sontec 1 RU build thread

The difference for 150pf is high frequency stability (pole compensation) for discrete op-amps used in "original" build.
It is possible to completely avoid these 150pf with fast op-amp.

Well, right now I have the 150pF and 5pF caps in the circuit. Don'T think theres any need to remove them.

Sehr schön und sauber gebaut-Respekt!

Udo

Hi,
The transformer,is that a fully sealed type from Schuro Electronics?

Thx,

Udo.

Tonleitungsubertrager faterland!

Ah yep. I finished another one with MS option few days ago...

Builds look great!

Nearly finishe mine, just did some testing with the psu board. I'm new to this stuff, is the power LED supposed to take a while to switch off? I found some spare from an old project and no idea of the voltage but it's the right size for the front panel. How can I make it switch off immediately?

druu said:

Nearly finishe mine, just did some testing with the psu board. I'm new to this stuff, is the power LED supposed to take a while to switch off?

Click to expand...

It happens if you use especially big electrolytic caps on the PSU and if the unit isn't big on drinking current. I like it personally, same for the delayed clickety-clack of relays in a similar case.

Yeah I guess it's a good notification of when it's safe to touch the boards if required. I don't mind it, just used to instant off's hehe.

Hi guys! Just checkin here.. Im just finished populating boards im really excited! (igor i sent u the list of missing stuff, a tag to your 2254 pictures also eheheh, to your email and payed for the shipping )

i got to finish reading the thread, ill post doubts if any but at the moment all is very self explanatory!

Just one question... The frequency pots... The pcb has 6 holes, the pots have 7 legs, 6 stacked like the pcb and an extra one behind... What do i do?

Theyre alphastat pots from the BOM just with detent positions..
thanks
All the best!
Patricio

The 7th pin on the pot is just a ground connection to its metal housing. You have to remove it with a wire clipper.

Thanks for the quick reply!

Having a hard time trying to find some knobs for my EQ. Farnell (Element14 in Australia) or RS don't seem to have the right type I want. :s

i been thinking of knobs... (dont laugh hehe)...

.. damn hard to pick

ptron said:

i been thinking of knobs... (dont laugh hehe)...

.. damn hard to pick

Click to expand...

Hmmmm.....Sifam?Or are you searching for a special look?

Udo.

Tell me about it ptron, i've literally spent two days so far trying to figure out what to get!

I think i've settled on some though, ones from RS that dagoose used on his stepped EQ. Thing is, there's not a lot available that match that type that have a 1/8" shaft for the shape controls.

Sifam knobs are all right and not so expensive. Ordered It from sibalco.de. Holger putted the right references previously in this thread.

The article # is 3001768 for the 15mm and 3000195 for then 10mm knobs

Click to expand...

By the way thanks Holger for thoses references ! =)

druu said:

Tell me about it ptron, i've literally spent two days so far trying to figure out what to get!

I think i've settled on some though, ones from RS that dagoose used on his stepped EQ. Thing is, there's not a lot available that match that type that have a 1/8" shaft for the shape controls.

Click to expand...

You might use reducers to open up your choices: http://ca.mouser.com/ProductDetail/TE-Connectivity/KR104/?qs=uxvR3OIxFgcf%2fvZL7XsX4Q%3d%3d

wow guys thanks a lot!! this is tons of info i can see some of u have spent some time looking for these  damn things... 

rmaier, thanks a lot! didnt even know those existed !!!

j3j0rn, i thought sifam was overly expensive! ill give em a shot, thanks a lot. since holger already done the work for us... (thanks holger!)

druu... i feel ya mate... theyre so many shaft sizes..

Udo, i dont know! a bit of myself would like it to have the nice colorful look u know.. easy to get the right parameter like this... up for anything tho, i mostly like the knob to feel heavy.. not light... (i feel this makes it easier to control with heavy knobs rather than lighter ones)

btw.. did any of u order tat`s case?? i found the gain pots`holes are a bit smaller than the actual thread of the pot... so had to chew a bit on those holes.. and the toggles... i thought they were ok to solder right against the board but theyre off by a mm or so... mm might have to chew a bit of those too..

thanks a lot guys!!

i have a question about the resistors RF 1/2/3 B/C (and RF4B/C1) on the BOM the resitors should be 7.5k, but there is a note, that i can use 4.7k for more gain. Do i have +/- 12db with 4.7k and +/- 6db with 7.5k?

dryman said:

i have a question about the resistors RF 1/2/3 B/C (and RF4B/C1) on the BOM the resitors should be 7.5k, but there is a note, that i can use 4.7k for more gain. Do i have +/- 12db with 4.7k and +/- 6db with 7.5k?

Click to expand...

No. With perfect value center tapped pots (they won't be perfect), 4.7K resistors will give you a +/-12dB range of boost/cut. Using 7.5K resistors instead in these voltage dividers will decrease this range to +/-11.3dB. If you want halve of this +/-12dB range, double up the resistor values of R18 ... R21 for a +/-6dB range of cut/boost.