gyraf

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #100 on: January 06, 2006, 11:05:00 AM »
Quote
i want t build this unit for like 3 band eq but not for mastering pruposal... mostly live preformance and 'ruff' mixing


Build the Calrec clone instead then - that one is simple, proven, and sounds very good.

Much easier than the Sontec..

Jakob E.
..note to self: don't let Harman run your company..


Viitalahde

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #101 on: January 06, 2006, 11:08:00 AM »
I agree with Jakob. If you're not an experienced builder, go for the Calrec. Leave the Sontec for later.



..This beast almost drove me nuts! But it serves well now.  :cool:

5meo-geo

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #102 on: January 06, 2006, 11:09:11 AM »
hmm true....
i dig ya...
10x again

ohh 1 more thing if i use switch fter all.....
i understand that all DKxx goes to output legs of the switch
where the input leg of the sitch connected to???
talking about this layout
http://www.thediypill.phx.com.br/DIY_SONTEC/SONTEC_PARTS.pdf???
is it to DK1 and DK2 at 'FREQ' lbeled controler?

deveng

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #103 on: January 06, 2006, 11:27:32 AM »
Jaako,

Very nice work (and a lot of it!).  

Who makes the chassis?  I need a channeled side panel like that to maximize internal mounting room for my projects. Is that a Schaeffer?

Regards,
Jeff

cstella

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #104 on: February 03, 2006, 10:41:50 AM »
Hi I am finally getting started on my Sontec and had a couple questions. What Elma 2 x 24 switch is being used? I am guessing 04-2130?

Also were the freq select resistors for this switch ever posted? I may have missed them.

Thanks! Charles.

Nadege

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #105 on: March 29, 2006, 03:23:15 AM »
Hi

I was wondering wich kind of power supply do you used for the Sontec?

Do you have a schematic somewhere?

Thanks

Viitalahde

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #106 on: March 29, 2006, 03:37:22 AM »
I'm using a pretty standard +/-24v PSU with LM317/337's, straight out of the datasheets. Separate regulators for L/R and all the protection diodes/adjust pin caps installed.

No schematic drawn but bipolar LM317/337 PSU schematics are everywhere..

VXO

Stray noises. Ew.
« Reply #107 on: June 15, 2006, 07:57:51 PM »
Hey guys... greetings, from Radiate FM, in sunny 'n' humid Miami, FL!
http://wrgp.org

We've been remodelling a bit lately. As a result, on my desk, I've got an actual Sontec MEP250. It lived in our station's production studio, FORGOTTEN, connected to nothing but AC power, for around 18 years!

The other night, we were going to hook up a turntable into our beloved old Pacific Recorders & Engineering BMX-II console, and the old Stanton phono preamp we pulled out of the closet had weird frequency response. The GM tried to hook it up through the Sontec, but he just got terrible noise and distortion on the right side.

I found a spare Sontec op-amp module in an envelope in my documentation file (sadly, no actual Sontec documentation there!), and tried swapping out the amps on that side one by one. That didn't fix it. The noise would come up when it was taken out of bypass; 60 hz hum with lots of harmonics (which could be manipulated amusingly using the higher freq. bands). It sounded clipped, no less. Ew.

I tried all sorts of nonsense - unplugging and reconnecting the individual active filter modules at the front of the Sontec one by one, and the buzz just refused to make itself scarce. Finally, I moved the gain pot on one of the filters with them all plugged in... and it disappeared!

The left side, meanwhile, had been operating perfectly all this time. However, I discovered a strange behavior .. if I turn the gain on more than one or two of the filters all the way down, the buzz reappears, loudly. If they're all up near -5 or above, the Sontec's quiet and works just fine. The Q and center freq controls seem to very slightly interact with this effect, but only just barely.

A possible clue: The Sontec op-amp boards run warm. Oscillation? I tried holding a piece of sheetmetal between the transformer/power supply area and the filter boards on the right; this didn't change the buzz at all, though putting my hand too close to both the transformer and the filter boards couples a mighty 60 hz. Bronx cheer into the system.

Forgive me if this is off-topic or anything... resources on the web on the Sontec seem to be few and far between. Consul pointed me this way. I tried the links earlier in the thread, but those pages seem to, sadly, be dead.  :cry:

I think I definitely need to hang out on this forum more. One of our DJs is really interested in homebrew synth (and so am I). Yay.
Pentooooooooooode. Say it with me now... Pentooooooooooode. Amusing, isn't it?

dmlandrum

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #108 on: June 15, 2006, 08:16:00 PM »
Hey, VXO. I'm posting this while in IRC with you. Go figure.

Everyone else: He's a cool guy, so go easy on him. :green:
Darren Landrum

Be comforted that in the face of all aridity and disillusionment
And despite the changing fortunes of time,
There is always a big future in computer maintenance.

JayDee

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #109 on: September 16, 2006, 08:41:59 AM »
can someone please tell me , is R80 4k7 or 6k4 ? partlist does not make it clear...

and what about R78 filterboard, which has place on the pcb but doen´t appear on the partslist. schem says omit...what did you guys here...?


nrgrecording

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #110 on: September 17, 2006, 08:59:35 AM »
Quote from: "JayDee"
can someone please tell me , is R80 4k7 or 6k4 ? partlist does not make it clear...

and what about R78 filterboard, which has place on the pcb but doen´t appear on the partslist. schem says omit...what did you guys here...?


R80:
I used 4K7 and it worked fine. R80 Is also 4K7 at the original schematics (take a look at the inverting input from the output amp)

R78:
just don't put anything in there
Frank Röllen. www.energyrecording.de [FORUM · DIY WEBSITE · STUDIO]°°°° www.frontpanels.de [Engraved Frontpanels]°°°°

JayDee

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #111 on: September 17, 2006, 02:52:47 PM »
Frank. I just have the "redrawn" schematics and there is a mark (handwritten) which maybe adds or replaces the 4k7 to 6k4...

That´s why I am asking...

But as your 4k7 is working I will try that one first.

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #112 on: September 23, 2006, 11:07:26 PM »
Hello,

I am trying to begin to construct eq Sontec. I have pcb of Fabio and bought quite material.
My problem is that after reading all the thread to me, I have some doubts, which I consider by important that I cannot continue.

1) Which are the values of R75 and R76?

2) In which cases are used R75 and R76? I create to understand that it is when the filters are of the Shelving type.

3) When they are used R75 and R76 in short circuit, according to the original scheme, they would be in short circuit but with respect to which? in which circuit points are connected?

According to it formulates it of Jaakko:
fc = 159000 / ((R73+R75) * C27 * (R74+R76) * C28)^0.5

4) In case R75 and R76 are not used, Its value is 0?

I have tested of I calculate according to formulates it of Jaakko, on the frequency of 34,6 herzios with real values and the result gives the following thing me:

8.84152372=159000/((1600+3300) * 0,015 * (1000000+1000000) * 2,2)^0,5

5) I do not know if I am calculating this good.
This would be I calculate correct? If it is thus, the value of the resistance would be 8,84 ohms?

6) For the control of level and shape, in the scheme there is pots of 50k for the level and 5k for shape. If I want to change this by a rotating switch, How many positions would have the rotating switches and as they would be the values of the resistance?

If somebody can help me, thank you very much.

olafmatt

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #113 on: October 07, 2006, 07:17:51 AM »
After having read this thread over and over again I thought I'd ask whether anybody here has ever build a Sontec MES 430 series clone?

On one of the first pages of this thread there is some talk about the shelving filters, the 430 series EQs use a different circuit for shelving: RC filter for HighShelf and a gyrator for the LowShelf. Has anybody here build/tested these? It results in one more opamp being in the signal path, but probably also reduces the work the opamp for the parametric filters has to do.

Since ages I have a partly finished PCB layout for the 430 on my computer, everything on one PCB (15x20cm per channel) with connectors for the pots/switches and space for 990-style opamps. But I'm still unshure whether it's wort continuing with this, or whether I should just build the 250.

Olaf

Nadege

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #114 on: November 08, 2006, 02:47:05 PM »
Hi,

my questions will probably look stupid for most of you but anyway,... :oops:

I don't really understand the formula to setup rtesistor value for the frequency switch...

And also, I don't really understand how to wire the switch to the PCB.

Thanks for your help

Nadege

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #115 on: November 09, 2006, 02:44:09 AM »
Hello,
Still my doubts continue yet the exposed thing above... I believe that the things to carry out them are fundamental and basic to understand them completely. For that reason when one does not know, I believe that he is better to ask, to see if somebody helps a little us... It makes much illusion me continue with this project, I know that it is very difficult, but have much interest in trying to learn.
Thanks beforehand.

olafmatt

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #116 on: November 09, 2006, 04:04:10 AM »
Quote from: "Nadege"
I don't really understand the formula to setup rtesistor value for the frequency switch...


http://www.groupdiy.com/index.php?topic=2399&highlight=sontec

[silent:arts]

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #117 on: November 09, 2006, 05:15:48 AM »
I did this Excell Sheet once to calculate the Rs for given Freq. and Cs.

just.sounds

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #118 on: January 22, 2007, 08:45:19 AM »
Ah that's so cool! saves me some headeache!

josh

The Sontec thread! <ATT. BUILDERS - C22 & C23>
« Reply #119 on: June 20, 2007, 10:52:57 PM »
Hi all,

I am ordering parts for my Sontec, and I'm at the Audio Opamps.  You can use NE5534 or OPA604 or OPA627 in the filter board, and the sane in the amp board.  So I need 12.

The OPA627 is around 20$ each new, but I found a source where I can get 13 Burr Brown OPA627AP's for about 140$ which is a bit cheaper.

What can you guys tell me about these?  If they are going to put his one over the top in terms of quality, then I may go for it.  But, if I need to have thousands of dollars in Apogee converters and clocking to hear a difference, then I won't bother.
Thanks,
Josh


 

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