[bernbrue]

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. 




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






 

[bernbrue]

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.







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





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):



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

[bernbrue]

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

[bernbrue]

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

[rob_gould]

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

[bernbrue]

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

[bernbrue]

Some updates in the second post.
Bernd

[bernbrue]

Some info on heater wiring and discharging tool.
Bernd

[kambo]

so the mystery about discharging tool finally clears 

[zayance]

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 :/...

[mrcase]

Wow! Great Project! When will the PCBs be available. And will you put some soundexamples online?
congrats guys! looking awesome.

[bernbrue]

Did I mention that my unit works fine? !!

[nickhepfer]

Awesome project guys!
Did you compare it to the original Retro?
I really need a set of these PCBs, are they still availible?

[Winetree]

Could we see how it all mounts together in a front hinged case.
How the boards mount inside, Transformer placement, front panel pots,  etc.

[bernbrue]

Hi,
I attached a pdf file in the first post with some pictures. Enjoy.
Bernd

[bernbrue]

Tube balancing procedure (calibration) added to second post.

[bernbrue]

Some observations and measurements of my build added in 2nd post.
Bernd

[bernbrue]

Further measurement in my 3rd post. Results are fantastic. I´m done and going to put the lid on. What about you? 
Bernd

[nickhepfer]

Hey Bernd,
where did you get this authentic enclosure from?
Best,
Nick

[dipfrik]

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