sontec 1 RU build thread

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sedit1 said:
Just measured capacitances. Allmost all the values were in line with eatchother but how colose do you need to match the channels?
My 0.47uf caps were littlebit off 3x~0.47 and one 0.49uf. Is it better to order more 0.47uf and try to match the caps better?
Click to expand...
This 20nF difference with all other parts spot on will change frequency range from 125.8/7,987Hz to 123.2/7,822Hz. You could overwrite the '0.49' uF value with this '0.49' in maybe cell F15 to see the consequnces and if these matter to you.  Ordering more 0.47uF (or paralleling 22nF caps to the 3 remaining 0.47uF) might be the easiest way for a better match. You could as well decrease Rx.9 and Rx.10 to 1K567 and decrease the substituted pots resistance for this specific band to 98K instead of 100K for Rfreq.1 and Rfreq.2 to get you back on track.
 
Harpo said:
sedit1 said:
Just measured capacitances. Allmost all the values were in line with eatchother but how colose do you need to match the channels?
My 0.47uf caps were littlebit off 3x~0.47 and one 0.49uf. Is it better to order more 0.47uf and try to match the caps better?
Click to expand...
This 20nF difference with all other parts spot on will change frequency range from 125.8/7,987Hz to 123.2/7,822Hz. You could overwrite the '0.49' uF value with this '0.49' in maybe cell F15 to see the consequnces and if these matter to you.  Ordering more 0.47uF (or paralleling 22nF caps to the 3 remaining 0.47uF) might be the easiest way for a better match. You could as well decrease Rx.9 and Rx.10 to 1K567 and decrease the substituted pots resistance for this specific band to 98K instead of 100K for Rfreq.1 and Rfreq.2 to get you back on track.
Click to expand...

So ordering more it is  :) Thanks!
 
Seems like there is a lot of sontec orders... But no group buy on the pots necessarily to build it?  Who is down? GROUP BUY, GROUP BUY, GROUP BUY!  You guys who are building them in the states... Is there any other kind of pot we could substitute? 

Also, any kind of pot which would be easier to build stepped gain with?

Thanks ! 
 
colombian said:
any idea where to get the Forssell 990 DOA in US?  I have been unable to source them!
Click to expand...

None of the 99x DOA's are made by Mr. Forssell any longer. :-[ I had inquired about it to him awhile ago. Apparently the parts are no longer available. Sometimes they come up for sale on this forum. I had a couple of his 992's around and I used those. They really sound great in this circuit.

Charles
 
Hey Charles!  Thanks for replying!!

Yeah, very hard to get, I looked everywhere and I am a good searcher!  I did find these:

http://johnhardyco.com/990OpAmpDetails.html

Seem like they are based on the old JE990 and have the same Pinout that could potentially fit in the board for the summing section.  They are $50 a piece and I am thinking to build it with 604s first and then try a couple of those.....  after I am sure it lights up fine!  :)

regards

Ludwing
 
Hi!

Yes the Hardy 990's will work on the summing boards. The pin out is the 990 standard. They are not JFET based as the Forssell's but use a matched Bi-polar transistor. They sound great just different. You may need to play with the compensation cap value to use these though.

Charles
 
OK.... Ready?

http://www.groupdiy.com/index.php?topic=48527.0
 

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Those will fit fine:

http://il.farnell.com/harwin/h3161-01/socket-pcb-tin-knurled-1mm/dp/149318?Ntt=149318
 
Igor said:
Those will fit fine:

http://il.farnell.com/harwin/h3161-01/socket-pcb-tin-knurled-1mm/dp/149318?Ntt=149318
Click to expand...

They definitely don't fit! Maybe you've changed your boards in the meantime, mine are Rev 1.6.

Mouser No. 575-032620 barely fits, but I have to force them in. :(
 
I'll try to us the male pins soldered to the female pins as a workaround. That's a bit loosely but at least it fits without having to drill anything and destroy the contacts:

DOA-Workaround-4-Sontec_Forssell.jpg
 
Biasrocks said:
Those look backwards, that's probably why they didn't fit.
Click to expand...

I don't get it. Backwards?
The smaller side doesn't fit, so obviously the bigger side doesn't fit, too. By using the gold plated males as seen in the picture it fits but the DOA sits very high.
 
Yeah, looks like my description kind of sucked. ;)

The issues with the drilling made me think about this workaround. The downsides are that it's a bit more expensive and the DOA sits ca. 5 mm higher than with just the female pins. But I don't care much for both.
 
Would this particular switch work for a stepped version? I think they have a few options and $38 for a prepopulated switch doesn't seem too bad?

http://www.analogmetric.com/goods.php?id=1000
 
druu said:
Would this particular switch work for a stepped version? I think they have a few options and $38 for a prepopulated switch doesn't seem too bad?

http://www.analogmetric.com/goods.php?id=1000
Click to expand...
Might work when you use the "Please contact to our sales for other customized values" for a reverse log increase for the rheostats (not ladder attenuators), or you only use the switches Rg part and are comfortable with having the rotation reversed from usual behaviour ...
 
OR build it yourself :), EDIT: "i guess" they are using 1% resistors, and you might get to their same price using 0.1% ones tough (SMD)
There is a Log Excel file here that harpo and AndreasS were kind enough to provide to the community.
Takes that away in the equation also.

http://www.groupdiy.com/index.php?topic=48566.0
 

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