Drip STA Level build (now finished !)

[Sparqee]

I notice the Drip Sta PCB is labeled with different power supply capacitor values than the BOM gives.
BOM:
C12B 1&2 = 8.2uf / 630v
PCB:
C12B 1&2 = 10uf / 450v

BOM:
C12A = 47uf / 630v
PCB:
C12A = 22uf / 450v

BOM:
C7 A,B&C = 22uf / 630v
PCB:
C7A= 15uf / 450v
C7B= 22uf / 450v
C7C= 10uf / 450v

I ordered the values on the BOM and I'm just wondering if there will be any problem since they are different than the original PCB specs.

Thanks,

Sparqee

 

[desol]

Aren't the speeds the standard speeds on a vintage sta level?

It was normal for what it was intended for back in the day, program material, and why unaltered units work so good on bass(long release). I can tell you that with four or five different time constants(attack release settings) it's way more usable on stuff. It has a tough time tho...with too fast of attack settings which I am unsure as to the reasoning of(not enough power on the sidechain maybe..)....which results in(I think) small clicks....when set too fast.

 

[Bowie]

I notice the Drip Sta PCB is labeled with different power supply capacitor values than the BOM gives.
BOM:
C12B 1&2 = 8.2uf / 630v
PCB:
C12B 1&2 = 10uf / 450v

BOM:
C12A = 47uf / 630v
PCB:
C12A = 22uf / 450v

BOM:
C7 A,B&C = 22uf / 630v
PCB:
C7A= 15uf / 450v
C7B= 22uf / 450v
C7C= 10uf / 450v

I ordered the values on the BOM and I'm just wondering if there will be any problem since they are different than the original PCB specs.

Thanks,

Sparqee

I seem to recall that is has to do with the Drip using the 5AR4 rectifier instead of the original 5Y3 (I could be wrong).  I have tried both in my Drip and I prefer a vintage 5AR4.  Wonderful vibe with that one.

 

[jdiamantis]

Aren't the speeds the standard speeds on a vintage sta level?

It was normal for what it was intended for back in the day, program material, and why unaltered units work so good on bass(long release). I can tell you that with four or five different time constants(attack release settings) it's way more usable on stuff. It has a tough time tho...with too fast of attack settings which I am unsure as to the reasoning of(not enough power on the sidechain maybe..)....which results in(I think) small clicks....when set too fast.

The original use was as a slow agc for broadcast use. The original Gates manual had a list of components to "modify" the release and gain reduction ratio of the unit.

The clicks may be due to insufficient current in the side chain. More likely is "control feed-through" due to slight imbalances in the 6386 tube/circuitry/etc. 

jdiamantis

 

[jdiamantis]

BTW, great looking build!

You'd cry if you knew how many originals were tossed in the trash in the late 70s/80s by radio station staff as they were considered "old tech".

 

[Rlucas41]

Completed my Drip Gates Sta-Level build and wanted to share some photos!

 

[Rlucas41]

I want to thank Majestic12 for his help with the output pad!

 

[Rlucas41]

It worked from the first power up... sounds awesome and is very quiet
!Thanks to Gregory for the PCB and Dan Deurloo for the great case!

 

[Beauvais]

I realise this thread has been resting for a while, but starting a new one probably wouldn't make sense either.

Anyway, I'm pretty much finished with stuffing/soldering my drip STA-Level PCB and have run into a few questions.

(disclaimer. I've built several preamps and comps before, but I'm mostly just good with a soldering iron and not making mistakes. My understanding of what I'm actually doing is rather limited and the fact that the drip forum isn't accessible anymore doesn't help)

No 1. How do I wire the Sowter output transformer? I assume the blue and grey wires go to the output pad as they're the only ones not marked on the PCB. If this is correct, which one is which for the unit to be in phase? (And on a side note, why do the brown and green wires go to the PCB if it's only about connecting them?)

No. 2. Somebody please tell me I'm on idiot if I'm being one here, but I'd like to build the unit itself without any pads both on the input as well as on the output, just for flexibility's sake and patch in pads as needed. Perhaps it might be cool to use the STA as a mic preamp sometime or even drive a speaker. How would I best go about this? On the input, I reckon I can just assemble the pad as if it were actually inside the unit and patch it in at will, but how about the output? There the pot is 'part of the pad' so to speak, what would a pad have to look like that comes after the pot?

No. 3. Any recommendations on meters? I'm located in Berlin, Germany and the original Simpson meter is not easy to get here. And I've read conflicting opinions on using 'normal' VU meters in this circuit.

Thanks for bearing with my ignorance.. 

 

[Bowie]

I realise this thread has been resting for a while, but starting a new one probably wouldn't make sense either.

Anyway, I'm pretty much finished with stuffing/soldering my drip STA-Level PCB and have run into a few questions.

(disclaimer. I've built several preamps and comps before, but I'm mostly just good with a soldering iron and not making mistakes. My understanding of what I'm actually doing is rather limited and the fact that the drip forum isn't accessible anymore doesn't help)

No 1. How do I wire the Sowter output transformer? I assume the blue and grey wires go to the output pad as they're the only ones not marked on the PCB. If this is correct, which one is which for the unit to be in phase? (And on a side note, why do the brown and green wires go to the PCB if it's only about connecting them?)

No. 2. Somebody please tell me I'm on idiot if I'm being one here, but I'd like to build the unit itself without any pads both on the input as well as on the output, just for flexibility's sake and patch in pads as needed. Perhaps it might be cool to use the STA as a mic preamp sometime or even drive a speaker. How would I best go about this? On the input, I reckon I can just assemble the pad as if it were actually inside the unit and patch it in at will, but how about the output? There the pot is 'part of the pad' so to speak, what would a pad have to look like that comes after the pot?

No. 3. Any recommendations on meters? I'm located in Berlin, Germany and the original Simpson meter is not easy to get here. And I've read conflicting opinions on using 'normal' VU meters in this circuit.

Thanks for bearing with my ignorance.. 

Most of that info was available on the Drip Forum but it seems that even backdoor access has been nixed .  Fortunately, I saved a lot of info in my files and here's what I found;
"Sowter OT is wired out of phase (blue and grey) for some people."
"Sowter says grey wire is hot."
Take that for what you will.  I bypassed the pad and wired mine directly to the destination in the circuit so I can't tell you which goes where without pulling it apart.
Edit; I found this which Sowter sent me; https://www.dropbox.com/s/nqbvr9iof5hdttx/9185s.pdf?dl=0

  Regarding the meter, there's a place in the states that makes them but I'll be damned if I'm going to spend $125+shipping for  a meter so I picked up an NOS Wesson 200uaDC meter that looks just like the original for $25 on ebay.  Spent 30 cents to have this; https://www.dropbox.com/s/ldw55grwpvitowl/STALEVELMETER.jpg?dl=0  printed up, and it saved me over $100.  I tried to find the box to look up the model # but I don't know where I stashed it.  200uaDC meters with that housing show up on ebay every couple weeks or so.

The manual does not properly impress upon the reader that you can easily go wrong without proper padding on the unit.  Mine didn't work for 6 months because I followed a couple of the options in the manual.  In the end, I stripped off the input pad, used a Mallory T-600 instead of a PEC pot, and padded the output a little.  The output on these can drive a guitar amp so you really have to get it under control or you may be overdriving your A/D at only 15% on the output knob.  I don't recall what my output turned out to be (in terms of resistor values) but if you get a Mallory in there and need help, I'll open the case and check.  As is, I'm usually around 40 to 60% on the knob when tracking, less when mixing.
With no input pad, I can get 10dB reduction with the input knob around 40 to 60% open on most sources. 
Both those are very comfortable levels for me as I have a lot of room to play with in either direction.

Being that the input feeds the 6386 directly I don't know that you could make it a mic preamp without creating another stage.  Otherwise, you'd be a little out of control and implementing compression haphazardly.  With something like an LA-2A, you can adjust the compression separately, which is why those work as mic preamps.

Hope that helps.

 

[Beauvais]

Most of that info was available on the Drip Forum but it seems that even backdoor access has been nixed .  Fortunately, I saved a lot of info in my files and here's what I found;
"Sowter OT is wired out of phase (blue and grey) for some people."
"Sowter says grey wire is hot."
Take that for what you will.  I bypassed the pad and wired mine directly to the destination in the circuit so I can't tell you which goes where without pulling it apart.
Edit; I found this which Sowter sent me; https://www.dropbox.com/s/nqbvr9iof5hdttx/9185s.pdf?dl=0

  Regarding the meter, there's a place in the states that makes them but I'll be damned if I'm going to spend $125+shipping for  a meter so I picked up an NOS Wesson 200uaDC meter that looks just like the original for $25 on ebay.  Spent 30 cents to have this; https://www.dropbox.com/s/ldw55grwpvitowl/STALEVELMETER.jpg?dl=0  printed up, and it saved me over $100.  I tried to find the box to look up the model # but I don't know where I stashed it.  200uaDC meters with that housing show up on ebay every couple weeks or so.

The manual does not properly impress upon the reader that you can easily go wrong without proper padding on the unit.  Mine didn't work for 6 months because I followed a couple of the options in the manual.  In the end, I stripped off the input pad, used a Mallory T-600 instead of a PEC pot, and padded the output a little.  The output on these can drive a guitar amp so you really have to get it under control or you may be overdriving your A/D at only 15% on the output knob.  I don't recall what my output turned out to be (in terms of resistor values) but if you get a Mallory in there and need help, I'll open the case and check.  As is, I'm usually around 40 to 60% on the knob when tracking, less when mixing.
With no input pad, I can get 10dB reduction with the input knob around 40 to 60% open on most sources. 
Both those are very comfortable levels for me as I have a lot of room to play with in either direction.

Being that the input feeds the 6386 directly I don't know that you could make it a mic preamp without creating another stage.  Otherwise, you'd be a little out of control and implementing compression haphazardly.  With something like an LA-2A, you can adjust the compression separately, which is why those work as mic preamps.

Hope that helps.

Thanks, that does help! Also the pdf for the Sowter is fantastic, just what I needed. Now the only question is whether I should go with 150 or 600 ohms output impedance..

And yes, these new meters are not only expensive, their website is also a bloody mess. I actually did score a vintage Simpson Model 27 200uA meter on ebay, but after almost four months of that thing crossing the atlantic twice and countless emails with the seller, calls to the German postal service, customs and what not, when the box finally got here there was some type of Simpson meter in it which is neither electrically nor physically compatible. That's why I'm kind of inclined towards a 'proper' store preferably within the EU. But I guess I'll try my luck again on ebay..

Regarding the pads. I think I'll install the output pad as it is intended in the original schematic. After all I don't have anything that could handle the unpadded output really. However the idea of leaving the input unpadded and patch in 10dB or 20dB pads as needed is still rather appealing to me and I don't see how that would affect the circuit? Of course when putting a mic into it, there will be compression happening and whether or not thus makes sense depends on the situation I guess. I was just thinking that a STA-level has so much gain, why not make (optionally) useable by 'outsourcing' the input pad.

 

[Backlash]

Just a quick notice. Don-audio in Germany has the Simpson model 27 meter here: https://www.don-audio.com/Vintage-Audio-Level-VU-Meter-VM-S27-Simpson-Model-27-47

/peter

 

[Beauvais]

Ah cool. But ouch, that's a lot of money. Plus it's specified as a VU meter.

And ebay is full of Simpson Model 27 meters for usually around 25 bucks (shipping across the pond is about 25$ as well). When it comes to those vintage meters, what do I need to look at? I suppose a 0-75 DC mA type is the exact same thing as a 0-100 DC mA type with a different scale, no? How different is a DC volt type? Does it matter at all (the one don-audio is carrying is labeled as suited for a STA-level despite being labelled as VU)? Again, pardon my ignorance.

 

[bsconz]

This thread has been more than useful. Thank you to Majestic12 and everyone who has contributed information to this topic.

I'm at the final assembly stages of my Sta-Level build but I'm having a hard time deciding how to terminate  the 3 ground wires from the PCB. There's 1 at the far left with only ground symbol marking and 2 on the far right, 1 labelled audio ground and 1 labelled power ground. Just curious how others dealt with this. I'm sort of making sure not to cause a ground loop situation.

Any suggestions?!

Happy Holidays as well...if you're reading this now then I know you are a true nerd like me...2 days before Christmas and all I can think about is getting this Sta-Level completed!