sontec 1 RU build thread

[TornadoTed]

I fired mine up today with my friend who is an infinitly more knowledgable tech than I am.

It worked pretty well but we had a litle oscillation on the high shelf only at -9 dB cut though so he installed a small cap (can't remember what value) on the feedback resistor and it went away.

We also found that as the Q and Freq pots don't go through the case they weren't grounded as well as they could be. Rocking them slightly caused hum to come and go. We soldered wire between all the pots and then to ground and it disappeared. It doesn't look very neat but it worked a treat.

Anyway apart from just over an hours troubleshooting all is good and I have a fully functioning EQ.

Thank you to all who have made this possible and anyone who has helped me along the way. :thumb:

Incidently I went for OPA604 in the end as pennies are a little tight at the moment. I will upgrade to Forssells once I've built the 8 channel S800 EQ and save a bit of money.

 

[khstudio]

I PM'd Igor this question but if anyone else can help, please do.

Hi Igor,

I'm currently finishing my Sontec EQ & mounting the front PCB's to the face plate.

Did you used washers or spacers on the "GAIN" shafts ??? (that bolt onto the front panel)

I'm asking because there are little "Nubs.. or Tabs" on the flat part of the Pots which stops them from being mounted "Flush" to the face plate. Should they be filed off???

I looked at your pics & it looks like you used washers or spacers... are they needed?

Thanks,
Kevin

 

[AW_music]

Hi all,
just finished mine.

http://www.groupdiy.com/index.php?topic=30060

Easy project and KILLER Eq !!

:thumb:

 

[khstudio]

[quote author="Igor"]

Damn... I just checked & I ordered 3mm

They do NOT fit!!!

Great... over $100 for knobs & I get the wrong ones.
Time for careful drilling... wish me luck.

Ahemmm.... I had same prob with 6.3mm Grayhill switches
and Elma 6mm knobs, used friend's Proxxon lathe, solved ...
Anyway, if you don't have small lathe, try to fit collet into drill chunk,
but leave 2/3 outside of chunk - not to press the collet much,
otherwise hole will be too big.
With some care, should work.
Good luck :sam: :guinness:[/quote]

The Collette in the chuck worked GREAT!!!

Thanks for the tip. :thumb:

 

[Igor]

Enjoy

 

[Igor]

By the way.
Received small package with Alpha pots....
The rest is coming at end of november-december.
People, who asked about pots, can share some for kits.
http://www.groupdiy.com/index.php?topic=29771

 

[crisotop]

Finally finished mine too (thanks for the pot Igor!) - I have slightly different curve on the 6dB setting on the high shelves - look at the measurement:

I haven't matched the caps, but all other bands are perfectly fine - any suggestions?

Thanks!
Christoph

 

[Igor]

Actually one curve looks 100% right
(resonant 12db/oct filter as it supposed to be) but second looks like
one cap or 100k pot's half missing...check caps, pot, switches,
resistors-all in this arrea.

 

[crisotop]

Both curves are measured on the 6dB setting?!

Green or yellow, which one is right? the 12dB shelve is much steeper, and has a deeper cut right before the slope starts to boost.

thanks!
christoph

 

[khstudio]

[quote author="crisotop"]Both curves are measured on the 6dB setting?!

Green or yellow, which one is right? the 12dB shelve is much steeper, and has a deeper cut right before the slope starts to boost.

thanks!
christoph[/quote]

If it's not the 6 - 12 switch... what are your sweeps from?

- Movement of GAIN or FREQ?

 

[crisotop]

doesn't matter how gain and/or frequ is adjusted, always the same slope (one channel is rising softly, one has a small cut before the boost starts)

cheers
christoph

 

[khstudio]

[quote author="crisotop"]doesn't matter how gain and/or frequ is adjusted, always the same slope (one channel is rising softly, one has a small cut before the boost starts)

cheers
christoph[/quote]

Ohhhhhhhhh... it's Left & Right channels.

You never mentioned that. :razz:

 

[crisotop]

haha - sorry my bad

I hope my problem makes more sense now :grin:

cheers
christoph

 

[Igor]

So, you solved the prob?
:twisted:
:shock:
:roll:
:grin:
:wink:

 

[crisotop]

nope, not yet - which curve looks right for the 6 dB setting? then I'll start digging around

Thanks Igor + Matt!
Christoph

 

[khstudio]

[quote author="crisotop"]nope, not yet - which curve looks right for the 6 dB setting? then I'll start digging around

Thanks Igor + Matt!
Christoph[/quote]

I think he said the "Smooth" one... without the dip. :idea:

 

[khstudio]

Igor,

I just got my JLM 99v op-amps (for the outputs), Hybrids (inputs) & remanding parts in today & was hoping to finish this EQ up tonight but I have a problem...

The DOA Sockets I have won't fit in the holes on the PCB.

What size are the holes on your PCB :?:

I have 2 different types here:

1.87mm (got these from JLM)
1.65mm (these are pretty standard for all my other builds so I got 100 & thought they'd fit your PCB too & don't)

I thought about drilling out the holes but they're "Thru" holes... makes me nervous.

 

[Igor]

Ahem....yes, there was an error with drill size tolerances.
Updated on new pcb's.
One thing is possible to do there, is just put pins on DOA's then
solder them to PCB from upside. IIRC someone did so...search....
Or, solder DOA's directly to PCB
(personally...don't like these pins on DOA).

 

[Igor]

edit: d-leted (double post)

 

[khstudio]

[quote author="Igor"]Ahem....yes, there was an error with drill size tolerances.
Updated on new pcb's.
One thing is possible to do there, is just put pins on DOA's then
solder them to PCB from upside. IIRC someone did so...search....
Or, solder DOA's directly to PCB
(personally...don't like these pins on DOA).[/quote]

Strange I never saw this mentioned or posted.

But, it's a good thing I'm handy... I just put the sockets in the chuck of my drill press, then used a small metal (smooth) file to taper them down and it worked.
Not the easiest thing to do & also time consuming.

I should have it done by the weekend. :green: