Gates Sta Level !! protoboards preorder !!

[kubi]

Nach langem Hin und Her (lies: Herr Reinhöfer antwortet nicht auf Fragen), habe ich mich noch einmal auf die Suche nach einem Ausgangsübertrager begeben. Offensichtlich läuft das Geschäft bei bestimmten Anbietern wohl zu gut, sodass man es nicht nötig hat, sich auf Sonderanfertigungen einzulassen.
Ein Schätzchen ist mir über den Weg gelaufen, wo ich einfach mal sagen würde, der passt perfekt: Hammond 1650G.
Bei dem Übertrager muss man auch nichts umwickeln, was viele gar nicht machen würden oder könnten, sondern kann ihn direkt so verwenden. Außerdem ist er weltweit gut erhältlich. Mit 35W ist er zwar etwas größer als dir ursprünglichen 10W, aber wenn die anderen Werte passen und der Preis sich um 70Eur bewegt, dann ist das auch ok.
6000 Ohm an der Anode fühlen sich bei der 6V6 mit der Rückkopplung richtig an und 200mA max. Anodenstrom geben viel Luft nach oben: Die 6V6 sind im Gates Sta Level mit ca. 35 mA dabei, wenn ich es im Kopf richtig überschlagen habe.

[jensenmann]

Ich dachte ihr wollt einen Kompressor und keine Endstufe bauen????

[moatl]

Hallo zusammen!

Bin auch gerade am sammeln von Fakten zum STA-Level. Bernd, Du hast ja schon echt viel zusammengetragen!
(Hier schreibt übrigens der Martin dem Du vor kurzem auf GDIY das Beete Meter für den P2P LA2A verkauft hast )

Jedenfalls wäre ich im Prinzip auch dabei, allerdings würde ich es lieber P2P machen - zumindest hatte ich es bislang so vor...
Bernd hast Du einen Link zu dem P2P Layout, dass Du im ersten Post erwähnt hast? Auch wenn es fehlerhaft ist, man könnte es ja mal durchgehen
und mit Fotos vom Inneren und dem Schaltplan vergleichen.
Hab auch schon ewig gesucht, was im Original von Gates für Übertrager drin waren, aber hab nix ergiebiges gefunden. Dachte auch UTC, aber welche genau?

Beim Gehäuse würde ich es auch versuchen so original wie möglich zu halten, aber ich möchte hier auf keinen Fall quer schießen hehe!
Ich war gerade nur eh auf der Suche nach infos zum STA-Level und bin dann auf den Thread hier gestoßen

Ich bleib einfach mal dran und schau was sich hier so tut

Martin

[bernbrue]

Hi Martin,
wir sind beim Ausgangsübertrager und beim Platinenlayout stecken geblieben. Für letzteres ist kompetente Unterstützung in Sicht Später mehr dazu!!!

LG
Bernd

[AndreasS]

.... Herr Reinhöfer antwortet nicht auf Fragen...

Hallo Darius,

ja, leider ist Gerd für viele unerwartet sehr früh verstorben...

Gert bemüht sich, die Arbeitsplätze in der Firma zu erhalten (das Hauptgeschäft liegt ja nicht im Übertragerbau), aber auch die Fertigung von Übertragern soll weitergehen - schließlich gibt es heute nur sehr wenige, die dies in hoher Qualität können.

Gruß Andreas

[bernbrue]

Hi,
first: very sad news about Gerd. I recently experienced what a loss of a good friend/family member means. Anyway, life goes on.

second: you might wonder, why I turned over to English? Well, I would like to welcome Tony (aka ZAYANCE) to our forum and especially this project. During the "Rude Tube IVORY" project we had a vivid discussion about pcb design and wrote hundreds of emails to make it just perfect. Very early we decided to do the IVORY pcb first and than go on with the GATES STA Level. So Tony, a very warm welcome!

What we need is your input. Here are some ideas we developed so far:
1) We would like to do a complete panel with individuals "break out" pcbs for mainboard (mono), psu, relay bypass board, a logo pcb (golden letters on red pcb with golden frame) and other gadgets if space allows
2) transformers will be off board
3) option to use original 6386 tube or two 6BA6/6BZ6
4) using modern tube variants
5) Are there any modifications to the original schematic (input/output pad ?) we have to consider?
6) ............

We are going to collect your ideas and suggestion in the first thread, which I´m going to modify for that.
The journey continues!!! YEAH!!!!
Bernd

[zayance]

Hi There!

Thanks for turning into English Bernd, hope this doesn't bother folks here .

So Basically Bernd already gave suggestions,

I had one also:

Making the PCB Mechanically fit inside the rack, in a normal way
AND
Also have the option to fit it at the back of the Rack for having the Tubes fitted outside the rack if possible.
Would need some "optional" connectors, and PCB holes to allow cables to run from Top board to Bottom etc..
But just an idea, and not something i have digest really.

Waiting for yours, as i'm for now too busy to start designing the thing, but i'll follow up here and get toughts and ideas you guys would have etc...
And will show up things when we things get started with Bernd, so to correct errors with you guys, and mod things etc...


Thanks.


T.

[[silent:arts]]

Welcome Tony!

[bernbrue]

Just to add: the tube psu and the relay boards are ready. Only the main board has to be done including all the options and modification we should imply.

Feel free to download the schematic (original version) and draw in the modifications (e.g. Single/Double/Triple switch, Release mod, input/output pads, additional/optional trimpots on mainboard, etc.) Please mail the modified schematic to me in order to be up to date. I´m going to post the latest schématic in the first thread. Let´s rock the baby!!
Bernd

[bernbrue]

Ok, I started to modify the schematic and included the variable recovery time mod as done by DRIP and others. I found an interesting statement, supposed to be made by Phil from RETRO about how they implemented the triple mode:

The Retro Sta-Level has all the same circuitry and component values as an original Gates. The slowest setting of recovery is the original 4.7 Meg. The five faster settings are derived from a ladder of 330K resistors that are added in parallel with the 4.7 Meg. The added resistance values are 1.98 Meg, 1.65 Meg, 1.32 Meg, 990K, 660K (fastest CW).

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 an intelligent 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.

Measured recovery time in seconds from 15 dB gain reduction back to 0 in single mode: 20 (CCW), 9, 7, 6, 5, 4(CW). In double and triple mode, recovery times are 70% faster, but exhibit a non-linear rate, with recovery slowing until fully recovered. This is mostly applicable to the full CCW setting.

In addition to our model, Retro has modded over a hundred original Sta-Levels this way.

So the recovery mod was done slightly different as DRIP did but basicly with the same result. I posted the modified schematic in the first thread.
Bernd

[bernbrue]

Can anyone have a look at the psu on the original schematic? We need to know which parts of the original psu can be ommitted and substituted by our solid state psu. Do we need the O82 tube/neonlamp?
Bernd

[bernbrue]

Oh, haven´t seen that the 25V is derived from the B+ voltage. So if we provide R33 &34 directly with 25V we can leave out the voltage drop resistor the voltage divider and the OB2. Can somebody confirm, plz?
Bernd

[kubi]

Oh, haven´t seen that the 25V is derived from the B+ voltage. So if we provide R33 &34 directly with 25V we can leave out the voltage drop resistor the voltage divider and the OB2. Can somebody confirm, plz?
Bernd

Yes and no.
The +25V voltage is used to positively bias the diodes and thus provide a threshold level for the reduction to kick in.
Since your gain structure inside the device is completely different from the original one (due to different input and output transformers) you will mostlikely need a completely different bias voltage here.
You'll be fine by replacing the OB2 (=100V regulator) with a normal sand-state regulator like TL783 adjusted to 100V. Then replace R32 and R39 with a 100kOhm variable resistor to match your needed and desired threshold level.

[bernbrue]

Hi Darius,
very well explained. So it would be fine to take the 105V from B+, substitute the OB2 with a TL783 and make the bias voltage for the 6AL5 variable with a 100K trimpot.
Thanks
Bernd

[zayance]

Hi There,

I've started to fiddle around the design, and some toughts popped out that i shared with Bernd but i think it would be better to share here.

So, i was having some toughts on the PSU, Bernd and I were going to use the same "from paper" solid state PSU made for the Rude Tube,
so with Three rails B+/Filament/V+...
But while copy pasting the design in Eagle, i tought maybe it would be better to dump the Heater DC supply here (so wire heaters directly from AC) and exchange with
the Bias circuit, made with a TL783 as Kubi Suggested, and so maybe even add two different Bias Circuitry Onboard for folks that would need a stereo unit, or leave the second one if not etc....
But first tought was to add this Bias Circuit on each Mono Motherboard PCB's etc...

I guess second option is maybe more elegant, but feel free to share critics and toughts, even if we need to redesign things or dump stuff etc...

EDIT: And maybe it is too pretentious to feed two Motherboards with one PSU, while it would be better to actually take the advantage of using two separate PSU's and
just feed them in the same unit with one Beefy or two power transformer etc...

Thanks!