GroupDIY

Project Specific Discussions => Dynamic Processors => Topic started by: bernbrue on March 23, 2015, 09:47:55 AM

Title: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 23, 2015, 09:47:55 AM
Hi,
I would like to provide you with some files, information and recommendations for the STA LEVEL built based on our new developed pcb [Zayance & bernbrue].

First batch has been ordered.  We are going to offer another batch in the near future. When you are interested in buying a pcb, please watch Tonys WM Thread here:  http://groupdiy.com/index.php?topic=53011.0

The pcb provides the T-bar adapter for using two triode wired 6BA6 as substitutes for the 6386. Moreover we included the triple mode and variable recovery time constants. For these controls we used a separate pcb with Lorlin switches. The PSU is devided into two parts, the main psu with three rails for B+, regulated DC heater voltage and an additional rail for lights, relays etc.. The bias voltage is derived from B+ and is adjustable.  There are many optional footprints provided for various capacitor and resistor sizes.  In addition to that the panel provides a lot of little helpers like resistor bending tool, relay bypass pcbs and so on.  As you can see, there are two silver/red logos included for your frontpanel.  8)

(http://www.xaudia.com/BB/GatesPCB.JPG)


PARTLISTS & SCHEMATIC:

MAIN PCB BOM: https://docs.google.com/spreadsheets/d/10sKO--nnTlVR6BXe0ZkCjNowlfY3lcPBVqrNZa4Rv6M/edit?usp=sharing

PSUs
https://docs.google.com/spreadsheets/d/1dvWUDpbunUqhFar242MGlqALWurB_1tjE75uaozCxbQ/edit#gid=0

and EXTRAS: https://docs.google.com/spreadsheets/d/174EJKQd_gsURI7UF7PxU2kEWWTwFB6rkeiwdDHOTx-A/edit?usp=sharing

Schematic: http://www.xaudia.com/BB/STA_LEVEL_SCHEMATIC.pdf

PCB silkscreen: http://www.xaudia.com/BB/STA_LEVEL_PCB_SILK.pdf


READING STUFF

Original Manual: http://www.realoldiesradio.com/docs/StaLevel/Sta-Level_Manual.pdf

Nice compressor comparison with soundclips. Listen to the GATES soundclips
http://www.gearslutz.com/board/gear-shoot-outs-sound-file-comparisons-audio-tests/482178-retro-sta-level-cl1b-mc77-distressor-el8-processed-files.html

The world best compressors ranking list: http://www.attackmagazine.com/features/top-20-best-hardware-compressors-ever-made/6/

ADDITIONAL FILES AND LINKS

adapter for 6386 tube (this adapter is already included in our pcb!!!!): http://twin-x.com/groupdiy/albums/userpics/6386-Subsitution-Adapter%5B1%5D.pdf

meter scale: http://twin-x.com/groupdiy/albums/userpics/Brezovnik-D-16509.pdf

meter scale for Simpson Model 27 (as used in the original unit): http://twin-x.com/groupdiy/albums/userpics/Gates_simpson_model_27_scale.pdf

Balanced T pad calculator in order to tame the hot output level: http://www.nu9n.com/tpad-calculator.html

TRANSFORMERS:

You can use Sowter transformers for input/output:
http://www.sowter.co.uk/specs/9062.htm

9185 GATES STA-LEVEL M5167 Line Output

For input transformers there are quite a lot of different option that have to be tested. When using input transformers with lower ratio the input pad must be modified. I´m going to test a few and report my results.

Edcor has got a nice output transformer as well (CXPP106008K). Good news for people from Europe: Don Audio  is going to offer this transformer in his WM Thread/online shop here: https://www.don-audio.com/Edcor-CXPP10-600-8K-Push-Pull-Tube-Output-Transformer_1

Another alternative output transformer could be the Hammond 1650G. We haven´t tested it so far, but data sheet looks promising.
http://www.tube-town.net/ttstore/Transformatoren/Ausgangsuebertrager/Audio-PP/Hammond-1650G::802.html
http://www.hammondmfg.com/pdf/EDB1650G.pdf

Don Audio is also offering a suitable custom transformer for this project:
https://www.don-audio.com/TB3009S-Audio-Power-Toroidal-Transformer-Sec-300V-9V-5V-Shield_1
There are other suitable transformers as well. At least you need:
sec.1: 300V/200mA
sec.2: 9V/4A
sec.3: 5V/1A
 
Steve (Kid Squid) offers power transformers for this project as well. Have a look at this thread:
http://groupdiy.com/index.php?topic=59744.0

TUBES

V1= 6386  or 2x EF93 (=6BA6=6K4P-EV)
V2= 12AT7 (= ECC81)
V3&4= 6AQ5 (=EL90)
V5= 6AL5 (=EB91)

Our power supply is solid state. You don´t need OB2 and 5Y3 tubes.

FRONTPANELS & CASES

We have designed two sorts of "look alike" frontpanels. There will be one for a standard 3HE enclosure and another one for hinged frontpanel enclosures.
-----------------------------------------------------------------------–----------------------------
Frank (http://www.frontpanels.de/)  does a fantastic frontpanel service and now offers both types of frontpanel for the GATES project. You can also have an "all in one" solution together with his new enclosures as well. Highly recommended !!!
http://www.frontpanels.de/miscellaneous-frontpanels/
-----------------------------------------------------------------------–----------------------------
Don Audios offers frontpanels for this project as well. Thanks a lot Aaron!
https://www.don-audio.com/Frontpanel-STA-Level-Gates_1
-----------------------------------------------------------------------–----------------------------
For U.S. members Dan is going to offer frontpanel and case for this project as well. Have a look at his shop here: http://groupdiy.com/index.php?topic=41963.0
-----------------------------------------------------------------------–----------------------------
Steve (Kid Squid) designed a very nice enclosure with hinged frontpanel . Please discuss specific details here:
http://groupdiy.com/index.php?topic=59745.0

He also offers a high quality power transformer with enclosure for mounting on backplane.
http://groupdiy.com/index.php?topic=59744.0
--------------------------------------------------------------------------------------------------------------------

The following frontpanels have the Simpson Model 27 dimensions drawn in.
Eurorack hinged frontpanel:

screenshot: http://www.xaudia.com/BB/Frontpanel_hinged.JPG
FPD file: http://www.xaudia.com/BB/STAlevel_Frank1Standard_SimpsonMeter_Eurorack.fpd

Standard 3HE frontpanel:

screenshot: http://www.xaudia.com/BB/Frontpanel_standard.JPG
FPD file: http://www.xaudia.com/BB/STALevel_Frank1Standard_SimpsonMeter.fpd

KNOBS
big knobs are 44mm
small knobs are 19mm

https://www.don-audio.com/Schwarzer-Drehknopf-Aluminium-Platte-44mm
http://www.musikding.de/Knebelknopf-schwarz


___________________________________________________________________________________________________________________________________________

Stay tuned. This thread will be updated regularly!

More to come.
Bernd






 
Title: Re: STA LEVEL PCB OFFICIAL [BUILD & HELP THREAD]
Post by: bernbrue on March 23, 2015, 09:58:55 AM
Hi,
The boards are on their way or have already  arrived . There are a  few things I would like to point out before you start to build.

1) Don't break the two control boards (mode & recovery) if you use the frontpanel layout posted in the first thread. The lorlins will fit perfectly with the distance of the holes given in frontpanel design.

2) On the control boards there are three wire bridges to be soldered in. When breaking the control board because of a different frontpanel design you need to use some longer wires.

3) On the mainboard there are three bridges as well. Here you don't need to solder any wire bridges since there are tracks on the solder side . On the picture you'll see that I accidentally soldered  in some wire , but there is no need to do so.

4) Don't break main psu and bias psu if don't need to. In my enclosure space is very tight so that I have to mount these boards separately.  The bias voltage is derived from the B+. Thus you have to provide two wires from B+ - out (main psu)  to B+- in (bias psu).

5) Before you solder the tube sockets you have to solder the screw connectors for the heater supply from underneath. Only the heater connector on the top right is soldered from component side.

6) The small solder pads with letters from A to T are test points for measuring voltages. You will find reference voltages in the original schematic. Next to the tube sockets there are dots indicating pin 1 of the tube.

7) Next to some of the molex connectors you'll find small symbols. They show the orientation of the connectors.

8.) Heater wiring

Pay attention to the polarity. F+ F- is marked on the pcb.

(http://www.xaudia.com/BB/heaterwiring0.JPG)

(http://www.xaudia.com/BB/heaterwiring1.JPG)

(http://www.xaudia.com/BB/heaterwiring2.JPG)

9) Discharging tool
attention high voltage!! Please use it for your own safety. Caps keep their charge for quite a long time!

(http://www.xaudia.com/BB/discharger2.JPG)

(http://www.xaudia.com/BB/discharger1.JPG)

10) Calibration:  make shure that heater (f-) is connected with a wire  to chassis ground. Make this connection switchable by using a momentary switch.  As soon as the reference to ground is interrupted the unit starts to hum. Turn the trim pot between the two EL90s until hum is reduced to a minimum. That's it. See attached file.

11) Complete wiring guide by user Monoklang (thanks a lot, John):

(http://www.xaudia.com/BB/wiringguide20160325.jpg)

12) relay pcbs: you can power the relays either in parallel (bridge //+ and //-, don't bridge S) or in series (bridge S only).  Make the +5V switchable.

Cheers
Bernd
Title: Re: STA LEVEL PCB OFFICIAL [BUILD & HELP THREAD]
Post by: bernbrue on March 23, 2015, 09:59:21 AM
Hi,
Some notes and observation of my build. Configuration: Jensen 1:4 input transformer, with input pad, Edcor output transformer, don audio power transformer.  B+ voltage 312V

1) changed R3 (B+ psu) to 940 ohm ( you can take 1k) in order to tame AC voltage coming from power transformer.

2) replaced B+ trim pot with a solder bridge.

3) This advice is only for people with boards from the first run.  It will be fixed in the next run!!
RVD1 and RVD2 ( bias psu) , both 68K must be set in parallel, making 32K. For some reason the values from original schematic resulted in a way too low bias voltage. With 32K we finally get 25V bias voltage as marked in the original schematic.  See attached picture !

4) edit: leave R7s as it is (68R). Depending on your meter you may change to 100R. I tested an ordinary VU meter. It works as well.

5) Here are some voltages taken from the test points as marked on the pcb (reference to chassis ground). Keep in mind that 10% tolerance is absolutely normal in a tube circuit.

A= 82v
B= 0v
C= 0,6v
D= 0,5v
E= 0,6v
F= 0v
G= 82v
H=142v
I= 168v
J= 0
K=2,58v
L=2,61v
M=0v
N=162v
O= 305v
P= 10mV
Q= 10mV
R= 305v
S=201v
T= 25v

6) A few things to keep in mind when using different input tubes (6386 or 6BA6 combo): 
- with the 6BA6 combo the unit sounds almost the same as with the 6386 tube, but the gain structure and threshold is completely different.
-  First I tested the 6BA6 combo with a 1:4 input transformer, input pad, all values according to original schematic: works fantastic and sounds very good.
- Then I replaced the combo with a single 6386 tube.  I had to crank up the input pot in order to get some slight compression. Not very satisfying.
- So I removed the input pad and lowered the threshold by reducing R32 (24K). I replaced the resistor with a 20K pot plus a 4K7 to ground in order to find the right threshold. Finally ended with around 18K. The unit works fantastic.

More tests and measurement will be added here soon.
Bernd
Title: Re: STA LEVEL PCB OFFICIAL [BUILD & HELP THREAD]
Post by: bernbrue on March 23, 2015, 09:59:44 AM
EDIT (12/03/16) These first measurements were done with the sta level inserted into my ADT 5MT mixing console. I used two 6BA6 as input tubes. I´m going to test other input tube later.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: rob_gould on March 25, 2015, 11:48:52 AM

Hi Bernd

There are some recommendations in the BOM for very posh (and expensive!) Sprague TVA capacitors. 

Have you done listening tests with these caps?  How much difference do they make to the sound compared to the alternative Panasonics in the BOM?

Thanks,

Rob
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 25, 2015, 12:23:00 PM
Hi,
The caps in the BOM are just components you can use. They are  recommendations not  in terms of sound quality but in terms of parts that fit the pcbs.  I always had good results with WIMA caps.  Since there are multiple footprints for the caps, it's basically your choice, which parts you want to use.  Personally I don't believe that there are good or bad sounding caps.  I just take what is commonly available.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 03, 2015, 02:10:32 PM
Some updates in the second post.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 09, 2015, 03:48:42 AM
Some info on heater wiring and discharging tool.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kambo on May 09, 2015, 04:16:37 AM
so the mystery about discharging tool finally clears  ;D
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: zayance on May 09, 2015, 08:56:57 AM
Nothing much, just something to point out "physically".
It would be better to add a Heatshrink on all the assembly of the discharging tool, leaving just windows open for the DMM to still ba able to be connected to track the process.
You can choose to add a crocodile clamp as i did and so clamp on the wherever on the chassis (except powder coated areas) and have a adequat length of cable with crocodile clamp on the other hand, or a testing point, up to taste.
Anyway sorry for the late info on this one :/...
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mrcase on May 09, 2015, 01:58:01 PM
Wow! Great Project! When will the PCBs be available. And will you put some soundexamples online?
congrats guys! looking awesome.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 22, 2015, 12:02:37 PM
Did I mention that my unit works fine? !!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: nickhepfer on May 23, 2015, 02:48:13 AM
Awesome project guys!
Did you compare it to the original Retro?
I really need a set of these PCBs, are they still availible?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Winetree on May 23, 2015, 02:54:17 AM
Could we see how it all mounts together in a front hinged case.
How the boards mount inside, Transformer placement, front panel pots,  etc.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 23, 2015, 05:49:14 AM
Hi,
I attached a pdf file in the first post with some pictures. Enjoy.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 23, 2015, 08:18:22 AM
Tube balancing procedure (calibration) added to second post.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 24, 2015, 03:30:42 PM
Some observations and measurements of my build added in 2nd post.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 26, 2015, 08:12:01 AM
Further measurement in my 3rd post. Results are fantastic. I´m done and going to put the lid on. What about you?  :)
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: nickhepfer on May 27, 2015, 01:20:37 PM
Hey Bernd,
where did you get this authentic enclosure from? :)
Best,
Nick
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dipfrik on May 27, 2015, 01:26:10 PM
Quote
We have designed two sorts of "look alike" frontpanels. There will be one for a standard 3HE enclosure and another one for hinged frontpanel enclosures.
-----------------------------------------------------------------------–----------------------------
Frank (http://www.frontpanels.de/)  does a fantastic frontpanel service and now offers both types of frontpanel for the GATES project. You can also have an "all in one" solution together with his new enclosures as well. Highly recommended !!!

http://www.frontpanels.de/miscellaneous-frontpanels/

-----------------------------------------------------------------------–----------------------------
Don Audios offers frontpanels for this project as well. Thanks a lot Aaron!

https://www.don-audio.com/Frontpanel-STA-Level-Gates_1

-----------------------------------------------------------------------–----------------------------
For U.S. members Dan is going to offer frontpanel and case for this project as well. Have a look at his shop here:
http://groupdiy.com/index.php?topic=41963.0

;)

Cheers, Sven
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: nickhepfer on May 27, 2015, 01:49:06 PM
yeah, got that, but I am looking for the whole chassis with a hinged front panel, not only the faceplate ;)

Or did I miss something?

frontpanels.de offers powder coating, cutting and engraving, if you send them the existing enclosure... but i can not find this authentic style of chassis... but maybe I'm stupid ::)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dipfrik on May 27, 2015, 01:56:58 PM
No, you are not stupid! ;)

Ok, all three are delivering "normal" enclosures as well. You don't need to send them an existing enclosure.

But you are talking about somenthing like this or? ;)

http://www.ladislavbrezovnik.com/diy/STA-LEVEL/Gates%20STA-Level%20M5167/Gates_Sta-Level_7.jpg

Cheers, Sven
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: nickhepfer on May 27, 2015, 04:31:22 PM
exactly! ;)
Obviously the original enclosure has not enough depth to fit an PCB, so I am looking for a reissue with an authentic hinged faceplate; like Bernd's.
Therefore I asked where Bernd got his fancy case from :)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Jim50hertz on May 30, 2015, 05:48:38 AM
Hi Benrd

Did you use the 6386 or the 6BA6 in your build?

Thanks

Jim
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 30, 2015, 05:55:59 AM
2x 6BA6. Performs quite nice.
EDIT: now using 6386 tube. Needs some tweaking in order to work correctly.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Jim50hertz on May 30, 2015, 05:57:34 AM
Thanks!  8)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kambo on May 31, 2015, 12:57:48 AM
how much current going through input and output pots ?
thanks
kambo
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 31, 2015, 03:57:37 AM
Hi,
Nothing fancy here. Take standard pots which are commonly available.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Kid Squid on May 31, 2015, 06:01:57 AM
Hi Chaps,
Got some original style hinged cases coming soon, I'll put some pics up as soon as I get them back from the Manufacturer.
Just another option !
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 31, 2015, 07:31:22 AM
Hi,
All depend on the depth of your case. Since this project is pcb based it won't fit in cases made to the original sizes. If your cases are at least 18cm deep, you are our man. Looking forward to see some pictures.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Dr_J on May 31, 2015, 07:56:26 AM
Hi bernd,

just a quick one. Meter Simpson Model 27 200mA AC?
Not DC and not Voltage, right!?

ROCK-ON!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 31, 2015, 08:09:09 AM
You'll need a DC meter.  I do not really remember how much mA the meter I use has got. 200mA should do.
Edit: a standard VU meter works fine as well, although meter movement doesn't reflect the faster attack/release values as nice as a DC meter.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: EmRR on May 31, 2015, 09:09:02 AM
It's a 1mA meter
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Dr_J on May 31, 2015, 09:19:28 AM
Thanks!
I'll have a look on evil bay.

Just ordered from Sowter the input and output transformers - when my PayPal invoice popped up my heart stopped beating
for a while... hell!!  :o  :o
I'm happy not decided to go for a stereo build.

Now putting the mouser card together...

ROCK-ON!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Majestic12 on May 31, 2015, 02:51:39 PM
The original unit uses a 200uA (micro) meter. I have tried to use a 1mA in my Drip Sta Level built, but It's not possible to adjust it correctly.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mrkrawn on May 31, 2015, 03:43:11 PM
Hi bernd

Glad to see  your new project.
It seems to be an amazing project for the vintage lovers.
How it sound with your wima and nichiden caps ?

best
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 31, 2015, 03:55:09 PM
I used Vishey (?) caps. Well , the units sounds really great. The thing I love most is that you can't hear any compression (artefacts) at all. You wouldn't believe that it compresses until you watch the meter and look at the waveform. The huge amount of gain is just insane.  Today I plugged in a tube mic directly into the compressor. Just crazy.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mrkrawn on June 01, 2015, 12:44:56 AM
Yeah I know this beast
I had a chance to play some hours with on a Sta Level few years ago.
it was a killer in the 60s
.I'm curious to hear the demo samples  of your clone on drums ,bass ,vocal.

best
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: zamproject on June 01, 2015, 07:26:09 AM
Interested in this  ::)

Just to be sure, we talk about a build in the 1k-1k5 € range ?

Zam
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 01, 2015, 07:31:17 AM
It depends very much on the transformers you are going to use.  Tube projects are alway more expensive than solid state projects.  I didn't really take care about costs, but my impression is that you can build it for less.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: zamproject on June 01, 2015, 08:16:49 AM
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

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 01, 2015, 08:38:59 AM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 09, 2015, 02:42:40 PM
Updated 1st post. Added some downloadable audio files (vocals, 16 bit 44Khz, mono)
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on June 11, 2015, 12:55:54 PM
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!



Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 11, 2015, 01:06:24 PM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on June 15, 2015, 05:12:10 AM
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.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2015, 05:44:10 AM
Great, did you already fire it up? Would love to see some pictures of your build in progress.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Kid Squid on June 15, 2015, 08:41:13 AM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2015, 09:00:04 AM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Kid Squid on June 16, 2015, 09:01:26 AM
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.

(http://i848.photobucket.com/albums/ab41/lazylizardlabs/Custom%20Cases/STA-Level%20Case%20185mm_zps5aj5odwe.jpg) (http://s848.photobucket.com/user/lazylizardlabs/media/Custom%20Cases/STA-Level%20Case%20185mm_zps5aj5odwe.jpg.html)

Steve
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 16, 2015, 09:09:59 AM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Kid Squid on June 17, 2015, 12:05:21 PM
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
(http://i848.photobucket.com/albums/ab41/lazylizardlabs/Custom%20Cases/Sta%20Level%20exploded%201_zpsevf8ysb3.jpg) (http://s848.photobucket.com/user/lazylizardlabs/media/Custom%20Cases/Sta%20Level%20exploded%201_zpsevf8ysb3.jpg.html)

Best,
Steve
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on June 18, 2015, 06:34:37 AM
Hey Bernd,
as requested, here are some Pictures:

This is a topview of my PSU.

(http://i1148.photobucket.com/albums/o579/DonnieDarko333/IMG_9029_zpszojxyk1v.jpg) (http://s1148.photobucket.com/user/DonnieDarko333/media/IMG_9029_zpszojxyk1v.jpg.html)

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

(http://i1148.photobucket.com/albums/o579/DonnieDarko333/IMG_9030_zpselqbqnzc.jpg) (http://s1148.photobucket.com/user/DonnieDarko333/media/IMG_9030_zpselqbqnzc.jpg.html)

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.

(http://i1148.photobucket.com/albums/o579/DonnieDarko333/IMG_9031_zpsvtpd3kys.jpg) (http://s1148.photobucket.com/user/DonnieDarko333/media/IMG_9031_zpsvtpd3kys.jpg.html)

Still waiting for some very last SMDs which weren´t in stock at the time, looking forward to fire this up.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 18, 2015, 06:42:04 AM
 :o 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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on June 18, 2015, 09:37:31 AM
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.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on June 30, 2015, 11:04:53 AM
So, got everything finished, but waiting on some last tubes.

Guts of the PSU:

(https://c1.staticflickr.com/1/461/18675244284_771cf921a0_k.jpg) (https://flic.kr/p/usgvuq)IMG_9172 (https://flic.kr/p/usgvuq) by Donnie Darko (https://www.flickr.com/photos/[email protected]/), on Flickr

Guts of the Main Unit:

(https://c1.staticflickr.com/1/356/19291753302_9e7e350757_k.jpg) (https://flic.kr/p/voKh9f)IMG_9171 (https://flic.kr/p/voKh9f) by Donnie Darko (https://www.flickr.com/photos/[email protected]/), 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.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 30, 2015, 11:58:05 AM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on June 30, 2015, 12:33:31 PM
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…
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on July 02, 2015, 05:36:19 AM
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
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 02, 2015, 05:44:56 AM
Should work. There is a 10K trimmer to calibrate the meter. So the range of possible meters is very large.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 04, 2015, 06:17:53 AM
I completed the build and started the unit up.

All voltages check out good, they are in a 5% range to that listed by Bernd in the second post if not even closer.

Audio passing fine, meters can be calibrated nicely, no hum oder noise present.

Input Iron is UTC M-8369 wired to 600k/50k from Douglas, Output are the Edcors from Don-Audio.

I did the BIAS calibration method mentioned with ground F- to case, minimizing the hum, but  something still seems wrong with the BIAS.

Some small issues:


Any help would be appreciated!

Thank you in advance guys!

Here is the completed unit sitting in good company:

(https://c4.staticflickr.com/4/3682/18780269414_43fe752a73_b.jpg) (https://flic.kr/p/uBxMNw)IMG_9190 (https://flic.kr/p/uBxMNw) by Donnie Darko (https://www.flickr.com/photos/[email protected]/), on Flickr

(https://c1.staticflickr.com/1/554/18782175293_6195fb3711_b.jpg) (https://flic.kr/p/uBHymv)IMG_9189 (https://flic.kr/p/uBHymv) by Donnie Darko (https://www.flickr.com/photos/[email protected]/), on Flickr
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 04, 2015, 06:39:14 AM
Hi,
I assume, you basically know how this compressor behaves.

Output pot: it's only a variable 6dB pad, so even turned fully counterclockwise the unit passes audio.

Input pot: did you wire the dual pot according to the wiring guide in the first posts? In my unit compression already starts with input pot at 9 o'clock. When turning up the pot, the unit doesn't really get louder, it just compresses more heavily.

modes: there must be some wiring error with the lorlin. In your pictures I can see, that you didn't solder the lorlin directly to the control board, so I would start there.  Check, if the two control boards are connected (3  connections).

So check second post 2), 7), 11)
I'm shure we are going to fix it.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 04, 2015, 06:57:08 AM
Hey Bernd,

Yeah, I did double check the Lorlin and the connection of the two small boards, they appear to be correct.

I used stepped switches for Input and Output, but also wired them accordingly to your drawing that you added recently in the second post.

I guess it´s the bias that is somehow wrong or maybe I need to address the input pad.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 04, 2015, 07:21:59 AM
Hi,
I'm quite shure that you error is in the side chain, i.e. on the control boards.
You could check a few things:

Pull the 6AL5 tube, so that the side chain is deactivated and only the amp can be check. Verify that the input and output pot work as they should. The input pot should behave like a volume pot.

Check the orientation of the 3 pin molex connector from main board to control board.

Check the orientation of the mode and recovery boards ( component side/solder side). Maybe you turned them around

Check max. Voltage rating of  c10s/c11s

Report your finding, please.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 04, 2015, 07:33:03 AM
Thanks Bernd! I will do so!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 04, 2015, 08:03:45 AM
Just to clarify, the trim pot between the two output tubes is just for balancing the bias of these two tubes and has nothing to do with the bias voltage derived from B+.  The 25V for the 6AL5 tube, derived from B+ is setting the bias of this tube and influences the threshold/compression curve of the unit.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 04, 2015, 09:23:41 AM
Yeah, sure.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 06, 2015, 09:04:50 AM
Hi Donnie,
any news?
I had a closer look at your pictures and I saw that you used metal standoffs for the two controlboards. One of these standoffs is very close to one of the caps next to it, so it might be better to use plastic standoffs here. I´m not shure if this helps but at least you could avoid that there is any contact , except the three bridging wires, between the two boards.

Another things I realized is that for the mode switch basicly only a few wires are needed. In you picture I can see a whole bunch of wires. So I would really double check the wiring of the control boards.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 07, 2015, 05:36:17 AM
Hey Bernd,

yeah, I got some news.

First off, Recovery and Mode Switches are working good and wired all correctly (even though some of the wiring might be obsolete). Caps are allright, everything else checks out good, too.

I had a tech look at the unit with some fresh eyes and he found that I installed a 50K lin output pot, which was noted in the version of the BOM that I went with.

Upon checking, this was changed now to 1k lin. I will correct this.

Also in some recovery settings, the compressor seems to jump and click when turning the input pot. Is this normal?  I can´t check with my other STA since it doesn´t have the Recovery Mod.

Now for the  calibration procedure:

I disconnect F- and temporarily connect this to case ground, which is about 160 mV different fromt the F- Ground. Then I will look to minimize the occuring Hum and then put the ground in F- again for use.

Right?


Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 07, 2015, 06:25:36 AM
Hi,
Clicking and jumping when turning the input pot is not normal. There is still something wrong. 

Balancing procedure:  the heater supply minus needs a reference to ground, otherwise you'll get hum. Make this reference to ground switchable. As soon as the reference to ground is interupted and the unit starts to hum, you can trim the 100r trim pot for minimal hum. 
As far as I can see, you have one wire for B- and H- to ground in your psu. Please rearrange it, so that B- has a fixed reference to ground and the H- reference to ground is switchable. Don't disconnect H- from the tubes.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 07, 2015, 06:59:25 AM
Hey Bernd, you mean F- instead of H- right?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 07, 2015, 07:12:35 AM
Yes, filament minus. (F-)
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 07, 2015, 11:11:39 AM
Donnie,
I attached a file in the second post, explaining the grounding of F+. Sometimes a picture tells more than 1000 words.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 07, 2015, 01:44:28 PM
Ah, allright, thanks!

I did exchange the output pot to a new stepped switch reading 1K, double checked all the wiring, resoldered the input put.

The unit works - on  one channel.

I made you guys a video:

http://we.tl/TVpoB5Rti5

You only hear one channel at once.

First, you will hear the left channel. This is the bad one. On 0:10 for example you can see and hear, how the compression bangs in with a THUMP, then only very slowly returns.

After that, i switched to the right side. This side sounds better and reacts very fast, off course depending on the setting.

I did switch back and forth the Input Pot, Recovery + Mode switch,  Input tranny and most of the tubes from the good and the bad channel, to rule them out as causes for the problem.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 07, 2015, 02:19:26 PM
Ok, saw the video. A few observations.
It´s strange, that you have to really crank up the input pot before the unit starts to compress.  Your input transformer has quite a high ratio (1:9?) and should deliver such a strong signal that the unit should start to compress very early.
For me it seems that the bad channel has got some kind of ground issue. Since your psu is external I would check ground connection from psu to main unit. Measure if the control boards have connection to ground as well. I would like to see the results of your measurement. Maybe a bit stupid but you should check the XLR wiring as well. My unit behaved almost the same as yours until I found out that my XLR were not wired correctly.  :o
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 07, 2015, 02:35:23 PM
Hey Bernd, did check the gorunds, they seem to be fine.

XLRs also double checked.

Yeah, i found the late compression strange too. However, we are driving this rack with our rednet units, maybe the signal from them is not lound enough or was turned down a few db before. Will look into that!

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 07, 2015, 03:13:58 PM
Hi Donnie,
Just for comparison a video with some vocal compression. Input poti is only around 9 o'clock. Output pot is turned fully ccw.

http://we.tl/Z5hTvnesB8

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mrcase on July 08, 2015, 05:19:54 AM
wow donnie, your gear looks absolutely fantastic!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 08, 2015, 06:07:47 AM
Just a guess, but maybe you hooked up the input transformer the wrong way, i.e. step down instead of step up?
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: DonnieDarko on July 08, 2015, 06:51:31 AM
I will change the input with the output of the transformer, easy thing to do.

However, I think that the input of the interface might be turned down a notch.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 15, 2015, 06:02:48 AM
Hi Donnie,
Any progress on your build? Would love to hear your comment especially in comparison with your drip sta level.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Purup on July 18, 2015, 01:58:30 PM
Hi Bernd and anyone else who can help,

I have found some nice Jørn Schou input transformers that I plan to use in my build. They are 5K:250K giving a ratio of 1:7 - close to the 1:8 of the Sowter trafo.
Now the question is how to make the input pad. I could make one with different amount of attenuation to compensate for the changed ratio of the input transformer, but how would you suggest to change the input and output impedance of the H attenuater in order to match the transformer and maybe give a higher input impedance for the compressor? Could it be 5K for both input and output impedance of the H attenuator?
Also guessing I need to increase the size of the input pot. But to which value?

Hope you can help.

Mikkel


Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 18, 2015, 02:34:26 PM
Hi,
I suggest to build it according to the values given by the schematic. Then test and modify it if necessary. I have to admit that I'm not good at determining impedance. Maybe an expert can chime in.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Purup on July 20, 2015, 02:40:47 PM
Hi Bernd,

I decided to go with impedance matching between the pad and input transformer and modified it into a 20dB pad with 5k input and 5k output impedane. Will see how it works.
 
Another question for you:
I do not see R43S (200K ohm) in the original schematic. What is the reasoning to put this resistor in parallel with the input pot?

Cheers,

Mikkel
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 20, 2015, 03:44:23 PM
Hi Mikkel,
There is a later revision of the schematic (1958). You'll find the 200K there.  Concerning impedance matching you can always change the pad later.  Report back when you fire it up.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 26, 2015, 05:48:03 AM
Added some observations when using different input tubes (6BA6 combo or single 6386 tube). See 3rd posting.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on July 31, 2015, 02:15:08 PM
Greetings all

Thanks to Bernbrue and Zayance for this project, this'll be my first project with so much iron and tubes  ;D Looking forward to it...!

I haven't found much info in this thread regarding the meter. The one on Don Audios page looks great but is over £150!! I looked on ebay for Simpson Model 27 meters and there are several in the States for around $30, are these a good match? Such as:

http://www.ebay.co.uk/itm/Simpson-Model-27-DC-Volts-Analog-Panel-Meter-0-500V-/181785254004?pt=LH_DefaultDomain_0&hash=item2a533ed874 (http://www.ebay.co.uk/itm/Simpson-Model-27-DC-Volts-Analog-Panel-Meter-0-500V-/181785254004?pt=LH_DefaultDomain_0&hash=item2a533ed874)

Would also be interested to hear subjective opinions on the sound of finished unit or audio demos... !

I'm likely going to use a 6386 valve. Does anyone have any good sources for these? I found one in the UK but am keen to keep the price down on the overall project so any advice is appreciated.

Thanks, Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 31, 2015, 04:37:00 PM
Hi Gareth,
Original meter is 200 micro ampere (DC) . You can try other values, e.g. 100 micro ampere or 1mA. They should work as well. Sound wise there are some demos on YouTube. The 6386 tube is very nice. A good pair of 6BA6 performs extremely well, too. So it's your choice. Being very careful while building saves a lot of time afterwards.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on August 07, 2015, 02:24:44 PM
Boards arrived. Look great, thanks very much!

£419 for all 3 transformers from Sowter. Not too bad I guess. How much difference sonically would you be looking at between the Edcor's, Hammonds, Sowters etc?

I'm also interested to hear what other people are doing regarding meters?

Can't wait to start this, looks like a lot of fun, this is my first tube compressor project and I'm looking forward to learning.

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 07, 2015, 03:02:36 PM
Sonical differences are marginal. I've built another vari mu with Sowter and the same circuit with lundahls. I can't hear any difference. In the end it's your choice how much money you want to invest. Sowter transformers are very good but in my opinion a bit overpriced . You can also use a Sowter for input and an Edcor or Hammond for output.
This one looks good. It'll work fine.
http://www.ebay.de/itm/Vintage-Ernest-TurnerMoving-Coil-Meter-1mA-FSD-GWO-/221841837891?hash=item33a6cdcf43

This one is used in the original and has even the same specs.
http://www.ebay.de/itm/DC-MicroAmmeter-Simpson-Model-27-0-500DC-UA-3-1-2-Meter-New-in-Box-USA-/161787425817?hash=item25ab483419

Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on August 07, 2015, 05:01:33 PM
Hi Bernd

Thanks for the information. If I'm going to invest in one Sowter, would you say Input is the best position for it? Then go for Hammond power transformer and Edcor on the output. I'm looking for good sonics, but am on somewhat of a budget, if I get the money together I'll go all Sowter.

Appreciate the heads up on the meters too...

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 07, 2015, 05:10:54 PM
Hi
I would take the input transformer from Sowter , Edcor or Hammond output transformer and the don audio power transformer.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 13, 2015, 05:46:31 AM
Hi,
Are there any finished units out there? We are of course interested in some feedback, questions, suggestions or just some pics.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: djfatum on October 13, 2015, 07:22:41 AM
It's a great project
very professionally produced PCBs
I intercede some pictures of my building  8)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xta1/v/t1.0-9/12115863_694363900694523_2419751563033506839_n.jpg?oh=d1a91000592d6fe0a98e30a44059b48c&oe=56C975E4)


(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/11059971_694363904027856_5444325531625431046_n.jpg?oh=bdad1b0890b920a3b69c5222f53c70d4&oe=56CA4CEA)


(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xat1/v/t1.0-9/12079593_694364210694492_600427106736855685_n.jpg?oh=283449297bb9b540d5c1d12a4c63217c&oe=56C792C9)


(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/1781923_694364154027831_653241250391908587_n.jpg?oh=e787870dcd927ddb3779039506d7ec4c&oe=56CCD02B)


(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xat1/t31.0-8/s960x960/12120122_694364287361151_3876681828166072892_o.jpg)

Heater regulator mount on the heatsink
Use insulating pads

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/12115557_694364277361152_7572309423122151768_n.jpg?oh=55533cd034d6202006a614e72b6490b8&oe=568C25B4)

regulators working with high voltage must be isolated from the heatsink for the safety remember it's high voltage !!!!!!

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xla1/v/t1.0-9/12143068_694364367361143_6776244440118917896_n.jpg?oh=3326f5e8bcc6dae2569d8f4b11dca1f1&oe=568596CA)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/12144730_694364384027808_4154650081612287143_n.jpg?oh=bbac34f9019b5b3d21ec84ef69c857f6&oe=56CF5DE2)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 13, 2015, 08:21:50 AM
 :) that's what we like to see, Andrej! Keep us up to date.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on November 10, 2015, 05:43:50 AM
Will LL1676 work on the input?

http://www.lundahl.se/wp-content/uploads/datasheets/1676.pdf

Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 10, 2015, 06:18:13 AM
Hi,
Wire it 1:4 and it should work. Leave out the input pad.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on November 10, 2015, 11:32:09 AM
Thanks!

Can I use 6k4p tubes in place of 6ba6?
I have about 50pcs...
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 10, 2015, 11:39:46 AM
Yes, we can!  ;D

http://www.radiomuseum.org/tubes/tube_6k4p.html

Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on November 12, 2015, 11:51:23 AM
In the PSU BOM there is a line: for mono 1000uf for stereo 2200uf.
Why is that? Is the PSU capable of running a stereo unit?

Peter
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 12, 2015, 12:06:43 PM
Not really.  The comment is referring to the rude tube which has the same psu. For this project I recommend to use two individual psu for a stereo unit.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on November 23, 2015, 07:26:30 PM
Parts are currently arriving, I went for Sowter in and out TX. What is the norm for fixing transformers to chassis? Some sort of metal bracket?

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 24, 2015, 03:24:53 AM
There is no norm. You might have a look into the spec sheet. It'll give you details about how to mount the transformers.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Kid Squid on November 26, 2015, 06:37:07 AM
Gareth,
I've amended my case designs to suit my type Power transformer, and Sowter I/O, heres the post -
http://groupdiy.com/index.php?topic=59745.0

Best,
Steve
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on December 03, 2015, 06:03:40 AM
Is 2 vu meters necessary  for a stereo set?
I plan to build it looking mono but inside stereo, with more gangs on the rotary switches.
Does this design need a vu meter on both sides to work properly?

Can someone advice me a calculator or resistor values for the input and output switches to replace the pots?

Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 03, 2015, 06:51:15 AM
Hi,
Should be possible with a single, switchable meter. Measure the internal resistance of the meter you're going to use and take a resistor with the same value. The input pot in a mono unit is already a dual pot. For a stereo unit you need a rotary switch with four decks. There is a resistor calculator for log pot to rotary switch around here.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on December 03, 2015, 07:15:55 AM
Thank you again! ;)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: zayance on December 21, 2015, 06:17:25 AM
Hi There,

There is a limited time price drop on the PCB Panel. Check my  WM.

Thanks a lot.


Best,


T.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Dr_J on December 21, 2015, 07:00:12 PM
Hi Guys,

have we already some running units around? Some nice inside pix would be great.
I'm on my way putting things together.

Here are some things i stumbled across and i'm not sure...
- The BOM calls for C11S 470uF, the PCB 1uF?!
I'll think 1uF is right, isn't it? YES!

- The BOM calls for 6 Relays, but how do they fit all on the relay board?! Do I miss something?

- For the Lorlins, is there a hint for mounting them in the right position? PCB S2 => #2 Lorlin ?

- C7SA/B/C I used some "normal" (little) Caps (they look a bit lost on the pcb?!), do these have an audible effect?
Is it worth to try some "higher" quality caps there?
Or what was the intension for the big space around there?


ROCK-ON!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 22, 2015, 04:02:04 AM
Hi,
there is a pdf file with lots of pictures attached in the
first post that will almost all of your questions.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Dr_J on December 22, 2015, 05:11:54 AM
HI Bernd,

thanks for pointing me to these files again .
I totally forgot about these, it was to long ago when i down loaded them.

But concerning the relay board i'm still confused?! Is this just an option?


ROCK-ON!
 
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 22, 2015, 07:23:56 AM
Yes, you can use the true bypass pcb for the gates optional. You only need two relays for the bypass pcb.
C11s is 1uF. In fact the lorlins can't really be mounted wrong.  Verify that A1 is at about 1 o'clock .  C7abc can be axial or radial. Size doesn't matter as long as the values are right. My unit works extremely well. I'm using 6386 input tube. Tested 6BA6 tubes as well. Behaviour is a bit different. Soundwise I can't hear any significant difference.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Dr_J on December 22, 2015, 06:47:54 PM
Hi Bernd,

thanks a lot.
For the Lorlin, i'll try to figure it out (50:50 chance, i'll think).

An other short one.
I missed ordering D19 (BIAS PSU). What are the critical electrical characteristics if looking for a replacement?
I found at Conrad 2 that might be close enough?! ZPY130V and Z1SMA100 (maybe just as an in between solution).

ROCK-ON!


Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 23, 2015, 06:10:58 AM
Any 110V, 5W diode will work.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Petertjed on December 30, 2015, 03:13:06 PM
How does it sound? Compared to the Drip and the original? Looks like a nice new project!

Thanks,

Peter
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 30, 2015, 04:34:59 PM
Hi,
I have neither the Drip nor the Gates, but the circuit is close to the original. For my ears it sounds great!
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bomper on January 15, 2016, 05:54:11 AM
Hey

A question about the rotary switches you use. According to the BOM at the beginning of this topic I should use a 1x12 Lorlin for the recovery PCB. But when I look at the schematics it's that it should be a 2x6 Lorlin. Or am I missing something?

Mvg, Thomas
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 15, 2016, 08:15:24 AM
Mode 4x3
Recovery 2x6
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bomper on January 15, 2016, 08:39:42 AM
I also seem to have some trouble finding the 6AL5 rectifier tube. Can I use an alternative dual rectifier tube that's more commonly available?

Regards, Thomas
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 15, 2016, 08:55:19 AM
http://www.radiomuseum.org/tubes/tube_6al5.html

Take any of these.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: G-Sun on January 15, 2016, 11:25:13 AM
What is the attack-time on these units?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 15, 2016, 12:12:46 PM
Hi,
I haven´t really measured the attack time. In single and double mode it´s stock, in triple mode attack time is lowered drastically.

In single mode, the release C is 1 uF + 0.5 uF or 1.5 uF. The double mode hangs the 1 uF capacitor from a 10 Meg resistor. This provides a dual time constant where the .5 uF gives the fast attack/fast recovery and the 1 uF sets a variable gain-riding plateau. The triple mode uses double recovery and decreases the 56K attack R to 4.7K.

best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bowie on January 15, 2016, 06:34:38 PM
I also seem to have some trouble finding the 6AL5 rectifier tube. Can I use an alternative dual rectifier tube that's more commonly available?

Regards, Thomas
The 6AL5 diode is extremely common.  In EU you may find it easier looking for EB91, EAA91, or any of the designations in the link Bernbrue gave.
If your issue is the rectifier, then perhaps you meant the 5Y3?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bomper on January 18, 2016, 09:54:10 AM
The 5Y3 was in the original PSU for STA Level. I'm making Bernbrue's design so this uses a solid state PSU. So, no need for the 5Y3. I'll continue my search...

Thx, Thomas
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on January 20, 2016, 09:47:38 AM
Hi, some help needed:

I bought the Sowter 9185 and 9062 transformers and I'm not sure, how to connect them.
I guess, the color codes on the pcb are taken from the originals ?

Output TX 9185
my guess for primary (first color is on pcb, 2nd Sowter TX)
Pink - Blu
Red - Orange
Brn - Violet

secondary; (in series for 600 ohm)
Grn - Grey
Blk - Blu
green and brown are connected

Input TX 0962
Primary
Blu - Pink
Brn - Grey
White unconnected ?

Secondary:
no clue: the 9062 has 2 pairs for 10k red/blue and violet/yellow
I don't know, wether to use only one pair (as the original is 600R:10K, 1:4) or put them parallel...

I attach the data sheets of both transformers.
thanks alot
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 20, 2016, 10:07:37 AM
Hi,
Almost right. Just a slight error.

To Output TX
Blue - pink
Red - orange
Brown - violett

From Output TX
As you mentioned

Input tx primary is fine as you mentioned, but the original is 1:8, so put the two secondaries in series.
Best
Bernd


Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on January 20, 2016, 11:04:56 AM
Thank you very much !
See, I thought, the original uses 1:4, can't recall, where I found this info...

Everythings here and connected, I will do the first test-drive tonight :)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 20, 2016, 11:12:10 AM
Did you buy the pcb from the second or later batch? If so, the input pot wiring is different than shown in the first thread. Wire deck 2 exactly like deck 1. You don't need to twist the wires.

In case the pcb is from the first run you just wire the pot as shown in the first thread.
Report back.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on January 20, 2016, 11:31:41 AM
I'm from the 2nd run and already discovered this !
Everything looks pretty good, B+ a tad high (320) and my 5Volts are a bit shy (4.4V) but I guess, it's not a biggy.
Using the  Don Audio toroid, btw
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 20, 2016, 01:57:43 PM
I will do the first test-drive tonight :)

Please report your first impressions.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on January 20, 2016, 05:27:48 PM
First test is done,
audio passes, the unit compresses fine, input and output works, controlboard works, even my old Klangfilm meter works
and it's pretty quiet, lying here on my bench without a case.
Voltages are okay, compared to Bernds list
BUT
R3 is cooking, it got so hot, I could lift it off the pcb with my pliers. (1k 3W)
So I'm pretty sure, I wired something wrong.
I have one B- on the psu connector left empty. Is this correct ?
I connected every ground and the mass (on the Bias Mainboard) to one star ground.
Any ideas ?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 21, 2016, 03:55:36 AM
Ok,
You need two wires from B+ and B- (main psu) to B+ in and B -  in (bias psu).  From their you need two wires going from BS and GND (bias psu) to BS and GND (bias main board ).  Additionally you need to provide the main board with B+ and B-. So take two wires leading from B+ and B- (main psu) to B+ and GND, marked as PS on mainboard.

Grounding: you can either make the grounding to star ground from the main psu or from the main board. In my build I just lead a single wire from the mainboard (it's the connector next to BS and GND) to a single point that connects chassis/mains ground. On the main psu I connected only the filament minus to star ground.  I made this connection switchable for the EL90  balancing procedure.

For HT TRIM on the main psu you should just use a wire bridge, no resistor at all. If nothing helps you might reduce R3 to 470R and use a 10W resistor that can be bolted to chassis.

Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on January 21, 2016, 09:30:04 AM
thanks again, you are so quick and very helpful !
I drove down to BanzaiMusic and bought two 470R 25W resistors, put them in series and bolted them to my biggest heatsink, to be sure.
Now, they get about lukewarm, so everything should be fine, if I mount them on the chassis.
The unit is incredibly quiet, I nearly couldn't believe it.
Put some music and vocals thru it, wonderful, everything works as expected.

I wrote down some voltages for comparison:

BS is around 97V
Voltage @ R3is 411V

A 75
C 1.31
D 0.67
E 1.33
G 74
H 123
I 170
K 2.76
L 2.74
N 170
O 321
P 0.005
Q 0.036
R 320
S 217
T 19

I only have to order a case now...
and btw: I can easily use it as a mic preamp !
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 21, 2016, 09:37:21 AM
I´m glad you were sucessful. I wouldn´t run the unit too long without cooling the LM338 regulator. It´s getting hot as well. Concerning cases there are quite a lot options.
best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 22, 2016, 03:44:58 PM
Hi,
Although I completely understand your situation, I honestly have no info about the DRIP version of  this compressor and would recommend you to start a new thread.  I'm quite shure there will be people around that have successfully built the DRIP version. This thread is meant to support people who bought the version from Zayance and me.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: nielsk on January 27, 2016, 11:10:04 AM
A few initial questions for my build:

Is there any problem/ changes required using 6v6 tubes on the output like the original one does instead of the EL90s?

Are the LEDs on the power supply boards just for power present indication, and can be left out (along with the current limiting resistors)?

I do not see R5 (B+ PS) on the BOM

Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 27, 2016, 12:13:47 PM
Hi,
The 6V6 has a completely different tube socket and as far as I know the pin layout is different. Why not using the EL90/6AQ5 ? Technically speaking the 6V6 and EL90 are identical.

LEDs on psu can be left out.

R5 (psu) is 47K, 3 Watt

Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: nielsk on January 27, 2016, 07:10:57 PM
I had been collecting 6v6s for this... :P
The local tube house has (for cheap!)6AQ5A and 6AQ5W, any preference?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bowie on January 27, 2016, 08:02:45 PM
I had been collecting 6v6s for this... :P
The local tube house has (for cheap!)6AQ5A and 6AQ5W, any preference?
The designation at the end (W, WA, etc) is not as important as the brand.  6AQ5s are generally not as rugged as 6V6s but RCA, Sylvania/Phillips, and GE 6AQ5s are all good, fairly common, cheap, and should work great in this circuit. 
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on January 29, 2016, 08:34:06 AM
Hi!

I have 3,8v instead of 5. I cannot turn the trimmer any more:)
How can I solve this problem?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 29, 2016, 10:50:01 AM
What did you take for R8? Solderbridge?
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on January 29, 2016, 01:45:57 PM
Yes
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 30, 2016, 04:39:39 AM
Can you measure AC voltage coming from the transformer?
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 06, 2016, 05:52:11 AM
Hi!

I have a working unit now:)
I have ll1676 in 1:4 configuration and russian 6k4p-ev tubes.
Everything works fine, but I have too high output even at minimum output level on the pot.
When I increase the input I hardly get any compression, because the the output is too high for my interface.
I will change R32 as mantioned before, but I need some change on the output structure.
Any advice?:)

I have the following:

ll1676 1:4
6K4P-EV
12AT7 (jj gold)
6H2P-EV (EAA91 substitution)
6P1P-EV (EL-90) I had to use socket converter for these
Edcor output

I like russian millitary tubes because of their long life and (to my ears) better sound:)

The most important, the unit sounds awesome, just too much output:)

Thanks for this great project!

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 06, 2016, 05:52:58 AM
Another pic:)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 06, 2016, 06:38:59 AM
Very nice! Interesting tube choice. The output pot is just a pad.  You can't cut down the output volume completely. And yes, the output is extremely hot. Have a look at the gates sa 38 schematic. There you'll find multiple output pads stacked. Just add a second output pad to the already included one. You can take the same values.
http://farm3.static.flickr.com/2680/4150163073_b7c2b5b94a_o.jpg
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 07, 2016, 11:49:54 AM
Thanks for the help!
Output level solved!:)

Is it possible to change the compression ratio, by changing a component value?

Thanks again!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 07, 2016, 12:00:49 PM
I found a very interesting thing.

It felt like, if I incearse the input with the pot, it started to sound a bit blur.
I changed the pot for fix resistors and it sounds flawless.
I measured the pot in the middle position and on the first gang it was 50k on the second it was about 56k.
On a balanced signal this can be a problem, so I will use  stepped switches.
The difference is clearly audible.

Another:
1:4 for the input is a bit overkill knowing the unit's very hot level. I changed to 1:1 and now it's easier to adjust the controls.
I used ll1540. What do you think about it?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 07, 2016, 12:04:16 PM
The unit needs a certain level to start compressing. There might be some impedance mismatch using the 1540, but it basically works as well.  Stereo pot tolerance is certainly an issue. Stepped pots with precision resistors will be better.
Can you give us some values measured at the test points on the pcb? What is your bias voltage at test point T? There is a nice explanation in the original manual of how to alter compression ratio. Definitely worth reading. Please report back.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 07, 2016, 12:59:35 PM
Test points:
A:60,2
B:0
C:1.2
D:0.6
E:1.16
F:0
G:61.9
H:106
I:164
J:0
K:2.1
L:2.2
M:0
N:161.5
O:278
P:0
Q:277
R:279
S:200
T:16.8

R32 is 18k changed from 24 to lower the threshold point.

B+:283
F+:6.22
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 07, 2016, 01:11:44 PM
Can you measure at Q once again?
Which power transformer are you using? All in all your voltages are a bit on the low side but definitely nothing to worry about.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 07, 2016, 01:15:35 PM
Yes:)

Q is 0.03v
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 07, 2016, 01:59:49 PM
I have lower values...
Is this because of the lower B+?

I have custom made power toroid.

I have hum at around -75db. Can I lower it somehow?
The noise level is around -100-110db.
Its not in the box yet. Connecting the ground doesn't make any sense.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 07, 2016, 02:13:54 PM
What are the specs of your costum made transformer? B+ coming from psu should be 300V. You should put it in a box before making reliable measurement. Anyway, your measured values are nothing to worry about.
Go ahead and show us pictures of your new compressor.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 07, 2016, 02:23:34 PM
I had 320v B+ before, but I changed the resistor in the AC circuit. It's 1K now I think.
Now it's 283v. Tomorrow I will measure the voltages coming from the transformer.
The last thing is to lower the hum and the comp will be perfect:)
I will make R32 switchable to get different ratios. With 18k instead of 24, its smoother now. I want to use it for mastering as well so I need even lower ratios.
Soundwise its killer:) My favourite varimu now:)
Pictures to come after finishing the box!

What can be the final hum level in your opinion?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 07, 2016, 02:29:25 PM
My unit has no hum at all. You need a proper grounding especially for the heater.  You'll find the measurement of my unit in the 3rd post. (Attached PDF)
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 08, 2016, 10:26:38 AM
How can I ground the heater?
On a picture on the 3rd page I can see only I wire connected to the ground point of the psu pcb to the case.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 08, 2016, 11:49:48 AM
You've got a GND connector on the psu. From there you can connect B- and F- with two wires to your star ground point.  Make the F- to star ground connection switchable.  Then connect audio ground  from main pcb (it's the third screw connector next to bias GND) to the same star ground point. Then connect the main ground from your iec inlet to the very same star ground point. Make shure that there is a direct connection to the metal of your enclose. Check continuity with your multimeter. Now you've got a proper grounding.

We need the switchable F- to ground connection for the balancing procedure. As soon as the F- connection to ground is interrupted, the unit starts to hum. Turn the balance pot (bias of the EL90 tubes) until hum disappears (or is hardly audible).  Then reconnect F- to ground. That's it.

Sorry, for me as a non native speaker it's a bit hard to explain such a technical procedure. I hope you got it.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prescott on February 08, 2016, 11:55:08 AM
It clearly understandable:) ;)
Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on February 12, 2016, 10:52:09 AM
Bernd, do you have a drill template for the boards ?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 12, 2016, 11:49:23 AM
You can print out the silkscreen. See first post.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brewbacca on February 13, 2016, 07:32:30 PM
What value of fuse should this use? I'm in the US, but it would probably be good for EU people to know also.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Monoklang on February 14, 2016, 01:16:59 AM
I'm new into the tube world. And I've been searching around for tubes. Where do you European guys buy tubes? New or old?

I've found this Swedish radio museum selling tubes for these prices:
1  6386: 47€
1  12AT7: 10€
2  6AQ5: 32€
1  EB91: 2,5€

Good?

There are 7 tubes in this STA right? I might have misunderstood the part with solid state power/last 2 tubes...
Do I need the other 2 as well?

I searched for OB2 and 5Y3 but couldn't find them. Are there other names?

Kind regards
John
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 14, 2016, 04:30:27 AM
Hi John,
The prices for the tubes are quite good, especially for the 6386. You should ask whether the tubes are NOS (new old stock) or used.
There are 5 (6) tubes in this project. We made a solid state power supply so that the OB2 and 5Y3 are not needed here.
The 6386 is a very rare tube and hasn't been in production for quite a long time.  That's why this double triode has been replaced by two pentodes (EF93) wired as triodes. This so called T bar adapter is included on the pcb. In other words: you can either use a single, quite expensive 6386 tube or two EF93 tubes instead.
I would grab the 6386 and the other tubes from Swedish radio museum and build it with 5 tubes.
Hope that helps
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 14, 2016, 04:50:40 AM
What value of fuse should this use? I'm in the US, but it would probably be good for EU people to know also.

 250V, 2A Slo-Blo (mouser part#576-0218002.HXP)

Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Monoklang on February 14, 2016, 06:38:36 AM

Hi John,
The prices for the tubes are quite good, especially for the 6386. You should ask whether the tubes are NOS (new old stock) or used.
There are 5 (6) tubes in this project. We made a solid state power supply so that the OB2 and 5Y3 are not needed here.
The 6386 is a very rare tube and hasn't been in production for quite a long time.  That's why this double triode has been replaced by two pentodes (EF93) wired as triodes. This so called T bar adapter is included on the pcb. In other words: you can either use a single, quite expensive 6386 tube or two EF93 tubes instead.
I would grab the 6386 and the other tubes from Swedish radio museum and build it with 5 tubes.
Hope that helps
Bernd
Ok so those 5 tubes are enough then. I'll call the museum tomorrow and check tube status.

If they are used, should I pass or take them anyway?

Thanks.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 14, 2016, 06:53:49 AM
Normally used tube are tested. If they are tested "good" you should buy them.
Tube town is a good address for new tubes.
http://www.tube-town.net/ttstore/Roehren:::1.html?MODsid=7ior23l7cgajoaiu69askm4n13

Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brewbacca on February 15, 2016, 02:04:23 AM
Awesome! Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Matt55 on February 15, 2016, 05:49:20 AM
I am also wondering about the tubes.

Is there certain tubes in the design that you would spend more money on than say others because they affect the sound more or less?

Bernbrue would it be possible to list the exact tubes you used and their prices? It might help others like me who know less about tubes have more understanding!

Thanks, Matt

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 15, 2016, 07:38:47 AM
Hi,
I can't say it clearer than in the 1st post:

V1= 6386  or 2x EF93 (=6BA6=6K4P-EV)
V2= 12AT7 (= ECC81)
V3&4= 6AQ5 (=EL90)
V5= 6AL5 (=EB91)

Prices are relativ. A new JJ 6386 costs about 110€ here in Europe, used ones are difficult to get. Buy new tubes and you are on the save side. If you don't want to spent that much for a new 6386 tube, buy 2x 6BA6 instead.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kml23956 on February 15, 2016, 11:48:49 AM
Has anyone done this or tried it yet?

http://twin-x.com/groupdiy/albums/userpics/6386-Subsitution-Adapter%5B1%5D.pdf
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 15, 2016, 12:30:52 PM
Yes, I did it and this T bar adapter is already provided on the pcb!!! So buy a few 6ba6 and save some money for buying a 6386 later.
 ;D
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brewbacca on February 18, 2016, 01:45:03 AM
So I've got the build mostly complete and all the boards wired etc. I'm having a lot of issues getting decent signal levels.

1. My output pot only seems effective until about 12 'o clock, and then it doesn't seem to raise the volume at all
I'm using the Edcor with it wired as picture in the gearporn.pdf

2. The input seems quiet, I have to crank it to get decent levels.
I'm using the Sowter 9062 as input and have blue and purple connected, and white not connected to anything. I have Yellow to BRN, Red to BLU, Grey to BLK, and Pink to GRN. Is there a different resistor value I should be using somewhere?

3. Is there a trick to using the simpson meter? I'm able to zero it without problems, but when I crank the input, it doesn't seem to be showing many dbs difference.

4. My voltages from B+ are a little high (325V) and my V+ is low (4.3V). The low V+ seems to be messing with the functionality of the relays. Has anybody else been able to fix the low v+ values if you ran into them?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 18, 2016, 02:15:22 AM
Hi
1) output pot is only a 6 dB pad, behaviour seems normal or you've bought a log pot. It needs to be a linear pot.
2) you wired the input transformer the other way round. Just exchange wires " from input tx" with "to input tx"
3) you'll get more gain reduction after you've fixed step two
4) probably a mistake in the V+ psu or the bypass pcb. Disconnect the bypass pcbs and measure voltage coming from Psu. What is the VAC coming directly from the power tx?

What are the voltages at the various measure points?
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brewbacca on February 18, 2016, 07:17:37 PM
1. I used the pot from the BOM, so I guess it's normal.

2. DERP. Ok, everything that I mentioned seems to be working now.

3. The meter also seems better, but just to double check, do I need a 3.6K resistor in series with it?

4. I don't think anything is in the wrong place, but the 317 in the BOM isn't TO220, so I went and bought an NTE brand one locally. Maybe it's not a good regulator? My AC voltage coming in is 5.69 V, and at the input of the regulator it's 5.98 V dc. The regulator is currently outputting 4.3 V dc. I checked for a short between the regulator and the heatsink, but didn't find one.

Here are my voltages:
A: 58.5
B: 0
C: 1.42
D: 0.722
E: 1.41
F: 0
G: 59.39
H: 110.9
I: 174
J: 0.002
K: 2.75
L: 2.72
M: .002
N: 176
O: 318
P: .143
Q: .005
R: 321.1
S: 214.5
T: 24.69

(By the way, thanks for adding these test points!)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 19, 2016, 02:16:20 AM
Well, we are almost done. V+ with 5,98V at the input of the regulator is a bit low. Please check orientation of the diodes D12-15 and D17. What kind of regulator did you use?  You don't need a resistor in series for the meter. The voltages at the test points seem to be in tolerance range . Do you use a 6386 tube or two 6BA6 instead? You have to decide on your own, how smooth you want the compressions to set in. You can reduce R32 in order to lower the threshold so that compression starts earlier. Anyway, you did it, congratulations! Pictures??!
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brewbacca on February 21, 2016, 09:07:34 PM
Diodes and everything is in the right place. I used the NTE brand 317 but took that out this weekend after some better parts arrived. I put a fairchild LM317 in and replaced the diodses and was able to get slightly better voltage, but it goes down again when I hook up the lamp. The relays seem to be working in any case. Also added a 1W 1K trim pot for the H-Trim to try and get the 325 V down, but it didn't seem to help much.

I used two 6BA6 tubes.

Here's some pictures! I didn't plan the layout as well as I would have liked, so the wiring is kind of a mess. I used the case from Frank.

EDIT: I fixed the loose ground wire on the main board B+ connection.

(http://i.imgur.com/Gi43g5R.jpg)

(http://i.imgur.com/RMp0glM.jpg)

(http://i.imgur.com/qPpSP8O.jpg)

(http://i.imgur.com/Pq80yNc.jpg)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 22, 2016, 06:43:19 AM
Very nice build. You've provided a bypass switch as well, great. I hope you like what it does.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: porkyman on February 23, 2016, 02:35:21 AM
can i ask a couple questions.

R2 (Bias Board) says 1% on the bom but the part # is 5% and mouser doesnt have a 220 1%  right now. is 5% ok?

i dont understand the different voltage options for ex: v+red =  24v, 12v, or 5v. im a little lost there.

v+red 24v calls for a 4.8k  1/4w but the part# comes back 34.8k . which one is right?

cx2 . im totally lost here. 100 - 220 nf.  is this transformer dependent or does the value not matter as long as its between 100 and 220 nf?

thanks
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 23, 2016, 03:10:48 AM
Hi,
You can take a 5% tolerance resistor here, but mouser has got a 220 Ohm 1W, 1% resistor in stock as well, which you can take instead.  The red LEDs on the psu need a resistor in series. The value of the resistor depends on the secondary voltage of your transformer.  For 24V you need a 4,8 K resistor, for 12V a 2,4 K and for 5V a 100R resistor.
Sorry, where did you find Cx2? Main board, psu, bias psu?
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: porkyman on February 24, 2016, 08:00:50 PM
thank you. the cx2 is on the pcb pictured below.  another questio. which direction do the leds go ?  -  to outside pcb  is what i did. thanks.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 26, 2016, 12:44:48 PM
Take 100N X2. It's listed in the bom for mains and extras.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on February 29, 2016, 04:44:01 PM
Hi everybody, mine is up and running !
I took it to my studio today and I'm extremely pleased with the sound.
I have to tackle 2 small problems:

1. I use the bypass board and  the relays hang, means, when I switch from bypass to "on", I get no sound. but when I tap with the fingers on the relays, it jumps back to on. I measure 4 v on the bypass board, is this too low for the 5v relays ?

2. Output too hot. I don't understand, where i can mount all the attenuator pads, that Bernd mentioned earlier. Do you build them on breadboard or solder a spiderweb hanging around in the unit ?  Has anybody done this and can upload a picture ?

In the moment, I favor the T Pad solution, where I use a U-Pad followed by a T-Pad attenuator
http://groupdiy.com/index.php?topic=56485.msg720958#msg720958

what a nice compressor :)
will upload a few pics in the next days



Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 01, 2016, 03:18:36 AM
Hi,
Im happy that you like it.   :)
Well, yesterday I tried to tame the real hot output of my sta level as well and just soldered one of the H pads shown above together.  Even with this attenuation output is still too hot.  I have to try another solution. I used the output screw terminal to fix the resistors. You could either solder the resistors directly to the XLR out or change the values of the already existing output pad. I have to admit that I haven't found the ideal solution for that. 
The low output of the 5V rail and the hanging relay is really strange. I have to talk with Tony about that.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 01, 2016, 04:11:38 AM
Hi,
Well, the relays should work even with 4V. In case you installed the control led for the 5V rail you could try to take it out in order to reduce current consumption.  Check, if you powered the relays in series or in parallel, not both at the same time!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 01, 2016, 09:37:39 AM
How do I power them in series ?
Here's how I connected the relays
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 01, 2016, 10:04:29 AM
Bridge the two solderpads marked "S" (series) and make the + 5V switchable.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Monoklang on March 02, 2016, 03:24:49 AM
I will soon populate my PCB's, should I wait until this "hot output / output pad" problem is solved?

Or is that something that not everyone got?

John
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 02, 2016, 04:37:19 AM
Well, all the parts in the bom are basicly stock values. The output stage is similar to a 10W guitar amp. So yes, the output is hot. We decided to stick to the values in the schematic, since we can't know, which input/output transformers people will use, whether they use the input/output pad or not.  It seems reasonable to build this compressor with stock values and adapt things to your personal needs. You can always modify it later or add another pad in addition to the already built in pad. So I would stuff the boards right now, test it in your studio environment and modify it accordingly.

@ Kosi: Would you draw your pad solution on a piece of paper?
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Monoklang on March 02, 2016, 08:54:16 AM
Ok. Am I right here regarding the input and output:

Increasing input gives more compression but not a higher output.

And the output is just a 6dB attenuator.

So the design itself got a hot output?
Wouldn't a -20dBfs uncompressed signal (with input at its minimum) come out as a -20dBfs signal?

John
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 02, 2016, 10:14:07 AM
I installed the U-pad followed by a T-pad attenuator from CAPI and the first tests are perfect.
The output works like a "normal" compressor, e.g. I have Input and Output at 12 o'clock and the volume is about the same bypassed and compressor engaged.
I used 1/2 W resistors and the CAPI T Pad Adapter, I attach a picture.


Regarding my relay problem: I connected my relay as you said, but the problem remains....
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 02, 2016, 04:36:13 PM
Hi,
Thanks for the nice drawing. I posted a link to a balanced t pad calculator. See first post.  Input/output impedance is 600 ohm. You can set the amount of attenuation you need/want and the values for the resistors are calculated. Can anyone who has already finished his unit chime in and test it? I'm quite busy at the moment and won't have time to do intensive test. Moreover my mixer has got +6db broadcast level and although the output of my sta level is hot it is still operating in the headroom of my mixer.

@ Kosi: is it possible that you bought relays for 12 or 24 volt? I found a detailed datasheet of the relays. Please check your mouser shopping list and the datasheet
http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Specification+Or+Standard%7F108-98007%7FL%7Fpdf%7FEnglish%7FENG_SS_108-98007_L.pdf%7F1-1393793-2

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 02, 2016, 06:22:26 PM
Just to make sure, I meant a variable T-pad attenuator, not a simple T-Pad.

relay: these are definitely the 5V versions. I changed the switch, but no solution. I can hear the relay clicking, btw.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 03, 2016, 01:48:09 AM
Well, then one of the relays seems to be defective.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 03, 2016, 06:38:30 AM
Bingo !
I removed the V+ Led and the resistor like you suggested. Now I have 4.5V and it works like a charm.
Should have tried earlier, but I was too lazy to lift the psu board again...

Thank you :)

All I have to do now, is think about a proper way to mount my U Pad. in the moment, it's free floating :)

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 03, 2016, 06:43:48 AM
Pictures, pictures!!  ;D :D  :)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 06, 2016, 04:20:20 PM
here it is !
As you see: no proper knobs, but the rest is finished
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 06, 2016, 04:20:58 PM
my very diy U pad holder...
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on March 06, 2016, 04:21:25 PM
inner goods
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 06, 2016, 04:50:03 PM
Congratulations,  that's a very nice build.  You've found an elegant solution for the bypass switch. I would love to hear the Sowter transformers. I've built mine with Jensen input and Edcor output and honestly it's my best sounding vari mu compressor . I hope you like yours as well.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 28, 2016, 12:21:06 PM
Updated 2nd post with wiring guide made by Monoklang! Thanks a lot, John.

Ethan, thank you very much for fixing the page 11 issue! Works great now!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Matt55 on March 28, 2016, 04:18:01 PM
I would like to add a huge thanks for the wiring diagram, will help me out no end when I come to build my one. Im still gathering parts and waiting for the cases from Steve but im excited already!!! Thanks, Matt
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: core13 on March 28, 2016, 05:05:41 PM
Hi bern do you think it can be interesting to put carbon resistor?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 29, 2016, 04:19:43 AM
Honestly I doubt that carbon resistors would improve anything. For me they do the same as all other resistors, they resist  :)
Edit:  found a good article about this topic
http://www.aikenamps.com/index.php/resistor-types-does-it-matter
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: core13 on March 29, 2016, 11:06:09 AM
thanks for the link it's interesting
I will try to learn more about that
it's sure if it just bring some noise it's not interesting
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Krcwell on April 02, 2016, 03:19:35 PM
Hi Bernd, I'm shopping around for an input transformer. It looks like this is the Jensen you are using, JT-6610k-B? How do you have it wired?

http://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-6610k-b1.pdf (http://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-6610k-b1.pdf)

Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on April 02, 2016, 03:25:38 PM
Like in the test circuit shown in the data sheet, just the other way round. No zobel network.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: zayance on April 02, 2016, 11:10:04 PM
oh wow, Thanks for your work on the wiring guide Monoklang! I've missed that one.


T.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Monoklang on April 03, 2016, 01:13:00 AM
Well, since this is my first tube project I wanted to understand the connections and wirings before I actually do them.
But please check so I don't have done any mistakes.

A question: is it wise to have more then one star ground connected to the chassis?

I read somewhere that the IEC ground can be close to the IEC/power transformer. But to avoid hum, put another chassis ground near the input tx. ??

John
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on April 03, 2016, 03:02:09 AM
No, only one star ground near IEC.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Monoklang on April 03, 2016, 08:38:25 AM
Ok. Good.

I saw that I missed to connect the relay board to star ground I the wiring guide.

John
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: porkyman on April 13, 2016, 08:19:57 PM
BOM says output pot should be 1k lin but the mouser part number came back  50k. can i use it or should i order a new one? thanks
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on April 14, 2016, 12:52:33 AM
We definitely need a 1 K pot here.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on April 14, 2016, 03:45:24 AM
while you're at it: there's also the switch missing for the relay board

Ok. Good.

I saw that I missed to connect the relay board to star ground I the wiring guide.

John
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: porkyman on April 26, 2016, 01:26:03 PM
does anyone know how to hook up the don audio trafo in 120v? thanks.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on April 26, 2016, 02:45:50 PM
Here is a diagram that should give you an idea.

http://electro-dan.co.uk/electronics/wiring.gif

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: porkyman on April 26, 2016, 09:24:14 PM
thanks.. sorry for all the stupid questions but none of the colors in the diagram correlate to the trafo.  it has orange,  purple,  white, yellow, and yellow with green stripes.  the diagram is brown,  white,  black,  and pink. thanks agin.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on May 10, 2016, 07:00:03 AM
Hi

I cannot seem to find this info.
I see jumpers being used on the input pad and one other on the main pcb.

I plan on using Sowter in & out, do I need to jump these positions?
And am I ok with using the resistor values on pcb?

Thanks
Neil
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 10, 2016, 07:05:39 AM
Build it stock with resistors for input and output pad. When using sowter tx you'll need the input pad anyway. As far as I remember you don't need any jumper on the mainboard (read first post), but there need to be jumpers on the control board.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 22, 2016, 03:51:50 PM
Zayance ordered a new batch of pcbs.

http://groupdiy.com/index.php?topic=53011.0

Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prepanic on May 30, 2016, 11:48:56 AM
I´m still biulding the Sta-Level, the most ist finished and i tried it yesterday.
The Resistor R3 in the Power Supply was cooking so i changed it with a 25 W / 1K Ohm Resistor.
The new Resistor is still very hot and also the Voltage Regulator for the Heater.

Is it normal?

All Voltages are ok.

B+ is 305 V
Bias is 96 V

Also the Voltages on the Mainboard looks good.

Any Ideas?

Best
Patrick
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 30, 2016, 12:25:49 PM
Hi Patrick,
Voltage regulator for heater needs to be mounted on chassis. Don't forget the isolation washer. For R3
I would also mount it on the chassis.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 13, 2016, 05:16:27 PM
Currently building mine and I had a couple of quick questions to see if anyone might have encountered a similar problem—I figure this might help diagnose it more quickly.

I followed the Monoklang's wiring diagram exactly, yet my V+ LED is not lighting up. Anyone else had this issue? Also, my Simpson meter is not lighting up, nor is my pilot light. Is the Pilot supposed to be an LED and not a Type 47 bulb?

Lastly, some of the voltages at the test points are a bit high, but I suspect that it may be connected to the V+.

I'll wait for your advice—thank you.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prepanic on June 14, 2016, 02:29:08 AM
Is it possible to let the LED and the both LED-Resistors for B+ and Heater out from the PSU-Board?

Best
Patrick
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 14, 2016, 03:18:00 AM
Hi,
Notification via email doesn't work, sorry.

@ prepanic: yes

V+ LED not lightening up = led  wrong orientation . It's optional anyway, you can leave it out.
But: do you get 5V from the psu? Measure, please.

Verify what kind of bulb/led is used in your Simpson meter/pilot light. Check the polarity.

As long as your voltages are in the 10% range there is no problem.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 14, 2016, 02:18:12 PM
@bernbrue

Even though the original LED was oriented correctly, I removed the V+ LED just to be sure and replaced with another. Still no light, but I noticed I get the smallest flickering on the filament of the T47 bulb in my pilot. Then I tried it without any LED and yielded the same result.

As I said before, the bulb in my pilot is a Type 47 bayonet bulb. The meter is a NOS Simpson 47 rated for 200ma DC, and I must confess I know nothing about these. Is there a chance that it doesn't have a backlight? I assumed the spade would at least jump as the unit powered, but there's nothing going on here.

Does that help you understand my problem better?

Thanks for your patience.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 14, 2016, 03:06:17 PM
Hi,
You need to know wether your bulb needs 12V, 6V or whatever. Take out the bulb and try to identify what is written on the bulb. Have you measured your voltages with a multimeter? Please measure at all the test points provided on the main pcb.

Your meter is not suitable for this build. You need a 200 micro ampere or at least a 1 mA, not a 200 milliampere. Take any VU meter you've got and just test if the needle rises when powering on.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 14, 2016, 05:26:33 PM
Sorry Bernd, I really meant in the last post to write down what I was finding at the test points. I'll do so here:

A  81 V
B  10 mV
C  1.3 V
D  0.668 V
E  1.29 V
F  11 mV
G  80.6 V
H  128.6 V
I  188.1 V
J  3.1 mV
K  2.5 V
L  2.3 V
M  3 mV
N  199.6 V
O  321 V
P  15 mV
Q  2.5 mV
R  327 V
S  229 V
T  24.8 V

Looking at the pilot light bulb, which I assume is a 6.3V/150mA, I can't find any information that indicates anything to the contrary.

If I've left out any other pertinent information, just let me know. I'm very sorry for being a hassle—and I'm very thankful for your patience and help.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 03:32:45 AM
Hi,
Your voltages seem allright. At some test point they seem a bit high but within the acceptable range.

Please disconnect everything from the 5V rail and measure the output voltage. You can take out all the test LEDs with their corresponding resistors as well. They are optional and not necessarily needed.

Then connect your pilot lamp and see what's happening. In case both, the relays and the pilot lamp are powered from the 5V rail, I recommend to connect the pilot lamp to the 6,3V heater supply.

A picture could help.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prepanic on June 15, 2016, 04:42:51 AM
My finished Sta-Levels "PRO"

I made some modifications like a variable Threshold and a sidechainfilter.
Also i put the switch and the pot for the bias adjust on the back, so it is not nessacary to
open the chassis to calibrate.

 

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 15, 2016, 02:20:53 PM
Bernd,

     Just reconnected the pilot to the 6.3V and it works now like a charm. I went ahead and ordered a couple of new 200μa meters. That was a stupid mistake on my part, I misread the parts list. I've also removed the V+ LED and resistor—I want to leave the LED on the B+, if for no other reason than to see that the capacitors have completely drained.

Now testing the V+, I'm getting a reading of around 12V.  Here's a picture:
(http://img.photobucket.com/albums/v203/groselicain/File%20Jun%2015%201%2009%2054%20PM_zpskmoiombd.jpeg)

I'm testing right from the terminal, so this should be what the relays are seeing. Is this too much? Should I be seeing a change when I adjust the V+ trim? It doesn't appear to be working. Maybe you'll see an error in my power supply. If I should post more pictures, just let me know. I apologize for my rat's nest of wiring.

Thanks again so much for your patience and help, Bernd.

Cody
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 02:26:20 PM
Very nice units! Great work! I hope you like what they do!
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 02:33:05 PM
Hi Cody,
What kind of power transformer do you use? The secondary of the transformer should deliver 300V, 9V and 5 VAC.  I'm a bit astonished that you've got 12V. So we need the specs of your power transformer.

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 15, 2016, 02:37:19 PM
Agreed on the transformer. It's the Don-Audio that was specified for the project.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 02:42:11 PM
and your LM350 regulator mounted to chassis  is in danger of causing a short because of the extremely bent pcb. Normally regulator and pcb are in a 90 degree angle.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 02:44:29 PM
Ok, than I suppose that you connected the 9V secondary to the 5V rail of the psu and vice versa.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 15, 2016, 02:56:30 PM
Bernd,

     I'll fix the PCB for the regulator now. I'll check the secondaries now and see if I that fixes things.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 03:01:41 PM
Take your time.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 15, 2016, 03:06:06 PM
Well, I can say with a fair amount of certainty that it wasn't the secondaries being switched.

(http://img.photobucket.com/albums/v203/groselicain/File%20Jun%2015%201%2057%2030%20PM_zpsqgdvwkbf.jpeg)

The jump to around 20V definitely reflects the additional voltage that's mysteriously appearing along the V+ PSU. I'm going to go through now and make sure it's not something I've done. Let me know if you come up with any other ideas.

Thanks so much, Bernd.

EDIT: I think I have an idea. At the last minute, I decided to change from the 24V relays to the 5V after seeing the pictures of others' builds. I never removed R8 after this, so the 3.9K resistor is still there. I'm removing it now.

SECOND EDIT: Never mind. Still hovering around 12V.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 15, 2016, 03:25:59 PM
From your multimeter It looks as if you are measuring AC. We get DC there. Maybe I'm wrong.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 15, 2016, 04:58:00 PM
Stupid mistake on my part. I wasn't paying attention. It all appears correct now. However, now that I have everything running correctly at the PSU, I just hooked it up to calibrate and noticed I'm not getting any output. I'm going to wait until I have the new meters in to replace the wrong one I had before—then I'll see if the unit is getting anything on input. I think it has something to do with the output, however, as even pushing the momentary switch to set the bias isn't producing any noise.

I'll update you when I have the new meter. Thank you again Bernd for working with me—you're much too kind.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prepanic on June 18, 2016, 06:40:13 AM
Hi, how did you fix the phase invert on the outputs?

I changed the hot and cold pin at the output. Any other ideas?

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 18, 2016, 07:25:24 AM
I have no inverted phase on the output.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: prepanic on June 18, 2016, 08:19:07 AM
Ok, that´s strange.

Did you try it with a parallel signal?

My output is inverted.

Isn´t it right?

In my opinion the first tube stage make a 180° Degree Phas Shift, the second stage too.

But the output Transformer get the same signal as the feedback from the EL90 Tubes.

Ans this signal is phase inverted to the second stage.

So i get an phase inverted singal at the output!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 18, 2016, 11:51:25 AM
Hi Patrick,
Test your unit with Rightmark Audio Analyser (RMMA). Besides frequency response and other useful tests it checks the phase/polarity of your compressor. I'm quite shure that a wiring mistake (input or output transformer) is the reason for your phase inversion.

http://audio.rightmark.org/download.shtml

Your should pull the 6AL5 tube before testing.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 18, 2016, 05:04:58 PM
Big edit: After all my other posts today, I decided to delete them and report that my relays were the issue with no input or output. I've removed that board temporarily to figure out what their deal is, but until then I'm passing audio just fine and I've sorted wiring to have as much isolation from the PSU as possible. I also used the SPST to set the bias, and I have a really close to no-noise unit.

I have but one last—I promise, this should be all—question. I'm experiencing almost no headroom on the input, and I'm getting quite a bit of distortion. As such, by the time I get the needle moving it's just unreasonably distorted. Any ideas?

Thanks so, so much for all of your patience and help.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 19, 2016, 05:42:26 AM
Hi,
With the Input pot you should be able to completely shut down the signal (ccw) whereas the output pot is just a variable output pad. You can't shut down the signal completely with the output pot, even when it's turned completely counter clock wise.

Bias voltage of 25V is mentioned in the manual but in fact a voltage of about 18V is preferable. By lowering the voltage compression sets in earlier.
Tweaking bias voltage is described earlier in this help thread. Will come back to you later.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 19, 2016, 08:48:44 PM
Bernd,

    So you think this distortion is related to Bias? Which test points relate to bias—the ones by the 6AL5? Also, should I be concerned that one of the EL90s doesn't appear to be heating or glowing? I've switched them back and forth and the one closest to the 6AL5 never seems to heat while the one closest to the 12AT7 is quite hot. Is this normal?

Cody
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 20, 2016, 06:07:41 AM
Hi Cody,
No, that's not normal. Check your heater wiring especially around the not glowing EL90. Pull the 6AL5 tube and measure the amp with RMAA (download link a few posts above). Which output transformer do you use?
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 20, 2016, 12:02:29 PM
Bernd,

     I used the same Edcor you used. I'll check the heaters momentarily and get back to you.

EDIT: I've checked the heaters, and now all tubes are glowing equally well. However, I'm still getting the same distortion if I push the input gain even past 12 o'clock. I'm giving very little preamplifier signal on input as well, so there's no way I'm somehow clipping the input. Any ideas?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 21, 2016, 02:49:12 PM
Input pad? Which input transformer? Which input tube? 6386 or 2x 6BA6? Input pot wiring correct?
Are you shure you're clipping the input? The Sta level has an extremely hot output level. Could it be that your mixer/sound card is clipping?

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 21, 2016, 04:51:35 PM
I'm using all the resistors on the pad since I'm using the Sowter 9062 input transformer. Input tube is a 6386, and the pot is wired exactly as the wiring guide. I'm definitely not clipping the converters, as my meters are registering way below zero. The clipping is somewhere in this unit.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 22, 2016, 03:47:15 AM
Is the clipping still there when you pull out the 6AL5? Please use RMAA to check levels, distortion, frequency response et al.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 22, 2016, 01:17:45 PM
Bernd,

Yes, the distortion is there regardless. I've attached the readout from RMAA.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 22, 2016, 02:04:26 PM
Oh, there is something very strange going on.
1) verify that you used the correct values for C1-6
2) bad tubes?
3) wiring of the output transformer could be wrong.

What did you do with the not used wires of the Edcor output tx? The color code of the Sowter output transformer in the wiring guide is NOT suitable for the Edcor output transformer. Be careful! High Voltage!
Please post a picture of your build.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: groselicain on June 22, 2016, 04:59:39 PM
Bernd,

     I gathered as much, haha! In order,

Here's pictures of the build.
(http://img.photobucket.com/albums/v203/groselicain/IMG_1090_zpsbrwhax99.jpg)
(http://img.photobucket.com/albums/v203/groselicain/IMG_1091_zpsuki5tzxo.jpg)
(http://img.photobucket.com/albums/v203/groselicain/IMG_1092_zpsdbuvmpzk.jpg)
(http://img.photobucket.com/albums/v203/groselicain/IMG_1093_zpspx2vmin9.jpg)
(http://img.photobucket.com/albums/v203/groselicain/IMG_1094_zpsml2vvsin.jpg)
(http://img.photobucket.com/albums/v203/groselicain/IMG_1095_zpsvnrjio47.jpg)
(http://img.photobucket.com/albums/v203/groselicain/IMG_1096_zps6ng0rf44.jpg)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 22, 2016, 06:03:53 PM
A few observation/questions

1) What kind of pcb is right behind the power switch? Looks frightening. Oh, this pcb is meant to be a power transformer primary selector and switches between 115V + 115V = 230V (European countries) and 2x115V in parallel (USA et al).  Powertransformer primary needs to be hardwired to this pcb. It has nothing to do with the power switch.

2) input and output pot wiring can cause a short. Lots of solder lead around.
3) At least one voltage regulator is not isolated from ground./chassis. The plastic isolation washer must be between the back of the regulator and the heat sink. Check the others as well.
4) double check the values of C1s - C6s on the mainboard.
5) double check the wiring of the output and input transformer
6) .........

I'm quite shure that either there is a wiring mistake or a wrong/broken/dead component in your build.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: j.frad on August 03, 2016, 12:55:08 PM
I'm close to finishing my unit here,
R3 is burning up too, even with 1K.
I hear something buzzing in the power supply, could it be R3?
Also I the bias procedure doesn't seem to work, the buss doesn't change when turning the trimpot...

Also testpoints  A,G and H read full B+ voltages, 310V... I find out why.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: j.frad on August 03, 2016, 02:02:19 PM
Hmmm  ok
voltages settle after 20sec or so, but R3 still smokes a little bit...
The Bias trim pot doesn't change the hum level at all though.

Edit:
I read 420V after the retifier and 330V after R3.

I used edcor input transformer (wsm600/15k) for now, had to bypass the input pad to get the unit to compress and used Avdos output pads.
The unit's audio is quiet but distorts with modes 2 and 3.
The release switch behaves strangely, the shortest release in in the middle of the range.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 05, 2016, 01:48:38 PM
Hi,
your voltages are quite high. Try to bring them down. Maybe use one of these resistors and bolt it to chassis.
(https://img.conrad.de/medias/global/ce/4000_4999/4200/4210/4211/421111_BB_00_FB.EPS_150.jpg)

This compressor (and the real one as well) is prone to distortion in double and triple mode  when fed with bass heavy signals. Sometimes a bad rectifier tube (6AL5) can lead to distortion as well. Pull out this tube and measure the amp only. Concerning strange release setting, please check the wiring of the backpanel pcb and check the values of the resistors 1-6 on the recovery pcb. I think you didn't put them in in the right order.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: j.frad on August 07, 2016, 05:54:58 AM
Hi,
thanks I remember doing something similar in my daoc, bringing the AC lines down helped also.
I already bumped R3 to 1K, will try something bigger.
The distortion I hear is present also with vocals. I will do as you suggest and see what happens.

How effective is the bias pot, I mean, when doing the calibration procedure, by how much should the hum drop?
I can barely hear it changing.

Jules
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 07, 2016, 07:44:33 AM
Hi,
I don't know if you followed the wiring guide and if your grounding is properly done. So I can only guess. The bias pot is only for balancing the cathodes of the output tubes. As soon as you disconnect the heater supply from ground (use a switch) the unit should start to hum. Then you turn the trim pot until hum is reduced to a minimum. Reconnect heater supply to ground. That's it.

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: j.frad on August 07, 2016, 10:25:19 AM
Wel i Will double check but im pretty sure i followed it accurately.
Disconnecting the heated supply does make the unit hum but the trim doesn't change the hum level, does it reduce it by a lot?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 07, 2016, 11:56:13 AM
Hi,
It's not the entire heater supply that needs to be disconnected, it's just the connection to ground. The wiring guide shows it quite clearly. See picture attached in the second post of this thread. The pot reduces hum, but not that much. When reconnected to ground, hum should completely disappear.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: j.frad on August 08, 2016, 05:26:52 AM
Yes absolutely, This was very clear  :)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on August 27, 2016, 05:41:20 AM
Hi Bernd

Can work as output transformer for this project?

http://www.audiomaintenance.com/acatalog/CA-18-VTB2290_extended_info.html

Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 27, 2016, 03:25:13 PM
Not really shure. It's not said how much watt this transformer can handle. Ratio is different as well. Please ask audio maintenance for further details.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on August 31, 2016, 04:36:03 PM
Thanks Bernd!
I've just buyed from a member this:

From sowter:

1232 Altec 436C Line output

23kCT/150+150 ohm output transformer for driving a balanced line from push-pull 6CG7 etc. 100% M6 core for high level capability and low distortion. Twin secondaries for 600/150 ohm outputs. Voltage ratio 12.4CT:1+1 Max dc per side of primary 20 mA. Similar to Peerless 16402. Colour coded leads. Supplied with end frames for vertical or horizontal mounting style o. Fully shrouded style "s" option. Rectangular Mumetal Can with threaded grommet style "e" option.


Could be a good options for the Sta Level?
THANKS!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on September 01, 2016, 08:51:17 AM
Honestly, I'm not really a transformer guy. Specifications sound good.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Paperweight on September 11, 2016, 03:02:49 PM
I finally got around to slapping together a uTracer vacuum tube curve tracer. Going through about 100 JAN 5749W/6BA6 tubes and trying to match them wired as triodes. Well guess what?  The old fashioned matching by current draw method works just as well.

I've gone through 10 of the tubes so far. To simplify the testing process, I set it up to measure at -1 on the grids and vary the plate voltage from 2 to 150 volts over 20 intervals. I kept track of the measurement at the top end on a sheet of paper so I could circle close matches. Tube #2 read 146.58 volts at 30.785mA. Tube #10 read 146.58 volts at 30.714mA. I did 10 tests on a single tube and the current reading can vary at times by about .300mA up and down. Not too bad. So these looked like a decent match.

(http://i65.tinypic.com/2111oa8.jpg)

Here the #2 tube is the dotted line and the solid line is #10. This is the curves from -1 through -15. Not bad.

(http://i66.tinypic.com/21mthfk.jpg)

This is the curves from -16 through -30.

(http://i67.tinypic.com/2quup35.jpg)

Finally, the curves from -31 to -50. I probably shouldn't have tried to squeeze so many into the last plot.

So, anyway, if you can devise a way to measure the current draw of a 6BA6 wired as a triode, you can test and match them and get some decent pairs for $5-10 depending on price and availability. It should save quite a bit over the cost of a NOS or new production 6386. Surplus Sales of Nebraska has 28,000 GE made mil spec 6BA6/5749W at $2.75 each.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on September 12, 2016, 11:37:31 AM
Very interesting tests. I´ve tested only a few 6BA6 in my build and had always the impression that they perform extremely well. In direct comparison with a 6386 I can´t really hear any difference. The only thing you have to do is to tweak the bias voltage.

Have you finished your build yet? Please show us your Sta level.
cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Paperweight on September 17, 2016, 10:50:55 PM
I wanted to build a dual version from scratch on turret boards and house it in a wooden case. It would probably cost over $200 just for two board sets otherwise. I have a pair of meters and a possible chassis but no faceplate. I'll probably save this until I get some other things finished

The boards are stuffed and soldered but I still have to wire up a Dual LA-2A, dual 1176 Rev D, Gyraf G9 mic pre and a quad of SC-1 mic pres. All of these have cases except for the SC-1 pres which need to have the faceplate drilled. I hate metal work.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 12, 2016, 05:05:48 AM
Just a test! I get notifications via email that people have posted in my thread but infact there is no post.  I just wanted to test, that I can see all the latest posts.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on October 12, 2016, 10:33:37 AM
Hi Bernd!
My Sta level is Alive!!!

2  test point are bit off ( 82v Your refernce):
A 58.1v
G 56v
could be a problem?

I'm tring to use a meter that is specified to be 0 - 30  full scale 100 mV.
It's working but I can't go to 0  ( full scale)
could I change some resistor to go up?

Last :
I'm using Edocor CXPP 10 600 8k
The 2 cables marked as screen must be connected somewhere?

The output it's too hot could I use a Tpad between transformer and xlr out?
THANKS!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 12, 2016, 11:24:38 AM
Hi,
the wires marked as screen must be isolated. Cut them at the end and use some sort of shrinking hose.
Are you using a 6386 tube or two 6BA6? What is your voltage at test point H and your overall B+ voltage?
Congratulations for your successful build.
Cheers
Bernd

Edit: use this pad calculator
http://www.nu9n.com/tpad-calculator.html
and insert the H Pad right between molex connector "XLR out" and the wires going to the XLR out.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on October 12, 2016, 12:30:56 PM
Now with meter calibrated ( I don't know if it have influence:
A  60v ( as sta level schematics)
G 58V
H  108v
Main B+ 302 v

T pad it's not usable?
Thanks!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 12, 2016, 12:42:09 PM
Your voltage are alright, nothing to worry about. Of course you can use a variable t pad attenuator. There is a drawing how to wire it a few post before. In case you want to use a fixed pad I would use a 15dB H-pad. Just take a few 220 Ohm resistor and you're done. Pictures?
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on October 12, 2016, 02:36:03 PM
Thanks Bernd
n the next days I will post some Images, just the time to finish all  mod...
I've tried the t pad and it's much better!
Could be a problem if I remove the pot and insert 1k resistor for have the same ammount of pad but with addition of T pad between output transformer and xlr?
Thanks!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on October 14, 2016, 04:11:56 PM
Sta Level !
Thanks Bernd for this great project!!!
Incredible sound!!!
for now,some crappy images...
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on October 14, 2016, 04:14:37 PM
inside :)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 14, 2016, 04:31:02 PM
Well done! Very nice build!  8)  ;D
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on October 20, 2016, 07:31:24 AM
Hi Bernd
Wich fuse value  for EU operation?
Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 20, 2016, 08:58:08 AM
Hi,
Original manual says 2A for 115V operation. I would try a 1A.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: djfatum on October 21, 2016, 11:57:16 AM
The first ready  8)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14729401_873004202830491_1327618783050818388_n.jpg?oh=40a1d9f0f4383aefe5bed5a51435ef4d&oe=5895821A)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14713754_873004209497157_2839229436884556532_n.jpg?oh=5aa402454f9c743c1a2fd8f73e43d98f&oe=58611C7F)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14725595_873004316163813_6938164859915530970_n.jpg?oh=7a792509061c93e4efd32b2ae6a4833d&oe=58A18F19)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14702332_873004466163798_6290729289309778235_n.jpg?oh=4cad8331aeef8b081de3f5ba7201fdc8&oe=58AD3A65)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14666307_873004499497128_3584705109950817773_n.jpg?oh=0deb9f7506dbe734d09048e0cc294205&oe=588FF883)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14690857_873004666163778_4340765775782846509_n.jpg?oh=8147dbec45c7fda3d8f467f9b9995059&oe=58A0E0BB)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14725467_873004719497106_910579294574429420_n.jpg?oh=f949065245991d2f035a3bab579ad014&oe=589F08A0)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14680691_873004739497104_6081679806526845194_n.jpg?oh=917b8f8502e80fd83d06923ff2717930&oe=5895CBFB)

https://youtu.be/YSgwCePI6BE (https://youtu.be/YSgwCePI6BE)

My DIY projects :-)
(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/14650489_873004306163814_5715142529171657800_n.jpg?oh=74d439c5379e6dc480756d21cb5f9112&oe=58618495)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 21, 2016, 12:36:53 PM
Very nice! I really like the round meters. And soon in stereo, whow!
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on November 08, 2016, 02:33:43 PM
Hi Bernd
original H pad + 1k pot  need to be terminated with 600 ohm resistor?
Thanks!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 08, 2016, 02:43:22 PM
Not really needed.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: ilfungo on November 13, 2016, 11:39:50 AM
Finally with standard pad (10db+1k pot) + another 6 db fixed H pad  I'm in the right spot for my work!
UTC 0-1 input
Edcor Output

Noise is incredible low for a tube comp!!!
Sound is icredible!
Thanks  bernbrue Great project!!!

Some samples - wetransfer:
https://we.tl/qwIat9x6Lv


Thanks!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 13, 2016, 12:42:14 PM
Thank you. You're welcome!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: j.frad on December 05, 2016, 01:32:07 PM
Hi guys!
I finished building my sta level a few weeks back and I'm test driving it.

It compresses nicely but sounds a bit too fuzzy too quickly.
It's fantastic for bass, but I can't see myself tracking vocals through it with a risk of sudden distortion.
It was my understanding that unless using too short release times, it should not sound distorted.

Do you have a clue of what it could be?

I am also using an edcor input transformer until I know the unit works perfectly (then I'll invest in sowter).
I had bad surprises using edcor transformers (took them out of my daoc because of distortion, wouldn't work in my NYD EQ...)
I know the input transformer shouldn't be influenced by how I drive the unit but what is you experience using an edcor input transformer?

thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 05, 2016, 02:16:01 PM
Hi,
You may want to read the chapter "In use" carefully.

http://www.soundonsound.com/reviews/retro-instruments-sta-level

The faster the time constants the more likely the unit starts to distort especially with bass heavy signals. I had very good results with Edcor transformers on the output. I wouldn't use an Edcor input transformer in this circuit.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: techineer on December 22, 2016, 11:53:13 AM
Are there any specifications for this version, or are they the same as the original Gates unit?

I've been reworking a build that was done by one of the members of this group, and after getting it (apparently) working, it seems to require a very high level input signal before compression occurs, resulting in a very high level output. 

I'm wondering if it really is working properly, or if something else needs to be diagnosed.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: techineer on December 22, 2016, 11:59:39 AM
In post #69, Bernd recommended a switch to ground in the F- line.  I am assuming from what I'm reading (correct me if I'm wrong) that the F- line should normally be connected to ground.   If you use a pushbutton type switch, be sure to use one that is NORMALLY CLOSED and is rated to carry the filament current.   Such a switch is usually described as ON/(OFF) in the catalogs.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: techineer on December 22, 2016, 12:26:21 PM
Beginning around message #220 and possibly some others is mention of a problem in the +5V supply.   This unit was sent to me to iron out the bugs, and I see what is probably a design flaw in the 5V supply. 

The secondary winding for this supply is 5VAC (measures 5.6VAC RMS) After rectification it should measure up to 6.7VDC (or less, depending on load)  (5VRMSx1.414 (peak) -1.2V (Diode drops)).  The LM317 requires at least 3 volts greater input voltage than the desired output voltage in order to maintain regulation, or more as the load current increases.  http://www.ti.com/lit/ds/symlink/lm317.pdf (See page 9.)   

In order to have a regulated 5 volts output, the DC input voltage must be at least 8 volts and preferably more.  The AC voltage required for this is at least 6.5VAC.  ([5v out +3v (reg I/O diff) +1.2V (diode drops)]/1.414 =9.2v/1.414=6.5VAC rms)  I would suggest another 9V winding instead of a 5V one. 

You could also jumper the 9VAC input from the filament circuit over to the 5VAC input, as there should be some excess capacity in that winding.  The tube filament current ratings add up to 2.1A, while the transformer winding is rated at 4A.  The 5V regulator is limited to 1A, so that should be usable.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 22, 2016, 03:59:11 PM
Are there any specifications for this version, or are they the same as the original Gates unit?

I've been reworking a build that was done by one of the members of this group, and after getting it (apparently) working, it seems to require a very high level input signal before compression occurs, resulting in a very high level output. 

I'm wondering if it really is working properly, or if something else needs to be diagnosed.

I need to know if the input pad is installed, which input transformer was used and what the voltages are at the dedicated test points. The other aspects you mentioned are basically right or have already been discussed before.
Best
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dmp on December 22, 2016, 06:20:36 PM
Quote
Beginning around message #220 and possibly some others is mention of a problem in the +5V supply.   This unit was sent to me to iron out the bugs, and I see what is probably a design flaw in the 5V supply.
The secondary winding for this supply is 5VAC (measures 5.6VAC RMS) After rectification it should measure up to 6.7VDC (or less, depending on load)  (5VRMSx1.414 (peak) -1.2V (Diode drops)).  The LM317 requires at least 3 volts greater input voltage than the desired output voltage in order to maintain regulation, or more as the load current increases.  http://www.ti.com/lit/ds/symlink/lm317.pdf (See page 9.)   
In order to have a regulated 5 volts output, the DC input voltage must be at least 8 volts and preferably more.  The AC voltage required for this is at least 6.5VAC.  ([5v out +3v (reg I/O diff) +1.2V (diode drops)]/1.414 =9.2v/1.414=6.5VAC rms)  I would suggest another 9V winding instead of a 5V one.
You could also jumper the 9VAC input from the filament circuit over to the 5VAC input, as there should be some excess capacity in that winding.  The tube filament current ratings add up to 2.1A, while the transformer winding is rated at 4A.  The 5V regulator is limited to 1A, so that should be usable.

The V+ rail is only used for the relays, which should be 5v versions if you are setting up a 5v V+ rail. Usually relays will still work with slightly less voltage. And I expect the LM317 will delver pretty close to 5v. I would suggest measuring your v+ voltage with the relays engaged and off. If you have anything else on the v+ rail you could move it to the 9v or, if it is a bulb, the 5v AC. But I expect it should work with 5v AC in and 5v relays.  The higher the supplied voltage to a rectifier, the more heat you have to dissipate to keep the rectifier happy.

 
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 23, 2016, 01:36:17 PM
Are there any specifications for this version, or are they the same as the original Gates unit?

I've been reworking a build that was done by one of the members of this group, and after getting it (apparently) working, it seems to require a very high level input signal before compression occurs, resulting in a very high level output. 

I'm wondering if it really is working properly, or if something else needs to be diagnosed.

You will find a PDF file with specs in the third post. In the second post you'll find further information on F- to ground.


10) Calibration:  make shure that heater (f-) is connected with a wire  to chassis ground. Make this connection switchable by using a momentary switch.  As soon as the reference to ground is interrupted the unit starts to hum. Turn the trim pot between the two EL90s until hum is reduced to a minimum. That's it. See attached file.

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: frederickalonso on December 28, 2016, 08:36:56 AM
Thinking to make one in the future.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on January 31, 2017, 07:19:41 PM
I've started the build, I have a tube noob question, which gauge hookup wire should I be using? Voltage rating and so on? Some parts will need larger gauge than others?

I look forward to having it up and running, have gone for Sowter input and output and Don Audio power.

Thanks for any advice.

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 01, 2017, 04:34:09 AM
Hi Gareth,
I always recycle wire from old computer psu and other electronic junk. For the molex connectors I take preconfigured connector with wires.

e.g. http://de.manu-systems.com/images/L/DEV-5-WAY-MOLEX.jpg

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: techineer on March 03, 2017, 06:30:36 PM
I need to know if the input pad is installed, which input transformer was used and what the voltages are at the dedicated test points. The other aspects you mentioned are basically right or have already been discussed before.
Best
Bernd

Input pad is installed. Input transformer is the Sowter 9062E, output transformer is a blue Edcor (no visible part number). 

Testing with a 400 Hz sine wave input across pins 2&3 (L&R) of the input connector, with the input level control at maximum, compression just begins to move the needle at about 60 mV RMS.  At that level, the output is minimum 1VRMS, and up to 6.2V RMS at max.  Seems awfully hot for any line level signal.

No-signal DC voltages with respect to ground are:

+V  4.1V
B+ 323V
F+ 6.3V
BS 99.7v
A - 70.2V
B - 0v
C - 1.33v
D - 0.68v
E - 1.33v
F  - 0v
G - 69v
H - 119v
I - 177v
J - 0v
K - 2.65V
L - 2.49v
M - 0v
N - 186v
O - 316v
P - 0v
Q - 0v
R - 318v
S - 221v
T  - 24.6v

(Any reading less than 0.1V was considered to be 0V.)

So, my question is,  is this normal operation for this unit?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 03, 2017, 07:09:10 PM
Hi,
Can you check how the Sowter input tx has been wired , 1:4 or 1:8 ?
You can  either  remove the input pad or  bring down the bias voltage (25V ->18-20V).  You will need to install another output pad (10-15 dB) after the already existing to bring down the output level.

So I removed the input pad and lowered the threshold by reducing R32 (24K). I replaced the resistor with a 20K pot plus a 4K7 to ground in order to find the right threshold. Finally ended with around 18K. The unit works fantastic.

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: techineer on March 06, 2017, 12:10:16 PM
Hi,
Can you check how the Sowter input tx has been wired , 1:4 or 1:8 ?
You can  either  remove the input pad or  bring down the bias voltage (25V ->18-20V).  You will need to install another output pad (10-15 dB) after the already existing to bring down the output level.


He used the Pink and Grey primary leads and the Red and Yellow secondary leads, (Blue and violet connected together)  so I think that is 1:8.     Based on my input readings, the input sensitivity is probably OK, as a .775V RMS signal input brings the meter needle back to 75 uA /200 at full rotation of the input pot.  The output level is just excessive, so an additional pad on the output is probably the way to go if desired.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 06, 2017, 01:18:13 PM
http://www.nu9n.com/tpad-calculator.html

I think I went for a 15 dB  H-pad. You can connect it to the "audio out"  screw terminal.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Mulmany on August 03, 2017, 10:01:31 PM
What is the rough parts cost, USD, for this build?

Thanks
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 04, 2017, 05:10:41 AM
500-700 USD depending on the choice of components/transformers/case.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Mulmany on August 04, 2017, 10:34:09 PM
Thanks.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on August 16, 2017, 10:51:31 AM
Hello everyone.  I have completed my Sta Level using Steves case which I picked up from him a couple of weeks ago. It was a pleasure meeting you Steve and thanks for the case which is excellent. I am not quite sure how to get photos into my post but have attached a quick pic as a file attachment. if you are starting a build with Steves case you might want to make sure you are using 5mm standoffs as things get a bit tight in the power supply area with anything longer. Also the relay board can get a bit close to Vi with 10mm standoffs. I have measured voltages on the board and all seems within spec although I have to do it again properly now that all is connected. I am guessing a bit with the three gang attenuator pot but will experiment a bit. If anyone has any ideas I would love to hear. Steve has sent me a copy of it being used on the input of an1176 which will help. If i come across any problems (likely) i will try to run them past you guys. Hope all of your builds go well. PZJ
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 16, 2017, 11:00:03 AM
 :) Nice!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on August 17, 2017, 10:24:19 AM
Well testing has gone well I have balanced the valves and calibrated the meter. I was getting a short oscillation with the input pot at about three quarters on but this has gone since I have balanced the valves . I have wired the three gang output pot the way I thought it should be and it seems to work ok. The input is nice and clean and the unit is very quiet for a valve unit.
 I am going to shield the screen  wires from the input pot as they are V sensitive. I am waiting for some 5mm standoffs to arrive which I will use on the PSU and bias boards as well as the Relay board which is working fine now that I have wired it correctly (idiot). I have taken a supply from the heater supply with an appropriate resistor to the Meter LED to give it a fairly faint light. All the voltages are looking good and I can post them here if anyone is interested. Thats about it I cannot think of any other problems so far. Thanks Bernd for the boards and all the work you have put into the project. Thank you Steve for a great case. I look forward to putting it to use. I have used Sowter TX,s, the 9185s on the output and the 9062e on the input wired as per the excellent wiring guide. I used Steve's power tx and the voltages were spot on.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 17, 2017, 10:28:57 AM
Well, that's the way it should go! Congratulations! Zayance has done a great job as well!
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on August 17, 2017, 10:42:00 AM
Yes sorry thanks to Zayance also.  :)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on August 21, 2017, 05:53:41 AM
Hi all,
I am starting this build, and would like to know which wires would need to be shielded..
Kind regards,
Hugo
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on August 21, 2017, 06:15:52 AM
Hi Hugo,
I didn't use any shielded wire in my build. Check the measurement PDF, it's very quite. If you want to use shielded wires, use them for the pots.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on August 21, 2017, 12:41:36 PM
Hi Hugo,
I didn't use any shielded wire in my build. Check the measurement PDF, it's very quite. If you want to use shielded wires, use them for the pots.
Bernd

Thank you very much for the support.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mysticmerlin on September 12, 2017, 12:09:39 PM
Hi, I'm a puzzled with the V+ . I'm getting 5.6V DC at the input of the LM317T regulator on both my units . I have 5.2 v AC from the transformer, so normally I should be getting around 7v DC at the input of the regulator. So at the end I get something around 3.6V volts DC max for the relays which is not enough to close them. I have jumpered R8

Any ideas ?
Thanks
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on September 13, 2017, 07:49:17 AM
Hi Mystic. I have just checked the volts at my relay board and I am getting 3.7V across the switch terminals and the relays are switching OK. do you have the relays powered in series or Parallel? (Jumper the two pads marked -//   and    +//  on the relay board) then make the supply switchable.. which is what I have done. Hope this helps.

PZJ

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: StefanAC on September 13, 2017, 08:29:12 AM
Same here.  I got 3.7V DC at the terminal and wired the relay coils in parallel. Everything is working as it should.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mysticmerlin on September 13, 2017, 11:15:10 AM
Thank you for your help. I will check the relays again, at the moment I have removed them and I'm getting a distorted signal with a reduced low end on both units so the relays are not very important for the moment.
I'll post back once I've sorted this mess
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dogvoid on October 30, 2017, 03:16:48 PM
Hello everyone

I'm with the first tests and it sounds fantastic (I think it's my favorite compressor) Mode and recovery work perfectly and give it a lot of versatility.
The only problem is the output level, it is very high, the transformers are the pair of sowter 9062 and 9185, and everything checked and it is ok.
I need another h-pad between the pcb and the xlr? (That seemed to me understand reading other post)
The R40 does not appear in the original scheme, what function does it have?
R32 could be considered a kind of "treshold"? It would be fair to adjust an earlier compression.

Thank you all!
I hope to share some photos and demos when he is ready.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: 59flame on November 04, 2017, 04:31:59 PM
anyone have an extra 100k dual pot with switch  that was ordered from steve with the cases that would like to sell. I need one.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on November 08, 2017, 11:21:21 AM
Hi,
I finished the wiring, and i powered on. Without any tube, i got 2 of the 3 leds illuminated,but the third one remains unlighted.. Do i need to put the 6al5 to have It illuminated ? Also, i do not have light on the bulb and maybe those 2 things are related ?
Thank you
Hugo
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 08, 2017, 11:57:21 AM
Hi Hugo,
the LEDs just indicate a working psu. The third LED is probably the 5V rail. Just measure if you've got voltage there. I would suggest to power it up with everything connected and tubes plugged in. Without the tubes the voltages go up to heaven. So measure under load.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on November 10, 2017, 12:29:11 PM
Hi guys
I could need a little help with my build.
When I powered it up R3 instantly blew. Any suggestions where to look first?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: kosi on November 10, 2017, 07:15:33 PM
I changed R3 to two 470R 25W. my regular R3 got so hot, the solder was melting...
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on November 16, 2017, 01:02:34 PM
Hi,
I realised that i did not have any power on filaments, and after checking all components/connections, i just have a doubt on my LM338 TO-3 version... I respected the polarity of IN and ADJ, but in datasheet, there is written that the V out is "the case" of TO-3...should i add some connection ?. Also, i soldered it straight in the pcb, is it a problem ?
Thank you,
Hugo
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 16, 2017, 01:10:04 PM
Yes, you should mount it with isolation on chassis, otherwise it will get very hot and turn into thermal shutdown (-> no heater voltage).
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on November 16, 2017, 01:22:28 PM
Yes, you should mount it with isolation on chassis, otherwise it will get very hot and turn into thermal shutdown (-> no heater voltage).
Bernd

Ok, and regarding the V out, should i connect the TO-3 case to the Vout of the pcb ?..
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 16, 2017, 01:25:32 PM
You need a TO-220 voltage regulator.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on November 16, 2017, 02:25:55 PM
You need a TO-220 voltage regulator.
Bernd
Noted, thank you...
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on November 17, 2017, 05:12:59 AM
Ok, now the PSU seems to work (all leds are illuminated), but :

1 - the meter does not react when i power on the unit..even with trimmer fully CW.. Which part could i check for this ?.
2 - Is there a diagramm to wire an T-Pad as output ? I do not figure how to do..

Thank you
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on November 17, 2017, 05:22:09 AM
What are the specs of the meter? There is a meter trimmer as well. Are the tubes inserted?
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 17, 2017, 04:45:39 PM
I solved meter problem, but now i have an other issue...Sound passes fine through the preamp, the input poyt react well, but not any compression is applied to the signal.. How to check where i made a mistake ? I use a 6386 that i am not able to test...but before buying a new one i prefer to be sure it does not come from an other spot..

Thank you..
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 18, 2017, 02:01:02 AM
Hi Hugo,
Quote from my third post:

6) A few things to keep in mind when using different input tubes (6386 or 6BA6 combo): 
- with the 6BA6 combo the unit sounds almost the same as with the 6386 tube, but the gain structure and threshold is completely different.
-  First I tested the 6BA6 combo with a 1:4 input transformer, input pad, all values according to original schematic: works fantastic and sounds very good.
- Then I replaced the combo with a single 6386 tube.  I had to crank up the input pot in order to get some slight compression. Not very satisfying.
- So I removed the input pad and lowered the threshold by reducing R32 (24K). I replaced the resistor with a 20K pot plus a 4K7 to ground in order to find the right threshold. Finally ended with around 18K.

I hope that helps. I finally convinced the seller in Paris to ship the MKS30 to me!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 18, 2017, 10:55:29 AM
Thanks for replying...
Now i have compression, the T-pad is connected and everything seems to work fine EXCEPT:
- When i push the momentary switch, the ground loop disappear, and i have big noise when the swith is "off".. I tried to swap the star ground wire to the other lug of the momentary switch, and i have permanent humm. It should be the opposite, i can not understand why..
- Also, i have a saturation hearable when the track is mainly 1khz.
I will try to remove the input pad, and change R24 with 18k (i did not understood what you meant by 4k7 to ground)..
hugo
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 18, 2017, 11:05:49 AM
You need a "momentarily off" switch, i.e. when pushing the switch, the contact to ground is interrupted. This causes noise , which is taken as a kind of test signal in order to balance the two 6ba6 tubes and the two halves of the double triode output tube.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 18, 2017, 11:33:22 AM
You need a "momentarily off" switch, i.e. when pushing the switch, the contact to ground is interrupted. This causes noise , which is taken as a kind of test signal in order to balance the two 6ba6 tubes and the two halves of the double triode output tube.
Bernd

Yes, i just realized this ! :-) I will try to finish this evening...I already love that unit.
Oh i forgt to mention one point : I accidentally powered on the unit with Output Tx disconnected.. I saw smoke arround the 10w resistor, but i prefered to switch off the unit before breaking something, and i did not see fro which component exactly the smoke. I noticed at the same time that i made a big mistake by swapping one EL90 and the 6AL5..I corrected thos 2 points and unit started to work fine..But should i replace tubes, caps, or resistor in this case ?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 19, 2017, 02:19:14 PM
I installed the U-pad followed by a T-pad attenuator from CAPI and the first tests are perfect.
The output works like a "normal" compressor, e.g. I have Input and Output at 12 o'clock and the volume is about the same bypassed and compressor engaged.
I used 1/2 W resistors and the CAPI T Pad Adapter, I attach a picture.


Regarding my relay problem: I connected my relay as you said, but the problem remains....

The seller gave me 82R instead of 68R here.. Shoud it be a problem ?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 19, 2017, 02:33:14 PM
Hi Hugo,
where did you use 82R instead of 68R. I don't know what you are referring to, power supply, main board?
In case your 5V rail doesn't give you enough power you can connect the relays to the heater supply.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 19, 2017, 04:27:48 PM
Hi Hugo,
where did you use 82R instead of 68R. I don't know what you are referring to, power supply, main board?
In case your 5V rail doesn't give you enough power you can connect the relays to the heater supply.
Bernd

Oh sorry, i was replying to one koslik post, which describes a "U pad" with 2x 270R and one 68R, to put before a t-pad...
Everything works fine except the fastest recovery position, which does not recover at all...will take a look at the switchs board
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on December 20, 2017, 10:06:48 AM
Hi folks.
Finally solved my PSU problems, Voltages seem to be good but.
When Compressing Vocals / Bass / Guitars I am getting ugly Distortion Humps on low Compressions levels in all 3 Modes. Everything despite slowest release seems to be useless.

So. How do I configure the meter properly? Maybe I am compressing more than the meter shows me?
How is Bias calibrated correctly ( yes I did the listening method, but compression seems to be cleaner when the hum is louder).

I am using the Sowters, input Tx configured in 1:8
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 20, 2017, 04:19:50 PM
Hi,
When using a sowter 1:8 input transformer the input pad is mandatory. In case you haven't installed the input pad I would configure the input tx as 1:4 instead. Your distortion is most likely  in the first tube stage. What are you using, 6386 or 2x 6BA6?  Bias configuration, setting threshold, banlancing tubes etc. is described in the first posts of this thread and in the original manual. There is a meter trimmer for setting the meter to zero.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on December 20, 2017, 08:21:59 PM
Hi Bernd.
I am using 2 6BA6 tubes and all the pads are installed. I calibrated BIAS and the meter according to the manual and your posts, So far so good.
But pulling off the 6AL5 removes the previously described distortion artifacts. I can still distort my unit by cranking the input... (as I should be able to). Most of the artifacts happen between 5 and 10 dB Gain reduction. While compressing more they seem to be less strong.
Cheers
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 21, 2017, 02:33:29 AM
Ok, then your mistake/error can only be found on the frontpanel pcbs. Check the wiring. Also test another 6AL5 tube.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 21, 2017, 02:35:31 AM
On the control boards there are three wire bridges to be soldered in. When breaking the control board because of a different frontpanel design you need to use some longer wires.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on December 21, 2017, 06:22:59 AM
Double checked the control boards component values. Reheated everything. Cleaned everything again. Still the same problem.

https://www.dropbox.com/s/13lando1ieybied/IMG_0002.JPG?dl=0
https://www.dropbox.com/s/5zllunompw7w5ss/IMG_0003.JPG?dl=0

And a Video
https://www.dropbox.com/s/cjoozroqfd1b9tu/IMG_0004.MOV?dl=0

And another one that shows the problem a little better.
https://www.dropbox.com/s/wki2iomh7vq559x/IMG_0005.MOV?dl=0

And the Tube was replaced by another one.

I made one more obervation. In the Fastest Release Setting the Release seems to be nearly infinite.
EDITED:  Solved - one Position too much on the Lorlin Switch.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: mysticmerlin on December 21, 2017, 09:56:07 AM
Ok, I've got both units up and running. They both sound great and quiet.
One compresses more than the other and I have to figure out why the threshold is different .
I am going to lift the large resistors R3 , R23S and D1-D4 off the PCB because of heat.
Now I have to find  the issue with V+ for the bypass relays. 
Should I use the V+ Ground jumper so that this Voltage is referenced to ground?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on December 21, 2017, 10:27:29 AM
Message #293 helped me with my PSU Problems... Make sure that all the voltage regulators are isolated with the ISO Kits. Important!!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on December 22, 2017, 04:18:01 AM
My distortion problem - Video still exists, any thoughts?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 22, 2017, 04:37:16 AM
1) Did you verify that the two control pcb are connected with each other? You need to set wire bridges between the two boards.
2) Have you already done the calibration/balancing of the tubes?
3) Measure the amp without the 6AL5 tube using RMAA software. Is your distortion still there?
4) Did you set the Lorlin switches correctly?
5) I would wire the sowter transformer 1:4 and leave out the input pad.

Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on December 22, 2017, 05:56:26 AM
Hey Bernd. I did continuity Checks on the two boards. The Switches behave absolutely correctly. Optically the Release is fine. There is absolutely no distortion without the sidechain Tube installed (intact the STA Level seems to be a very nice Mic/Lineamp when not compressing). I calibrated the unit properly.  Checked all the testing points .

A 92V
B 0V
C 1,1V
D 0,6V
E 1,3V
F 0V
G 77V
H 130V
I 177V
J 0,1V
K 2,51V
L 2,51V
M 0V
N 177V
O 314V
P 5mV
Q 8mV
R 313V
S 209V
T 24V

I attached pictures of my control board and two videos of the discibed and unwanted behavior of my unit in post #345. Have a look at the please.
Removing the pad and wiring the tranny for 1:4 could be a next step, but without any general distortion, disabling the control circuit by pulling the tube, would that make any difference?

I checked the switches yesterday. They seem to be setup fine. Continuity while switching them between the switch position and the according resistor is fine. Resistors have he correct values. The two Caps are 250Vs, correct capacitance.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 22, 2017, 06:10:58 AM
Sorry, just a copy and paste from earlier post, but I recommend to lower the threshold first as described below and then maybe wire the input transformer 1:4. From the video I get the impression that you have to crank up the input pot way too much in order to get compression.

6) A few things to keep in mind when using different input tubes (6386 or 6BA6 combo): 
- with the 6BA6 combo the unit sounds almost the same as with the 6386 tube, but the gain structure and threshold is completely different.
-  First I tested the 6BA6 combo with a 1:4 input transformer, input pad, all values according to original schematic: works fantastic and sounds very good.
- Then I replaced the combo with a single 6386 tube.  I had to crank up the input pot in order to get some slight compression. Not very satisfying.
- So I removed the input pad and lowered the threshold by reducing R32 (24K). I replaced the resistor with a 20K pot plus a 4K7 to ground in order to find the right threshold. Finally ended with around 18K. The unit works fantastic.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 22, 2017, 11:56:07 AM
Sorry, just a copy and paste from earlier post, but I recommend to lower the threshold first as described below and then maybe wire the input transformer 1:4. From the video I get the impression that you have to crank up the input pot way too much in order to get compression.

6) A few things to keep in mind when using different input tubes (6386 or 6BA6 combo): 
- with the 6BA6 combo the unit sounds almost the same as with the 6386 tube, but the gain structure and threshold is completely different.
-  First I tested the 6BA6 combo with a 1:4 input transformer, input pad, all values according to original schematic: works fantastic and sounds very good.
- Then I replaced the combo with a single 6386 tube.  I had to crank up the input pot in order to get some slight compression. Not very satisfying.
- So I removed the input pad and lowered the threshold by reducing R32 (24K). I replaced the resistor with a 20K pot plus a 4K7 to ground in order to find the right threshold. Finally ended with around 18K. The unit works fantastic.

And dont short the middle resistor of Input pad, jumpers only on other resistors..or you will not have any sound entering the circuitry
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: hugo on December 27, 2017, 06:37:40 PM
I noticed a high distotion on my unit...
6386 (untested)
input pad is removed
threshold resistor 20k
U-pad followed by T-Pad on the output (recommended by Koslik on this thread)

I have to put output at maximum to have good level, matched with input
input pot at 7", it compress / 9" : usable / 12" : start to distord

Does somebody have an idea, how to solve this ?

Thanks
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 28, 2017, 04:28:25 AM
Pull out the 6AL5 tube and measure the amp with RMAA (Rightmark Audio Analyser ). With this you can find out if there is a mistake in the amp or in the sidechain. In case the amp hasn’t got any distortion, your 6386 and all other tubes in the amp are fine. The mistake must be somewhere in the sidechain.
See also the comments above about using different input tubes and gain structure.
Bernd

EDIT: it should be clear, that either a pair of 6BA6 or a single 6386 should be used, not all three tubes together!!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on January 02, 2018, 03:48:35 PM
My build is coming along nicely, I'm ready to hook up however, one of the 6AQ5's glass has broken, I'm assuming it's better to keep these two tubes as a same brand/model pair?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on January 02, 2018, 03:55:48 PM
For testing you can take any working 6AQ5 you have at hand. When doing final calibration you should have quality tubes.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on January 03, 2018, 08:15:41 AM
Hello Folks, hello Bernd.

I did everything as suggested to solve my problem, but the Pops on Compression still remain. To clarify the problem I upped an audio file:

https://www.dropbox.com/s/r8tf4o4lkjqwseh/GDIY%20Demo.mp3?dl=0#

Maybe someone has an idea what is going  wrong.

Thanks in advance
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Bassniac on January 11, 2018, 10:09:20 AM
Problem solved. Was a bad resistor in the Sidechain.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dustbro on January 27, 2018, 01:44:54 AM
I noticed a high distotion on my unit...

I've built a bunch of sta-levels I  the past.  They seem to be picky about their 6v6. Try some different pairs and compare distortion
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 16, 2018, 07:04:05 PM
Hi all,

I am just finishing my sta level build but am running in to some weird issues.

The B+ AC that comes from the don audio transformer gives me an ac voltage of 355v, which seems a little high.

My B+ DC voltage from the psu is high at 421v DC. Also, the leds on the psu are not lighting up. My power light does come on, so at least it indicates that there is some V+ current flowing.

Also, the tubes do not glow as there is no F+ coming from the PSU.

I am not super experienced in these types of builds, so any help would be greatly appreciated. Any ideas? Maybe the power transformer? I have hooked it up in series for 230v operation as per don-audio's instructions.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 17, 2018, 06:13:48 AM
Have you wired the heater underneath ? Pictures would help.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 17, 2018, 08:53:57 AM
Hi Bernd, thanks for your reply.

Yes, I have wired the F- and F+ underneath the board.

Here are some pics of my build https://imgur.com/a/bRW2d

The Lm338 is mounted to the case with insulator.

The power transformer seems to hum a little bit when turned on. Is this normal?

I have isolated the Edcor wires not in use.

Also, when I left the device on for a minute, all of a sudden the meter went all the way to the right and then slowly went back to the left. It is a nos 200mA DC meter.

Thanks for all your help.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 17, 2018, 09:58:49 AM
How did you wire the transformer primary? Measure all AC voltages coming from the transformer. Then measure all DC voltages going out from the psu.
Just for testing you could disconnect the bias pcb and check voltages once again.
What tubes have you got in there? Could it be possible that one of the tubes is broken?
Report back what you get.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 17, 2018, 12:11:37 PM
The transformer primaries are in series, for 230v operation. Those voltages seem to be right:

V+ AC = 4.9 V
B+ AC =  326 V
F+ AC = 9.3 V

And the PSU outputs with the bias psu pcb attached:

V+ = 3.6 V
B+ = 322 V
F+ = 0.13 V

PSU output without the bias psu pcb attached:

V+ = 3.69 V
B+ = 326 V
F+ ~ 0 V

Possibly a short somewhere in the F+ circuit in the PSU?

Thanks for all the help!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 17, 2018, 12:19:25 PM
Yes, there must be an error in the heater psu rail.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 17, 2018, 08:22:28 PM
Allright, put some hours into it and slowly making progress.

I checked the psu since I suspected a short somewhere. Did not really find anything.

I corrected the LED orientation and they now work. When powering the unit on again it had the same issue, but when I pressed the momentary switch the F+ led came on, and the tubes started to glow. The switch is supposed to be a momentary off-switch right?

Also, R3 is getting very hot (solder starting to melt).

Any ideas?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 18, 2018, 04:19:01 AM
The heater plus and minus must be connect with the tubes permanently, so no switch or anything else.  Additionally the heater minus must be referenced to ground. This will reduced hum considerably. This connection to ground can be interrupted by a switch, a momentary off switch.
You have placed the switch at the wrong place.

I suggest to mount R3 to chassis. Take one of these 20W resistors that are suitable for external mounting.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 21, 2018, 10:21:06 AM
The switch was in the right place, but I figured it out: it was a problem with the lm338 regulator.

My unit works now :) sounds really great. Still figuring out what threshold/input pad situation I like best, but getting there. Will probably leave both the in and output pad and drop the threshold a bit.

These are the voltages at the test points:

B+ 303V
V+ 3.44 V (seems low but the relays work and so does the power light)
F+ 6.4 V

A 60.3 V
B 0 V
C 1.3 V
D 0.64 V
E 1.25 V
F -0.04V
G 64.4 V
H 110V
I 161.5 V
J 0V
K 2.58V
L 2.54 V
M 0 V
N 163.4 V
O 297 V
P 3mV
Q 5mV
R 296 V
S 210V
T 22.9 V

Nothing out of the ordinary, no?

There is still one small issue: when powering on the unit is quite silent but when the tubes start to heat up and glow there seems to be a hum/buzz coming from the toroidal. Almost like its overloading a bit. Nothing too crazy but not that nice in a studio setting. Anyone know something that I can do against this?

Thanks!
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on March 21, 2018, 10:33:12 AM
Good news! You may loosen the power transformer bolt, move the transformer a bit and tighten it again.
Congratulations!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 21, 2018, 11:00:49 AM
Thanks :) and thank you and Zayance for the design and pcb!

The noise really seems to come from inside the transformer, so tightening it doesnt really help unfortunately. Maybe it's just something with this particular one. Once it's in the rack it will probably be less noticeable.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dmp on March 21, 2018, 11:13:28 AM
Does the power transformer have a high enough VA rating for the circuit?
What is the brand and model number?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on March 21, 2018, 11:14:28 AM
Yes, its the Don-Audio toroidal for this project.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: brndvnrdn on April 06, 2018, 11:45:02 AM
Still enjoying my sta level :) most issues are fixed now and it sounds lovely.

One thing I want to check: when using the double or triple mode and a fast recovery time, on percussion or drums there is almost a 'gated' like effect. It's almost chopping up the audio. I read the manual and the sound on sound article but wasn't sure if this is normal. Anyone?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: garp on April 09, 2018, 01:45:27 PM
In case of ... maybe someone has a spare gates logo unused ? PM me !
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on May 29, 2018, 07:36:00 AM
Hi all

Could someone please help me with the wiring for this board? I'm guessing I need to bridge the two '230V' solder points?

Output connector has B 115v and A 115v, where I should I go from for a 230v supply?

Thanks

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on May 29, 2018, 08:14:11 AM
You'll need this switch.

https://www.mouser.de/ProductDetail/Switchcraft/EPS3SL1/?qs=%2fha2pyFadugO9pDR5d23ezIZQLlI0srb1%252bCN9ThsCGY%3d

Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on May 29, 2018, 09:43:24 AM
I have powered her up, but a few things are off. The F+ LED does not light up. Voltages are as follows. Some seems. little off, others are quite close.

A 124 V
B -320 mv
C 1.04
D 0.5
E 1.07
F -112 mv
G 227
H 248
I 178
J 1.1 mv
K 2.5
L 2.47
M -100 mv
N 181
O 315.8
P 13 mv
Q 90 mv
R 315
S 229
T 23.9

All filaments glow it seems. The jewel light does not light up.

Any advice would be much appreciated. 

Gareth

 
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on May 30, 2018, 12:19:26 PM
Ok so after some further testing, the voltages are all pretty much spot on now.

The main issue I have is that the 0 v test points (B, F, M etc) are reading small voltages 27mv, and 24 mv for example. Does this mean there's current in the ground plane? Perhaps this will clear up when I calibrate.

I don't have a momentary switch, so I have connected some cable as per the wiring diagram, one of those cables is cut half way, I figure I can break this cable in order to test with the same result.

The other odd thing is test points P and Q on the EL90's. P = 8.6mv and Q = 262 mv

I'm going to swap out the F+ LED, perhaps it's faulty, as the filaments are getting a nice 6.3 v. I also think the jewel light may be blown as V+ voltages are at 3.6v, quite acceptable no?

Going to run some audio through and see how it goes.

Many thanks

Gareth

--
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on May 30, 2018, 03:00:28 PM
Ok, so she passes audio fine. However, I'm not seeing any movement on the meter, and no compression it seems. Recorded in to PT and could see no change in the waveform and nothing discernible to the ear either.

Also, there is a fair bit of noise. Tried disconnecting the cable to ground (from F-) no hum or no change in signal or noise.

If I tap the 6BA6 tubes I get noticeable microphonics in the output signal.

Not sure where to go from here. Any pointers are welcomed.

Gareth

--


Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on June 25, 2018, 03:00:03 PM
OK, so there is a lot of noise/hum/buzz in the audio.

I think it has something to do with the F+ heater circuit.

When I adjust the bias adjust trimmer between EL90's I can see a change occurring in the level on my interface input meter. However there is a good 20db of noise still. Only slight change.

I don't understand the test jig ON/OFF switch. I was measuring 6.3V between there and ground.

Appreciate this is DIY, but can anyone help out? I've gone over everything it looks ok, with no visible shorts, the voltages seem to add up ok as well. Not sure where this noise would be coming from. 

Many thanks

Gareth

--

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 25, 2018, 04:46:23 PM
Forget the momentary switch for now and check your wiring:

1) The 6,3V rail has got F+ and F-. F- needs to be connected to star ground. Of course star ground must be connected to IEC ground! If you do as described, you shouldn’t have any noise or hum at all. 

2) The connection F- to star ground can be made switchable by a momentary switch, which interrupts the connection to ground momentarily, when the switch is pushed. The lack of ground reference causes audible hum, which functions as a kind of “test signal “. So push down the momentary switch and trim the balance pots so that hum level is at its lowest level. Release the push button and you’ll have a perfectly balanced and hum free compressor.
Cheers
Bernd

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on June 25, 2018, 06:33:49 PM
Thanks Bern.

I have the momentary switch out of the circuit. I have two wires going from the two 'ground' points on the middle of the board, going to star ground. Star ground is also connected to IEC ground. All other connections to ground look ok and wiring seems correct.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 25, 2018, 07:09:25 PM
Ok, then test a few things:
1) Feed the compressor with a test signal. Turn the  input pot fully counterclockwise. Is there still a signal ? If there is, then the input pot wiring is wrong.
2) Set the input pot to 12 o’clock. The output pot should only attenuate the signal , not completely shut down the signal
3) does the hum increase when turning up the input pot?
4) Set input pot to maximum and feed the compressor with a strong signal. Does the meter start to move? Distortion? If so, your 6ba6 input tubes are bad/broken.
5) Take out the 6AL5 tube and switch the unit on. Still hum? If not, your problem is in the sidechain. If yes, your problem is in the amplifier, probably bad tube, wrong wiring of the input or output  transformer.
6) have a look at  the wiring diagram in the first/second post once again. Check your wiring, especially the grounding !
 This unit is the quietest tube unit I’ve got in my rack, so you made an error somewhere.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on June 25, 2018, 07:17:58 PM
Thank you that’s good advice.

There’s definitely a fault somewhere, it’s not normal behaviour, will go through your suggestions.

Best

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: gareth33 on June 26, 2018, 05:19:41 AM
1) Feed the compressor with a test signal. Turn the  input pot fully counterclockwise. Is there still a signal ? If there is, then the input pot wiring is wrong.

Input pot works fine.

2) Set the input pot to 12 o’clock. The output pot should only attenuate the signal , not completely shut down the signal

Works as expected

3) does the hum increase when turning up the input pot?

Doesn't really increase, does by turning the output pot. When I touch the casing of the input pot, hum increases a lot.


4) Set input pot to maximum and feed the compressor with a strong signal. Does the meter start to move? Distortion? If so, your 6ba6 input tubes are bad/broken.

Meter doesn't move at all, hard to say if it's distorting, I don't think so, might have blown something? As I turned up output pot there was a pop, maybe overloaded it too much?

5) Take out the 6AL5 tube and switch the unit on. Still hum? If not, your problem is in the sidechain. If yes, your problem is in the amplifier, probably bad tube, wrong wiring of the input or output  transformer.

Hum still there, there is now a lot more noise than before.

6) have a look at  the wiring diagram in the first/second post once again. Check your wiring, especially the grounding !
 This unit is the quietest tube unit I’ve got in my rack, so you made an error somewhere.

Going to check wiring again, but it looks fine.

When I tap the 6BA6 tubes, whilst connected to audio interface, I can hear the tapping amplified, it's very loud, if I scratch the PCB I also hear that amplified. Is this normal behaviour? What does that indicate?

Thank you for any advice.

Gareth
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on June 26, 2018, 06:17:09 AM
Typical signs of wrong grounding/wiring.
A few things to check:
1) XLR in to audio in (pcb connector)  polarity, same with XLR out to audio out (pcb connector)
2) Check input transformer wiring
3) main board grounding (outer right connector to star ground)
4) the two frontpanel pcb need to be connected with wire bridges
5) check orientation of the „to/from ctrl“ connector

Cheers
Bernd

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: core13 on July 25, 2018, 05:59:41 AM
Hello, my STA is working fine but input signal is very strong and I can barely move the input knob
I can't compress normaly because lot's of color (distortion)


R 32 is 18K

also my B+ is higher spec I need to increase value of R3
R is 335v
A is 72,5
O is 333v

I have kidsquid power transformer and output Tpad
sowter in/out
alps dual 100K input potentiometer and 6386 tube

do I need to put a pad before input?

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 25, 2018, 02:35:09 PM
Decrease the signal before it hits the compressor and test if everything works fine. Normally the sta level has got a very hot output level. With the sowter 1:8 ratio it’s most likely, that you need an input pad. For the moment I wouldn’t worry too much about the B+ voltages.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: core13 on July 25, 2018, 05:53:37 PM
Thank you Bernd
I used it at mixdown and compared to LA2A, I sent normal level in both units and LA2A work as expected but with the sta I can barely increase the input.
I am not using the relay board  and I connected the xlr input directly to input transformer, I strapped the input pad with 0ohm resistor to bypass it , maybe I need to put the input pad back?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on July 26, 2018, 05:02:22 AM
Yes.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: core13 on September 17, 2018, 09:05:05 PM
I built an H pad input 6db reduction
It's better like this


I also changed R3 with 1K to reduce my B+
I measured my voltage and some are off

this is what I have

are they normal?

A= 57,5v
B= 2.5mv
C= 1.33v
D= 0,65v
E= 01.33v
F= 3mv
G= 58.5v
H=109v
I= 164v
J= 3m
K=2,5v
L=2,55v
M=3mv
N=160v
O= 299v
P= 5mV
Q= 6.5mV
R= 298v
S=206v
T= 17.8v
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on September 18, 2018, 03:48:13 PM
Your voltages are ok. No reason to worry.
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: core13 on September 18, 2018, 06:14:59 PM
A G H and T are very low compared to the reference voltage

it is okay?

A= 82v
B= 0v
C= 0,6v
D= 0,5v
E= 0,6v
F= 0v
G= 82v
H=142v
I= 168v
J= 0
K=2,58v
L=2,61v
M=0v
N=162v
O= 305v
P= 10mV
Q= 10mV
R= 305v
S=201v
T= 25v

does the trim pot in the psu section can fix that?

thank you
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on September 21, 2018, 02:43:45 AM
As long as your compressor works flawlessly I wouldn’t care to much about voltages. The reference voltages are taken from my prototype, just to verify, if we are in the ballpark. You could do some measurements with RMAA.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: IanB on October 11, 2018, 09:39:14 AM
Late to the party.  Can I buy boards still?
Cheers
Ian
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on October 11, 2018, 09:57:22 AM
https://groupdiy.com/index.php?topic=53011.0
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: jensenmann on December 18, 2018, 10:29:28 AM
I didn´t read the entire thread, so maybe this has been addressed before. In case not here´s a problem I found:
I´m using Steve´s transformer with 5V AC for V+ and 5V relays. Without regulator installed I get 6,5V DC at the regulator input pin. With regulator installed the voltage drops to 4V at it´s input and I get 3,3V at the output. Several others have mentioned this before, but nobody did care.
The reason for this is that if we want to get 5V out of the LM317 regulator it needs to see at least 3V more at it´s input. But we only have 6,5V instead of necessary 8V. So it shuts down.

Several solutions are possible:
1) Throw D16, D17, R7, R8, V+ Trim, LM317, C17 out of the circuit. Connect 2 or 3 diodes (e.g. 1N4007), depending on what really comes out of your tranny, in series for a voltage drop of roughly 1,2 - 1,8V and solder them reversed (w.r.t. the silkscreen) into the D16 designation. Now we have an unregulated supply, but neither relays nor light bulbs care... Advantage here is the V+ is galvanic isolated w.r.t. everything else.
Edit: the unregulated output voltage depends a lot on how big the smoothing caps are. I have installed a total of 3000uF and still found the output voltage to be below 4V loaded, with the diodes across D16. So I skipped the diodes completely and simply installed a jumper. Now I get 5V.
2) Leave everything in circuit, but don´t use the 5V AC transformer winding to feed the V+ regulator circuit. Instead use the 9V AC output which is used for the filament heater by connecting the V+ AC input parallel to the F+ AC input. We lose galvanic isolation w.r.t. F+ that way, but it should not be a problem. Just make sure that the groundwire of the relay board doesn´t create a groundloop.
3) Skip the bridge rectifier circuit in the V+ section and cook your own voltage doubler circuit to feed the regulator input. It´s possible to install this into the PCB layout as it is.
(https://rn-wissen.de/wiki/images/5/54/Delonschaltung.GIF)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on December 20, 2018, 05:31:00 AM
Hi Jens,
Thanks for pointing that out and presenting a workaround! Happy Christmas!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: jensenmann on December 20, 2018, 11:00:53 AM
Another issue I found:
C9 in the B+ PSU is rated at 400V. That´s too low. I measure 422V DC here. Theory says 300V AC x 1,4 = 420V DC after the bridge rectifier. So make sure that you use 450V rated caps for C9.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: jensenmann on December 20, 2018, 12:17:50 PM
Next one: there are ground loops if you wire your Sta Level according to the wiring diagram on the first page of the thread.

Filament supply/ground is fine if you follow the wiring diagram. Just make sure your switch for bias adjustment is opening the contact if momentarily pushed.

V+ supply and it´s ground is fine, too. Since it supplies the light bulb and the relays only it has no connection to audio anyway, so it´s not relevant. But be aware of the relay board ground wiring. There are several possible ways to ground that thingy. The best way is to tie pin 1 of both XLR in and outs directly to the starground. That´s the shortest path to ground. But you should use shielded wire inside the box to connect both XLRs to the relay board as well as the main PCB to the relay board. The shield of those four wires should be tied to ground at one side only! E.g. connect all four shields to the relay board but not to the XLRs and the main board. Then tie the relay board to the starground. This way you have no groundloop which is what we want.

Bias and HT supply:
The bias supply gets its voltage from the output of the HT (B+) supply via two wires: B+ and B-. B- is the wrong name since it´s actually ground. But it´s necessary to understand that both supplies have a common ground, just look at the schematic. Now if you wire the B+ output to the main PCB with two wires and the Bias supply with another two wires then you already have a groundloop because on the main PCB both ground connections are tied together via the ground plane. So leave one of those ground wires unconnected.
The main PCB and the PSU needs to be connected to starground. There are two provisions to do so: the ground connector on the main PCB next to the bias voltage input as well as the ground connection on the HT PSU board next to the HT Trim resistor. Connect only one of these two grounds to the starground. Otherwise you get a loop from starground to the main PCB, then via the bias or B+ ground to the PSU PCB and then from it´s ground connection to starground again.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: zayance on December 21, 2018, 10:36:04 AM
Quote
C9 in the B+ PSU is rated at 400V. That´s too low. I measure 422V DC here. Theory says 300V AC x 1,4 = 420V DC after the bridge rectifier. So make sure that you use 450V rated caps for C9.

Good catch.  ::)
Well the BOM gives hints if what can be used, and people can fit whatever they like, Bernd and i don't go into the "kits" thingy so...
Dunno if all went 400V Caps way here, depends on the provider, some might have no other choice than 450VDC etc...

But thanks for shimming in and giving hints and infos, always welcome.
BOM Will have update on today.


T
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: madreza on February 04, 2019, 07:56:33 PM
Hi Everyone ,
and thanks to Bern and Tony for that project , that's awesome!
so glad , I'm almost there :D

a few questions :
I have Sowter In/Out Tranny  /  Avel Lindberg Power Trans.
6383 Tube
voltages seem to be fine
the input is wired 1:8
so , I have to leave the input pad soldered , reduce the Bias voltage to , around 20V , and use a T pad pot for the Output , right ?
and what about the R32 ? Do I need to set a 20K pot also ? with a 4.7K to the ground ? or can just use a regular resistor for that ?
any other changes ?
oh , and I have a Simpson 27  0.1 DC mA ( do i just have to calibrate it with the trimmer on the PCB or do I have to do any changes ? )

Thanks Guys

Cheers
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 05, 2019, 08:41:27 AM
Yes, use the input pad and T pad output pot, bias voltage 16-20V, depending on how the compressor behaves. R32 is the bias resistor, right?  Well, you might get it right with a fixed resistor. When you have to crank up the input pot too much, reduce value of R32. 100 uA meter  should work fine with onboard trimpot.
Cheers
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: madreza on February 05, 2019, 03:14:10 PM
Cool thanks for your reply :)
So I just try and replace R32 by something around 18K and see if it works !?
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 05, 2019, 03:27:08 PM
Yes  :)
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: madreza on February 09, 2019, 01:16:27 PM
One more question. When the VUmeter shows -20dB GR , does the track s volume should be -20dB lower ?  Or we should have more level as we push the input gain to make it compress more ?
( is my question clear ? In my head it is 😃)
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on February 09, 2019, 02:20:43 PM
https://youtu.be/AM6YEnD_Di8

Cheers
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: madreza on February 16, 2019, 11:23:04 AM
Ok , everything is almost fine.
I have the signal thumping when it compresses when in dual or triple mode

It comes for sure from the 6AL5
When I take it out , everything is fine ( except it is not compressing )
Checked the bias voltage : 18.6V

Could that be a bad tube ?
I M pretty sure that at first it was working fine.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: madreza on February 23, 2019, 12:41:32 PM
So , tested the tube on a tube tester , and it s in perfect shape.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on March 01, 2019, 11:52:48 AM
Is ptfe 20 awg ok for heater wires? Or should 18 awg be used?

Thanks
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: dmp on March 01, 2019, 02:28:10 PM
Is ptfe 20 awg ok for heater wires? Or should 18 awg be used?
Thanks

Add up how much current is going through the wire than look up the resistance / temperature rise for different AWG.
The current is calculated by the heater current required by each tube (check the datasheets)
I would use thick enough wire that you do not have much resistance / temperature rise.
The resistance is usually spec'd as ohms / length, so the shorter the wire the less overall resistance.

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on March 03, 2019, 04:42:11 PM
I have no idea how to wire the bypass switch that came from Steve.
Is it just the extra gang goes to the output?
Anyone?

Also, jumpers on the relay board.
Do I jump all three?
Using the 5V as I’m using sowters

Thank
Neil
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on March 08, 2019, 01:21:33 PM
Hi This is a pic of my bypass board. Hope it helps.
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on March 09, 2019, 02:55:55 PM
Helped me! 🙂

Thanks
Neil
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on March 17, 2019, 01:17:11 PM
Hello all

This is where I am stuck at the moment.
Those special pots that was included in Steve's groupbuy.

Any help with wiring??  ;D

The input pot has a push/pull switch for the two terminals on the end. Not sure where they go?
I believe they're supposed to be a bypass.

The output pot, do we connect all 3 terminals together and wire the same?

Thanks
Neil
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on March 17, 2019, 03:27:17 PM
Hi Neal. If you look at the photo of my bypass board you will see the black and yellow wires that form the switch that opens or closes the 5v supply to the relays. One leg is taken to the switch terminals on the rear of the dual pot switch on the front panel this provides switching for the 5v relay power. I can send you some more pics if you need more help.

Cheers Paul

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on March 17, 2019, 08:06:35 PM
I get it!

Thanks Paul   :D

Cheers
Neil
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on April 01, 2019, 09:14:52 AM
Ok

Need some transformer wiring advice

Canada so 120V
blue/blue white together
Brown/brown white together

Secondaries are straight forward and I’m assuming org/wht and org  can be reversed as long as they’re on the 300V pads?

Does the SCR wire go to ground?
I notice in the wiring diagram that there is also a yellow that goes to ground. Unfortunately at Don Audio I can’t reference what the yellow wire is.

And the rest of the primaries are heat shrunk and isolated.

Any help would be appreciated
Thanks!

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: pzjones on April 03, 2019, 12:11:05 PM
Hi Neil.

Your are correct in that the SCREEN yellow and green cable  goes to star ground.

You must be nearly finished, hope all is going well.

Cheers Paul
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on April 03, 2019, 12:34:46 PM
Perfect!

Thanks so much

Almost finished first one.
I’ll post pics once completed

Cheers
Neil
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Kid Squid on April 05, 2019, 08:17:21 AM
Hi Chaps,
Hope all is well !

Just got back into Sta-Land, been heavily involved with a project at work and its swallowed up pretty much all of my free time.
Great to see the various builds coming along  ;D

Had some bad news regarding my transformer contact at Avel, They closed down in January.
All of the winding machines etc have been shipped to the parent firm, but existing designs should still be available on request through Roshe Power UK. So if you need any more, get in touch with 'em.

Gutted.

Best
Steve

Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on April 19, 2019, 09:53:59 AM
Finished both and they sound great!
I had to do the 20watt chassis mount resistor at R3 for both. One with a 1k ohm and other 500 ohm to get voltages within range.

Oh, and did a Upad along with the T-Pad attenuators

Thanks for the project, case and any help I received, even to those that posted great information in this thread!

Cheers
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: Le Roux on April 19, 2019, 09:55:44 AM
Front
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: bernbrue on April 19, 2019, 11:31:46 AM
They look gorgeous! Congratulations!
Bernd
Title: Re: [BUILD] STA LEVEL PCB OFFICIAL BUILD & HELP THREAD
Post by: BramK on June 13, 2019, 06:52:42 PM
Has anyone opened up an old Simpson Model 27 meter to replace the dial? Any advice on how to approach this safely? I hear one needs to be careful with any ferrous objects (including the screwdriver) when opening one up.