sontec 1 RU build thread

[cstella]

Thanks. I am using the Hairball 30VA

http://hairballaudio.com/shop/product_info.php?cPath=33&products_id=37

Secondary is orange and black for 0V and Red and Yellow for 25V. On the primary side I have them setup in parallel.

Does that sound right?

Thanks, Charles

 

[Harpo]

No. http://www.avellindberg.com/transformers/tech_notes/tech_notes_comp.htm
You want your secondary windings connected in series. Exchange the black with red, so orange+red is your transformers secondary center tap connection to pcb.

 

[cstella]

Aha! Cool. Thanks for the help!

 

[Kingston]

And about the 2.7k pf mica with a width of 5 mm ... ? I searched mouser in every mica corner and couldn't find anything that'd match a width of 5mm.

There aren't small mica's available, they're big, clumsy and high voltage. But that's ok, they don't sound very good in filters, you don't want there here anyway. Use c0g or np0 ceramic caps everywhere. Technically these are the best option.

 

[cstella]

No. http://www.avellindberg.com/transformers/tech_notes/tech_notes_comp.htm
You want your secondary windings connected in series. Exchange the black with red, so orange+red is your transformers secondary center tap connection to pcb.

Thanks Harpo! I switched the secondaries this morning and now it works as expected! The transformer gets pretty hot though.

 

[cstella]

I was using a 1A slow blow fuse on the power supply and it works now but I was concerned that is too high for my 30VA 600mA transformer. The transformer was working but seemed to get hot. When I switched to 500mA Slow Blow it just blew the fuse. What are people using for US voltage on there Sontec?

Thanks, Charles

 

[cstella]

Hi Mark

Thanks for responding. 500mA should be fine right.

The heatsinks are raised of the board and not in contact with anything. They are also isolated from the regulators.

You are using the Hairball transformer right? I have the primaries wired in parallel brown+grey and blue+violet. Secondaries are as harpo corrected orange+red for CT. Is that what you have?

Thanks, Charles

 

[cstella]

Thanks Mark for the picture. 

That's what I originally had as my CT (orange + black). I just disconnected the PS and the transformer is still blowing fuses with orange+ red CT.

I'll try to switch it back and see what happens.

Thanks! Charles

 

[cstella]

OMG! I figured out what the problem has been. The transformer I have has some cuts in the tape exposing some of the windings and shorting itself to my case. I'm surprised it was brand new. I have re-taped it and now no shorts and I can ground AGND to power ground!

Thanks for everyone's help. Mark the pics helped a lot!

Charles

 

[cstella]

Well after all that the first channel works perfectly so far. OPA2604's on the filter board and the servo and Forssell DLR on the input and JFET990-2 on the output.

Now on to the next channel! 

 

[cstella]

Nice! In some great company there.

I hope to be joining you soon!

Thanks for your help.

Charles

 

[rocksure]

Thanks for everyone's help. Mark the pics helped a lot!
Charles

Awesome, glad you got it sorted Charles.

Here's my baby all dressed up and ready to rock, hangin' with some friends.

Regards,
Mark

Looks great! How does it sound? I have never used a Sontec EQ, kind of interested to know your experiences with it in use have shaped up.

 

[Nobieesd]

Hey guys,
I'm totaly new in this DIY audiogear-thing
but my brain doesn't stop working since I have seen this awesome Project, so i have decidet to build also one sontec eq
I have really no idea how to start with such a project, maybe someone could help me ?

- Should i start with searching for the parts from the BOM-list ?
- or first read the whole thread ?
- and, where can i get a cheap PCB for this projekt ?, this is it or not?:
http://market.diyrecordingequipment.com/red-sontec-stereo-pcb-set,name,100290,auction_id,auction_details
seems a bit expensive...

and sorry for my bad english, i'm from germany and haven't spoken or written this language since 2 years
thanks ahead for your help
cheers, Nobieesd

 

[cstella]

Just finished the Sontec! It all checks out on the scope and meter. Headed to the studio to put it through the paces. Still short a couple .1 bypass caps but they should come today.

After the power supply issues it all came together very smoothly.

Thanks Igor for a great project and Dan at Collective Cases for a beautiful enclosure. And thanks to the group for the build support!

 

[cstella]

and the guts...

 

[sonicwarrior]

Looks great.

Btw.: Was it hard to get the potentiometers from Alphastat?
I still haven't bought them.

 

[benlindell]

Looks great.

Btw.: Was it hard to get the knobs from Alphastat?
I still haven't bought them.

I was just about to ask where the knobs are from, I'd be curious to hear about them as well.

 

[sonicwarrior]

I meant the potentiometers.  :-[

 

[cstella]

Looks great.

Btw.: Was it hard to get the knobs from Alphastat?
I still haven't bought them.

I assume you mean the pots from Alphastat? They were not hard to get but a bit expensive. It took about 3 weeks to get them. You should have an easier time being in Germany I would think.

Looks great.

Btw.: Was it hard to get the knobs from Alphastat?
I still haven't bought them.

I was just about to ask where the knobs are from, I'd be curious to hear about them as well.

The knobs are Elma Classic Collet's 14.5mm's. I got them directly from Elma US in Fremont, CA.

http://www.elma.com/Americas/English/Products/RotarySwitches_4/Knobs_31/137.aspx

 

[Igor]

Awesome guys. I love these eq's by one simple reason: don't have to give any support, all works
Happy to see your units.

Regarding the PCB's pricing: I am more than happy to sell them lower,
but, to bring the price down, I have to order MOQ of 100 PCB's.
In case of 3-4 stereo pcb sets sold monthly, impossible.
You can organize group buy for say 20 stereo sets, the price will be 40% lower.