

Any help would be greatly appreciated - thanks!


pask

Re: Semrau mixer modification
« Reply #1 on: September 20, 2017, 04:46:50 AM »
Top view.
Cool thing is that the kind of meter bridge is of Danner size, which makes it possible to rack various EQ/comp/pres/fader modules.
I plan on using spare modules that I have around to extend the channel count of this mixer (which will be another project).

pask

Re: Semrau mixer modification
« Reply #2 on: September 20, 2017, 04:47:44 AM »
Another cool thing is that this mixer has 2 separate stereo sums (I usually use 1-2 for drums and 3-4 for the rest).

pask

Re: Semrau mixer modification
« Reply #3 on: September 20, 2017, 04:49:11 AM »
Input section

pask

Re: Semrau mixer modification
« Reply #4 on: September 20, 2017, 04:51:16 AM »
Top EQ section.

1 fixed to shelf (around 10k, I guess)
1 semi-param mid
2 fixed low shelf (around 60 Hz, I guess)
low-cut

EQ is bypassable

pask

Re: Semrau mixer modification
« Reply #5 on: September 20, 2017, 04:51:49 AM »
More EQ section

pask

Re: Semrau mixer modification
« Reply #6 on: September 20, 2017, 04:53:38 AM »
Aux & pan section

Pan is bypassable
Auxes are organized in 2x2 sends, switchable to pre, post or bypassed by pair

pask

Re: Semrau mixer modification
« Reply #7 on: September 20, 2017, 04:55:43 AM »
Fader section

Faders have a "fader off" position (all the way down), that lights a little "mute" red led (nice).
Mute and pfl on all faders, too.

pask

Re: Semrau mixer modification
« Reply #8 on: September 20, 2017, 04:56:33 AM »
Fader section close-up

I've never heard of that brand of faders, by the way.

pask

Re: Semrau mixer modification
« Reply #9 on: September 20, 2017, 04:58:31 AM »
Hopefully, I have all schematics
I'll try to make clean scans of them (they suffered from a severe water damage) but here are phone pictures in the meantime.



pask

Re: Semrau mixer modification
« Reply #10 on: September 20, 2017, 04:59:12 AM »
Right pic of the mic-line module schematics

pask

Re: Semrau mixer modification
« Reply #11 on: September 20, 2017, 05:02:51 AM »
Additional information:
As I have quite a few spare modules, I simply fit 2 of the mic-line ones on the right of the sum section (replacing some mysterious relay-based broadcast modules) and they simply worked. So the current config is
12+2 mic-line modules
4 mono mic-line modules
2x2 sum

As I said, I have a few stereo faders and EQs I'd like to rack in the meter bridge to reach the 32 channels count.

abbey road d enfer

Re: Semrau mixer modification
« Reply #12 on: October 01, 2017, 05:42:17 AM »
I'd ideally like to have the EQ sound a bit smoother and enlarge the Q of the mid band.
I can see it has quite a few ICs and I guess it would be possible to change some of these to stretch it a bit in the smoother/broader brushstrokes direction?
You won't change the character of the EQ with just replacing some IC's. You may want to tune some component values to broaden the curves of the midrange controls, but I'm somewhat skeptic about the shelves, unless their turnover points are severely misplaced.
Can't say more until you upload readable scans.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

pask

Re: Semrau mixer modification
« Reply #13 on: October 02, 2017, 03:39:48 AM »
OK - thanks for considering my very candid technical approach :-)

Let me upload those scans.