onlymeeee

500 series Sontec / GML type eq
« on: June 02, 2015, 08:53:20 PM »
Hi!
In my never ending hunt for the 'best' recording/mixing chain..  a great mixbus EQ had always escaped me..  I'm a GML 8200 lover and the amount of times that it's saved a mix of mine is countless!  It really should get the mix fee...!
 
So I made it my goal to attempt to recreate the magic in 500 series format..   This lead me of course to the original Sontec circuit..  (the orginal as opposed to the Igor modified one)

Some pictures!



I've seen inside a couple of Sontecs over the years and knew there were polystyrene caps in there so I used them where appropriate for the value.. 
I ended up socketing every cap in the unit (apart from power decoupling) in case my ears weren't impressed!


prototype with socketed caps ^ 

Now, everyone says the sound of the Sontec is the opamps..  so I put the two DOA footprints in case I needed to come up with a DOA to satisfy my ears! 
For my initial tests, I experimented with ICs..   I knew I wanted FET input, fast, low input current..  so I chose 5 that satisfied this and had "good reviews" online for my initial tests.. 
The OPA134, OPA827, OPA1641, ADA4627 & AD8512.

As it turns out..  I couldn't be happier with the sound!  I've been amazed at how much I can push the top end without it sounding harsh..  It's forced me to check the EQ curves several times as my brain refuses to believe it..   
To my ears it's smoother than a GML and cleaner than a Sontec..  It's now been permanently on my mix bus for a month & it's never leaving! 



bruno2000

Re: 500 series Sontec / GML type eq
« Reply #1 on: June 02, 2015, 09:15:20 PM »
That is absolutely stunning!  Where did you get the pots?
Best,
Bruno2000

weiss

Re: 500 series Sontec / GML type eq
« Reply #2 on: June 02, 2015, 10:34:09 PM »
Wow, these frequency selection pots look interesting!
Ansgar Scheffold
www.ansgarscheffold.com

Winetree

Re: 500 series Sontec / GML type eq
« Reply #3 on: June 02, 2015, 10:49:33 PM »
Are you teasing us? Or is this going to be your newest Kit?

frazzman

Re: 500 series Sontec / GML type eq
« Reply #4 on: June 02, 2015, 11:27:30 PM »
Wow... that is seriously impressive. You've succeeded in teasing us... well done.

leadbreath

Re: 500 series Sontec / GML type eq
« Reply #5 on: June 02, 2015, 11:56:01 PM »
i...want...
f**k marlbro's and weed ill stick to smoking germanium and silicon

Rocinante

Re: 500 series Sontec / GML type eq
« Reply #6 on: June 03, 2015, 03:19:47 AM »
Well done. Really. Please tell us this is going to be available soon.
If there's a harder way to do this, I haven't found it yet.

KDE

Re: 500 series Sontec / GML type eq
« Reply #7 on: June 03, 2015, 03:55:49 AM »
MUST HAVE NOW!
Some things are best left unsaid

pvision

Re: 500 series Sontec / GML type eq
« Reply #8 on: June 03, 2015, 06:11:38 AM »
Wow

Great panel layout - it looks like it will work really well

Nick Froome

Electrobumps

Re: 500 series Sontec / GML type eq
« Reply #9 on: June 03, 2015, 06:59:59 AM »
I've heard this baby and it can only be described as the most musical EQ you will ever hear.   Its like a GML but better.  I've never dialled in top end that sounds like this!



onlymeeee

Re: 500 series Sontec / GML type eq
« Reply #10 on: June 03, 2015, 09:22:24 AM »
Thanks everyone!  And especially Electrobumps who let me use his vastly experienced 'producer ears' as a test subject!

I don't currently have any spare boards..  although as there seems to be interest, there's no problems ordering a batch of kits..  and I will do so asap..   

The pots are by UK company Omeg who make fantastic handmade pots..  A thing that I like about them is the strong feel.. it means that they can't be moved just by a little flick which sometimes happens with concentric pots..  Often I'm moving the frequency on a GML and the Q gets turned by accident..  This doesn't happen with the Omegs..  They're very firm when turning..  also means that at the extremities of the frequency ranges, you can really dial it in accurately..

The centretapped pots are Alps..   As the centre of rotation is tapped and grounded in this circuit, it this lends itself nicely to a centre detent pot which these are.. meaning essentially a bypass for each frequency at the centre detent.

One thing I changed from the initial prototype is the shelf switch..  As you know, the shelf switch on a GML is on the Q pot..  and more specifically the widest Q..   So it's seamless operation...  however on the prototype, I had a separate switch which meant I had freedom to change the Q of the shelf too..  This was great, however, it felt a little wrong when on the sharpest Q setting..   As it wasn't really a shelf as such at the highest Q on shelf setting..
Of course I could have just always made sure to widen the Q but it just 'felt' wrong.
So what I did was:  when the shelf switch is pressed..  it also switches in a resistor to limit the sharpness of the Q possible on the shelf setting only..   this meant that it was always a shelf no matter what the Q..  and you still have the flexibility of the Q on the shelf. 
This wasn't a problem on the bottom shelf.

Any other questions just ask! 

Oh.. the other thing that I wanted to do was eliminate all wiring..  so the only thing that's needed is that one 10way ribbon cable!

Rocinante

Re: 500 series Sontec / GML type eq
« Reply #11 on: June 03, 2015, 10:25:28 AM »
Definitely interested,  down for two. Are the Omegs available from AML? How about the Alps?
The ribbon cable is a beautiful thing.
I have been waiting for this.
If there's a harder way to do this, I haven't found it yet.

Axelerator

Re: 500 series Sontec / GML type eq
« Reply #12 on: June 03, 2015, 01:46:21 PM »
amazing !
i still have to build the full blown igor version, bought the pcb´s right before everything went way down..
but sure i would be interrested in two kits if this comes true as i have unfilled slots in my 511 rack!
i hate unfilled slots  8)
axel

Re: 500 series Sontec / GML type eq
« Reply #13 on: June 03, 2015, 02:47:32 PM »
I'm in for a pair, great work!

weiss

Re: 500 series Sontec / GML type eq
« Reply #14 on: June 03, 2015, 02:57:34 PM »
interested in a pair!
« Last Edit: June 15, 2015, 07:31:47 PM by weiss »
Ansgar Scheffold
www.ansgarscheffold.com

KDE

Re: 500 series Sontec / GML type eq
« Reply #15 on: June 03, 2015, 03:23:44 PM »
Pair please  ;D
Some things are best left unsaid

petermontg

Re: 500 series Sontec / GML type eq
« Reply #16 on: June 03, 2015, 03:58:52 PM »
In for two pair 8)
« Last Edit: June 04, 2015, 05:04:43 AM by petermontg »

Ericbazaar

Re: 500 series Sontec / GML type eq
« Reply #17 on: June 03, 2015, 04:22:24 PM »
 :o i'm in for two ;)

shot

Re: 500 series Sontec / GML type eq
« Reply #18 on: June 03, 2015, 05:57:11 PM »
Wow! Impressive!

Needles to say - I'm interested in a pair too!

Since I'm not into 500 format, I'd rack it in a regular 19" case and have some space left inside maybe to fit Wayne Kirkwood's MS board! Hehe!

Except for pots maybe, are there any hard to get components?

Re: 500 series Sontec / GML type eq
« Reply #19 on: June 03, 2015, 06:42:12 PM »
I'm in for at least a pair. Are they mono or stereo units?
/
Emil