[BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD

[zamproject]

Bernd
I just have a look at Sowter, around 500€ for the set :
Mains trafo is the most expensive, Don Audio's one is 1/4price of the Sowter one
I will think about all this... temptation !!!
Zam

 

[bernbrue]

If you take a decent 1:4 input transformer, the Edcor or Hammond output transformer, don Audios power transformer, you could drastically lower the costs. The Edcor performes quite convincing in this circuit. I hope some people will try the Hammond as well.
Bernd

 

[bernbrue]

Updated 1st post. Added some downloadable audio files (vocals, 16 bit 44Khz, mono)
Bernd

 

[DonnieDarko]

Hey there,

I´m almost finished with my build.

Some questions though:

Bernd, you mentioned that R7s should be changed - do you happen to have the corrected value at hand? Didn´t find it in the posts.

I´m using the Edcor for Output Transformer as maybe many builders - are there resistors to be changed? Anybody wired this one already - asking for what cables to wire where.

For Input, I´m going with these:

http://www.worthpoint.com/worthopedia/pair-utc-rca-8369-33-85-100-340-50k-244488410

Did try to find out exact specs in the old UTC catalogues that they got on bunkerofdoom, without luck though. Does anybody know the specs and how input resistors should be changed?

Appreciate the help!

 

[bernbrue]

Hi,
Leave R7s as it is for now (68R).  See later, if your meter can be calibrated properly. You don't need to change any resistor with the Edcor output transformer. Take one of my build pictures and wire it as shown. Isolate the wires that are not needed. I'm going to check you input transformer later. Which power transformer did you use? It might be good to connect the psu to the mainboard and plug in the tubes already., before you switch it on. Without load you will get insane high voltages. Stay tuned.
Bernd

 

[DonnieDarko]

Hey Bernd,

I build a double PSU with the Don Audio Power Transformer. As it is not beefy enough for a stereo unit as you mentioned, i used a separate PSU PCB for each Transformer.

 

[bernbrue]

Great, did you already fire it up? Would love to see some pictures of your build in progress.
Bernd

 

[Kid Squid]

Bernbrue
Just been to see my metalwork guy, everything is going well - I've instructed him to make the cases 160mm deep as your previous post.
These are blank 2.5mm Aluminium cases, with hinged drop down fronts.
Have you got a drawing for the relevant holes for the front panel, and the rear valve sockets and transformer mounts etc ?
I can forward them to my metalwork guy and get cases ready with the cutouts done.
I should be looking at delivery of the prototype within two weeks.

Best,
Steve

 

[bernbrue]

Hi Steve,
My case is 180 mm deep. Please open a feeler for your cases and let people discuss their preferences.  You can print out the silk screen PDFs in the first post in order to provide holes for standoffs etc. Thanks a lot for your effort! You've got pm.
Bernd

 

[Kid Squid]

Hey Bernd,

Hows this look internal depth is 185mm. I'll update with the fixing holes as soon as I've printed out the PDF.



Steve

 

[bernbrue]

Hi Steve,
Looks great. I'm planning to build a second unit for stereo and would definitely like to have one. Please open another thread for this and let people discuss further details. You may refer to this build thread.
Good work!!
Bernd

 

[Kid Squid]

Cheers Bernd 
I've re-done the Cases as per this post
http://groupdiy.com/index.php?topic=59745.new;topicseen#new

they have now got removable top and bottom lids


Best,
Steve

 

[DonnieDarko]

Hey Bernd,
as requested, here are some Pictures:

This is a topview of my PSU.



I ordered my cases at nrgrecording. The PSU is connected with two 7pin XLRs to the main Unit.



This it the STA main unit, sitting on top of my third 670 clone, which has also a PSU in a separated housing for putting it floorside in a mixing desk and only keeping the important stuff topside with the engineer.

The meters in both units are from Meter Sales, all Big Knobs are sitting on stepped switches. Went for the kukaudio china version, as I found these to be very reliable and I´m really not a friend of ELMA  prices. Mounted about twenty of those in my recent MQ5 Build, and not one position was faulty or giving me any hassle. Really can recommend those.



Still waiting for some very last SMDs which weren´t in stock at the time, looking forward to fire this up.

 

[bernbrue]

oh la la, what a nice build!!!! You'll be amazed by the STA. I bet it's going to be your favourite compressor. Keep us  up to date!
Bernd

 

[DonnieDarko]

I already got one, built on that DRIP PCB. I´m curious how this one performs.

Favorite compressor at the moment is the LESO PWM though, very special unit.

 

[DonnieDarko]

So, got everything finished, but waiting on some last tubes.

Guts of the PSU:

IMG_9172 by Donnie Darko, on Flickr

Guts of the Main Unit:

IMG_9171 by Donnie Darko, on Flickr

Did get some M-8369 UTC Input Irons from Douglas, wired em to 340k / 50k, might have to address the input pad situation.

Looking forward to start this up.

 

[bernbrue]

Hi,
Looks fantastic. There are a few leftovers of wire isolation flying around in your build, pay attention to that. 6386 tubes, whow!! I would  at least solder in some noval tube sockets for the EF93, in case you like it  even better or just to have options.  It might be very difficult to solder them later.  No stereo link?
Cheers
Bernd

 

[DonnieDarko]

Yes, there´s a lot of stuff flying around, will turn the case upside down before powering up.

Will add the stereo link later off course. Waiting on the last tubes…

 

[kosi]

Look, what I have here:
an old Klangfilm dB meter. It says 106,25 uA, the Gates dB Meter has 200uA...

Any ideas, wether this could work in tha Sta ?

thanks

 

[bernbrue]

Should work. There is a 10K trimmer to calibrate the meter. So the range of possible meters is very large.
Cheers
Bernd