sontec 1 RU build thread

[Igor]

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.

 

[Majestic12]

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

 

[kante1603]

Sehr schön und sauber gebaut-Respekt!

Udo

 

[kante1603]

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

Thx,

Udo.

 

[Igor]

Tonleitungsubertrager faterland!

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

 

[druu]

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?

 

[Kingston]

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?

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.

 

[druu]

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.

 

[ptron]

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

 

[Majestic12]

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

 

[ptron]

Thanks for the quick reply!

 

[druu]

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

 

[ptron]

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

.. damn hard to pick

 

[kante1603]

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

.. damn hard to pick

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

Udo.

 

[druu]

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.

 

[i3j0rn]

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

By the way thanks Holger for thoses references ! =)

 

[rmaier]

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.

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

 

[ptron]

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!!

 

[dryman]

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?

 

[Harpo]

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?

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.